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18: Syncope

Brit Anderson; Seema Bhatt

IMMEDIATE MANAGEMENT OF LIFE-THREATENING PROBLEMS CAUSING SYNCOPE

Although vasodepressor syncope is the most common cause of syncope in older children and adolescents, cardiac causes are the most concerning and life threatening in this group. Approximately 2–6% of all cases of pediatric syncope can be attributed to the heart. The rare, yet life-threatening causes of syncope must be discriminated from more benign etiologies. History, physical examination findings, and electrocardiograph (ECG) findings can be used by the emergency medical practitioner to screen for patients who may be at risk for cardiac pathology. Historical “red flags” include syncope with exertion and a positive family history (Table 18–1). Cardiac causes of syncope can be divided into structural, functional, and primary electrical categories. Table 18–2 lists ECG findings associated with specific cardiac abnormalities.

Table 18–1.Historical findings for syncope.
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Table 18–1. Historical findings for syncope.

  • History of heart disease

  • Syncope during exercise or exertion

  • Absence of prodromal symptoms

  • History of chest pain, palpitations, difficulty breathing

  • Family history

    • Sudden death

    • Pacemaker placement

    • Car accidents/drowning

    • Dysrhythmia

    • SIDS

    • Deafness
Table 18–2.ECG findings associated with specific cardiac abnormalities.
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Table 18–2. ECG findings associated with specific cardiac abnormalities.
Disease ECG findings
Hypertrophic cardiomyopathy

LAE

LVH

Axis deviation

Abnormal ST-segments

Q waves in lateral leads

TWI
Aortic stenosis

LVH

LV strain
Vascular anomalies

ST/T wave changes

Q waves

Strain/infarction
Myocarditis

Sinus tachycardia

ST and T wave changes

Q waves

BBB

Wide QRS
Dilated cardiomyopathy

Sinus tachycardia

ST/T wave changes

Q waves

Dysrhythmias
Long QT syndrome QTc > 450 msec
Brugada syndrome ST elevation in right, precordial leads
Wolff-Parkinson-White syndrome

Short PR interval

Delta wave

SVT (usually narrow complex tachycardia with absent or polymorphic P waves)
Catecholaminergic polymorphic ventricular tachycardia Resting: Normal or sinus bradycardia, U wave

LAE, left atrial enlargement; LVH, left ventricular hypertrophy; TWI, T-wave inversions; LV, left ventricular; BBB, bundle branch block.

STRUCTURAL HEART DISEASE

Structural heart disease includes a wide range of pathologies defined by an alteration in the physical architecture of the heart. History of syncope with exertion and anginal chest pain are concerning for structural heart disease. Mechanisms by which structural heart disease can cause syncope include arrhythmias and outflow obstruction. Structural abnormalities include hypertrophic cardiomyopathy, anomalous coronary arteries, and congenital heart conditions that have undergone repair.

Hypertrophic Cardiomyopathy

Clinical Findings

Hypertrophic cardiomyopathy (HCM) is characterized by asymmetric hypertrophy of the left ventricle. It is the most common genetic cardiovascular disease with an autosomal dominant pattern of inheritance. It is caused by a mutation in one of several genes, which accounts for the heterogeneity of clinical presentation.

HCM can lead to outflow obstruction or arrhythmias. The rate of sudden death is approximately 1 in 200,000, most commonly occurring ...

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