Hypertrophic Obstructive Cardiomyopathy (HOCM) 
 
Definition 
 
HOCM is a type of hypertrophic cardiomyopathy (HCM) in which the heart muscle (especially the interventricular septum) becomes abnormally thickened (hypertrophied) and obstructs blood flow from the left ventricle to the aorta. 
 
Pathophysiology 

Primarily Genetic cause (often autosomal dominant). 
The thickened septum narrows the left ventricular outflow tract (LVOT). 
The mitral valve leaflet may be pulled toward the septum during contraction (systolic anterior motion, or SAM), worsening the obstruction. 
This leads to increased pressure, reduced cardiac output, and sometimes arrhythmias. 
 
Symptoms 

Dyspnoea (shortness of breath) 
Chest pain (especially with exertion) 
Syncope (fainting), especially during exercise 
Palpitations or irregular heartbeat 
Sudden cardiac death (especially in young athletes) 
 
Clinical findings 
Harsh systolic murmur (heard best at left sternal border) 
Increases with Valsalva or standing (less venous return) 
Decreases with squatting (more venous return) 
Possible bifid (spike-and-dome) pulse (two closely spaced peaks per cardiac cycle rather than the usual one). 
 
Diagnosis 
Echocardiogram (ECHO): asymmetric septal hypertrophy, SAM of mitral valve, LVOT obstruction. 
ECG: left ventricular hypertrophy, deep Q waves, or repolarization abnormalities. 
Genetic testing may confirm the diagnosis. 
 
Treatment 
Beta-blockers (first-line): reduce heart rate and contractility demand. 
Calcium channel blockers (verapamil): alternative. 
Avoid preload-reducing drugs (diuretics, nitrates). 
Surgical options: septal myectomy or alcohol septal ablation. 
Implantable cardioverter-defibrillator (ICD) for high-risk patients (to prevent sudden cardiac death).