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Wednesday, January 07, 2009

A young 25 year old male basket ball player suddenly collapsed while undergoing an athletic event and died.

Question 74
A young 25 year old male basket ball player suddenly collapsed while undergoing an athletic event and died. At Autopsy the septum was hypertrophied. The most probable diagnosis is
a.       HOCM
b.      Right Ventricular Conduction Abnormality
c.       Epilepsy
d.      Snake bite
a.       HOCM
Harrison 17th Edition page 1410
Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy, typically of a nondilated chamber, without obvious cause such as hypertension or aortic stenosis. It is found in about 1 in 500 of the general population.
Two features of HCM have attracted the greatest attention: (1) heterogeneous left ventricular hypertrophy, often with preferential hypertrophy of the interventricular septum resulting in asymmetric septal hypertrophy; and (2) a dynamic left ventricular outflow tract pressure gradient, related to a narrowing of the subaortic area as a consequence of the midsystolic apposition of the anterior mitral valve leaflet against the hypertrophied septum, i.e., systolic anterior motion (SAM) of the mitral valve. Initial studies of this disease emphasized the dynamic "obstructive" features, and it has been termed idiopathic hypertrophic subaortic stenosis and hypertrophic obstructive cardiomyopathy. It has become clear, however, that only about one-quarter of patients with HCM demonstrate an outflow tract pressure gradient. The ubiquitous pathophysiologic abnormality is not systolic but rather diastolic dysfunction, characterized by increased stiffness of the hypertrophied muscle. This results in elevated diastolic filling pressures and is present despite a hyperdynamic left ventricle
The clinical course of HCM is highly variable. Many patients are asymptomatic or mildly symptomatic and may be relatives of patients with known disease. Unfortunately, the first clinical manifestation of the disease may be sudden death, frequently occurring in children and young adults, often during or after physical exertion.
In symptomatic patients, the most common complaint is dyspnea, largely due to increased stiffness of the left ventricular walls, which impairs ventricular filling and leads to elevated left ventricular diastolic and left atrial pressures. Other symptoms include angina pectoris, fatigue, syncope, and near-syncope ("graying-out spells"). Symptoms are not closely related to the presence or severity of an outflow pressure gradient.
Most patients with gradients demonstrate a double or triple apical precordial impulse, a rapidly rising carotid arterial pulse, and a fourth heart sound. The hallmark of obstructive HCM is a systolic murmur, which is typically harsh, diamond-shaped, and usually begins well after the first heart sound, since ejection is unimpeded early in systole. The murmur is best heard at the lower left sternal border as well as at the apex, where it is often more holosystolic and blowing in quality, no doubt due to the mitral regurgitation that usually accompanies obstructive HCM.

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