Cardiomyopathy III: Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy, or HCM, is an autosomal dominant genetic disorder characterized by asymmetric left ventricular hypertrophy without ventricular dilation.

Common genes involved include MYH7 and MYBPC3.

Mutations in these genes cause cardiac muscle cells to hypertrophy, become disorganized, and orient obliquely or perpendicularly to each other.

This disarray results in the thickening of the ventricular walls, especially the interventricular septum.

The thickened septum may obstruct blood flow out of the left ventricle. Additionally, the thickened walls decrease ventricular compliance, resulting in impaired ventricular filling during diastole, leading to diastolic dysfunction.

Patients with HCM may be asymptomatic or experience symptoms such as fatigue, angina, exertional dyspnea, and syncope.

Next, diagnosis of HCM primarily involves echocardiography to assess heart muscle thickness and outflow tract obstruction.

During chest palpation, an exaggerated, left-displaced apical impulse may be felt, and auscultation might reveal an S4 heart sound and a systolic murmur.

ECG findings include ST-T wave abnormalities and arrhythmias like atrial fibrillation.