BRS – Pediatrics: Cardiology
Source: BRS Pediatrics, 2019
I. Congestive Heart Failure (CHF)
A. Definition. Congestive heart failure (CHF) is a clinical syndrome defined as inadequate oxygen delivery by the myocardium to meet the metabolic demands of the body.
B. Pathophysiology. Signs and symptoms of CHF often result from compensatory mechanisms that lead to increased demand on an already compromised myocardium.
1. Hypoperfusion of end organs stimulates the heart to maximize contractility and heart rate in an attempt to increase cardiac output.
2. Hypoperfusion also signals the kidneys to retain salt and water through the renin– angiotensin system in an attempt to increase blood volume.
3. Catecholamines released by the sympathetic nervous system also increase heart rate and myocardial contractility.
C. Etiology. CHF may result from congenital heart disease (CHD), acquired heart disease, and a variety of miscellaneous disorders.
1. CHD may result in CHF.
a. Increased pulmonary blood flow may cause CHF. Examples of congenital lesions that cause increased pulmonary blood flow include a large ventricular septal defect (VSD), a large patent ductus arteriosus (PDA), transposition of the great arteries (TGA), truncus arteriosus, and total anomalous pulmonary venous return (TAPVR).
b. Obstructive lesions may also cause CHF. Examples include severe aortic, pulmonary, and mitral valve stenosis, coarctation of the aorta, interrupted aortic arch, and hypoplastic left heart syndrome.
c. Other causes include arteriovenous malformations and mitral or tricuspid regurgitation, which all lead to volume overload in the heart.
2. Acquired heart disease may also lead to CHF.
a. Viral myocarditis is a common cause of CHF in older children and adolescents.
b. Other cardiac infections (e.g., endocarditis, pericarditis), metabolic diseases (e.g., hyperthyroidism), medications (e.g., doxorubicin, a chemotherapeutic agent), cardiomyopathies, and ischemic diseases (e.g., coronary artery disease)
c. Dysrhythmias, including certain types of tachycardia and bradycardia
3. Miscellaneous causes of CHF include the following:
a. Severe anemia may cause high-output CHF.
b. Rapid infusion of intravenous fluids, especially in premature infants
c. Obstructive processes of the airway, such as enlarged tonsils or adenoids, laryngomalacia, and cystic fibrosis may cause CHF as a result of chronic hypoxemia that results in pulmonary hypertension and right-sided heart failure.
D. Clinical features
1. Tachypnea, cough, wheezing, and rales on examination and pulmonary edema on chest radiograph (CXR) are evidence of pulmonary congestion.
2. Tachycardia, sweating, pale or ashen skin color, diminished urine output, and enlarged cardiac silhouette on CXR are evidence of impaired myocardial performance and therefore poor cardiac output.
3. Hepatomegaly and peripheral edema are evidence of systemic venous congestion.
4. Other signs and symptoms include failure to thrive, poor feeding (common symptom in newborns), and exercise intolerance (common symptom in older children and adolescents).
5. Cyanosis and shock are late manifestations.
E. Management
1. Goals of medical management are to improve myocardial function and relieve pulmonary and systemic congestion.
a. Cardiac glycosides (e.g., digoxin) may increase the efficiency of myocardial contractions and relieve tachycardia.
b. Loop diuretics (e.g., furosemide, ethacrynic acid) reduce intravascular volume by maximizing sodium loss, which in turn leads to diminished ventricular dilation and improved cardiac function.
c. Inotropic medications (e.g., dobutamine, dopamine, epinephrine) are administered intravenously to augment cardiac contractility, thereby increasing the force of the heart’s contraction. They may be used to treat severe CHF.
d. Other medications, such as amrinone and milrinone (phosphodiesterase inhibitors) improve contractility and reduce afterload (the pressure in the aorta that the left ventricle must overcome to eject blood).
2. Interventional catheterization procedures can address some of the underlying causes of CHF (e.g., balloon valvuloplasty for critical aortic and pulmonary valve stenosis).
3. Surgical repair is often the definitive treatment of CHF secondary to CHD.
4. Cardiac transplant is reserved for the most severe cases of CHF that are refractory to medical management.
II. Innocent Cardiac Murmurs
A. Definition. Innocent murmurs result from turbulent but normal blood flow, are not caused by structural heart disease, and have no hemodynamic significance.
B. Epidemiology. Approximately 50% of children have an innocent heart murmur at some point during childhood.
C. Clinical features. The most common innocent heart murmurs are presented in Table 8-1.
Table 8-1
Clinical Features of Innocent Heart Murmurs
Murmur Age Location Characteristics
Still’s murmur (left ventricular outflow tract) Ages 2–7 years Mid-left sternal border Grade 1–3, systolic
Vibratory, twanging, or buzzing
Loudest supine
Louder with exercise and expiration
Pulmonic systolic murmur
(systolic ejection murmur) Any age Upper left sternal border Grade 1–2, peaks early in systole
Blowing, high-pitched
Loudest supine
Louder with exercise and inspiration
Venous hum Any age, especially school age Neck and below the clavicles Continuous murmur
Heard only sitting or standing
Disappears if supine; changes with compression of the
jugular vein or with neck flexion or extension
III. Acyanotic Congenital Heart Disease
A. Normal cardiac anatomy is depicted in Figure 8-1.
B. Clinical and diagnostic features. Physical examination, CXR, and electrocardiographic (ECG) findings of acyanotic CHD are presented in Table 8-2. Echocardiography confirms the specific anatomic lesions.
C. Atrial septal defect (ASD) (Figure 8-2)
1. Classification
a. Ostium primum. This type of ASD is a defect in the lower portion of the atrial septum. A cleft, or division, in the anterior mitral valve leaflet is almost always present and may cause mitral regurgitation. Ostium primum ASD is a common congenital heart lesion in Down syndrome.
b. Ostium secundum. This type of ASD is a defect in the middle portion of the atrial septum. Ostium secundum is the most common type of ASD.
c. Sinus venosus. This type of ASD is a defect superiorly and posteriorly in the septum near the junction of the right atrium and superior vena cava (SVC). In sinus venosus ASD, the right pulmonary veins usually drain anomalously into the right atrium or SVC instead of draining into the left atrium.
2. Pathophysiology. Blood flows across the ASD from the left atrium to the right atrium (i.e., left-to-right shunt). The direction of the blood flow is determined by the relative diastolic compliances of the right and left ventricles (which in turn are determined by systemic and pulmonary vascular resistances [SVR and PVR]). Blood therefore flows from areas of higher resistance to areas of lower resistance. Increased blood flow across the ASD leads to an increase in size of the right atrium and right ventricle and to increased pulmonary blood flow.
3. Clinical features
a. Symptoms are minimal, if any, except in patients with an ostium primum defect who develop mitral regurgitation that results in CHF.
b. Physical examination findings include the following:
1. Increased right ventricular impulse (manifesting as a stronger point of maximal impulse) as a result of right ventricular volume and pressure overload.
2. Systolic ejection murmur (from excessive pulmonary blood flow) best heard at the mid and upper left sternal borders. A mid diastolic filling rumble representing increased blood flow through the tricuspid valve may also be heard.
3. Fixed-split second heart sound. With blood shunting across the ASD from the left atrium to the right atrium to the right ventricle, the second heart sound is widely split because of the increased volume of blood that must be ejected from the right ventricle, leading to later closure of the pulmonic valve compared with the aortic valve (i.e., a wider split of the A2 and P2 components of the second heart sound). The splitting is fixed, and does not vary with respiration, because the blood shunting across the ASD ensures that the right ventricle receives a fixed volume of blood, by balancing the increased volume reaching the right ventricle with inspiration and the decreased volume of blood reaching the right ventricle with expiration (i.e., the normal physiologic variation in timing of aortic and pulmonic valve closure with respiration is absent).
4. Management. Treatment of primum and sinus venosus ASDs is closure by open heart
surgery to prevent right-sided heart failure, pulmonary hypertension, atrial dysrhythmias, and paradoxical embolism (a stroke caused by a blood clot traveling from the right atrium to the left atrium via the ASD). Most secundum ASDs can be successfully closed using interventional catheterization procedures with implantation of atrial septal occlusion devices.
D. Ventricular septal defect (VSD)
1. Classification. VSDs are classified by location as inlet, trabecular (muscular), membranous, and outlet (supracristal) (Figure 8-3).
2. Pathophysiology. After birth, as pulmonary vascular pressure decreases, blood flows across the VSD from the left ventricle to the right ventricle, owing to the lower resistance within the pulmonary circulation compared to the resistance within the systemic circulation. However, with time, the pulmonary vessels hypertrophy in response to this increased pulmonary flow. This hypertrophy may lead to increased PVR (pulmonary hypertension). If treated early, the increased PVR is usually reversible. If increased pulmonary blood flow persists, the pulmonary hypertension may become irreversible and even progress to Eisenmenger syndrome [see section III.D.3.d.(2)].
