Hypertrophic cardiomyopathy is a heart condition in which a portion of the myocardium is abnormally enlarged without any obvious cause. This hypertrophy of the heart muscle makes it harder for the heart to pump blood into the arteries. Hypertrophic cardiomyopathy is often asymmetrical, meaning one part of the heart is thicker than the other parts. The condition is usually passed down through families. It is believed to be a result of several problems (defects) with the genes that control heart muscle growth. The symptoms include chest pain, dizziness, high blood presure, heart failure, fainting, shortness of breath.
Individuals with hypertrophic cardiomyopathy have some degree of left ventricular hypertrophy. Usually this is an asymmetric hypertrophy, involving the inter-ventricular septum, and is known as asymmetric septal hypertrophy. This is in contrast to the concentric hypertrophy seen in aortic stenosis or hypertension. About two-thirds of individuals with hypertrophic cardiomyopathy have asymmetric septal hypertrophy. About 25% of individuals with HCM demonstrate an obstruction to the outflow of blood from the left ventricle during rest. In other individuals obstruction only occurs under certain conditions. This is known as dynamic outflow obstruction, because the degree of obstruction is variable and is dependent on the amount of blood in the ventricle immediately before ventricle systole.