Secrets – Pediatric: Cardiology

Secrets – Pediatric: Cardiology

CLINICAL ISSUES
1. Is cardiac pathology the most common cause of chest pain in children?
A cardiac cause of chest pain is very uncommon and represents less than 1% of cases in a published series. The most common identifiable causes involve musculoskeletal pain (e.g., strained intercostal muscles, costochondritis, Tietze syndrome, precordial catch syndrome), which occurs in one-quarter
to one-half of cases. Other causes are pulmonary disease (e.g., asthma, cough illness, pneumonia, pleurisy), gastrointestinal disease (e.g., reflux, esophagitis, gastroenteritis), and miscellaneous diseases (e.g., sickle cell crisis, herpes zoster). Other possibilities include psychogenic (e.g., anxiety, hyperventilation/disordered breathing) and the always present idiopathic diseases (which may represent the largest category).

Collins SA, Griksaitis MJ, Legg JP: 15-minute consultation: a structured approach to the assessment of chest pain in a child, Arch Dis Child Educ Pract Ed 99:122–126, 2014.

2. What is the clinical distinction between costochondritis and Tietze syndrome? Costochondritis involves sharp, anterior chest wall pain that emanates from multiple costochondral and costosternal junctions. Causes can be inflammatory; post-traumatic; or, less commonly, infectious (including bacterial or fungal). Because the costal cartilage is avascular, it is susceptible to infection following surgery or trauma. This can be delayed and insidious in presentation. Palpation and percussion over the affected areas typically reproduce the pain. Swelling is not a prominent feature.
Tietze syndrome is a localized form of costochondritis, usually involving just one costochondral junction (typically the second or third costochondral junction). A tender, swollen (but not hot) 1- to 4-cm mass is frequently palpable at the site. Onset is more commonly related to trauma.

3. What are potential red flags that increase the likelihood of a cardiac cause for chest pain?
• Personal history of acquired or congenital cardiac disease
• Exertional syncope
• Exertional cardiac-type chest pain (e.g., centrally located with radiation to left arm/jaw, crushing pain or heaviness)
• Hypercoagulable or hypercholesterolemic state
• Family history of sudden death <35 years, young-onset ischemic heart disease, inherited arrhythmias (such as long QT syndrome)
• Connective tissue disorders
• History of cocaine/amphetamine use

Collins SA, Griksaitis MJ, Legg JP: 15-minute consultation: a structured approach to the assessment of chest pain in a child, Arch Dis Child Educ Pract Ed 99:123, 2014.

4. A child with sharp, stabbing, very localized chest pain that occurs at rest and resolves completely without associated symptoms after 1 minute likely has what condition?
Precordial catch syndrome, also called Texidor twinge after the original 1955 describer, may be an underappreciated phenomenon in children with characteristic features that often prompt extensive and unproductive diagnostic workups. It manifests as a sudden-onset chest pain in children, very localized (patient points to area with one or two fingers), which occurs most commonly over the left sternal border, right anterior chest, or flanks with variation of site from episode to episode. The pain occurs typically at rest without provocation, is exacerbated by deep breaths (so the patient breathes very
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shallowly), and usually lasts 30 seconds to 3 minutes. Unlike cardiac, pulmonary, gastrointestinal, or chest wall causes, there is a paucity of associated symptoms (e.g., no palpitations, pallor, flushing, fever, tenderness, or near-syncope). Physical examination, when done during the episode, is normal. The cause is unknown. Pain may originate from the parietal pleura or chest wall (e.g., rib or cartilage), but is not cardiac or pericardial in origin. Ancillary testing, when done, is normal. Management is expectant with reassurance.

Gumbiner CH: Precordial catch syndrome, South Med J 96:38–41, 2003.

5. What is the significance of mitral valve prolapse (MVP)?
MVP occurs when one or both mitral valve leaflets billow excessively into the left atrium near the end of systole. Some studies show that up to 13% of normal children have some degree of posterior leaflet prolapse on echocardiography. There is a spectrum of anatomic abnormalities, the most minor of which are variations of normal. Children with clinical features of mitral valve insufficiency
constitute the pathologic category. Whenever auscultation reveals the classic findings of MVP, referral to a pediatric cardiologist is recommended. This allows for evaluation of the child for possible accompanying cardiac abnormalities (e.g., mitral insufficiency, secundum atrial septal defects)
and confirmation of the diagnosis.

6. What connective tissue diseases may be associated with MVP?
Marfan syndrome, Ehlers-Danlos syndrome, pseudoxanthoma elasticum, osteogenesis imperfecta, and Hurler syndrome may be associated with MVP.

7. What are the common types of vascular rings and slings?
Vascular rings occur when the trachea and/or the esophagus is encircled by aberrant vascular structures. Vascular slings are compressions (typically anterior) that are caused by nonencircling aberrant vessels (Table 3-1).

Table 3-1. Vascular Rings and Slings
FREQUENCY (%) SYMPTOMS TREATMENT
“Complete” Rings
Double aortic arch 50 Respiratory difficulty, Surgical division of a
worsened by feeding smaller arch (usually
or exertion (onset the left)
<3 mo)
Right aortic arch with left ligamentum arteriosum 45 Mild respiratory difficulty Surgical division of
(onset later in ligamentum arteriosum infancy); swallowing
dysfunction
“Incomplete” Rings
Anomalous innominate artery <5 Stridor and/or cough in Conservative management infancy or surgical suturing of
artery to the sternum
Aberrant right subclavian artery <5 Occasional swallowing Usually no treatment dysfunction necessary
Vascular sling or anomalous left pulmonary artery Rare Wheezing and cyanotic Surgical division of episodes during first anomalous left pulmonary weeks of life artery and anastomosis to
the main pulmonary artery; may also need tracheal reconstruction
Adapted from Park MK: Pediatric Cardiology for Practitioners, ed 5. St. Louis, 2008, Mosby ELSEVIER, p 578.

8. What evaluations are commonly done if a vascular ring is suspected?
• Chest radiograph: For detection of possible right-sided aortic arch
• Barium esophagram: Previously considered the gold standard for diagnosis (before magnetic resonance imaging); confirms external indentation of esophagus in up to 95% of cases (Fig. 3-1)
• Magnetic resonance imaging (MRI): Noninvasive and now used as the primary diagnostic modality
• Arteriogram: Precise delineation of vascular anatomy; rarely needed because of MRI
• Echocardiogram: Should not be relied on for identifying the ring itself, but important when evaluating for other congenital heart lesions that can occur in patients with vascular rings

Figure 3-1. Barium swallow in a toddler with posterior compression of the esophagus and trachea from a vascular ring. (From Zitelli BJ, DAVIS HW: Atlas of Pediatric Physical Diagnosis, ed 4. St. Louis, Mosby, 2002, p 540.)

9. Describe four categories of cardiomyopathy in children
• Dilated cardiomyopathy is the most common. Etiology is usually unknown. Anatomically, the heart is normal, but both ventricles are dilated. Older children exhibit symptoms of congestive heart failure (CHF). Infants demonstrate poor weight gain, feeding difficulty, and respiratory distress. In all pediatric age groups, a more acute presenting symptom can be shock.
• Hypertrophic cardiomyopathy with left ventricular (LV) outflow obstruction is also known as idiopathic hypertrophic subaortic stenosis and asymmetric septal hypertrophy. Of patients with this condition, most have some degree of LV outflow tract obstruction as a result of abnormal hypertrophy of the subaortic region of the intraventricular septum. Most of these defects are inherited in an autosomal dominant fashion.
• Hypertrophic cardiomyopathy without LV outflow obstruction is also usually of unknown etiology. It may be associated with systemic metabolic disease, particularly a storage disease. Cardiomegaly is a constant feature.
• Restrictive cardiomyopathy is associated with abnormal diastolic function of the ventricles. The ventricles may be of normal size, or they may be hypertrophied with normal systolic function. The atria are typically enlarged. The etiology is usually unknown but restrictive cardiomyopathy may be seen with storage diseases.

Pettersen MD: Cardiomyopathies encountered commonly in the teenage years and their presentation, Pediatr Clin North Am 61:173–186, 2014.
Watkins H, Ashrafian H, Redwood C: Inherited cardiomyopathies, N Engl J Med 364:1643–1656, 2011.

10. What mineral is added to hyperalimentation fluids to prevent a potential cardiomyopathy?
Selenium is routinely added to hyperalimentation fluids to prevent selenium deficiency, which can be a cause of both skeletal weakness and cardiomyopathy. This “acquired” heart disease has been described in patients on long-term hyperalimentation (before modern hyperalimentation); patients with acquired immunodeficiency syndrome (AIDS), chronic diarrhea, and wasting disease. It has also been described in children living in the Keshan province of China, where the soil is naturally low in selenium. It is typically reversible with the addition of selenium to the diet or intravenous fluids.

11. What are the cardiac causes of sudden cardiac death in children and adolescents? Sudden death occurs because of ventricular fibrillation in the setting of myocardial or coronary abnormalities or underlying primary rhythm disorders. The main structural causes are hypertrophic cardiomyopathy (particularly with extreme LV hypertrophy), anomalies of the coronary artery (congenital or acquired), Marfan syndrome, and arrhythmogenic right ventricular (RV) dysplasia. Children with CHD (e.g., severe aortic stenosis, Ebstein anomaly) are at higher risk for sudden death. ECG abnormalities which can lead to sudden death include Wolff Parkinson White (WPW) syndrome, prolonged QT syndrome, AV block and Brugada syndrome.

Rowland T: Sudden unexpected death in young athletes: reconsidering “hypertrophic cardiomyopathy,” Pediatrics
123:1217–1222, 2009.

12. What historical features may identify the patient who is at risk for sudden death?
• Sudden death may be associated with previous symptoms of exertional chest discomfort; dizziness; or prolonged dyspnea with exercise, syncope, and palpitations.
• A family history of premature cardiovascular disease (<50 years), hypertrophic or dilated cardiomyopathy, Marfan syndrome, long QT syndrome, other clinically significant arrhythmias or sudden death may be elicited.
• Previous recognition of a heart murmur or elevated systemic blood pressure are significant findings.

Mahmood S, Lim L, Akram Y, et al: Screening for sudden cardiac death before participation in high school and collegiate sports, Am J PREV Med 45:130–133, 2013.

13. What features in the preparticipation sports physical examination identify patients at risk for sudden death?
• Marfanoid features: Tall and thin habitus, hyperextensible joints, pectus excavatum, click and murmur suggestive of MVP
• Pathologic murmurs (any systolic murmur grade 3/6 or greater, any diastolic murmur)
• Weak or delayed femoral pulses
• Arrhythmia: Rapid or irregular heartbeat

Singh A, Silberbach M: Cardiovascular preparticipation sports screening, Pediatr REV 27:418–423, 2006.