3. Clinical features and course vary greatly depending on the magnitude of the left-to- right shunting across the VSD. The amount of blood flow directed from one side of the heart to the other side (i.e., the shunt) is determined by both the size of the VSD and the degree of PVR. For example, the larger the VSD and the lower the PVR, the greater the blood flow across the VSD and into the pulmonary vessels. The greater the pulmonary blood flow, the more symptomatic the patient. Typical clinical presentations include the following:
a. Small VSDs have little to no shunt across the VSD and may close spontaneously. On examination, small VSDs typically have a high-pitched holosystolic murmur ranging from a grade 3 to grade 4 murmur. A thrill at the lower left sternal border and a grade 4 high-pitched holosystolic murmur is indicative of a very restrictive defect with a high flow velocity across the VSD. Key point: As the size of the VSD decreases, the intensity of the murmur increases.
b. Moderate VSDs may have a large shunt across the VSD that may result in signs and symptoms of CHF. A holosystolic murmur is usually present, and its intensity depends on the size of the shunt. If the left-to-right shunt across the VSD is large (2:1 pulmonary-to-systemic flow—i.e., twice as much blood flows to the lungs as to the systemic circulation), then a diastolic murmur of mitral turbulence may also be heard at the apex (mitral filling rumble representing the excess blood from the lungs now passing through the mitral valve).
c. Large VSDs often cause signs and symptoms of CHF. They have less turbulence across the VSD, so the systolic murmur is shorter and lower in pitch. A mitral filling rumble may be heard at the apex. The S2 tends to be loud and more narrowly split than usual, with P2 (pulmonary closure sound) being accentuated due to high pulmonary artery pressure.
d. PVR may eventually become elevated in moderate or large VSDs in response to chronically high pulmonary flow. When this occurs, clinical features change.
1. When PVR becomes elevated, the right ventricular impulse is noticeably increased and the second heart sound may be single and loud. The mitral filling rumble disappears because of diminished pulmonary blood flow as a result of decreased left-to-right shunting. Symptoms of CHF also diminish as PVR increases, because of the decrease in pulmonary blood flow.
2. If PVR remains elevated, pulmonary hypertension may become irreversible, even if the VSD is surgically closed. In the extreme situation in which PVR
increases and exceeds SVR, shunting changes from left-to-right to right-to-left (a condition termed Eisenmenger syndrome). The right-to-left shunt is manifested by cyanosis.
4. Management
a. Medical management of CHF is indicated in a symptomatic child. Large shunts are also associated with a high incidence of pulmonary infections from excessive blood flow.
b. Surgical closure is indicated in the following circumstances:
1. Heart failure refractory to medical management
2. Large VSDs with pulmonary hypertension are usually surgically closed at 3– 6 months of age.
3. Small to moderate VSDs with persistent left ventricular (LV) volume overload are usually surgically closed between 2 and 6 years of age. Some small VSDs may be left alone if there is no LV volume overload in childhood. Sometimes, transcatheter closure of smaller VSDs can be done with excellent results.
E. Patent ductus arteriosus (PDA)
1. Definition. In the fetus, the ductus arteriosus connects the pulmonary artery to the aorta. After birth, as the PaO2 rises, the ductus arteriosus normally fibroses. If it remains open, it is termed a PDA. The incidence of PDA is especially high in preterm infants.
2. Postnatal pathophysiology. In healthy infants the SVR exceeds PVR, and blood therefore flows through the PDA from the aorta to the pulmonary artery (left-to-right shunt). This leads to increased pulmonary blood flow (Figure 8-4).
3. Clinical features. Signs and symptoms depend on the size of the PDA and on the relationship between SVR and PVR.
a. Small PDAs usually produce no symptoms, but moderate or large PDAs almost always result in signs and symptoms of CHF due to increased pulmonary blood flow.
b. Physical examination findings
1. The classic murmur is a “machinery-like” continuous murmur at the upper left sternal border.
2. If the left-to-right shunt is large, there may also be a diastolic rumble of blood flow across the mitral valve at the apex, a widened pulse pressure (˃30 mm Hg) and bounding pulses.
c. Risk of pulmonary hypertension caused by excessive pulmonary blood flow through a large PDA over time.
4. Management
a. Indomethacin is often used in premature infants to close a PDA medically.
b. PDAs in the nonneonate are usually closed surgically by transcatheter insertion of a device.
F. Coarctation of the aorta
1. Definition. Coarctation of the aorta is narrowing of the aortic arch, just below the origin of the left subclavian artery and typically at, or just proximal to, the origin of the ductus arteriosus. It may be a discrete narrowing (hourglass) or a long-segment obstruction.
2. Pathophysiology. The narrowed segment obstructs or diminishes flow from the proximal to the distal aorta (Figure 8-5).
3. Clinical features. Signs and symptoms depend on the severity of the obstruction and on the presence of any other associated cardiac abnormalities.
a. Neonates or infants with severe coarctation may depend on a right-to-left shunt through the PDA for perfusion of the lower thoracic and descending aorta. Such
infants may be minimally symptomatic initially, but as the PDA closes, symptoms of CHF develop and progress.
1. Blood pressure may be elevated in the upper extremities and low in the lower extremities before the onset of CHF (before the PDA becomes narrower or closes).
2. Once the neonate or infant develops CHF, pulses in all four extremities are poor due to low cardiac output.
b. Older children or adolescents may have no symptoms and may have only hypertension or a heart murmur. Hypertension is typically noted in the right arm, and commonly in the left arm as well, with reduced blood pressure in the lower extremities.
1. Femoral pulse, which normally precedes the radial pulse, is dampened and delayed until after the radial pulse (radiofemoral delay).
2. Blood pressure and pulse findings may be less prominent if collateral vessels (intercostal arteries) develop, which allow the ascending aortic pressure and flow to circumvent the coarctation.
3. Bicuspid aortic valve or aortic stenosis is present in 50% of patients with coarctation of the aorta. If either of these conditions is present, a systolic murmur of aortic stenosis may be heard [see section III.G.3].
4. Bruit of turbulence through the coarctation may be audible at the left upper back near the left scapula.
4. Management
a. Initial management in the symptomatic neonate is directed at improving circulation to the lower body.
1. Intravenous prostaglandin E (PGE) is given urgently to open the ductus arteriosus.
2. Inotropic medications are given to overcome myocardial depression, and low-dose dopamine is used to maximize renal perfusion and function.
b. Corrective repair
1. Surgery is the usual approach in newborns and infants and involves excision of the narrowed segment followed by end-to-end anastomosis. Late recurrence of narrowing may occur in up to 50% of patients.
2. Balloon angioplasty with or without endovascular stent placement is the treatment of choice for short segment coarctations in school-age children and teens who have not undergone surgical correction. It is also the primary intervention for recurrent coarctation after surgical correction.
5. Prognosis is excellent, but long-term concerns include recurrence of coarctation and upper extremity hypertension with exercise.
G. Aortic stenosis
1. Definition. Aortic stenosis is narrowing of the aortic valve. Pathologically, aortic stenosis typically appears as commissural fusion of the three normal leaflets, leading to a bicuspid or unicuspid valve.
2. Pathophysiology. Aortic stenosis results in reduced LV output. At the myocardial level, aortic stenosis results in an imbalance between myocardial oxygen demand (which is higher than usual owing to the increased ventricular work as a result of outflow obstruction) and supply. This may lead to myocardial ischemia. In the neonate, severe aortic stenosis may be associated with hypoplasia of the left ventricle as a result of impaired fetal LV development.
3. Clinical features. Signs and symptoms depend on the severity of the stenosis and age.
Physical examination findings are presented in Table 8-2.
a. Neonates with severe stenosis (“critical aortic stenosis”) appear normal at birth but develop signs and symptoms of CHF at 12–24 hours of age. Once the PDA closes, all systemic flow must be ejected through the aortic valve. However, in critical aortic stenosis this is not possible and adequate perfusion to the body cannot be maintained.
b. Older children generally have no symptoms until the stenosis becomes severe. Once severe, symptoms include exercise intolerance, chest pain, syncope, and even sudden death.
4. Management. Indications for intervention include CHF, symptoms such as chest pain or syncope, and documentation of a high resting pressure gradient across the aortic valve (˃50–70 mm Hg).
a. Balloon valvuloplasty is often the initial management approach for aortic stenosis without associated significant regurgitation.
b. Surgery is often required for aortic stenosis with regurgitation and for recurrent stenosis. The aortic valve is replaced with either the patient’s own pulmonary valve (Ross procedure) or a prosthetic valve.
