Definition
A.Syncope is a brief, sudden loss of consciousness and muscle tone secondary to cerebral ischemia, or inadequate oxygen or glucose delivery to brain tissue. Recovery is spontaneous.
Incidence
A.Syncope is a common problem in all age groups. Between 12% and 48% of healthy young adults have lost consciousness (one-third following trauma), but most do not seek medical attention. Adults older than age 75 in long-term care facilities have a 7% annual incidence of syncope, and 30% have had previous episodes. Syncopal episodes account for approximately 1% to 6% of hospital admissions and 3% of ED visits.
Pathogenesis
The most common cause of syncope is inadequate cerebral perfusion caused by one of the following:
A.Vasomotor instability associated with a decrease in systemic vascular resistance and/or venous return. The following may cause syncope:
1.Vasovagal episodes.
2.Situational syncope, from coughing, micturition, and defecation.
3.Medications:
a.Vasodilators.
b.Antiarrhythmics.
c.Diuretics.
d.Neurologic agents.
e.Glucose-regulating drugs.
f.Impotence therapy.
B.Decrease in cardiac output caused by blood-flow obstruction within the heart or pulmonary circulation or by arrhythmias. This may be caused by the following:
1.Aortic, pulmonic, and mitral stenosis.
2.Idiopathic hypertrophic subaortic stenosis (IHSS) or hypertrophic obstructive cardiomyopathy (HOCM).
3.Pump failure.
4.Subclavian steal syndrome.
5.Seizures.
C.Focal or generalized decrease in cerebral perfusion leading to transient ischemia due to cerebrovascular disease:
1.Carotid arterial disease.
D.Metabolic abnormalities:
1.Hypoglycemia.
2.Hypocarbia and hypoxia usually do not result in syncope unless they are profound, although consciousness may be altered.
E.Psychiatric illnesses associated with syncope include the following:
1.Generalized anxiety.
2.Panic attacks.
3.Major depressive disorders.
F.Unexplained cause.
Predisposing Factors
A.Advanced age, caused by altered regulation of cerebral blood flow and/or systemic arterial pressure due to aging process and increased medication use.
B.Other factors, depending on etiology.
C.Medication use (previously noted).
Common Complaints
A.Dizziness.
B.Lightheadedness.
C.Fainting with no memory of events.
Other Signs and Symptoms
A.Neuroautonomic regulations:
1.Event triggered by changing position, turning head, wearing tight collars.
2.Nausea, warmth, diaphoresis, weakness 1 hour after eating.
B.Cardiac causes: Exercise-induced palpitations, chest pain, shortness of breath (SOB), with no warning prior to episode.
C.Neurologic causes:
1.Vertigo.
2.Diplopia.
3.Facial paresthesias.
4.Ataxia.
5.Auditory, visual, or vestibular disturbances.
D.Metabolic or endocrine causes:
1.Restlessness.
2.Anxiety.
3.Confusion.
4.No recent food intake, low glucose level.
E.Psychiatric: Graceful fainting in presence of an audience.
Subjective Data
A.Inquire if the patient ever experienced similar symptoms or episodes before. If so, when and at what age did it begin?
B.Ask the patient or witness of the episode to give a detailed description of loss of consciousness. Was loss of consciousness complete, and if so for how long? What was the posture of the patient before, during, and after the event? Did it occur abruptly, or were there symptoms leading up to the event?
C.Question the patient regarding events leading up to the episode, noting prodromal symptoms such as headache, aura, nausea/vomiting, lightheadedness, diaphoresis, feeling, or warmth.
D.Obtain a detailed account of symptoms during and after the episode, noting mental status. Did the patient recover on his or her own, or did patient require assistance? Were there any associated symptoms that occurred during the event? SOB, chest pain, loss of bowel, or bladder control?
E.If syncope has occurred in the past, are there any events that precipitate an episode? Exertion, exercise, coughing, standing quickly?
F.Obtain a detailed medication history, addressing prescribed and over-the-counter (OTC) drugs, alcohol, and illicit preparations.
G.Review the patient’s past medical history.
Physical Examination
A.Check temperature, if indicated, pulse, respirations, and blood pressure (BP):
1.Measure BP and pulse in both arms and legs. Note BP differences between the arms.
2.Measure BP several times during a 2-minute period with the patient standing.
3.Check for orthostatic hypotension, which is defined as a drop of 20 mmHg or more in systolic blood pressure (SBP) on standing:
a.First, measure BP after the patient lies supine for 5 to 10 minutes.
b.Then have the patient stand, and measure BP several times during a 2-minute period.
B.Inspect the range of motion in the neck.
C.Palpate the abdomen, noting pulsatile expansion.
D.Auscultate:
1.Auscultate the heart with position changes. Note murmurs or extra heart sounds to rule out structural disease. Identify dysrhythmias such as bradycardia, supraventricular tachycardia, tachycardia, AV blocks, atrial fibrillation (AF), bundle branch blocks, and sinus pauses or arrests.
2.Auscultate the carotid arteries.
3.Auscultate the abdomen for bruits.
E.Neurologic exam: Perform a complete exam, if indicated, including assessing second to 12th cranial nerves, Babinski’s reflex, and gait.
F.Mental status: Assess mental health, if indicated.