14. Should an electrocardiogram (ECG) be included in the preparticipation screening of young athletes? This remains a hotly debated topic. The potential value is that an ECG could identify at-risk athletes with hypertrophic cardiomyopathy, severe cardiac hypertrophy, arrhythmogenic RV cardiomyopathy, WPW, AV block and long QT syndrome. Proponents argue that the use of history and physical examination alone is not decreasing the rate of sudden cardiac death. Some even call for universal screening of all children. Opponents argue that sudden cardiac death is a rare event and that the ECG is an inexact screening tool because of the overlap between normal and abnormal tracings. The European Society of Cardiology recommends ECG screening, but the American Heart Association, as of 2014, has not endorsed ECG use as part of the preparticipation process.

Friedman RA: Electrocardiographic screening should not be implemented for children and adolescents between ages 1 and 19 in the United States, Circulation 130:698–702, 2014.
Vetter VL: Electrocardiographic screening of all infants, children and teenagers should be performed, Circulation 130: 688–697, 2014.

15. Name five disorders in which a screening ECG might identify a subject at risk for sudden death
• Wolf-Parkinson-White syndrome: short PR, delta wave, T wave abnormalities leading to supraventricular tachycardia and ventricular fibrillation
• Prolonged QT syndrome: Secondary to congenital channelopathy, electrolyte or drug-induced abnormality leading to ventricular tachycardia and torsades de pointes
• Brugada syndrome: Right ventricular conduction delay with profound ST elevation in V1-V3 leading to ventricular fibrillation
• Hypertrophic cardiomyopathy
• AV block

16. What is the likely diagnosis in a 10-year-old little leaguer who develops sudden cardiac arrest after being struck in the chest by a batted baseball? Commotio cordis. This is a life-threatening arrhythmia that occurs as a result of a blunt, nonpenetrating direct blow to the chest. The precordial force is often only low or moderate and typically not associated with structural injury. Ventricular fibrillation is thought to occur when impact is applied during the vulnerable phase of repolarization, which occurs 30 to 15 milliseconds before the peak of the T wave. Prompt cardiopulmonary resuscitation followed by defibrillation improves the chance of survival.

Maron BJ, Estes NAM III: Commotio cordis, N Engl J Med 362:917–927, 2010.

17. In which patients is syncope more likely to be of a cardiac nature?
• Sudden onset without any prodromal period of dizziness or imminent awareness
• Syncope during exercise or exertion
• History of palpitations or abnormal heartbeat before fainting
• Syncope leading to a fall which results in an injury
• Family history of sudden death

18. What arrhythmias may be associated with syncope?
See Table 3-2.

Table 3-2. Syncope

DIAGNOSIS HISTORY AND PHYSICAL EXAMINATION ELECTROCARDIOGRAPHIC FINDINGS
WPW Family history of WPW, known hypertrophic cardiomyopathy, or Ebstein anomaly Short PR interval, presence of delta waves
Prolonged QT syndrome Family history of prolonged QT, sudden death, and/or deafness Borderline QTc ¼ 440–460 msec
Prolonged QTc ¼ > 460 msec
Atrioventricular block Myocarditis, Lyme disease, acute rheumatic fever, maternal history of lupus First-, second-, or third-degree heart block
Arrhythmogenic right ventricular dysplasia Syncope, palpitations, positive family history PVCs, ventricular tachycardia, left bundle branch block
Ventricular tachycardia Most ventricular tachycardia occurs in abnormal hearts; requires extensive evaluation Ventricular tachycardia
PVCs Premature ventricular contractions; QTc corrected QT interval; WPW Wolff-Parkinson-White syndrome.
From Feinberg AN, LANE-DAVIES A: Syncope in the adolescent, Adolesc Med 13:553–567, 2002.

KEY POINTS: SYNCOPE MORE LIKELY TO BE OF A CARDIAC NATURE
1. Occurring during exercise
2. Sudden onset without prodromal symptoms or awareness
3. Complete loss of tone or awareness leading to injury
4. Palpitations or abnormal heartbeat noted before event
5. Abnormal heart rate (fast or slow) after event
6. Family history of sudden death

19. What are the most common clinical signs of coarctation of the aorta (Fig. 3-2) in older children?
• Differential blood pressure: arms> legs (100%)
• Systolic murmur or bruit in the back (96%)
• Systolic hypertension in the upper extremities (96%)
• Diminished or absent femoral or lower-extremity pulses (92%)

Ing FF, Starc TJ, Griffiths SP, Gersony WM: Early diagnosis of coarctation of the aorta in children: a continuing dilemma,
Pediatrics 98:378–382, 1996.

Figure 3-2. Magnetic resonance imaging of coarctation of the aorta. (From Clark DA: Atlas of Neonatology. Philadelphia, 2000, WB Saunders, p 119.)

20. How much does peak exercise affect cardiac output? Cardiac output is calculated by the formula: Cardiac output Heart rate x Stroke VOLUME. Cardiac output at peak exercise will increase up to approximately 5 times the baseline value. In upright exercise, stroke volume increases early in exercise by 1½ to 2 times baseline values, but then plateaus at that level. Heart rate will also increase early in exercise, but will continue to rise up to the maximum predicted value of about 200 beats/minute at peak exercise.
21. What cardiac lesions can lead to thrombosis and stroke?
• Arrhythmias: chronic atrial fibrillation, atrial flutter
• Cardiomyopathies: decreased cardiac function is associated with increased risk for thrombus formation; therefore, many of these patients are on aspirin or warfarin.
• Mechanical valves: These patients require lifelong anticoagulation.
• Patients with Fontan circulation are at increased risk for thrombosis.
• Patients with systemic-to-pulmonary shunts, such as Blalock-Taussig shunts, are at risk for shunt thrombosis.
• Patients with Kawasaki disease with coronary aneurysms are at risk for thrombosis in the coronary arteries.

22. What are two of the more common neuromuscular diseases in which a cardiac consultation is routinely recommended?
• Duchenne muscular dystrophy is an X-recessive disease with an abnormality in the dystrophin gene, which leads to muscle necrosis and fibrosis. Although the majority of deaths are due to respiratory insufficiency, death from cardiomyopathy can occur in up to 25% of patients. Symptoms of heart disease are typically hidden by the skeletal myopathy that masks any exercise-induced complaints such as shortness of breath with exertion. Therefore, screening echocardiograms and ECGs are recommended for long-term follow-up.
• Friedrich ataxia is an autosomal recessive disorder involving a gene encoding frataxin, a mitochondrial protein. Symptoms include ataxia and muscle weakness, typically manifesting by 9 years of age. Cardiac abnormalities include both dilated and concentric cardiomyopathies. Atrial fibrillation and atrial flutter are commonly reported arrhythmias. Because muscle weakness and ataxia will prevent prolonged exertion, periodic echocardiograms and ECGs are recommended.

23. Why are chemotherapeutic agents that use arsenic of cardiac concern? Arsenic may cause prolonged QT and lead to torsades de pointes and ventricular fibrillation. Periodic ECG monitoring is recommended in these patients.

CONGENITAL HEART DISEASE
24. What prenatal maternal factors may be associated with cardiac disease in the neonate?
See Table 3-3.

Table 3-3. Prenatal Maternal Factors Associated With Cardiac Disease in Neonates
PRENATAL HISTORICAL FACTOR
ASSOCIATED CARDIAC DEFECT
Diabetes mellitus Left ventricular outflow obstruction (asymmetric septal hypertrophy, aortic stenosis), D-transposition of great arteries, ventricular septal defect
Lupus erythematosus Heart block, pericarditis, endomyocardial fibrosis
Rubella Patent ductus arteriosus, pulmonic stenosis (peripheral)
Alcohol use Pulmonic stenosis, ventricular septal defect
Aspirin use Persistent pulmonary hypertension syndrome
Lithium Ebstein anomaly
Diphenylhydantoin Aortic stenosis, pulmonary stenosis
Coxsackie B infection Myocarditis
From Gewitz MH: Cardiac disease in the newborn infant. In Polin RA, Yoder MC, Burg FD, editors: Workbook in Practical Neonatology, ed 3. Philadelphia, 2001, WB Saunders, p 269.

25. In a cyanotic newborn, what test can help distinguish pulmonary disease from cyanotic congenital heart disease (CHD)? Hyperoxia test. The infant is placed on 100% oxygen, and an arterial blood gas level is obtained. A PaO2 of greater than 100 mm Hg is usually achieved in infants with primary lung disease, whereas a PaO2 of less than 100 mm Hg is characteristic of heart disease. Typically, children with cyanotic heart disease also have a low or normal PCO2, whereas children with lung disease have an elevated PCO2. However, the hyperoxia test does not usually distinguish children with cyanotic heart disease from those with persistent pulmonary hypertension.

26. Which congenital heart lesions commonly appear with cyanosis during the newborn period?
Independent pulmonary and systemic circulations (severe cyanosis)
• Transposition of great arteries with an intact ventricular septum
Inadequate pulmonary blood flow (severe cyanosis)
• Tricuspid valve atresia
• Pulmonary valve atresia with intact ventricular septum
• Tetralogy of Fallot
• Severe Ebstein anomaly of the tricuspid valve
Admixture lesions (moderate cyanosis)
• Total anomalous pulmonary venous return
• Hypoplastic left heart syndrome (HLHS)
• Truncus arteriosus

Victoria BE: Cyanotic newborns. In Gessner IH, Victoria BE, editors: Pediatric Cardiology: A Problem Oriented Approach. Philadelphia, 1993, WB Saunders, p 101.

KEY POINTS: CARDIAC CAUSES OF CYANOSIS IN THE NEWBORN
1. Transposition of the great arteries
2. Tetralogy of Fallot
3. Truncus arteriosus
4. Pulmonary atresia
5. Total anomalous pulmonary venous return
6. Tricuspid atresia
7. Hypoplastic left heart

27. In the patient with suspected heart disease, what bony abnormalities seen on a chest radiograph increase the likelihood of CHD?
• Hemivertebrae, rib anomalies: Associated with tetralogy of Fallot, truncus arteriosus, and VACTERL syndrome (vertebral abnormalities, anal atresia, cardiac abnormalities, tracheoesophageal fistula and/or esophageal atresia, renal agenesis and dysplasia, and limb defects)
• 11 pairs of ribs: Seen in patients with Down syndrome
• Skeletal chest deformities (e.g., scoliosis, pectus excavatum, narrow anterior-posterior diameter): Associated with Marfan syndrome and mitral valve prolapse
• Bilateral rib notching: Coarctation of the aorta (seen in older children)
28. How do pulmonary vascular markings on a chest radiograph help in the differential diagnosis of a cyanotic newborn with suspected cardiac disease? The chest radiograph may help differentiate the types of congenital heart defects. An increase or decrease in pulmonary vascular markings is indicative of the amount of pulmonary blood flow:
Decreased pulmonary markings (diminished pulmonary blood flow)
• Pulmonary atresia or severe stenosis
• Tetralogy of Fallot
• Tricuspid atresia
• Ebstein anomaly
Increased pulmonary markings (increased pulmonary blood flow)
• Transposition of great arteries
• Total anomalous pulmonary venous return
• Truncus arteriosus
29. What ECG findings suggest specific congenital heart conditions?
• Left axis deviation: Endocardial cushion defects (both complete atrioventricular [AV] canal and ostium primum atrial septal defects), tricuspid atresia
• WPW syndrome: Ebstein anomaly, L-transposition of the great arteries (L-TGA)
• Complete heart block: L-TGA, polysplenia syndrome, maternal lupus

30. What chest radiograph findings (Fig. 3-3) are considered characteristic for various CHDs?
• Boot-shaped heart: Tetralogy of Fallot
• Egg-shaped heart: Transposition of great arteries
• Snowman silhouette: Total anomalous pulmonary venous return (supracardiac)
• Rib notching: Coarctation of the aorta (older children)

A

Figure 3-3. Abnormal cardiac silhouettes. A, “Boot-shaped” heart seen in cyanotic tetralogy of Fallot or tricuspid atresia. B, “Egg-shaped” heart seen in transposition of the great arteries. C, “Snowman” silhouette seen in total anomalous pulmonary artery venous return (supracardiac type). (From Park MK: Pediatric Cardiology for Practitioners, ed 5.
Philadelphia, Mosby ELSEVIER, 2008, p 68.)