H. Pulmonary stenosis
1. Definition. Pulmonary stenosis is narrowing of the pulmonary valve. Pathologically, fusion of the valve commissures is typically seen.
2. Pathophysiology. Pulmonary stenosis results in increased right ventricular pressure and reduced right ventricular output.
3. Clinical features. Physical examination findings are presented in Table 8-2.
a. Severe pulmonary stenosis in the neonate may be manifested by cyanosis as a result of right-to-left shunting at the atrial level through a patent foramen ovale (PFO).
b. For most children, outflow obstruction is mild to moderate and symptoms are absent.
4. Management. Treatment is balloon valvuloplasty for symptomatic infants with critical pulmonary stenosis, and for older children with significant gradients across the pulmonary valve (˃35–40 mm Hg) or high right ventricular pressures.
FIGURE 8.1 Anatomy of the normal heart. Ao = aorta; MPA = main pulmonary artery; SVC = superior vena cava; IVC = inferior vena cava.
Table 8-2
Key Differentiating Clinical Features of Acyanotic Congenital Heart Disease
Heart Lesion Physical Examination Findings ECG Chest Radiograph
Atrial septal defect Systolic ejection murmur mid-left sternal border
and ULSB RAD, RVH, and RAE Right atrial and ventricular
enlargement
Fixed split S2 Increased PVM
Diastolic rumble LLSB
Ventricular High-pitched holosystolic murmur at LLSB, with
septal defect or without a thrillDiastolic rumble at apex if pulmonary blood flow is high If small: normal or
mild LVH If small: normal
If moderate: LVHRVH if pulmonary hypertension present If moderate or large: cardiomegaly and increased
PVM
If elevated PVR: normal or
decreased PVM
Patent ductus arteriosus Continuous murmur at ULSB; “machinery-like” LVHRVH if Cardiomegaly with increased
pulmonary PVM hypertension present
Brisk pulses
Coarctation of the aorta (older child) Elevated BP in right arm Normal or LVH Normal heart sizeRib notching
(evidence of collateral flow)
Reduced BP in legs
Dampened and delayed femoral pulse
Bruit left upper back
Aortic Ejection click at base and apex (fixed with Normal or LVH Normal or mild
stenosis respiratory cycle) cardiomegalyProminent ascending aorta (poststenotic dilation)
Systolic ejection murmur at base with radiation to
URSB, apex, suprasternal notch, and carotids
Thrill at URSB and suprasternal notch
Pulmonary stenosis Ejection click at apex (variable with respiratory
cycle) RVH NormalProminent main pulmonary artery due to
poststenotic dilation
Systolic ejection murmur at ULSB
ECG = electrocardiogram; ULSB = upper left sternal border; LLSB = lower left sternal border; URSB = upper right sternal border; S2 = second heart sound; LVH = left ventricular hypertrophy; RVH = right ventricular hypertrophy; BP = blood pressure; RAE = right atrial enlargement; RAD = right axis deviation; PVM = pulmonary vascular markings; PVR = pulmonary vascular resistance.
FIGURE 8.2 Location of atrial septal defects (ASDs). Arrows designate the direction of blood flow. Thick arrows designate increased blood flow. The right atrium and the right ventricle are enlarged. The location of the sinus venosus ASD is the posterior–superior aspect of the atrial septum.
FIGURE 8.3 Trabecular (muscular) ventricular septal defect (VSD). Arrows designate the direction of blood flow. Thick arrows designate increased blood flow.
FIGURE 8.4 Patent ductus arteriosus (PDA). Arrows designate the direction of blood flow. Thick arrows designate increased blood flow.
FIGURE 8.5 Coarctation of the aorta. Arrows designate the direction of blood flow.
IV. Cyanotic Congenital Heart Disease
A. General concepts
1. Cyanosis may be peripheral, central, or both. Peripheral cyanosis is usually caused by vasomotor instability or vasoconstriction as a result of cold temperature. Central cyanosis, especially apparent in the tongue and inner mucous membranes, may be attributable to both cardiac and noncardiac causes:
a. Noncardiac causes of central cyanosis include pulmonary disease, sepsis, hypoglycemia, polycythemia, and neuromuscular diseases that impair chest wall movement.
b. The most common cardiac causes of central cyanosis may be remembered using the mnemonic “5 T’s”: tetralogy of Fallot, transposition of the great arteries, tricuspid atresia, truncus arteriosus, and total anomalous pulmonary venous return.
2. Evaluation
a. A thorough physical examination is essential.
b. Other initial studies include pulse oximetry (in room air), complete blood count (CBC), arterial blood gas (ABG), ECG, and CXR. The degree of pulmonary blood flow seen on CXR may be useful in diagnosis (Table 8-3).
c. The 100% oxygen challenge test suggests cyanotic CHD when the PaO2 fails to rise above 100–150 mm Hg despite the administration of 100% oxygen.
d. Echocardiogram provides a definitive diagnosis.
3. Diagnosis. The distinguishing features of the five types of cyanotic CHD are presented in
Table 8-4.
B. Tetralogy of Fallot is the most common cause of central cyanosis presenting beyond the newborn period.
1. Definition. Tetralogy of Fallot has four anatomic components:
a. VSD
b. Overriding aorta (aorta overlies a portion of the ventricular septum)
c. Pulmonary stenosis
d. Right ventricular hypertrophy (RVH)
2. Pathophysiology. As a result of right ventricular outflow tract obstruction (RVOT; pulmonary stenosis), blood flows from right to left across the VSD and into the overriding aorta (Figure 8-6), resulting in cyanosis.
3. Clinical features. Signs and symptoms depend on the severity of the RVOT obstruction.
a. Physical examination findings include an increased right ventricular impulse because of RVH, a systolic ejection murmur representing pulmonary stenosis (see Table 8-2), and cyanosis.
b. Cyanosis depends on the interplay between the resistance to flow out of the RVOT and the SVR. It is important to remember that blood always flows from higher resistance to lower resistance.
1. Actions that decrease SVR (e.g., exercise, vasodilation, volume depletion) or increase resistance through the RVOT (e.g., crying, tachycardia) increase right-to-left shunting from the right ventricle through the VSD and to the aorta, resulting in cyanosis.
2. Actions that increase SVR or reduce resistance through the RVOT (e.g., volume infusion, systemic hypertension, Valsalva maneuver, bradycardia) reduce the right-to-left shunt through the VSD and therefore increase systemic arterial saturation.
3. Neonates with severe pulmonary stenosis or atresia present with cyanosis
immediately after birth once the PDA closes. These patients are dependent on the PDA for blood flow to the lungs.
c. Tetralogy of Fallot (hypercyanotic or “tet”) spells are characterized by sudden cyanosis and decreased murmur intensity.
1. The trigger may be any condition such as dehydration or crying that decreases arterial oxygen saturation.
2. With desaturation, the child typically becomes irritable and cries, which increases resistance through the RVOT, worsening the cyanosis by increasing the right-to-left shunt, resulting in a cycle of increasing cyanosis.
3. Alterations in consciousness and hyperpnea may occur as a result of severe hypoxia and acidosis.
4. To compensate, a child with tetralogy of Fallot learns to squat. This position (knee-chest position in an infant) increases venous return to the heart and increases SVR, thereby decreasing the right-to-left shunt.
4. Management (Table 8-5 describes management of “tet” spell)
a. Definitive management is complete surgical repair at 2–8 months of age.
b. Some infants with unfavorable anatomy (small pulmonary arteries) or with recurrent tetralogy of Fallot spells may initially undergo a palliative procedure to improve systemic saturation and encourage pulmonary growth. The procedure involves either a modified Blalock–Taussig shunt (Gore-Tex graft interposed between the subclavian and ipsilateral pulmonary artery) or balloon pulmonary valvuloplasty. In the neonate who requires intervention, transcatheter stenting of the PDA is also an option.
C. TGA
1. Definition. TGA occurs when the aorta arises from the right ventricle and the main pulmonary artery from the left ventricle.
2. Pathophysiology (Figure 8-7)
a. Pulmonary and systemic circulations are in parallel, rather than in series.
b. Adequate saturation can only be achieved by shunting blood from one circulation to the other through a PFO, ASD, VSD, or PDA.
3. Clinical features
a. Cyanosis is present at, or shortly after, birth. Cyanosis is more intense if the PFO is small. Cyanosis is less intense if the PFO is large or if there are additional sites of mixing, such as an ASD or VSD.
b. Physical examination findings include an infant who appears healthy but who has central cyanosis, a quiet precordium, and on auscultation, a single S2 (because the aortic valve is anterior and the pulmonary valve is posterior in TGA, the closure of the pulmonary valve is difficult to hear) and no murmur.
