Hypertrophic cardiomyopathy - signs and symptoms, causes, pathophysiology, treatment
2 months ago
Hypertrophic cardiomyopathy (HCM) is the most common primary cardiomyopathy, with a prevalence of 1:500 persons. It is defined as left ventricular hypertrophy without chamber dilation. It is caused by autosomal dominant mutations of genes that code for sarcomere proteins. The most common mutation is of the myosin heavy chain. Secondary causes of hypertrophic cardiomyopathy is chronic hypertension and aortic stenosis. In Hypertrophic cardiomyopathy there are two main types of disease. The classic obstructive type which is characterized by ventricular hypertrophy as well as interventricular septal hypertrophy. The second type is the non-obstructive type which is just your basic Hypertrophy of the ventricles meaning increased ventricle wall thickness. In both obstructive and non-obstructive cases the cardiac output is reduced (more so during exercise) causing dyspnoea, presyncope, angina and increasing risk of arrhythmia. On examination, physicians may hear a systolic murmur typically a crescendo - decrescendo murmur that increases in intensity during Valsalva manoeuvres. There is a S4 gallop. It is best heard with the bell of the stethoscope at the apex of the heart. Additionally, electrocardiography findings often show left ventricular hypertrophy, deep q waves and left atrial enlargement. All patients with HCM should undergo these risk stratifications for sudden cardiac death and be evaluated for placement of an implantable cardioverter-defibrillator. Patient should avoid strenuous exercise as again this exacerbates the ventricular outflow tract obstruction. Beta blockers are the initial therapy in patients with symptomatic HCM.
Video by: Armando Hasudungan