31. What are the common ductal-dependent cardiac lesions?
Ductal-dependent pulmonary blood flow
• Critical pulmonary valve stenosis
• Pulmonary atresia
• Tetralogy of Fallot with severe pulmonary stenosis
• Tricuspid atresia with pulmonary stenosis or pulmonary atresia
Ductal-dependent systemic blood flow
• Coarctation of the aorta
• HLHS
• Interrupted aortic arch

32. What types of CHDs are associated with the right aortic arch?
• Tetralogy of Fallot with pulmonary atresia (50%)
• Truncus arteriosus (35%)
• Classic tetralogy of Fallot (25%)
• Double-outlet right ventricle (25%)
• Single ventricle (12.5%)

Crowley JJ, Oh KS, Newman B, et al: Telltale signs of congenital heart disease, Radiol Clin North Am
31:573–582, 1993.

33. Name 5 different types of left ventricular outflow tract stenosis
• Aortic valve stenosis (more common in males)
• Supravalvular aortic stenosis (Williams syndrome)
• Subvalvular aortic stenosis due to a subaortic membrane
• Subvalvular aortic stenosis due to hypertrophic obstructive cardiomyopathy
• Subvalvular aortic stenosis due to fibromuscular tunnel

34. Which genetic syndromes are most commonly associated with CHD?
See Table 3-4.

Table 3-4. Genetic Syndromes Associated with Congenital Heart Disease

SYNDROME PERCENTAGE OF PATIENTS WITH CHD PREDOMINANT HEART DEFECTS
Down 50 ECD, VSD, TOF
Turner 20 COA
Noonan 65 PS, ASD, ASH
Marfan 60 MVP, AoAn, AR
Trisomy 18 90 VSD, PDA
Trisomy 13 80 VSD, PDA
DiGeorge 80 IAA-B, TA
Williams 75 SVAS, peripheral PS
AoAn Aortic aneurysm; AR aortic regurgitation; ASD atrial sepal defect; ASH asymmetric septal hypertrophy; CHD congenital heart disease; COA coarctation of the aorta; ECD endocardial cushion defect; IAA-B interrupted aortic arch type B; MVP mitral valve prolapse; PDA patent ductus arteriosus; PS pulmonary stenosis;
SVAS supravalvular aortic stenosis; TA truncus arteriosus; TOF tetralogy of Fallot; VSD ventricular septal defect. From Frias JL: Genetic issues of congenital heart defects. In Gessner IH, Victoria BE, editors: Pediatric Cardiology: A Problem Oriented Approach. Philadelphia, 1993, WB Saunders, p 238.

35. Which infants with CHD should be evaluated for other anomalies? In the evaluation of the newborn with heart disease, several known associations between CHD and other anomalies should be considered, especially for the patient with more complex disease. Syndromes such as CHARGE (coloboma, heart disease, choanal atresia, retarded growth and development or central nervous system anomalies, genital hypoplasia, ear anomalies and/or deafness) or VACTERL may first be identified by the presence of heart disease. An association between conotruncal defects (tetralogy of Fallot, truncus arteriosus, and interrupted aortic arch) and deletions on chromosome 22 is often seen. Some of these patients may have DiGeorge syndrome or velocardiofacial syndrome, but others may have only minimal palatal dysfunction. For this reason, patients with conotruncal cardiac defects should undergo screening for deletions on chromosome 22; if these are found, these patients should be referred to a geneticist for special testing and evaluation.

36. Describe the clinical manifestations of a large patent ductus arteriosus (PDA)
• Tachypnea and tachycardia
• Bounding pulses
• Hyperdynamic precordium
• Wide pulse pressure
• Continuous murmur (older child)
• Systolic murmur (premature infant)
• Labile oxygenation (premature infant)
• Apnea (premature infant)

37. How commonly do PDAs occur in premature infants?
They are evident in 40% to 60% of infants with birth weights of 501 to 1500 g.

38. Is a “to-and-fro” murmur a good description for the heart murmur of a PDA? No. The heart murmur of a typical PDA is usually continuous or at least “spills from systole into diastole.” In a small preterm infant, the diastolic portion may be difficult to discern. The direction of blood flow is from the aorta to the pulmonary artery in systole and continues from the aorta to the pulmonary artery during diastole. A to-and-fro murmur describes blood flow in semilunar valvular lesions such as the combination of aortic stenosis with aortic insufficiency or pulmonary stenosis with pulmonary insufficiency. The blood flow in these examples goes “antegrade” during systole and “retrograde” during diastole. This back and forth flow is aptly described as to-and-fro.

39. How can you explain a PaO2 of more than 400 mm Hg in a blood sample from an umbilical catheter in a newborn with transposition of the great arteries?
A very elevated PaO2 can be observed if the umbilical vein catheter has passed from the inferior vena cava to the right atrium and into the left atrium. The PO2 in the left atrium represents the pulmonary venous oxygenation and not the arterial oxygen level. In cyanotic heart disease, the alveolar and pulmonary vein PO2 values are usually normal. It is the arterial oxygenation concentration that is severely diminished in children with cyanotic heart disease.
40. How do the presenting symptoms of ventricular septal defect (VSD) and atrial septal defect (ASD) differ?
VSD: In an infant with a large VSD, signs of CHF generally appear at 4 to 8 weeks of age, when the pulmonary vascular resistance drops and pulmonary blood flow increases. CHF is due to a large left-to-right shunt and increased pulmonary blood flow and may be associated with failure
to thrive or recurrent respiratory infections. The child with a small VSD may have a systolic murmur during the first few weeks of life. These infants do not develop CHF, and spontaneous closure
often occurs.
ASD: Most children with an isolated ASD are not clinically diagnosed until they are 3 to 5 years old. Most are asymptomatic at the time of diagnosis. Rarely, infants with an ASD demonstrate signs of CHF during the first year of life.
41. What is the primary concern of the pediatric cardiologist if a child with a large VSD is lost to follow-up and comes back after 2 years of age?
Although even large VSDs may close spontaneously in childhood, the child with a large VSD can develop irreversible pulmonary vascular disease as a sequela of the long-term increased pulmonary blood flow and pulmonary hypertension (Eisenmenger syndrome). This complication is usually preventable if the VSD is closed before 18 to 24 months of age.
42. What are some of the common presenting symptoms in older children with primary pulmonary hypertension?
In the early stages of the disease, children are asymptomatic at rest. Children with primary pulmonary hypertension may present with symptoms such as fatigue, dyspnea, chronic cough and shortness of breath with exercise. They may also present with chest pain, syncope, and atypical seizures. These symptoms are easily confused with other chronic diseases such as asthma, recurrent pneumonia, or a seizure disorder.

Nicolarsen J, Ivy D: Progress in the diagnosis and management of pulmonary hypertension in children, Curr Opin Pediatr
26:527–535, 2014.

43. What examination features are suggestive of pulmonary hypertension?
Physical examination may reveal a RV heave or lift suggestive of RV hypertrophy. The pulmonary component of the second heart sound is usually loud. There may be a 1-2/6 diastolic decrescendo murmur of pulmonary insufficiency at the left upper sternal border and a 1-2/6 holosystolic murmur of tricuspid insufficiency at the left lower sternal border. Eventually, signs of right heart failure with peripheral edema, neck vein distention, ascites, and hepatomegaly may develop.
44. What is the anomaly in Ebstein anomaly? The septal and posterior leaflets of the tricuspid valve are thickened and displaced inferiorly into the right ventricle. In its most severe form, the tricuspid valve is severely incompetent, profound right atrial enlargement results, and signs of CHF predominate.
45. What are the four structural abnormalities of tetralogy of Fallot?
• Pulmonary stenosis with RV outflow tract obstruction
• VSD
• Aorta overriding the VSD
• RV hypertrophy
46. What occurs during a “Tet spell”? Tet spells are hyper cyanotic episodes that occur in patients with tetralogy of Fallot. The pathophysiology is thought to be related to a change in the balance of systemic-to-pulmonary vascular resistance. Spells

may be initiated by events that cause a decrease in systemic vascular resistance (e.g., fever, crying, hypotension) or by events that cause an increase in pulmonary outflow tract obstruction. Both types of events lead to more right-to-left shunting and increased cyanosis. Hypoxia and cyanosis can result in metabolic acidosis and systemic vasodilation, which cause a further increase in cyanosis. Anemia may be a predisposing factor. Although most episodes are self-limited, a prolonged Tet spell can lead to stroke or death; therefore, a spell is an indication for surgery.

47. Name two conditions in which the murmur has disappeared or diminished in intensity and yet the patient is actually worse
Tetralogy of Fallot. The systolic heart murmur represents blood flow across the narrow RV outflow tract. With worsening RV outflow tract obstruction or during a cyanotic spell, less blood crosses the valve, and the heart murmur consequently diminishes and may actually disappear completely.
VSD with Eisenmenger syndrome. The left-to-right shunt across the VSD diminishes because of the increase in pulmonary vascular resistance. The heart murmur lessens and may disappear. A “honeymoon period” with no shunting is then followed by the progression of increased right-to-left shunting and cyanosis. The pulmonary component of the second heart sound begins to increase in intensity, and visible cyanosis and clubbing of the nail beds are
often seen.

48. After what age does a presumed peripheral pulmonic branch stenosis murmur deserve more detailed study?
The murmur of peripheral pulmonic branch stenosis—a low-intensity systolic ejection murmur heard frequently in newborns—is the result of the relative hypoplasia of the pulmonary arteries as well as the acute angle of the branching of pulmonary arteries in the early newborn period. A murmur which persists beyond 6 months of age should be investigated.

49. What is the role of pulse oximetry in screening for complex congenital heart disease (CCHD) in asymptomatic infants in the newborn nursery?
Of the approximate 1 in 100 children born with congenital heart disease, 25% will have CCHD, defined as a condition that requires surgical or catheter intervention in the first year of life. When the diagnosis is delayed, there can be a significant impact on morbidity and mortality. These delays can occur because of limitations in the value of the physical exam (particularly in those lesions without distinct murmurs), difficulty in identifying cyanosis in anemic or dark-pigmented neonates, and early hospital discharge for ductal-dependent lesions when the ductus arteriosus has not yet closed. Discharged infants may later present in extremis with sudden and profound clinical worsening, including shock, due to changes in pulmonary vascular resistance and ductal closure. Universal pulse oximetry screening of newborns, ideally done after 24 hours, is now recommended by the AAP as a means of identifying infants with CCHD before leaving the nursery. The rationale is based on the fact that hypoxemia is present to some degree in the majority of cases of CCHD. The screen is felt to have a sensitivity of 60% to 70% for CCHD, so a normal screen does not rule out heart disease.