4. Management
a. Neonates may require initial management with PGE to improve oxygen saturation by keeping the ductus patent. Emergent balloon atrial septostomy (Rashkind procedure) is an often life-saving procedure that increases the size of an ASD or PFO.
b. Definitive repair is the arterial switch operation, in which the great arteries are incised above their respective valves and implanted in the opposite root. The coronary arteries are attached to the original aorta, so the coronaries must also be incised and reimplanted.
D. Tricuspid atresia
1. Definition. Tricuspid atresia is defined anatomically as a plate of tissue located in the floor of the right atrium in the location of the tricuspid valve. An ASD or PFO is always
present to allow for right-to-left shunting.
2. Pathophysiology. Whether a VSD is also present plays a significant role in determining the clinical presentation.
a. If no VSD is present and the ventricular septum is intact, pulmonary atresia is also present. For blood to flow to the lungs in this situation, a PDA must be present. As the PDA constricts after birth, visible cyanosis develops.
b. If a VSD is present, blood flow from the left ventricle through the VSD and into the pulmonary artery (left-to-right shunt) may be adequate, facilitating acceptable systemic oxygen saturations (Figure 8-8).
3. Clinical features. Signs also depend on anatomy.
a. Patients with an intact ventricular septum and pulmonary atresia have no murmur
and a single S2.
b. Patients with a VSD have a VSD murmur (see Table 8-2).
c. ECG shows right atrial enlargement, left axis deviation (LAD), and left ventricular hypertrophy (LVH). Tricuspid atresia is the only cause of cyanosis in the newborn period that results in LAD and LVH.
4. Management. Treatment includes staged surgery with eventual Fontan procedure at 3– 6 years of age.
a. A bidirectional Glenn shunt (SVC is anastomosed to the right pulmonary artery) is usually performed at 4–6 months of age.
b. In the Fontan procedure, flow from the inferior vena cava is directed into the pulmonary arteries, usually by means of an extracardiac conduit.
c. The net result of these procedures is systemic venous return directed to the pulmonary artery.
E. Truncus arteriosus
1. Definition. Truncus arteriosus occurs when the aorta and pulmonary artery originate from a common artery, the truncus. The pulmonary arteries usually originate from the proximal truncus, and the truncal valve may be regurgitant or stenotic. A VSD is almost always present.
2. Pathophysiology. Because the aorta and pulmonary arteries are connected and the pulmonary arteries are well formed, excessive blood flows to the lungs and CHF commonly develops. Mixing of desaturated and saturated blood occurs within the truncus, and patients are commonly only mildly desaturated and mildly cyanotic (Figure 8- 9).
3. Clinical features
a. Signs and symptoms of CHF are common.
b. Physical examination findings
1. Systolic ejection murmur at the base from increased flow across the truncal valve and a single S2 caused by the presence of only one atrioventricular (AV) valve
2. Diastolic murmur of flow across the mitral valve at the apex as a result of excessive pulmonary blood flow that returns to the left atrium
3. High-pitched diastolic murmur at the base indicates regurgitation of the truncal valve.
4. Management. Treatment includes medications for CHF and surgical repair early in infancy to close the VSD and to place a valved cadaveric homograft between the right ventricle and pulmonary artery.
F. TAPVR
1. Definition. TAPVR occurs when the pulmonary veins drain into the systemic venous side rather than into the left atrium. Sites of pulmonary venous drainage include
supracardiac (into the right SVC or innominate vein), cardiac (into the right atrium or coronary sinus), and infracardiac (into the portal system and eventually into the inferior vena cava).
2. Pathophysiology. Systemic and pulmonary venous blood enters the right atrium and mixes together. As a result, this mixture of systemic and pulmonary venous blood is present in all four cardiac chambers (blood also passes across a PFO or ASD into the left side of the heart), pulmonary arteries, and aorta, resulting in desaturated systemic blood and visible cyanosis on examination.
3. Clinical features
a. Cyanosis is present, and if severe, may indicate obstruction of pulmonary venous return.
b. Pulmonary flow murmur at the mid-left sternal border is caused by increased pulmonary blood flow.
4. Management. Treatment is surgical repair shortly after diagnosis. The pulmonary veins are anastomosed to the back of the left atrium, and the PFO or ASD is closed.
Table 8-3
Cyanotic Congenital Heart Disease Lesions and Pulmonary Blood Flow on Chest Radiograph
Increased Pulmonary Flow Decreased Pulmonary Flow
Transposition of the great arteries Tetralogy of Fallot
Total anomalous pulmonary venous return Pulmonary atresia
Truncus arteriosus Tricuspid atresia
Single ventricle
Table 8-4
Key Differentiating Features of Cyanotic Congenital Heart Disease
Heart Lesion Physical Examination Findings ECG Chest Radiograph
Tetralogy of Fallot Systolic ejection murmur of pulmonary stenosis (Table 8-2)
RVH Upturned cardiac apex (“boot shaped”)
Decreased PVM
Right aortic arch (commonly)
Transposition of the great arteries No murmurSingle S2 Normal or RVH Small heart with narrow mediastinum (“egg-on-a-
string” appearance)
Increased PVM
Tricuspid atresia No murmur and single S2 if no VSD LAD,
RAE, and LVH Small heart
If VSD is present, systolic
murmur of VSD (Table 8-2)
Decreased PVM
Truncus arteriosus Single S2 CVH Enlarged heart
Systolic ejection murmur along
the left sternal border Increased PVMRight aortic arch (commonly)
Diastolic murmur at the apex
Total anomalous pulmonary venous return Pulmonary ejection murmur along the left sternal border RVH and RAE Enlarged heart in older, unrepaired children with
supracardiac drainage (“snowman appearance”)
Increased PVM
If obstruction is present, small heart and pulmonary
edema
RVH = right ventricular hypertrophy; LAD = left axis deviation; RAE = right atrial enlargement; CVH = combined ventricular hypertrophy; PVM = pulmonary vascular markings; LVH = left ventricular hypertrophy; VSD = ventricular septal defect; S2 = second heart sound.
FIGURE 8.6 Tetralogy of Fallot. Arrows designate direction of blood flow. Thick arrows designate increased blood flow. VSD = ventricular septal defect.
Table 8-5
Acute Management of a Tetralogy of Fallot (“Tet” or Hypercyanotic) Spell
Placement in knee-chest position (mimics squatting position)
Intravenous fluid bolus
Oxygen
Sedation (morphine) to decrease agitation, which will then slow down the heart rate
β-Adrenergic blocker (e.g., propranolol) to slow down the heart rate, reduce contractility in right ventricular outflow tract, and
augment pulmonary blood flow
Intravenous sodium bicarbonate to correct any acidosis from prolonged hypoxia
Correction of significant anemia with transfusion
Rarely, general anesthesia and surgery
FIGURE 8.7 Transposition of the great arteries. A ventricular septal defect (VSD) is present. Arrows designate the direction of blood flow.
FIGURE 8.8 Tricuspid atresia with atrial septal defect (ASD) and ventricular septal defect (VSD). Arrows designate direction of blood flow. Thick arrows designate increased blood flow.
FIGURE 8.9 Truncus arteriosus with ventricular septal defect (VSD). Arrows designate the direction of blood flow. Thick arrows designate increased blood flow. The dashed line represents the other border of the pulmonary artery at the back of the truncus.
V. Acquired Heart Disease
A. Kawasaki disease is the most common cause of acquired heart disease in children in the United States and is discussed in Chapter 16, section II.
B. Acute rheumatic fever is the most common cause of acquired heart disease worldwide and is discussed in Chapter 16, section VI.
C. Infective endocarditis
1. Definition. Infective endocarditis is a microbial infection of the endocardium, or internal surface, of the heart.
2. Epidemiology
a. Eighty percent of cases occur in children who have structural abnormalities of the heart. Endocarditis may also occur in anatomically normal hearts, especially in the hearts of neonates and infants.
b. Fifty percent of cases occur soon after cardiac surgery.
3. Etiology
a. Gram-positive cocci, including α-hemolytic streptococcus (Streptococcus viridans)
and Staphylococcus species, are the most common bacterial agents.
b. Gram-negative organisms are rare causes of endocarditis.
c. Fungal endocarditis is extremely rare but may occur in a chronically ill child.
4. Pathophysiology
a. Bacteria are introduced into the blood spontaneously or during an invasive procedure. Bacteria then infect injured cardiac endothelium.
b. Fibrin and platelets adhere to the site of injury, creating a growth or vegetation. The vegetation may lead to incompetency of a valve.
c. Distal manifestations of disease may occur, including embolic phenomena and immunologic sequelae (e.g., nephropathy).
