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 Graphic Jump Location Table 18–1.Historical findings for syncope. ||Download (.pdf) 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
Table Graphic Jump Location Table 18–2.ECG findings associated with specific cardiac abnormalities. ||Download (.pdf) Table 18–2. ECG findings associated with specific cardiac abnormalities.
|Disease ||ECG findings |
|Hypertrophic cardiomyopathy || |
Q waves in lateral leads
|Aortic stenosis || |
|Vascular anomalies || |
ST/T wave changes
|Myocarditis || |
ST and T wave changes
|Dilated cardiomyopathy || |
ST/T wave changes
|Long QT syndrome ||QTc > 450 msec |
|Brugada syndrome ||ST elevation in right, precordial leads |
|Wolff-Parkinson-White syndrome || |
Short PR interval
SVT (usually narrow complex tachycardia with absent or polymorphic P waves)
|Catecholaminergic polymorphic ventricular tachycardia ||Resting: Normal or sinus bradycardia, U wave |
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 (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 ...