Thangaratinam S, Brown K, Zamora J, et al: Pulse oximetry screening for critical congenital heart defects in asymptomatic newborn babies: a systemic review and meta-analysis, Lancet 379:2459–2464, 2012.

50. What is the AAP screening protocol for CCHD using pulse oximetry?
Oxygen saturation is measured in the right hand and either foot. The screen is failed if oxygen level is <90% in either limb. If oxygen saturation is > 90% and <95% in both limbs or there is
>3% difference between the hand and foot, repeat testing should be done in 1 hour. If persistent, the
screen is failed. For a failed screen, cardiology consultation is recommended and an echocardiography is
generally indicated.

Mahle WT, Martin GR, Beekman RH III, et al: Endorsement of Health and Human Services recommendation for pulse oximetry screening for critical congenital heart disease, Pediatrics 129:190–192, 2012.
Kemper AR, Mahle WT, Martin GR, et al: Strategies for implementing screening for critical congenital heart disease,
Pediatrics 128:e1259–e1267, 2011.

51. Which ductal-dependent lesions are the AAP’s primary targets for screening with the use of pulse oximetry?
HLHS, pulmonary atresia, tetralogy of Fallot, total anomalous pulmonary venous return, transposition of the great arteries, and truncus arteriosus are the primary targets for screening with pulse oximetry.

52. What should parents be told about the risk for recurrence of common heart defects? The risk for CHD in pregnancies after the birth of one affected child is about 1% to 4%. With two affected first-degree relatives, the risk is about 10%. With three affected children, the family may be considered at even higher risk.

Congenital Heart Information Network: www.tchin.org. Accessed on Jan. 6, 2015.

53. Can you think of a “handy” way to remember the congenital cyanotic heart diseases?
See Figure 3-4.

Truncus Arteriosus

Transposition of the Great Arteries

Tricuspid Atresia

Tetralogy of Fallot

Total Anomalous Pulmonary Venous Drainage

Hypoplastic Left Heart

Pulmonary Atresia

Ebstein Tricuspid Valve Disease

Single Ventricle

Figure 3-4. Congenital cyanotic heart disease hand signatures.

CONGESTIVE HEART FAILURE
54. Identify the clinical signs and symptoms associated with CHF in children.
These may be grouped into three categories:
• Signs or symptoms of impaired myocardial performance: cardiomegaly, tachycardia, gallop rhythm, cold extremities or mottling, growth failure, sweating with feeding, pallor
• Signs or symptoms of pulmonary congestion: tachypnea, wheezing, rales, cyanosis, dyspnea, cough
• Signs or symptoms of systemic venous congestion: hepatomegaly, neck vein distention, peripheral edema (seen in the older patient)
55. How is heart size assessed in older children?
Cardiothoracic (CT) ratio: This is derived by comparing the largest transverse diameter of the heart to the widest internal diameter of the chest: CT ratio (A+ B)/C, as shown in Figure 3-5. A CT ratio of >0.5 indicates cardiomegaly.
56. In infancy, how does the likely cause of CHF vary by age?
See Table 3-5.

Figure 3-5. The cardiothoracic ratio is obtained by dividing the largest horizontal diameter of the heart (A + B) by the longest internal diameter of the chest (C). (From Park MK: Pediatric Cardiology for Practitioners, ed 5. Philadelphia, 2008, Mosby ElsEVier, p 66.)

Table 3-5. Causes of Congestive Heart Failure
AGE OF ONSET CAUSE
At birth HLHS with restrictive foramen ovale Volume overload lesions:
Severe tricuspid or pulmonary insufficiency (i.e., severe Ebstein, tetralogy of Fallot with absent pulmonary valve)
Large systemic arteriovenous fistula Arrhythmia
0-7 days TGA and VSD
PDA in small premature infants HLHS
TAPVR, particularly those with pulmonary venous obstruction Systemic arteriovenous fistula
Critical AS or PS
1-6 wk COA isolated or with associated anomalies Critical AS
Large left-to-right shunt lesions (VSD, PDA, AVC) All other lesions previously listed
6 wk-4 mo Large VSD Large PDA
Others such as anomalous left coronary artery from the PA
AS aortic stenosis; AVC atrioventricular canal; COA coarctation of the aorta; HLHS hypoplastic left heart syndrome; PA pulmonary artery; PDA patent ductus arteriosus; PS pulmonary stenosis; TAPVR total anomalous pulmonary venous return; TGA transposition of the great arteries; VSD ventricular septal defect.
Adapted from Park, Myung K: Pediatric Cardiology for Practitioners, ed 5. St. Louis, 2008, Mosby, p 462.

KEY POINTS: COMMON CARDIAC CAUSES OF CONGESTIVE HEART FAILURE IN A 6 -WEEK-OLD INFANT
1. Ventricular septal defect
2. Atrioventricular canal
3. Patent ductus arteriosus
4. Coarctation of the aorta

57. What are the typical ages for the presentation of CHF with CHD?
As a general rule, large-volume overload lesions (e.g., Ebstein anomaly or arteriovenous (AV) malformations) present soon after birth, ductal-dependent lesions present in the first week when the ductus closes, and lesions with significant left-to-right shunting present over the first 1 to
2 months as the normal pulmonary vascular resistance falls (with increased systemic-to-pulmonary shunting).

58. If a patient develops CHF and cardiomegaly during the newborn period, but no heart murmur is heard, what is the differential diagnosis?
• Myocarditis
• Cardiomyopathy as a result of asphyxia or sepsis
• Glycogen storage disease (Pompe disease)
• Cardiac arrhythmia: paroxysmal supraventricular tachycardia, congenital heart block, atrial flutter
• Arteriovenous malformations (e.g., liver, vein of Galen)

59. If a patient develops CHF and cardiomegaly after the newborn period, but no murmur is heard, what is the differential diagnosis?
Myocardial diseases
• Myocarditis (viral or idiopathic)
• Glycogen storage disease (Pompe disease)
• Endocardial fibroelastosis
Coronary artery diseases resulting in myocardial insufficiency
• Anomalous origin of left coronary artery from pulmonary artery
• Kawasaki syndrome (acute vasculitis of infancy and early childhood)
• Calcification of the coronary arteries
CHD with severe heart failure
• Coarctation of the aorta in infants
• Ebstein anomaly (may have gallop rhythm)

ELECTROCARDIOGRAMS AND ARRHYTHMIAS
60. How does the ECG of a term infant differ from that of the older child?
• Birth: At birth, the ECG reflects RV dominance. The QRS complex consists of a tall R wave in the right precordial leads (V1 and V2) and an S wave in the left precordial leads (V5 and V6). The axis is also rightward (90 to 150 degrees). T waves are initially variable with relatively low voltage. They are upright in anterior precordial leads (V1 to V3-4), invert beyond 7 days of age and can remain inverted until about 12 to 13 years.
• Toddler age (2 to 4 years): There is an axis shift from the right to the normal quadrant, and the R wave diminishes over the right precordial leads. The S wave disappears from the left precordium.
• School age: At this age, the ECG has a nearly adult pattern, with a small R and a dominant S in the right precordial leads and an axis in the normal quadrant.

Price A, Kaski J: How to use the paediatric ECG, Arch Dis Child Educ Pract Ed 99:53–60, 2014.

61. What are the characteristic features of the ECG of a premature infant?
In the premature infant, there is less RV dominance. The R wave may be small in the right precordial leads, and there may be no significant S wave over the left precordium. The electrical axis is often in the normal quadrant (0 to 90 degrees).

62. Describe the ECG abnormalities associated with potassium and calcium imbalances
See Figure 3-6.

Potassium imbalance

<2.5 mEq/L

Normal

>6.0 mEq/L

>7.5 mEq/L

>9.0 mEq/L

Depressed ST Segment Diphasic T Wave Prominent U Wave Long QT

Tall Peaked T Wave

Long PR Interval Wide QRS Duration Tall Peaked T wave

Absent P Wave Sinusoidal Wave

Calcium imbalance

Hypercalcemia Normal Hypocalcemia
Figure 3-6. Electrocardiogram abnormalities associated with potassium and calcium imbalances. (From Park MK, Guntheroth WG: How to Read Pediatric ECGs, ed 3. St. Louis, 1992, Mosby, pp 106–107.)
63. What is the difference between a QT interval and a corrected QT interval (QTc)? The QT interval represents the time required for ventricular depolarization and repolarization. It begins at the onset of the QRS complex and continues through the end of the T wave. This interval varies with the heart rate. The QTc adjusts for heart rate differences. As a rule, a prolonged QTc interval is diagnosedwhen the QTc exceeds 0.44 second using the following formula, known as the Bazett formula, with RR representing the interval from the onset of the preceeding QRS complex to the onset of the next QRS complex:
QTc ¼ QT (in seconds)/pffiRffiffiRffiffi interval (in seconds)

Al-Khatib SM, LaPointe NM, Kramer JM, Califf RM: What clinicians should know about the QT interval, JAMA
289:2120–2127, 2003.
64. What causes a prolonged QT interval?
Congenital long QT syndrome
• Hereditary form: ion channelopathies (genetic defects in specific potassium and sodium channel genes), Jervell and Lange-Nielsen syndrome (associated with deafness), Romano-Ward syndrome
• Sporadic type
Acquired long QT syndrome
• Drug-induced (especially antiarrhythmics, tricyclic antidepressants, phenothiazines)
• Metabolic and electrolyte abnormalities (hypocalcemia, hypokalemia, very-low-energy diets)
• Central nervous system and autonomic nervous system disorders (especially after head trauma or stroke)
• Cardiac disease (myocarditis, coronary artery disease)

Behere SP, Shubkin CD, Weindling SN: Recent advances in the understanding and management of long QT syndrome, Curr Opin Pediatr 26:727–733, 2014.
Roden DM: Long QT syndrome, N Engl J Med 358:169–176, 2008.
SADS (Sudden Arrhythmia Death Syndromes) Foundation: www.sads.org. (Available is a list of drugs which should be avoided in patients with long QT syndrome.) Accessed on Mar. 31, 2015.

KEY POINTS: ELECTROCARDIOGRAMS
1. As compared with adults, newborns and infants normally have right ventricular dominance.
2. Premature atrial beats in children are usually benign.
3. QT intervals must be corrected for heart rates.

65. What ECG features are found in the long QT syndromes?
These are disorders of repolarization with prolongation of the QT interval, corrected for heart rate (QTc). Other ECG findings are relative bradycardia, T-wave abnormalities, and episodic ventricular tachyarrhythmias, particularly torsades de pointes (Fig. 3-7).