5. Clinical features (Table 8-6)
6. Diagnosis. History and physical examination, in addition to several other studies, are the basis of diagnosis.
a. Blood culture is the single most important laboratory test. Three sets of aerobic and anaerobic blood cultures should be drawn to maximize the likelihood of identifying the infecting organism. Because bacteremia is continuous in endocarditis, blood cultures may be drawn even if the patient is afebrile.
b. The erythrocyte sedimentation rate (ESR) is usually elevated, unless polycythemia is present. (Patients with cyanotic CHD may have reactive erythrocytosis.)
c. Other acute-phase reactants (e.g., rheumatoid factor) are found in 50% of patients.
d. Although transthoracic echocardiography may detect vegetations, transesophageal echocardiography is more sensitive than transthoracic echocardiography at identifying vegetations. However, a normal echocardiogram does not exclude endocarditis.
7. Management
a. Intravenous antimicrobial therapy is directed against the identified organism. Treatment for 4–6 weeks is required.
b. Because endocarditis is rarely a medical emergency, therapy may be safely withheld until an adequate number of blood cultures are obtained and the diagnosis is confirmed.
8. Antibiotic prophylaxis for endocarditis is recommended before invasive procedures in certain patients. Such procedures include dental work likely to produce bleeding, surgery (including tonsillectomy), and invasive gastrointestinal or urologic procedures.
This applies to a patient with any of the following circumstances:
a. A prosthetic cardiac valve or prosthetic material used for a valve repair
b. A personal history of infective endocarditis
c. CHD
1. Unrepaired cyanotic CHD
2. Completely repaired CHD with prosthetic material or device by surgery or catheter intervention within 6 months after the procedure
3. Repaired CHD with residual defects at or adjacent to a site of a prosthetic patch or device
d. A patient with a history of cardiac transplantation who develops a cardiac valvulopathy (e.g., valvular regurgitation or stenosis)
D. Pericarditis
1. Definition. Pericarditis is inflammation of the pericardial space.
2. Etiology. Causes most commonly include infection, collagen vascular disease (e.g., systemic lupus erythematosus [SLE]), uremia, and inflammatory response after cardiac surgery (postpericardiotomy syndrome).
a. Viral infection is the most common cause of pericarditis in children. Viruses include coxsackievirus, echovirus, adenovirus, influenza, parainfluenza, and Epstein–Barr virus (EBV).
b. Purulent pericarditis is usually caused by bacterial infection, either primary infection or disseminated from pneumonia or meningitis.
1. Staphylococcus aureus and Streptococcus pneumoniae are the most common agents.
2. Patients with purulent pericarditis have a high incidence of constrictive pericarditis owing to the intense inflammatory response.
c. Postpericardiotomy syndrome may occur in as many as one-third of patients whose pericardium has been opened during surgery. Patients typically present 1– 6 weeks after cardiac surgery with fever, pleuritis, and pericarditis with or without a pericardial effusion.
3. Pathophysiology. Inflammation of parietal and visceral pericardial layers leads to exudation or transudation of fluid and impairment of venous return and cardiac filling.
4. Clinical features
a. Symptoms include fever, dyspnea, malaise, and chest pain most intense while supine and relieved when sitting upright.
b. Physical examination findings include a pericardial friction rub, distant heart sounds if the effusion is large, pulsus paradoxus (˃10 mm Hg reduction in systolic blood pressure on deep inspiration), and hepatomegaly. Cardiac tamponade, or critically impaired LV output due to an acute accumulation of pericardial fluid, may occur and is life-threatening.
5. Diagnosis
a. Pericarditis should be considered in any child with dyspnea and fever, and in any patient who recently underwent cardiac surgery and has hemodynamic instability or nonspecific complaints of dyspnea or malaise.
b. Pericardiocentesis, in which a needle is inserted into the pericardial sac and fluid is withdrawn, is both diagnostic and therapeutic. Fluid should be sent for cell and serologic analysis and for culture.
c. ESR, although not specific for pericarditis, is elevated.
d. Imaging studies
1. ECG may show diffuse ST-segment elevations (Figure 8-10) or low-voltage QRS complexes in patients with large pericardial effusions.
2. CXR shows an enlarged heart shadow in patients with large effusions.
3. Echocardiogram demonstrates the size of the pericardial effusion.
6. Management
a. Appropriate antibiotics should be given if bacterial pericarditis is suspected.
b. Anti-inflammatory agents, such as aspirin or steroids, are indicated for viral pericarditis or postpericardiotomy syndrome.
c. Drainage of pericardial effusion by placement of a pericardial catheter or surgical window may be indicated.
E. Myocarditis
1. Definition. Myocarditis is inflammation of the myocardium, characterized by cellular infiltrate and myocardial cell death.
2. Epidemiology. Myocarditis is one of several common causes of sudden death in young athletes. Overall incidence is unknown, but evidence of myocarditis is apparent in 20% of children who die suddenly.
3. Etiology
a. Viruses, such as enteroviruses, especially coxsackievirus
b. Bacteria, such as Corynebacterium diphtheriae, Streptococcus pyogenes, S. aureus, and
Mycobacterium tuberculosis
c. Fungi, such as Candida and Cryptococcus
d. Protozoa, such as Trypanosoma cruzi (Chagas disease)
e. Autoimmune diseases, such as SLE, rheumatic fever, and sarcoidosis
f. Kawasaki disease
4. Pathophysiology. Myocarditis may involve infectious infiltration that damages myocardial cells, or activated lymphocytes that are misdirected to attack the myocardium.
5. Clinical features
a. Myocarditis frequently follows a viral or flul-ike illness.
b. Symptoms include dyspnea and malaise.
c. Physical examination shows resting tachycardia, muffled heart sounds, gallop heart rhythm, hepatomegaly, tachypnea, and pulmonary rales.
6. Diagnosis
a. Laboratory studies. Findings include elevated ESR, creatine kinase (CK)–MB fraction, troponin, and C-reactive protein (CRP) in most, but not all, cases. The etiologic organism may be identified by viral serology or polymerase chain reaction (PCR) of endomyocardial biopsy specimens.
b. Accessory tests
1. ECG may show T-wave and ST-segment changes. Atrial or ventricular dysrhythmias may be present.
2. Echocardiogram shows an anatomically normal heart with global ventricular dysfunction. Pericardial effusion and valvular regurgitation may be present.
7. Management. Treatment is largely supportive, with use of inotropic agents, diuretics, and afterload-reducing drugs as needed. Intravenous immune globulin may be helpful in some cases. Cardiac transplantation is an option for patients with CHF refractory to medical management.
8. Prognosis. Outlook is variable. Mortality is 10–20% and is especially high in young infants and in those with ventricular dysrhythmias.
F. Cardiomyopathy
1. Definition. Cardiomyopathy is defined as an abnormality of cardiac muscle manifested by systolic or diastolic dysfunction. There are three types of cardiomyopathy, including dilated cardiomyopathy, hypertrophic cardiomyopathy, and restrictive cardiomyopathy.
2. Dilated cardiomyopathy
a. Definition. This primary myocardial disorder (i.e., not attributable to valvular, coronary artery, pericardial, or CHD) is characterized by ventricular dilation and reduced cardiac function.
b. Etiology. Dilated cardiomyopathy is frequently idiopathic, but many causes have been identified.
1. Viral myocarditis
2. Mitochondrial abnormalities
3. Carnitine deficiency
4. Nutritional deficiency, such as selenium and thiamine deficiency
5. Hypocalcemia
6. Chronic tachydysrhythmias
7. Anomalous origin of left coronary artery from the pulmonary artery
(ALCAPA), which results in myocardial ischemia and infarction
8. Medications (e.g., doxorubicin)
c. Clinical features. Signs and symptoms of CHF may be present.
d. Diagnosis. Evaluation should include viral serologies and serum carnitine level. In addition:
1. ECG shows sinus tachycardia, low cardiac voltage, and ST-segment and T- wave changes. With ALCAPA, evidence of infarction is typically noted, with Q waves in leads I and aVL.
2. Echocardiogram shows a dilated left ventricle with poor ventricular function.
e. Management
1. Medical management of CHF
2. Treatment of underlying metabolic or nutritional problem
3. Surgical repair of ALCAPA (implantation of left coronary artery into the aortic sinus)
4. Cardiac transplantation if CHF is unresponsive to medical management (true for all cardiomyopathies, including those listed below).
