0071643192.pdf

A 17-year-old male presents to the ED after passing out during basketball

practice. He has no symptoms now, but his mom insisted he come in

because his cousin died while playing basketball 2 years ago. On exami-

nation, there is a systolic murmur that worsens with standing. What is the most

likely diagnosis?

Hypertrophic cardiomyopathy. Syncope is an independent predictor of sudden

cardiac death in patients with HCM. This patient requires hospitalization for further

monitoring and evaluation.

Hypertrophic Cardiomyopathy (HCM)

HCM was previously referred to as idiopathic hypertrophic subaortic stenosis
(IHSS). This is often an autosomal dominant disorder, so always ask about
sudden death or early cardiac disorders in family members. It is characterized
by asymmetric thickening of the LV septal wall.

PATHOPHYSIOLOGY

■ Decreased diastolic filling (diastolic dysfunction) from reduced compliance
■ Obstruction of the LV outflow tract
■ Overall cardiac function is usually normal.

SYMPTOMS

■ Dyspnea
■ Exertional syncope or sudden cardiac death
■ Chest pain
■ Palpitations and decreased exercise tolerance

EXAM

■ Loud crescendo-decrescendo systolic murmur heard best at the left lower
sternal border.
■ Murmur increases with ↓LV filling (standing, valsalva) by increasing
obstruction of LV outflow tract.
■ Murmur decreases with LV filling (squatting, leg elevation, or Trende-
lenburg) by lessening obstruction.
■ Paradoxically split S2
■ Bifid arterial pulse

DIFFERENTIAL

■ Aortic stenosis, pulmonary stenosis, VSD, mitral regurgitation

DIAGNOSIS

■ Suspect in any young person with exertional syncope, family history of
sudden death or characteristic murmur
■ ECG: Left atrial enlargement and LVH, septal Q waves
■ CXR: Mild cardiomegaly
■ Echo: Confirmatory: Left ventricular hypertrophy, asymmetric septal
hypertrophy

TREATMENT

■ Counsel avoidance of exertion.
■ Endocarditis prophylaxis

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CARDIOVASCULAR EMERGENCIES

Murmur of hypertrophic

cardiomyopathy

↓LV filling (standing,

valsalva)= murmur.

LV filling (squatting, leg

elevation)=↓murmur.

This is the opposite of aortic

stenosis!

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