Lead II Lead V5
Bazett formula: QTc = QT
R-R
Figure 3-7. Long QT syndrome, leads II and V5. Note long QT interval and T-wave alternans (alternating upright and downgoing T waves). (From Towbin JA: Molecular genetic basis of sudden cardiac death, Pediatr Clin North Am 51:1230, 2004, Fig. 1.)

66. What characterizes torsades de pointes? From the French for “to turn on a point,” this is a ventricular tachycardia of varying forms characterized by abrupt changes in amplitude and polarity (Fig. 3-8). It is a pathologic tachyarrhythmia seen in patients with prolonged QT syndromes and the use of certain drugs (e.g., cisapride, thioridazine).

Figure 3-8. Torsades de pointes polymorphic ventricular tachycardia. Note the phase change (arrow) with change in QRS polarity. (From Samson RA, Atkins RA: Tachyarrhythmias and defibrillation, Pediatr Clin North Am 55:891, 2008.)

67. When should amiodarone not be used as the first-line therapy in patients with ventricular tachycardia?
In patients with torsades de pointes (polymorphic ventricular tachycardia with a long QT interval) or with ventricular tachycardia and a long QT interval, amiodarone should not be used. Amiodarone is a class III antiarrhythmic agent and will lengthen the QT interval, predisposing the patient to further arrhythmias.

68. What are the ECG findings in patients with complete heart block? The atrial and ventricular activities are entirely independent. P waves are regular, and QRS complexes are also regular, with a rate slower than the P rate (Fig. 3-9).

Figure 3-9. Complete heart block. Tracing demonstrates atrial activity (arrows) independent of slower ventricular rhythm. (From Zitelli BJ, DAVIS HW: Atlas of Pediatric Physical Diagnosis, ed
4. St. Louis, 2002, Mosby, p 144.)

69. How abnormal are premature atrial contractions?
Premature atrial beats are usually benign, with the exception of patients with an electrical or anatomic substrate for supraventricular tachycardia (SVT) or atrial flutter.
70. How does SVT in children differ from physiologic sinus tachycardia?
SVT typically has the following features:
• Sudden onset and termination rather than a gradual change in rate
• Persistent ventricular rate of >180 beats/minute
• Fixed or almost fixed RR interval on ECG
• Abnormal P-wave shape or axis or absent P waves
• Little change in heart rate with activity, crying, or breath holding
71. When are isolated premature ventricular contractions (PVCs) usually benign in the otherwise healthy school-aged child?
• Structurally normal heart
• ECG intervals, especially QTc, are normal
• No evidence of myocarditis, cardiomegaly, or ventricular tumor
• No history of drug use
• Electrolytes and glucose are normal
• Ectopy decreases with exercise
72. Name the two most common mechanisms of SVT
• WPW syndrome (due to an accessory bypass tract)
• AV nodal reentry
73. What are the clinical settings in which SVT may occur?
• Structurally normal heart: Accessory bypass tract or AV nodal reentry
• Congenital heart disease (preoperatively or postoperatively): Ebstein anomaly, L-TGA with VSD and pulmonic stenosis; after Mustard, Senning, Fontan procedures
• Hypertrophic cardiomyopathy
• Dilated cardiomyopathy
• Drug-induced: Sympathomimetics (e.g., cold medications, theophylline, beta-agonists)
• Infections: Myocarditis
• Hyperthyroidism
74. What are some of the causes of a wide QRS complex?
• Premature ventricular contraction
• Ventricular tachycardia
• Premature atrial contraction with aberrant conduction
• SVT with aberrant conduction
• Bundle branch blocks
• Preexcitation syndromes (WPW syndrome)
• Electrolyte abnormalities
• Myocarditis
• Cardiomyopathy
• Electronic ventricular pacemaker

75. What vagal maneuvers are used to treat paroxysmal SVT in children?
Infants
• Place plastic bag filled with crushed ice over forehead and nose
• Induce gag with tongue blade
Older children and adolescents
• Above methods
• Unilateral carotid massage
• Valsalva maneuver (abdominal straining while holding breath)
• Doing a headstand
In general, the Valsalva maneuver and carotid massage are not as effective for children younger than 4 years. Ocular pressure is not recommended because it has been associated with retinal injury. Vagal stimulation slows conduction and prolongs refractoriness of the AV node, thereby interrupting the reentrant circuit.

76. In addition to vagal maneuvers, what treatments are used acutely for managing SVT?
If a patient’s clinical condition has deteriorated, synchronized direct-current cardioversion is indicated. In patients who are stable and for whom vagal maneuvers have failed, adenosine has replaced digoxin and verapamil as the first drug of choice. An initial bolus of 100 mcg/kg will exert an effect in 10 to 20 seconds by slowing conduction through the AV node. If this is ineffective, the dose can be increased in increments of 50 to 100 mcg/kg every 1 to 2 minutes to a maximum single dose of 300 mcg/kg. The usual starting dose in adults is 6 mg and then 12 mg if the tachycardia persists.

77. Why should an electrographic tracing (preferably with multiple leads) be carried out while administering intravenous adenosine?
Adenosine is used to convert reentrant SVT to sinus rhythm. During the conversion, observation of the termination of the arrhythmia on ECG can often reveal the mechanism of the tachycardia. If the tachycardia does not terminate other information can be obtained from the ECG including,
• The tachycardia is atrial in origin; one can observe varying degrees of AV block with the atrial tachycardia persisting (e.g., atrial flutter).
• The tachycardia is junctional or ventricular with 1:1 ventriculoatrial (VA) conduction; adenosine may induce VA block with VA dissociation.
• The tachycardia terminated and was immediately restarted by a premature atrial beat.

78. In what settings should the dose of adenosine be modified for a suspected cardiac arrhythmia? Adenosine should not be routinely used in post–cardiac transplantation patients. Previous experience with adenosine in these patients has produced asystole with no underlying escape rhythm. Because the heart in these patients does not have normal sympathetic and parasympathetic innervation following transplantation, the response to catecholamines is typically blunted, and the heart rate is generally slower than normal. Additionally, many cardiac transplant recipients are taking dipyridamole (Persantine), which potentiates the effects of adenosine, thereby prolonging the duration of AV block. In patients with working pacing wires, it may be possible to use a lower dose of adenosine.
Due to the abnormal flow patterns in patients with the Fontan procedure, these patients frequently require higher doses of adenosine for the treatment of cardiac arrhythmias.
79. Which children are candidates for transcatheter ablation techniques for SVT? Ablation therapy is used most commonly in children with arrhythmias that are refractory to medical management and in those with life-threatening symptoms or possible lifelong medication requirements. Ablation is now commonly performed in children who are symptomatic from WPW or AV nodal reentrant tachycardia. Recommendations for transcatheter ablation are changing as evidence of increased safety and efficacy of the procedure is gathered. Recommendations vary with the age of the patient, the severity of the arrhythmia, the type of lesion, the difficulty with medical control of the rhythm disorder, and the skill of the operator.

McCammond AN, Balaji S: Management of tachyarrhythmias in children, Curr Treat Options CARDIOVASC Med
14:490–502, 2012.

80. What is the lethal arrhythmia of WPW syndrome? The lethal arrhythmia in patients with WPW is atrial fibrillation with a rapid ventricular response that degenerates into ventricular fibrillation. The rate of the ventricular response in these patients is dependent on the effective refractory period of the accessory pathway and not the AV node. This can result in ventricular rates of 250 to 300 beats per minute. Following ablation of the accessory pathway, these patients are no longer at risk for atrial fibrillation.
81. How is WPW syndrome diagnosed on the baseline ECG?
An accessory pathway bypasses the AV node, thereby resulting in early ventricular depolarization (preexcitation). It is the most common cause of SVT in children. In infants and younger children with rapid heart rates, the delta wave may not be as evident. Classic findings (Fig. 3-10) include:
• Slurring of the initial portion of the QRS (delta wave).
• PR interval of <100 msec
• QRS duration of >80 msec
• Nonspecific ST and T wave changes
• Additional clues that may be suggestive of WPW include the following:
• No Q wave in left chest leads
• Left axis deviation

Perry JC, Giuffre RM, Garson A Jr: Clues to the electrocardiographic diagnosis of subtle Wolff-Parkinson-White syndrome in children, J Pediatr 117:871–875, 1990.

Wolff-Parkinson-White Preexcitation

Figure 3-10. Wolf-Parkinson-White preexcitation. (From Goldberger AL, Goldberger AD, SHVIKIN A: Clinical Electrocardiography: A Simplified Approach, ed 8.
Philadelphia, 2013 ELSEVIER Saunders, p 208.)

• Short PR
• Wide QRS
• Delta Wave (arrow)

INFECTIOUS AND INFLAMMATORY DISORDERS
82. How many blood cultures should be obtained in patients suspected of bacterial endocarditis?
At least three separate blood cultures should be obtained. The use of multiple sites may decrease the likelihood of mistaking a contaminant for the true etiologic agent.
83. Why might properly collected blood cultures be negative in the setting of clinically suspected bacterial endocarditis?
• Prior antibiotic use
• Endocarditis may be right-sided
• Nonbacterial infection: fungal (e.g., Aspergillus, Candida ) or unusual organisms (e.g., Bartonella, Rickettsia, Chlamydia )
• Unusual bacterial infection: slow-growing organisms (e.g., Brucella, Haemophilus) or anaerobes
• Lesions may be mural or nonvalvular (i.e., less likely to be hematogenously seeded)
• Nonbacterial thrombotic endocarditis (sterile platelet-fibrin thrombus formations following endocardial injury)
• Incorrect diagnosis

Starke JR: Infective endocarditis. In Cherry JD, Harrison GJ, Kaplan SL, et al editors: Feigin and Cherry’s Textbook of Pediatric Infectious Diseases, ed 7. Philadelphia, 2014, Saunders Elsevier, p 358.

84. When is antibiotic prophylaxis for a dental procedure recommended?
In 2007, the American Heart Association made significant changes in antibiotic recommendations for cardiac patients. Only those with the highest risk for adverse outcomes from endocarditis are advised to receive dental prophylaxis. Prophylaxis with dental procedures is recommended for the following:
• Prosthetic cardiac valve
• Previous endocarditis
• Congenital heart disease (CHD): Unrepaired cyanotic CHD, including palliative shunts and conduits; repaired CHD with prosthetic material or device during the first 6 months after the procedure; repaired CHD with residual defects at the site of a prosthetic patch or prosthetic device (which inhibit endothelialization). Antibiotic prophylaxis is not recommended for any other forms of CHD.
• Cardiac transplantation recipients who develop cardiac valvulopathy

Wilson W, Taubert KA, Gewitz M, et al: Prevention of infective endocarditis: guidelines from the American Heart Association, Circulation 116:1736–1754, 2007.

85. How reliable is the echocardiogram for diagnosing bacterial endocarditis (BE)?
Echocardiography can sometimes identify an intracardiac mass that is attached either to the wall of the myocardium or to part of the valve. Although the yield of echocardiography for diagnosing BE is low, the likelihood of a positive finding is increased under certain
conditions (e.g., indwelling catheters, prematurity, immunosuppression, evidence of peripheral embolization). BE is a clinical and laboratory diagnosis (physical examination and blood cultures, respectively) and not solely an “echocardiographic” diagnosis. A negative study does not rule out BE.