3. Hypertrophic cardiomyopathy
a. Definition. Hypertrophic cardiomyopathy is LVH in the absence of any systemic or cardiac disease known to cause the hypertrophy. The most typical anatomic finding is asymmetric septal hypertrophy.
b. Etiology. Inheritance is autosomal dominant in 60% of cases. Infants of mothers with diabetes mellitus may have transient septal hypertrophy.
c. Pathophysiology
1. Poor LV filling due to reduced LV compliance
2. Dynamic left ventricular outflow tract (LVOT) obstruction is present and caused by the anterior mitral leaflet being swept into the subaortic region and coming into contact with the ventricular septum during systole.
3. Mismatch between myocardial oxygen demand and supply (owing to hypertrophy) may result in myocardial ischemia.
d. Clinical features. Hypertrophic cardiomyopathy is the most common cause of sudden death in athletes.
1. Symptoms may be absent until syncope or sudden death occurs, or may include chest pain and exercise intolerance.
2. Physical examination shows a classic harsh, systolic ejection murmur at the apex that is accentuated with physiologic maneuvers that reduce LV volume, such as Valsalva or standing (by reducing LV volume, these maneuvers worsen the outflow obstruction, increasing the intensity of the murmur).
e. Diagnosis
1. ECG shows LVH, ST-segment and T-wave changes, LAD, and abnormally deep and wide Q waves in the inferior and lateral leads.
2. Echocardiogram shows the hypertrophy.
f. Management. Treatment is generally reserved for patients with symptoms.
1. β-Adrenergic blockers or calcium-channel blockers reduce the LVOT obstruction and improve diastolic compliance.
2. Surgical myomectomy has been recommended for patients with severe obstruction refractory to medical management.
3. Antiarrhythmic medications may be needed, as ventricular dysrhythmias are common.
4. Automatic implantable cardioverter defibrillator, or AICD, is implanted in patients who are felt to be at high risk for ventricular dysrhythmias and sudden death.
5. Participation in competitive athletic sports should be prohibited.
6. β2-agonists, such as albuterol, are contraindicated in hypertrophic cardiomyopathy.
4. Restrictive cardiomyopathy
a. Definition. Restrictive cardiomyopathy is defined as excessively rigid ventricular walls that impair normal diastolic filling.
b. Etiology
1. Amyloidosis
2. Inherited infiltrative disorders (e.g., Fabry disease, Gaucher disease, hemosiderosis, hemochromatosis)
c. Clinical features
1. Symptoms include exercise intolerance (because of limitation of cardiac output), weakness, and dyspnea.
2. Physical examination shows edema, hepatomegaly, and ascites. These findings are caused by elevated central venous pressure (CVP).
d. Management. Treatment is related to reducing CVP with diuretics and improving diastolic compliance with β-adrenergic blockers and calcium-channel blockers.
Table 8-6
Clinical Features of Bacterial Endocarditis
Symptoms
Fever (most common symptom)
Nonspecific complaints, such as malaise, arthralgia, headache, weight loss, night sweats, and anorexia
Signs
New or changing murmur
Splenomegaly
Microscopic or gross hematuria (as a result of embolism or endocarditis-associated glomerulonephritis)
Splinter hemorrhages (linear hemorrhages beneath the nails)
Retinal hemorrhages
Osler nodes (small, raised pink, red, or blue swollen tender lesions on the palms, soles, or pads of the toes or fingers)
Janeway lesions (small, erythematous hemorrhagic lesions on the palms or soles)
Roth spots (round or oval white spots seen in the retina)
FIGURE 8.10 ST-segment elevation in a patient with acute pericarditis. A. Lead V3 shows the ST- segment elevation of acute pericarditis. B. Several days later, the same lead shows that the ST segments have returned to baseline and the T waves have inverted. There are no Q waves.
Reprinted with permission from Kline-Tilford AM, Haut C. Lippincott Certification Review: Pediatric Acute Care Nurse Practitioner. 1st Ed. Philadelphia: Wolters Kluwer, 2016.
VI. Dysrhythmias
The most common dysrhythmias of childhood include supraventricular tachycardia (SVT), heart block, and long QT syndrome.
A. SVT
1. Definition. SVT is an abnormally accelerated heart rhythm that originates proximal to the bifurcation of the bundle of His. SVT is the most common dysrhythmia in childhood. It is necessary to distinguish SVT from sinus tachycardia, as detailed in Table 8-7.
2. Pathophysiology. Two types of SVT occur.
a. Atrioventricular reentrant tachycardia (AVRT). Retrograde conduction through an accessory pathway leads to SVT.
b. Atrioventricular node reentrant tachycardia (AVNRT). The conduction abnormality occurs in different pathways within the AV node itself.
c. When anterograde conduction occurs through a bypass tract between the atria and ventricles, Wolff–Parkinson–White (WPW) syndrome is present. WPW is associated with sudden cardiac death.
3. Clinical features. Symptoms include palpitations, chest pain, dyspnea, and sometimes altered level of consciousness. Prolonged SVT may lead to signs and symptoms of CHF, especially in the neonate.
4. Diagnosis. WPW may be identified on ECG by the presence of a delta wave (i.e., slurred upslope of the QRS complex with a short PR interval; Figure 8-11).
5. Management
a. Vagal maneuvers, such as Valsalva, placement of an ice pack to the face, unilateral carotid massage, placing the child upside down, and orbital pressure in an older child may all convert SVT into a sinus rhythm.
b. Intravenous adenosine is the primary medication used for acute conversion to a sinus rhythm. Other medications used acutely include propranolol, digoxin, procainamide, and amiodarone.
c. Synchronized cardioversion may be used in patients who are hemodynamically unstable.
d. Chronic medical management typically includes ß-adrenergic blockers.
e. Patients with WPW should undergo an exercise stress test for sudden cardiac death risk stratification. If the delta wave disappears during exercise, the pathway is considered low risk. If the delta wave persists during exercise, patients should be referred to a cardiac electrophysiologist for possible ablation.
f. Radiofrequency catheter ablation may be used to remove the accessory pathway in chronic SVT or in high-risk WPW.
B. Heart block or AV block
1. Definition and classification
a. Definition. Heart block is delayed or interrupted conduction of sinus or atrial impulses to the ventricles.
b. Classification. Heart block is classified on the basis of ECG findings (e.g., first, second, or third degree) and by the ratio of atrial to ventricular impulses (e.g., 1:1, 3:1, 3:2, and so on).
1. First-degree AV block is prolongation of the PR interval.
2. Second-degree AV block
a. Type I, also known as Wenckebach, is progressive prolongation of the PR interval leading to failed AV conduction.
b. Type II is abrupt failure of AV conduction without progressive prolongation of the PR interval.
3. Third-degree AV block is a complete block, with no conduction of atrial impulses to the ventricles.
2. Etiology
a. Congenital third-degree AV block is associated with children born to mothers with SLE.
b. Postsurgical AV block may occur as a result of cardiac surgery, especially after closure of a VSD that lies close to the conduction system.
c. Bacterial endocarditis may be associated with AV block.
3. Clinical features
a. First-degree AV block is typically asymptomatic.
b. Second- and third-degree AV block can have clinical features ranging from being asymptomatic to developing fatigue, dizziness or syncope, and rarely, sudden death.
4. Management
a. No treatment is indicated for first-degree AV block.
b. No treatment is indicated for type I second-degree AV block.
c. Cardiac pacemakers are indicated in type II second-degree AV block and symptomatic third-degree AV block.
C. Long QT syndrome
1. Definition. Long QT syndrome is prolongation of the QT interval. Prolongation increases the risk of lethal ventricular arrhythmias known as torsades de pointes.
2. Etiology
a. In 50% of cases, inheritance is either autosomal recessive (i.e., Jervell–Lange- Nielsen syndrome, associated with congenital deafness) or autosomal dominant (i.e., Romano–Ward syndrome, not associated with deafness).
b. Some cases may result from the use of drugs, which may directly, or in combination, prolong the QT interval (e.g., antifungals, phenothiazines, tricyclic antidepressants, erythromycin, terfenadine).
c. The remainder of cases are likely due to deletions in genes that are normally responsible for repolarization.
3. Clinical features. Presenting signs and symptoms include syncope (most common), seizure, palpitations, or sudden cardiac arrest. Exercise and emotion are often inciting factors.
4. Diagnosis. The corrected QT interval (QTc) is calculated by taking the measurement of the QT interval divided by the square root of the previous RR interval. Diagnosis of long QT is made on the basis of ECG showing a QTc greater than 0.44 seconds (up to
0.49 seconds may be normal in the first 6 months of life).
5. Management. Treatment of symptomatic patients includes a β-adrenergic blocker to reduce symptoms, although the QT interval usually remains prolonged. Treatment of asymptomatic individuals is controversial. Other therapeutic modalities include cardiac pacing, left stellate ganglionectomy, and an AICD.
