What is hypertrophic cardiomyopathy (HCM)?
Hypertrophic cardiomyopathy (HCM) is a heart disease where areas of heart muscle enlarge and thicken. The left side of the heart is most commonly affected. The heart’s ventricle becomes smaller in capacity due to the thickening of its walls. Because the ventricle holds less blood, the heart must beat faster (tachycardia) to pump the same amount of blood to the body. As a result, the heart spends less time in diastole (the time between heartbeats) and therefore the ventricle does not fill as well. This decreases the amount of blood pumped out which again leads to an increased heart rate. While all this is occurring, the left atrium has to handle the same amount of blood returning to the heart. Since less is going into the ventricle with each beat, the atrium begins to stretch to accommodate the extra volume. Also, as changes in walls and pressures occur, the mitral valve (between the left atrium and ventricle) starts to leak, or regurgitate, blood back into the atrium when the ventricle