Starke JR: Infective endocarditis. In Cherry JD, Harrison GJ, Kaplan SL, et al editors: Feigin and Cherry’s Textbook of Pediatric Infectious Diseases, ed 7. Philadelphia, 2014, Saunders Elsevier, p 359–360.

86. When should myocarditis be suspected?
The presenting symptoms of myocarditis can be variable, ranging from subclinical to rapidly progressive CHF. It should be considered in any patient who experiences unexplained heart failure. Clinical signs include tachycardia out of proportion to fever, tachypnea, a quiet precordium, muffled heart tones, gallop rhythm without murmur, and hepatomegaly.

Pettit MA, Koyfman A, Foran M: Myocarditis, Pediatr Emerg Care 30:832–835, 2014.

87. What conditions are associated with the development of myocarditis?
Infections
• Bacterial: Diphtheria
• Viral: Coxsackie B (most common), coxsackie A, human immunodeficiency virus, echoviruses, rubella
• Mycoplasmal
• Rickettsial: Typhus
• Fungal: Actinomycosis, coccidioidomycosis, histoplasmosis
• Protozoal: Trypanosomiasis (Chagas disease), toxoplasmosis
Inflammatory
• Kawasaki disease
• Systemic lupus erythematosus
• Rheumatoid arthritis
• Eosinophilic myocarditis
Chemical and physical agents
• Radiation injury
• Drugs: Doxorubicin
• Toxins: Lead
• Animal bites: Scorpion, snake

88. A child visiting from South America presents with symptoms including unilateral eye swelling and new-onset acute CHF. What is a likely diagnosis?
Acute myocarditis as a result of Chagas disease (American trypanosomiasis) is likely. Romaña sign is unilateral, painless, violaceous, palpebral edema often accompanied by conjunctivitis. It is seen in 25% to 50% of patients with early Chagas disease in endemic areas. The swelling occurs
near the bite site of the parasitic vector, the reduviid bug. Chagas disease, a protozoan infection due to
Trypanosoma cruzi, is a common cause of acute and chronic myocarditis in Central and South America.

89. What are the common clinical signs and symptoms of pericarditis?
• Symptoms: Chest pain, fever, cough, palpitations, irritability, abdominal pain
• Signs: Friction rub, pallor, pulsus paradoxus, muffled heart sounds, neck vein distention, hepatomegaly

90. What is the position of comfort in the patient with pericarditis?
The typical patient with pericarditis prefers to sit up and lean forward.
91. What is Kawasaki disease?
Also called mucocutaneous lymph node syndrome, Kawasaki disease is a multisystem disease characterized by vasculitis of small and medium-sized blood vessels. If untreated, the condition can lead to coronary artery aneurysms and myocardial infarction. A high index of suspicion is important because Kawasaki disease has replaced acute rheumatic fever as the leading cause of identifiable acquired heart disease in the developed world.

Sundel RP: Kawasaki disease, Rheum Dis Clin North Am 41:63–73, 2015. Kawasaki Disease Foundation: www.kdfoundation.org. Accessed on Jan. 6, 2015.

92. What are the principal diagnostic criteria for Kawasaki disease?
The presence of fever and at least four of five other features are needed for the classic diagnosis. The mnemonic My HEART may be helpful:
• Mucosal changes, especially oral and upper respiratory; dry and chapped lips; “strawberry tongue”
• Hand and extremity changes, including reddened palms and soles and edema; desquamation from fingertips and toes is a later finding (second week of illness)
• Eye changes, primarily a bilateral conjunctival infection without discharge
• Adenopathy that is usually cervical, often unilateral, and 1.5 cm in diameter
• Rash that is usually a truncal exanthem without vesicles, bullae, or petechiae
• Temperature elevation, often to 40 ° C (104°F) or above, lasting for >5 days

93. What makes incomplete (or atypical) Kawasaki disease incomplete (or atypical)? Incomplete (or atypical) Kawasaki disease does not fulfill sufficient diagnostic criteria for classic Kawasaki disease. The clinical features are similar but differ in number. In incomplete disease, children have fever but fewer than four signs of mucocutaneous inflammation. About 15% to 20%
of reported Kawasaki cases are of the incomplete variety, particularly in children younger than 1 year. Despite not meeting the classic criteria, children with incomplete Kawasaki disease remain at risk for the same coronary artery changes.

Manlhiot C, Christie E, McCrindle BW, et al: Complete and incomplete Kawasaki disease: two sides of the same coin, Eur J Pediatr 171:609–611, 2012.

94. Which diagnostic manifestation of Kawasaki disease is most commonly absent? Cervical lymphadenopathy, in both complete and incomplete Kawasaki disease, is most commonly absent. Up to 90% of patients with incomplete disease and 40% to 50% of those who meet classic criteria for Kawasaki disease do not have adenopathy.

Fukushige J, Takahashi N, Ueda Y, Ueda K: Incidence and clinical features of incomplete Kawasaki disease, Acta Paediatr 83: 1057, 1994.

95. What laboratory tests are often abnormal in the first 7 to 10 days of the Kawasaki disease?
• Complete blood count: Fifty percent of patients have an elevated white blood cell count (>15,000) with neutrophilia and a progressive normochromic, normocytic anemia. Platelet count increases and peaks in the second to third week of illness.
• Urinalysis: Pyuria without bacteriuria (culture usually negative)
• Acute phase reactants: C-reactive protein, erythrocyte sedimentation rate significantly elevated in 80%
• Blood chemistry: Mild increase in hepatic transaminases, low serum sodium, protein, and/or albumin
• Cerebrospinal fluid: Pleocytosis (usually lymphocytic) with normal protein and glucose

Harnden A, Takahashi M, Burgner D: Kawasaki disease, BMJ 338:1133–1138, 2009.

96. What is the typical age of children with Kawasaki disease?
Eighty percent of cases occur between the ages of 6 months and 5 years. However, cases can occur in infants and teenagers. Both of these groups appear to be at increased risk for developing coronary artery sequelae. The diagnosis is often delayed, particularly in infants, because signs and symptoms of the illness may be incomplete or subtle. Of note, the condition is exceedingly rare in adults.

KEY POINTS: DIAGNOSTIC FEATURES OF KAWASAKI DISEASE
1. Erythema of oral cavity and dry, chapped lips
2. Conjunctivitis: Bilateral and without discharge
3. Edema and erythema and/or desquamation of hands and feet
4. Cervical lymphadenopathy
5. Polymorphous exanthem on trunk, flexor regions, and perineum
6. Fever, often up to 40 ° C (104°F), lasting ≤5 days
7. No other identifiable diagnostic entity to explain signs and symptoms
8. Incomplete Kawasaki disease (fever but fewer than four of the other criteria) is common in children
<1 year of age.

97. Why should all children with Kawasaki disease receive intravenous immunoglobulin (IVIG) therapy?
IVIG has been demonstrated to decrease the incidence of coronary artery abnormalities in children with Kawasaki disease. Additionally, fever and laboratory indices of inflammation resolve more quickly after treatment. The most common dosing is a single infusion over 8 to 12 hours of 2 g/kg. In children who remain febrile 36 hours after the first infusion, a second dose of 2 g/kg is recommended.
When administered 5 to 10 days after the start of fever, IVIG improves outcome, with coronary artery dilation developing in less than 5% of patients and giant coronary aneurysms developing in less than 1% of patients. At present, there is no reliable means of predicting which children with Kawasaki disease will develop coronary artery abnormalities. Therefore, all children with Kawasaki disease should receive parental immunoglobulin.
98. Is aspirin therapy of benefit for children with Kawasaki disease?
By itself, high-dose aspirin (80 to 100 mg/kg per day divided into doses taken every 6 hours) is effective for decreasing the degree of fever and discomfort in patients during the acute stages of illness. It is unclear whether high-dose aspirin has an additive effect for decreasing the incidence of coronary artery abnormalities when used in conjunction with IVIG. Aspirin may be beneficial when administered in low doses after the resolution of fever because of its effects on platelet aggregation and prevention of the thrombotic complications seen in children with Kawasaki disease. Therefore, when fever has been absent for 48 hours, the patient is switched to aspirin in low doses (3 to 5 mg/kg/day) which is continued for about 6 to 8 weeks. If a follow-up echocardiogram at that time reveals no coronary abnormalities, therapy is usually discontinued. If abnormalities are present, therapy is continued indefinitely.

99. What is the likelihood of a patient developing coronary artery pathology with and
without treatment for Kawasaki disease?
In 30% to 50% of patients, a mild diffuse dilation of coronary arteries begins 10 days after the start of fever. If untreated, 20% to 25% of these will progress to true aneurysms (Fig. 3-11). In about 1% of cases, giant aneurysms (>8 mm diameter) develop, which may heal with stenosis and lead to myocardial ischemia. With IVIG therapy, the incidence of aneurysms is reduced to less than 5%.

Harnden A, Takahashi M, Burgner D: Kawasaki disease, BMJ 338:1133–1138, 2009.

Figure 3-11. Lateral view of coronary angiogram showing right coronary artery with saccular aneurysm. (From Vetter VL, editor: Pediatric Cardiology: The Requisites in Pediatrics.
Philadelphia, 2006, Mosby, p 135.)

PHARMACOLOGY
100. How long before oral digoxin begins to work?
Oral digoxin reaches peak plasma levels 1 to 2 hours after administration, but a peak hemodynamic effect is not evident until 6 hours after administration (versus 2 to 3 hours for intravenous digoxin).
101. A child with WPW syndrome is given digoxin to prevent SVT. Why is the pediatric cardiologist concerned? Ventricular fibrillation has been reported in older children and adolescents with WPW who were treated with digoxin. Digoxin may shorten the effective refractory period of the bypass tract resulting in more rapid conduction through the accessory pathway. Digoxin also slows conduction through the AV node and this combination of effects may result in an increased risk of sudden death in patients with WPW who develop atrial fibrillation. For this reason, propranolol has replaced digoxin as the drug of choice for the treatment of children with WPW and SVT. Of note, verapamil may also both shorten the effective refractory period of the accessory pathway and raise the risk for sudden death in WPW patients should they develop atrial fibrillation.
102. When should indomethacin be administered to newborns with a PDA? Indomethacin is effective for closing a PDA within the first 10 days of life. The drug is indicated for preterm infants with a hemodynamically significant PDA, which is defined as one in which there is deteriorating respiratory status (e.g., tachypnea, apnea, CO2 retention, increased ventilatory support, failure to wean ventilatory support), poor cardiac output, or evidence of CHF.

Hamrick SEG, Hansmann G: Patent ductus arteriosus of the preterm infant, Pediatrics 125:1020–1030, 2010.