Table 8-7
Features Differentiating Sinus Tachycardia from Supraventricular Tachycardia
Feature Sinus Tachycardia Supraventricular
Tachycardia
Rate (beats/minute) <230 in newborns Frequently >250
<210 in children
Heart rate variation Present Absent
P waves on ECG Normal (axis is 0°–90°) Absent or abnormal axis
Predisposing factors Fever, infection, anemia, and
hyperthyroidism None
Response to intervention (e.g., adenosine,
antipyretics, fluids) Gradual Rapid
ECG = electrocardiogram.
FIGURE 8.11 Electrocardiogram in a patient with Wolff–Parkinson–White syndrome. Note the wide QRS complex, the presence of a delta wave (slurred upstroke of R), and the short PR interval.
Reprinted with permission from Fleisher GR, Ludwig S, Bachur RG. Textbook of Pediatric Emergency Medicine. 6th Ed. Philadelphia: Lippincott Williams & Wilkins, 2010.
VII. Chest Pain
Chest pain is a common presenting complaint in children and adolescents. However, this symptom is rarely of cardiac origin. Figure 8-12 schematically presents the differential diagnosis of chest pain.
A. Cardiac chest pain
1. Pericarditis is the most common cause [see section V.D].
2. Chest pain or chest pressure that occurs with exercise or is associated with syncope, shortness of breath, or abnormal heart rhythm should be investigated further by a cardiologist. Appropriate testing (e.g., continuous ECG monitoring, echocardiography, exercise stress test) is necessary.
B. Noncardiac chest pain. Common causes include asthma, esophagitis, and costochondritis (tenderness in one or more costochondral joints).
FIGURE 8.12 Differential diagnosis of chest pain in children and adolescents.
Review Test
1. You are called to the newborn nursery to evaluate a 2-hour-old newborn who has suddenly become cyanotic. The oxygen saturation on room air is 69%, and the patient is tachycardic and tachypneic. Oxygen is administered without improvement in the patient’s oxygen saturation. On examination, you hear a loud S2 and no murmur. A chest radiograph shows increased pulmonary vascular markings, a narrow mediastinum, and a small heart. Which of the following would be the next step in management?
A. Start digoxin.
B. Refer the patient to surgery for placement of a Blalock–Taussig shunt.
C. Refer the patient to surgery for repair of a ventricular septal defect.
D. Proceed with pulmonary balloon valvuloplasty.
E. Begin infusion of prostaglandin E (PGE).
2. A 20-month-old boy with tetralogy of Fallot is admitted for evaluation of cyanosis that is increasing in frequency. As you conclude your history and physical examination, you witness an episode of cyanosis when the patient’s brother makes him cry. As the crying increases, the patient becomes more and more cyanotic. On examination, his cardiac murmur is now much softer than before he began crying. What is the next most appropriate step in management?
A. Intubate and begin mechanical ventilation.
B. Administer intravenous dopamine.
C. Place the patient in a knee-chest position.
D. Administer subcutaneous epinephrine.
E. Call for a cardiology consult.
3. A 10-year-old girl is seen for a routine health maintenance evaluation. Five years ago, she underwent surgical repair of coarctation of the aorta. On examination, the blood pressure in her right arm is 173/81 mm Hg, and her oxygen saturation is 97% in room air. Auscultation reveals a systolic ejection murmur audible throughout the precordium. The patient is otherwise asymptomatic. Which of the following would be the most appropriate next step in management?
A. Check the blood pressure in all extremities.
B. Refer the patient to a cardiac surgeon promptly.
C. Obtain an echocardiogram to rule out a bicuspid aortic valve.
D. Recheck the oxygen saturation in 100% oxygen.
E. Have the patient return in 6 months for reevaluation.
4. A 7-year-old boy presents with a 3-day history of fever (temperature to 39.7°C [103.5°F]), shortness of breath, and weakness. He also complains of chest pain, which is most intense when he lies down and improves when he sits upright. His past medical history is significant for closure of a ventricular septal defect 2 weeks ago. Which of the following findings is consistent with the most likely diagnosis?
A. Splinter hemorrhages
B. Pulsus paradoxus
C. Heart rate of 260 beats/minute with absent P waves
D. Prolongation of his QT interval
E. Tenderness at two of his costochondral joints
5. A 1-month-old female infant is seen in your office for a routine health maintenance evaluation. On examination, you hear a grade 4 holosystolic murmur at the left sternal border. Femoral pulses and oxygen saturation in room air are normal. The infant is otherwise well and growing normally. Which of the following statements regarding this patient’s condition is correct?
A. Without intervention, congestive heart failure will develop.
B. Eisenmenger syndrome will eventually occur.
C. Surgical closure of the patent ductus arteriosus is indicated.
D. The murmur may disappear without intervention.
E. Balloon valvuloplasty is indicated.
6. You are called to the nursery to evaluate a male newborn with cyanosis. On auscultation, you hear a single S2 but no murmur. Pulse oximetry shows an oxygen saturation of 72% in room air. An electrocardiogram reveals left axis deviation and left ventricular hypertrophy. What is his likely diagnosis?
A. Tetralogy of Fallot
B. Transposition of the great arteries
C. Truncus arteriosus
D. Total anomalous pulmonary venous return
E. Tricuspid atresia with intact ventricular septum
7. A 4-year-old boy is in the office for a routine health maintenance evaluation. His examination is normal except for multiple deep dental cavities. You plan on referring him for dental evaluation and possible dental extraction. His mother reminds you that he has a “heart condition.” Which of the following cardiac conditions requires antibiotic prophylaxis against endocarditis?
A. Patch repair of ventricular septal defect repaired 4 months ago
B. History of uncomplicated Kawasaki disease
C. Wolff–Parkinson–White syndrome
D. Patent ductus arteriosus
E. Ostium secundum atrial septal defect
8. You see a 7-week-old male infant with cough and poor feeding. Examination reveals a respiratory rate of 72 breaths/minute and a heart rate of 170 beats/minute. His weight is
7 pounds 6 oz, just 2 oz more than his birth weight. You hear diffuse rales throughout the lung fields and a systolic murmur on auscultation. The liver is 4 cm below the right costal margin. Which of the following conditions is the most likely cause of his signs and symptoms?
A. Large ventricular septal defect
B. Ostium secundum atrial septal defect
C. Small patent ductus arteriosus
D. Critical or severe aortic stenosis
E. Mild to moderate pulmonary stenosis
9. A thin 5-year-old boy presents for a routine health maintenance evaluation. He feels well and is growing normally. On examination, you hear a continuous murmur below the right midclavicle. The murmur is loudest while the patient is sitting and disappears while he is supine. The femoral pulses are normal. Which of the following conditions is the most likely diagnosis?
A. Aortic stenosis with regurgitation
B. Venous hum
C. Patent ductus arteriosus
D. Still’s murmur
E. Pulmonic systolic murmur
10. A 15-year-old boy complaints of chest pain that occurs during basketball practice. He is otherwise healthy and has no history of cardiac problems. Examination is normal except for a harsh systolic ejection murmur at the apex that worsens with standing and the Valsalva maneuver. An electrocardiogram demonstrates left ventricular hypertrophy and left axis deviation. Which of the following is the most appropriate initial management at this time regarding the likely diagnosis?
A. Start propranolol to reduce left ventricular outflow tract obstruction.
B. Admit for urgent aortic balloon valvuloplasty.
C. Reassure the patient that the murmur is innocent and allow complete athletic participation.
D. Admit for surgical myomectomy for septal hypertrophy.
E. Begin albuterol, as the patient’s chest pain is likely caused by asthma.
The response options for statements 11–13 are the same. You will be required to select one answer for each statement in the set.
A. Sinus tachycardia
B. Supraventricular tachycardia
C. Third-degree atrioventricular (AV) heart block
D. Wolff–Parkinson–White syndrome
E. Second-degree AV heart block, Wenckebach type
F. Prolonged QT syndrome
G. First-degree AV heart block
For each patient, select the most likely associated heart rhythm abnormality.
1. A female newborn is born to a mother with systemic lupus erythematosus.
2. A 10-year-old girl has congenital deafness.
3. A 5-year-old boy has an electrocardiogram that demonstrates a slurred upslope of the QRS complex.
The response options for statements 14–17 are the same. You will be required to select one answer for each statement in the set.
A. Tetralogy of Fallot
B. Truncus arteriosus
C. Transposition of the great arteries
D. Total anomalous pulmonary venous return with supracardiac drainage
E. Tricuspid atresia with ventricular septal defect
For each clinical description, select the cyanotic congenital heart disease lesion.