Diagnostic Tests
The 2017 American College of Cardiology/American Heart Association (ACC/AHA) guideline for syncope recommends the following diagnostic tests based on history and physical findings:
A.If carotid sinus syndrome is suspected, carotid sinus massage can be attempted. Avoid in patients with history of transient ischemic attack (TIA) or stroke in the past 3 months and in patients with carotid bruits. Recommend physician or cardiology specialist assistance when performing carotid massage along with continuous cardiac monitoring. Use caution when performing carotid sinus massage. Please consider contraindications, complications, and guidelines for performing procedure.
B.Echocardiogram for patients with a history of heart disease, structural heart disease, or syncope secondary to cardiovascular cause (known heart disease), family history of unexplained sudden death in the family, syncope with exertion or supine, abnormal ECG, sudden onset of palpitation prior to syncope, or arrhythmia on ECG.
C.ECG for patients with suspected arrhythmia or cardiac disease. Identify acute and old ECG changes to rule out pathologic Q wave, ST segment elevation, and left ventricular (LV) hypertrophy.
D.Orthostatic challenge test if syncope is related to position change or suspect reflex mechanism.
E.Neurological/serum laboratory testing for other concerns of nonsyncopal loss of consciousness. Laboratory testing includes chemistry profile, thyroid-stimulating hormone (TSH), and free T4. Consider a glucose tolerance if diabetes is suspected. BNP may be useful to evaluate cardiac versus noncardiac cause for syncope.
F.Chest radiography, for essential baseline data. Wide mediastinum signals aortic dissection.
G.In-hospital monitoring is recommended for unstable, life-threatening patients.
H.Holter monitor for 24 to 48 hours.
I.External event monitor.
J.Exercise testing is recommended for patients with syncope that occurs during, or quickly after, cessation of exercise. Echocardiogram is recommended prior to this testing.
K.Cardiac catheterization.
L.Lung scan.
M.Treadmill test.
N.Electrophysiologic studies are recommended for patients with unexplained syncope.
Differential Diagnoses
A.Irregular neuroautonomic regulations:
1.Neurocardiogenic causes.
2.Situational causes, such as coughing, defecation, diving, micturition, sneezing, swallowing, trumpet playing, vagal stimulation, weight lifting, postprandial state.
3.Orthostatic causes:
a.Hyperadrenergic state.
b.Hypoadrenergic state, primary or secondary autonomic insufficiency.
c.Carotid sinus syncope.
d.Cardioinhibitory state.
e.Vasodepressor stimulation.
f.Mixed.
B.Cardiac causes:
1.Mechanical causes, such as aortic dissection, aortic stenosis, atrial myxoma, cardiac tamponade, global myocardial ischemia, hypertrophic cardiomyopathy, mitral stenosis, myocardial infarction (MI), prosthetic valve dysfunction, pulmonary embolism (PE), pulmonary hypertension (HTN), pulmonary stenosis, and Takayasu’s arteritis.
2.Electrical causes, such as AV block, long QT syndrome, pacemaker, sick sinus syndrome, supraventricular tachyarrhythmias, and ventricular tachyarrhythmias.
C.Neurologic causes:
1.Neuralgias: Glossopharyngeal, trigeminal.
2.Normal pressure hydrocephalus.
3.Subclavian steal.
4.Vertebrobasilar artery disease: Compression, migraine, TIA.
D.Metabolic or endocrine causes: Hypoadrenalism, hypoglycemia, hyponatremia, hypothyroidism, and hypoxia.
E.Psychiatric causes: Anxiety, hysteria, major depression, panic disorder, somatization, and hyperventilation syndrome.
Plan
A.General interventions: Management is directed at primary cause for the episode.
B.Patient teaching:
1.If the patient has orthostatic hypotension, suggest that he or she wear elastic stockings, change positions slowly, sleep with the head of the bed elevated, and exercise legs before standing.
2.If syncope is induced by situations, warn the patient to avoid or alter his or her approach to such precipitating events.
3.If the patient has prodromal symptoms, such as nausea, lightheadedness, pallor, sweating, or palpitations, advise him or her to lie down when they occur.
4.If the patient has hypersensitive carotid sinus reflex, recommend that he or she loosen his or her collar.
5.Tell patients to avoid prolonged standing. If they cannot avoid it, they should contract their calf muscles to increase venous blood flow.
6.Some driving restrictions exist for patients at risk for recurrent syncope. Driving restrictions are enforced by state law. Review restrictions with the patient and family as indicated by diagnosis.
C.Dietary management: If not contraindicated, instruct patients with orthostatic hypotension to use salt liberally.
D.Pharmaceutical therapy for neurocardiogenic syncope includes the following:
1.Nonpharmacologic methods suggested:
a.Avoid volume depletion.
b.Maintain adequate sodium levels by increasing salt intake in the diet.
c.Wear thigh-high elastic support hose with 30 to 40 mmHg pressure.
d.Orthostatic training is also recommended two times a day.
2.Drugs of choice: Beta-blockers (Inderal 80–160 mg/d, metoprolol 50–100 mg/d) for vasovagal syncope.
3.Fludrocortisone acetate (Florinef Acetate), a corticosteroid, may be used alone or with beta-blockers. Initial dosage is 0.1 to 0.4 mg/d; this may be increased gradually to 1.0 to 2.0 mg/d.
4.Other drugs include anticholinergic agents (disopyramide 100–200 mg twice daily sustained release), and selective serotonin reuptake inhibitors (SSRIs; Zoloft 50 mg/d, Prozac 20 mg/d, Paxil 20 mg/d).