103. What are the side effects of indomethacin in the neonate?
• Mild but usually transient decreased renal function
• Hyponatremia

• Platelet dysfunction producing a prolonged bleeding time
• Occult blood loss from the gastrointestinal tract
104. What are the contraindications for indomethacin therapy?
Indomethacin is contraindicated if the creatinine level is >1.8 mg/dL, the platelet count is
<60,000/mm3, or there is evidence of a bleeding diathesis.
105. What are the indications for prostaglandin E1 (PGE1) in the neonate?
PGE1 is indicated in cardiac lesions that depend on a PDA to maintain adequate pulmonary or systemic blood flow or to promote adequate mixing.
• Inadequate pulmonary blood flow (e.g., pulmonary atresia with intact ventricular septum, tricuspid atresia with intact ventricular septum, critical pulmonary stenosis)
• Inadequate systemic blood flow (e.g., critical coarctation of the aorta, interrupted aortic arch, HLHS)
• Inadequate mixing (e.g., transposition of the great vessels)
106. What are the major side effects of PGE1?
Apnea, fever, cutaneous flushing, seizures, hypotension, and bradycardia or tachycardia are the major side effects of PGE1.
107. How do α, β, and dopaminergic receptors differ?
α: In vascular smooth muscle, these receptors cause vasoconstriction.
β1: In myocardial smooth muscle, these receptors increase myocardial contractility (inotropic effect), cardiac rate (chronotropic effect) and AV conduction (dromotropic effect).
β2: In vascular smooth muscle, these receptors cause vasodilation.
Dopaminergic: In renal and mesenteric vascular smooth muscle, these receptors cause vasodilation.

108. How do relative receptor effects differ by drug type?
See Table 3-6.

Table 3-6. Relative Receptor Effects by Drug Type
DRUG α β1 β2 DOPAMINERGIC
Epinephrine +++ +++ +++ 0
Norepinephrine +++ +++ + 0
Isoproterenol 0 +++ +++ 0
Dopamine*
0 to +++
(dose related) ++ to +++
(dose related) ++
(dose related) +++
Dobutamine 0 to + +++ + 0
Effect of medication: 0 none; + small; ++ moderate; +++ large.
*For dopamine, at low doses (2 to 5 μg/kg/min), dopaminergic effects predominate. At high doses (5 to 20 μg/kg/min), increased α and β effects are seen. At very high doses (>20 μg/kg/min), a markedly increased α effect with decreased renal and mesenteric blood flow occurs. For dobutamine, β1 inotropic effects are more pronounced than are chronotropic effects.

109. How are emergency infusions for cardiovascular support prepared?
See Table 3-7.

Table 3-7. Emergency Infusions for Cardiovascular Support
CATECHOLAMINE MIXTURE DOSE
Isoproterenol, epinephrine, norepinephrine 0.6 mg× body wt (in kg), added to diluent to make 100 mL 1 mL/hr delivers 0.1 μg/kg/min
Dopamine, dobutamine 6 mg× body wt (in kg), added to diluent to make 100 mL 1 mL/hr delivers 1 μg/kg/min

PHYSICAL EXAMINATION
110. What causes the first heart sound?
The first heart sound is caused by the closure of the mitral and tricuspid valves.

111. What causes the second heart sound?
The second heart sound is caused by the closure of the aortic and pulmonary valves.

112. In what settings can an abnormal second heart sound be auscultated?
Widely split S2
• Prolonged RV ejection time
• RV volume overload: Atrial septal defect, partial anomalous pulmonary venous return
• RV conduction delay: Right bundle branch block
Single S2
• Presence of only one semilunar valve: Aortic or pulmonary atresia, truncus arteriosus
• P2 not audible: Tetralogy of Fallot, transposition of great arteries
• A2 delayed: Severe aortic stenosis
• May be normal in a newborn
Paradoxically split S2 (A2 follows P2)
• Severe aortic stenosis
• Left bundle branch block
Loud P2
• Pulmonary hypertension

113. What is the difference between pulsus alternans and pulsus paradoxus?
• Pulsus alternans is a pulse pattern in which there is alternating (beat-to-beat) variability of pulse strength due to decreased ventricular performance. This is sometimes seen in patients with severe CHF.
• Pulsus paradoxus indicates an exaggeration of the normal reduction of systolic blood pressure during inspiration. Associated conditions include cardiac tamponade (e.g., effusion, constrictive pericarditis), severe respiratory illness (e.g., asthma, pneumonia), and myocardial disease that affects wall compliance (e.g., endocardial fibroelastosis, amyloidosis).

114. How is pulsus paradoxus measured?
To measure a pulsus paradoxus, determine the systolic pressure by noting the first audible Korotkoff sound. Then retake the blood pressure by raising the manometer pressure to at least 25 mm Hg higher than the systolic pressure, and allow it to fall very slowly. Stop as soon as the
first sound is heard. Note that the sound disappears during inspiration. Lower the pressure slowly, and note when all pulsed beats are heard. The difference between these two pressures is the pulsus paradoxus. Normally, in children, there is an 8- to 10-mm Hg fluctuation in systolic pressure with different phases of respiration.

115. What is the differential diagnosis for a systolic murmur in each auscultatory area?
See Fig. 3-12.

116. What are the most common innocent murmurs?
See Table 3-8.

117. What is the effect of sitting up on the typical innocent murmur?
Sitting up usually brings out or increases the intensity of the murmur of a venous hum.
In contrast, the typical vibratory innocent murmur along the lower left sternal border is loudest in the supine child and will diminish in intensity and sometimes disappear while sitting upright.

Figure 3-12. Systolic murmurs audible at various locations. Many may radiate to other areas. Less common conditions are shown in smaller type. AS, aortic stenosis; ECD, endocardial cushion defect, HCM, hypertrophic cardiomyopathy. (From Park MK: Pediatric Cardiology for Practitioners, ed 4. St. Louis, Mosby, 2002, p 32.)

Table 3-8. Most Common Innocent Murmurs
TYPE (TIMING) DESCRIPTION OF MURMUR COMMON AGE GROUP
Classic vibratory murmur; Still’s murmur (systolic) Maximal at MLSB or between LLSB and apex
Low-frequency vibratory, “twanging string,” or musical
Grade 2-3/6 in intensity 3-6 years old; occasionally in infancy
Pulmonary ejection murmur (systolic) Maximal at ULSB Early to midsystolic
Grade 1-2/6 in intensity 8-14 years old
Pulmonary flow murmur of newborn (systolic) Maximal at ULSB
Transmits well to left and right chest, axillae, and back
Grade 1-2/6 intensity Premature and full-term newborns; usually disappears by 3-6 months of age
Venous hum (continuous) Maximal at right (or left) supraclavicular and infraclavicular areas
Inaudible in supine position
Intensity changes with rotation of head and compression of jugular vein
Grade 1-2/6 in intensity 3-6 years old
Carotid bruit (systolic) Right supraclavicular area and over carotids Occasional thrill over a carotid artery
Grade 2-3/6 intensity Any age
LLSB ¼ Lower-left sternal border; MLSB ¼ mid-left sternal border; ULSB ¼ upper-left sternal border.

118. What features are suggestive of a pathologic murmur?
• Diastolic murmurs
• Late systolic murmurs
• Pansystolic murmurs
• Continuous murmurs
• Murmurs associated with a thrill
• Murmurs at the aortic area (right-upper sternal border) and tricuspid area (left-lower sternal border)
• Harsh quality
• Associated cardiac abnormalities (e.g., asymmetrical pulses, clicks, abnormal splitting)

McCrindle BW, Shaffer KM, Kan JS, et al: Cardinal clinical signs in the differentiation of heart murmurs in children, Arch Pediatr Adolesc Med 150:169–174, 1996.
Rosenthal A: How to distinguish between innocent and pathologic murmurs in childhood, Pediatr Clin North Am
31:1229–1240, 1984.

119. If a murmur is detected, what other factors suggest that the murmur is pathologic?
• Evidence of growth retardation (most commonly seen in murmurs with large left-to-right shunts)
• Associated dysmorphic features (e.g., valvular disease in Hurler syndrome, Noonan syndrome)
• Exertional cyanosis, pallor, or dyspnea, especially if associated with minor exertion such as climbing a few stairs (may be a sign of early CHF)
• Short feeding times and volumes in infants (may be a sign of early CHF)
• Syncopal or presyncopal episodes (may be seen in hypertrophic cardiomyopathy)
• History of intravenous drug abuse (risk factor for endocarditis)
• Maternal history of diabetes mellitus (associated with asymmetrical septal hypertrophy, VSD,
D-transposition), alcohol use (associated with pulmonic stenosis and VSD), or other medications
• Family history of congenital heart disease

Etoom Y, Ratnapalan S: Evaluation of children with heart murmurs, Clin Pediatr 53:111–117, 2014.

KEY POINTS: PATHOLOGIC MURMURS
1. Diastolic
2. Pansystolic
3. Late systolic
4. Continuous
5. Thrill present on examination
6. Additional cardiac abnormalities (e.g., clicks, abnormal splitting, asymmetric pulses)

SURGERY
120. What are shunt operations? Arterial shunts are connections between a systemic artery and the pulmonary artery and are used to improve oxygen saturation in patients with cyanotic CHD and diminished pulmonary blood flow. Venoarterial shunts connect a systemic vein and the pulmonary artery and are also used for similar purposes.
121. Name the major shunt operations (Fig. 3-13) for CHD.
• The Blalock-Taussig (BT) shunt consists of an anastomosis between a subclavian artery and the ipsilateral pulmonary artery. The subclavian artery can be divided and the distal end anastomosed to the pulmonary artery (classic BT shunt), or a prosthetic graft (Gore-Tex) can be interposed between the two arteries (modified BT shunt). It allows for pulmonary blood flow in children with severe pulmonary stenosis or atresia.
• The Sano shunt (not pictured) is a conduit from the right ventricle to the pulmonary artery and is often used as an alternative to the Blalock-Taussig shunt in the Norwood procedure for HLHS.
• The Waterston shunt is an anastomosis between the ascending aorta and the right pulmonary artery. This procedure is rarely performed today.
• The Potts shunt is an anastomosis between the descending aorta and the left pulmonary artery. This procedure is rarely performed today.

Waterston

Blalock-
Taussig AO

PA

Gore-Tex

Potts

RA
LV

Figure 3-13. Major shunt operations. AO, aorta;
RV LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle. (From Park MK: Pediatric Cardiology for Practitioners, ed 4. St. Louis, 2002, Mosby, p 194.)

122. What is the purpose of the Fontan procedure?
The Fontan procedure (or operation) is designed to reroute systemic venous blood from the superior and inferior vena cava directly to the pulmonary arteries, thus bypassing the ventricle. It is most commonly used for any cardiac lesion with a single functional ventricle. A common current approach is anastomosis of the superior vena cava to the right pulmonary artery and redirection of flow from the inferior vena cava to the right pulmonary artery through either an intracardiac baffle or an extracardiac conduit. This deoxygenated blood flows passively to the lungs and returns to the ventricle to be pumped to the systemic circulation.

Tsai W, Klein BL: The postoperative cardiac patient, Clin Pediatr Emerg Med 6:216–221, 2005.