1. A male newborn has cyanosis and no heart murmur on auscultation.
2. When a 4-year-old boy with cyanosis squats, his cyanosis improves.
3. A male newborn with cyanosis has an electrocardiogram that demonstrates left ventricular hypertrophy.
4. An 8-year-old boy has a chest radiograph that shows cardiomegaly with a “snowman” appearance.
Answers and Explanations
1. The answer is E [IV.C.4]. This patient’s clinical presentation and physical examination are most consistent with transposition of the great arteries (TGA). Because the pulmonary and systemic circulations are in parallel, rather than in series, blood must be shunted from one circulation to the other for survival, either by a patent ductus arteriosus or by a patent foramen ovale. Intravenous prostaglandin E (PGE) helps keep the ductus patent, which improves oxygen saturation. In some cases, a balloon atrial septostomy will be indicated. This patient’s presentation is not consistent with a ventricular septal defect. Neither digoxin, pulmonary balloon valvuloplasty, nor a Blalock–Taussig shunt is indicated in the management of a patient with TGA.
2. The answer is C [IV.B.3.c and Table 8-5]. Tetralogy of Fallot (hypercyanotic or “tet”) spells are defined as paroxysmal episodes of hyperpnea, irritability, and prolonged crying that result in increasing cyanosis and decreasing intensity of the heart murmur. This condition is often triggered by crying. Initial management is to increase systemic vascular resistance by placing the patient in a knee-chest position. Other therapeutic modalities include the administration of morphine sulfate, sodium bicarbonate, and intravenous fluids and the use of oxygen. Mechanical ventilation in combination with general anesthesia may be effective but would only be used when other management options fail to reverse the cyanosis. Dopamine and epinephrine are contraindicated because they may worsen the spell. A cardiology consultation may be useful, but the acuity of the patient’s clinical presentation requires immediate intervention.
3. The answer is A [III.F.3.b]. Restenosis is a known complication from repair of coarctation of the aorta, and these clinical features are consistent with restenosis. Patients with coarctation of the aorta classically present with hypertension in the right arm, and commonly in the left arm, and reduced blood pressures in the lower extremities. Therefore, the most appropriate initial step in this patient would be to obtain blood pressures in all four extremities. Balloon angioplasty with or without endovascular stenting is the treatment of choice for restenosis, rather than surgical repair, after the patient undergoes a complete evaluation. Confirmation of a bicuspid aortic valve is important because it may accompany coarctation in up to half of patients; however, it is not the most appropriate initial step in this patient’s management. The oxygen saturation is normal in room air and therefore does not require reassessment in 100% oxygen. Given the significantly elevated blood pressure, it is not appropriate to wait 6 months for reevaluation.
4. The answer is B [V.D.2.c, V.D.4]. This patient’s clinical presentation is most consistent with pericarditis. The likely cause of his pericarditis is postpericardiotomy syndrome, given the recent closure of his ventricular septal defect before the onset of his symptoms. Postpericardiotomy syndrome is believed to be an autoimmune response to a concomitant viral infection and is associated with opening of the pericardium during cardiac surgery. Pulsus paradoxus, or a greater-than-10 mm Hg drop in systolic blood pressure on deep inspiration, is found in patients with pericarditis. Splinter hemorrhages are noted in patients with endocarditis, which is also associated with fever. Supraventricular tachycardia, which would present as a rapid heart rate with absent P waves on electrocardiogram, may cause chest pain, but the pain would not change with position and fever would be absent. Prolonged QT syndrome is most often associated with syncope and sudden cardiac arrest. Costochondritis is a common cause of chest pain, but fever is not associated with this diagnosis.
5. The answer is D [III.D.3]. This patient’s murmur is consistent with a small ventricular septal defect (VSD). With a small VSD, a patient is likely to remain asymptomatic with normal
growth and development. Typically, the smaller the VSD, the louder the murmur. Small muscular or membranous VSDs may close on their own without intervention. Small VSDs do not generally result in congestive heart failure or in Eisenmenger syndrome. A patent ductus arteriosus would more commonly present with a machinery-like continuous murmur at the upper left sternal border. Balloon valvuloplasty is not indicated for a VSD.
6. The answer is E [IV.D.3 and Table 8-4]. Tricuspid atresia is the only cause of cyanosis in the newborn period that manifests with left axis deviation and left ventricular hypertrophy on electrocardiogram (ECG). Patients with tricuspid atresia without a ventricular septal defect have a single S2 as a result of the usual coexistence of pulmonary atresia and do not have a murmur. Patients with tetralogy of Fallot present with a systolic murmur of pulmonary stenosis and right ventricular hypertrophy (RVH) on ECG. Patients with transposition of the great arteries also have no murmur and a single S2 but will have RVH on ECG. Similarly, RVH is present in total anomalous pulmonary venous return, along with a systolic murmur. Truncus arteriosus manifests as combined ventricular hypertrophy with both a systolic and diastolic murmur.
7. The answer is A [V.C.8]. Before any invasive procedures that may result in bacteremia, prophylaxis against bacterial endocarditis is required for any patient who had structural heart disease repaired within the past 6 months. Patients with uncomplicated Kawasaki disease and cardiac dysrhythmias, including Wolff–Parkinson–White syndrome, or with acyanotic structural heart defects, such as patent ductus arteriosus, do not require antibiotic prophylaxis.
8. The answer is A [I.C.1.a]. This patient’s signs and symptoms are consistent with congestive heart failure (CHF). Forms of congenital heart disease that increase pulmonary blood flow, obstruct outflow, or overload portions of the heart through valvular regurgitation are among the many causes of CHF. Of the choices listed, only a large ventricular septal defect, which has a large left-to-right shunt with increased pulmonary blood blow, would cause CHF in a child of this age. Atrial septal defects, small patent ductus arteriosus defects, and mild to moderate pulmonary stenosis do not typically cause CHF. Critical or severe aortic stenosis may cause CHF, but this usually occurs within 24 hours of birth.
9. The answer is B [Table 8-1]. This murmur is most consistent with a venous hum, an innocent heart murmur. Aortic stenosis with regurgitation presents with systolic ejection and decrescendo diastolic murmurs. The murmur of a patent ductus arteriosus (PDA) is generally continuous and machinery-like and does not vary with position. Patients with PDAs generally also have brisk pulses. Both a Still’s murmur and a pulmonic systolic murmur are innocent systolic murmurs. A Still’s murmur is usually a grade 1–3 systolic murmur best heard at the mid-left sternal border. A pulmonic systolic murmur is a grade 1–2 high-pitched systolic murmur best heard at the upper left sternal border. Both the Still’s murmur and the pulmonic systolic murmur are loudest supine.
10. The answer is A [V.F.3]. This patient’s presentation, including the heart murmur and electrocardiogram findings, is consistent with hypertrophic cardiomyopathy. Initial management typically includes medications, such as β-adrenergic blockers or calcium-channel blockers, to reduce the left ventricular outflow tract obstruction and improve ventricular compliance. Aortic balloon valvuloplasty is a treatment for aortic stenosis. In aortic stenosis, the murmur would not be expected to increase with the Valsalva maneuver or with standing. Patients with hypertrophic cardiomyopathy are at risk for sudden death and should be restricted from athletic participation. Myomectomy is recommended for severe obstruction refractory to medical management. Albuterol is a β2-agonist and is contraindicated in hypertrophic cardiomyopathy.
11. The answers are C, F, and D, respectively [VI.A–VI.C]. Congenital third-degree atrioventricular block is a complete heart block, with no conduction of atrial impulses to the ventricles. It is associated with infants born to mothers with systemic lupus erythematosus.
Long QT interval is a lengthening of the QT interval, which increases the risk of lethal ventricular arrhythmias. There are two inherited forms of the disorder, one associated with congenital deafness (autosomal recessive Jervell–Lange-Nielsen syndrome) and one not associated with congenital deafness (autosomal dominant Romano–Ward syndrome). Wolff– Parkinson–White syndrome is a form of supraventricular tachycardia that is identified by the presence of a delta wave (slurred upslope of the QRS complex) on electrocardiogram.
12. The answers are C, A, E, and D, respectively [IV.B–IV.D, IV.F, and Table 8-4]. Transposition of the great arteries presents with no murmur and a single S2 on auscultation. Squatting, or knee-chest positioning, increases systemic vascular resistance, which decreases the right-to-left shunt through a ventricular septal defect in tetralogy of Fallot. It is usually the first maneuver attempted to resolve a “tet” or hypercyanotic spell. Tricuspid atresia is the only cyanotic congenital heart disease lesion that manifests left ventricular hypertrophy on electrocardiogram in the newborn period. The classic chest radiograph in older children with unrepaired total anomalous pulmonary venous return and with supracardiac drainage is cardiomegaly with a “snowman” appearance.