123. What are the most common rhythm disturbances after the Fontan procedure? Because of the extensive atrial surgery in the Fontan procedure, there are two major cardiac rhythm issues.
• Loss of sinus rhythm with either a nonsinus atrial rhythm or junctional rhythm. Atrial pacing may be required in these patients to either increase heart rate or restore AV synchrony.
• Intra-atrial reentrant tachycardia was more common following the old-style Fontan procedure because of the incisional scars and size of the atrium. Although less common with the newer surgical techniques, it remains a major clinical problem in these patients; it is often drug resistant and requires either catheter or surgical ablation.

124. In what type of cardiac surgery is the complication of protein-losing enteropathy more common?
Fontan procedure. Protein-losing enteropathy, which occurs in 2% to 10% of cases, is a condition manifested by variable degrees of ascites, peripheral edema, diarrhea, malabsorption
of fat, and hypoalbuminemia. The cardiac function is often normal in these patients, and the cause is attributed to abnormal flow dynamics in the mesenteric vasculature secondary to high
pressures in the Fontan circulation.

125. What are some of the reasons to surgically close a VSD?
• Chronic respiratory failure secondary to heart failure
• Chronic heart failure
• Prevention of pulmonary vascular obstructive disease
• Growth failure secondary to chronic heart failure
• Persistent left heart volume load with chronic cardiomegaly
• Aortic valve prolapse with aortic valve insufficiency
• Recurrent endocarditis

126. What are the indications for closure of an atrial septal defect?
Asymptomatic children with a secundum atrial septal defect associated with RV dilation and increased pulmonary blood flow typically undergo elective closure between 3 and 5 years of age. Children with a typical secundum atrial septal defect can usually be closed with catheterization techniques. A primum or sinus venosus atrial septal defect is closed with surgery. In addition, a very large secundum defect or associated lesions are typically closed at surgery. The rare infant with a symptomatic atrial septal defect should undergo surgery at the time of diagnosis.

127. What is the typical timing for the three operations for children with HLHS?
• Newborn: Norwood procedure—reconstruction of the new aorta, atrial septectomy, and pulmonary shunt
• 4 to 8 months: Glenn shunt (hemi-Fontan)—superior caval to pulmonary artery connection
• 2 to 4 years: Fontan procedure—inferior vena cava to pulmonary artery connection

Barron DJ, Kilby MD, Davies MD, et al: Hypoplastic left heart syndrome, Lancet 374:551–564, 2009.

128. What are long-term survival rates for children who undergo surgery for HLHS? Before the advances of the Norwood procedure in the 1980s, children with HLHS invariably died in the first weeks of life. Following the introduction of the Norwood procedure, survival rates have steadily increased. In the multicenter randomized Single Ventricle Reconstruction trial of infants with HLHS, 3-year survival was 67% for Norwood procedure with a right ventricle-to-pulmonary artery shunt (Sano) versus 61% for infants with Norwood procedure with a modified BT shunt.

Newburger JW, Sleeper LA, Frommelt PC, et al: Transplantation-free survival and interventions at 3 years in the single ventricle reconstruction trial, Circulation 129:2013–2020, 2014.

129. What is the long-term prognosis for heart transplantation during infancy and childhood?
Survival statistics have improved dramatically during the past 10 years with the use of newer and safer immunosuppressive agents such as cyclosporine and FK506. However, children who receive transplanted hearts are at increased risk for cardiac rejection, infection, accelerated coronary artery disease, and lymphoproliferative syndromes. Recent estimated 5-year survival rates vary between 65% and 80%.
130. A 5-year-old girl, 2 weeks after an uncomplicated repair of a secundum atrial septal defect, presents with fever, respiratory distress, and a history of the need to sleep sitting up since discharge. What is the diagnosis of immediate concern?
Post-pericardiotomy syndrome (PPCS) and pericardial effusion. PPCS typically occurs between 7 to 21 days after any surgical procedure which opens the pericardial space. Symptoms may include fever, chest pain, irritability, dyspnea, and a preference for sitting up. Physical examination may show fever, tachycardia, increased respiratory rate, hypotension with decreased pulse pressure, muffled heart tones, distended neck veins, hepatomegaly, and pulsus paradoxus.
The differential diagnosis includes residual cardiac lesions, cardiomyopathy, pneumonia, sepsis, and pleural effusions.
131. What is the etiology of postoperative hypertension following repair of coarctation of the aorta?
POSTOPERATIVE hypertension is believed to be due to baroreceptor trauma secondary to surgery,
an increase in circulating catecholamines, and an exaggerated renin-angiotensin system response. Treatment with sedation, analgesia, esmolol, nitroprusside, and propranolol has been successful. These drugs can be changed to enalapril or captopril when oral feedings are resumed.
132. A 5-year-old boy, 6 days after an uncomplicated surgical repair of a coarctation of the aorta, presents with respiratory distress; a left pleural effusion is noted on a chest x-ray. What is the likely appearance and composition of the pleural fluid? Turbid, milky white, high in triglycerides and lymphocytes is consistent with a chylothorax. Following surgical repair of a coarctation of the aorta, patent ductus arteriosus or a vascular ring,

patients are at risk for chylous pleural effusions secondary to trauma to the thoracic duct. Injury to the thoracic duct can result in leakage of lymphatic/chylous fluid (of intestinal origin) into the pleural space. This typically starts after feedings are resumed and the patient starts to increase fat intake, which increases chyle formation. Children usually respond to a nonfat diet, but sometimes will need surgical ligation of the thoracic duct.
Acknowledgment
The editors gratefully acknowledge the contributions by Dr. Bernard J. Clark III that were retained from the first three editions of
Pediatric Secrets.

BONUS QUESTIONS
133. Can a patient with heart disease simultaneously be polycythemic and iron deficient?
Yes. Patients with cyanotic heart disease may develop both clinical entities. Initially, as a response to cyanosis, the hematocrit rises. In patients with iron deficiency, the hematocrit may remain elevated, and the mean corpuscular volume will be lower than normal. Detailed studies of iron stores often reveal a concurrent deficiency. Children with a history of poor nutrition and blood loss (e.g., previous surgery) are especially at risk for developing iron deficiency.

134. What syndrome should come to mind for the patient with pulmonary stenosis, liver disease, and hypercholesterolemia?
Alagille syndrome is associated with peripheral pulmonary stenosis and liver disease. These children have chronic cholestasis secondary to a paucity of intrahepatic interlobular bile ducts. Hypercholesterolemia is thought to be secondary to the liver disease. Other findings are peculiar facies, butterfly-like vertebral arch defects, and growth defects.
135. What is the difference between isotonic and isometric exercise?
Isotonic exercise is dynamic exercise (e.g., running), whereas isometric exercise is static
(e.g., lifting weights). Static exercise causes pressure overload on the heart, so dynamic exercise is usually preferred for patients with congenital heart disease.
136. What are some of the genetic diseases associated with pulmonary valve stenosis and/or pulmonary artery branch stenosis?
• Noonan syndrome: pulmonary valve stenosis (dysplastic pulmonary valve), small jaw, wide set eyes, low-set ears, drooping eyelids
• Williams syndrome: pulmonary valve stenosis, pulmonary artery branch stenosis, short stature, supravalvular aortic stenosis, coarctation of the aorta, hypercalcemia, auditory hyperacusis, elfin facies
• Alagille syndrome: pulmonary valve and pulmonary artery stenosis, liver disease and hypercholesterolemia
• Maternal rubella syndrome: pulmonary valve stenosis, pulmonary branch stenosis, patent ductus arteriosus, mental retardation
• Costello syndrome: pulmonary stenosis, hypertrophic cardiomyopathy, atrial tachycardia
• Cardiofaciocutaneous syndrome: pulmonary stenosis, hypertrophic cardiomyopathy
137. You are seeing a newborn with a heart murmur and the parents tell you that their obstetrician had obtained a fetal cardiac ultrasound, which was reported as normal. Could the newborn still have heart disease?
Yes. Because of the nature of the fetal circulation, the fetal study may not rule out some infants with ventricular septal defects, atrial septal defects, PDA, coarctation of the aorta, or coronary artery abnormalities.
138. What is the typical ventricular heart rate in newborns with atrial flutter?
The ventricular heart rate depends on the atrial flutter rate and the rate of conduction through the AV node. A typical atrial flutter rate in newborns is 300/min. The ventricular rate is usually an even multiple of the atrial rate. The ventricular rate can vary from 300/min with 1:1 AV conduction, to 150/min with 2:1 AV conduction and to 75/min with 4:1 conduction. Treatment for atrial flutter with DC cardioversion or atrial pacing is usually required to terminate the flutter.
139. What are the chances of an infant having complete heart block if the infant’s mother has systemic lupus erythematosus (SLE)?
For mothers with SLE who have anti-Ro/SSA and anti-La/SSB antibodies, the risk of having an infant with heart block is approximately 2% for first-time mothers. The risk is 18% if there is a previous infant with complete heart block.
140. What conditions should be considered in the differential diagnosis of Kawasaki disease?
• Viral infections (including adenovirus, enterovirus, Epstein-Barr virus, measles)
• Scarlet fever

• Staphylococcal scalded skin syndrome
• Toxic shock syndrome
• Bacterial cervical lymphadenitis
• Drug hypersensitivity
• Stevens-Johnson syndrome
• Juvenile idiopathic arthritis
• Leptospirosis
• Mercury hypersensitivity reaction (acrodynia)

Fimbres AM, Shulman ST: Kawasaki disease, Pediatr REV 29:308–311, 2008.

141. Is palpation for femoral pulses a reliable screening tool for coarctation of the aorta in infants and older children?
The detection of decreased lower extremity pulses seen in coarctation can be subtle and unreliable. In some infants, a PDA may provide blood flow to the lower extremities, thus bypassing a severe coarctation. Upper and lower extremity pulses may be equal as long as the ductus remains open. As the ductus closes, signs of coarctation of the aorta may appear with respiratory distress and cardiac failure. Decreased or absent pulses may then be noted. In older children, simultaneous palpation of upper and lower extremity pulses is important. If collaterals have developed, a delay
in pulse rather than diminished volume may be noted. In a study of older patients (>1 year old) with documented coarctation, only 20% had absent lower extremity pulses; therefore, distinguishing
a difference in quality between upper extremity and lower extremity pulses was unreliable. Thus, some authors recommend that screening for coarctation of the aorta be done by measuring blood pressure in both arms and one leg.

Ing FF, Starc TJ, Griffiths SP, Gersony WM: Early diagnosis of coarctation of the aorta in children: a continuing dilemma,
Pediatrics 98:378–382, 1996.

142. Where is the best place to position your stethoscope to hear an aortic ejection click?
Aortic ejection clicks are best heard at the apex. However, they can be heard anywhere along the “aortic runway,” an imaginary line running from the second intercostal space at the right parasternal area to the apex. A click is often heard in valvular aortic stenosis and is absent in subvalvular and supravalvular stenosis.
143. What is postcoarctectomy syndrome?
This is a rare complication following repair of coarctation of the aorta. The pathophysiology is believed to be secondary to mesenteric vasoconstriction following surgery. It is most commonly seen in older children with preoperative hypertension. It occurs in the early postoperative period and typically presents with hypertension, abdominal pain, and distention. Intestinal ischemia and infarction can result.