Hypertrophic Cardiomyopathy is a condition, often inherited, where the heart muscle becomes progressively thicker. This makes it harder for the muscle to relax and allow the ventricles to fill between each beat (diastolic dysfunction). In some this muscle thickening can be focal and immediately beneath the outflow (aortic) valve of the heart causing progressively more obstruction. This can be quite dynamic, increasing markedly with exercise, resulting in symptoms of breathlessness and lethargy. This is called Hypertrophic Obstructive CardioMyopathy (HOCM). The turbulence created can also distort the nearby Mitral Valve causing it to leak and increasing symptoms. This condition is very well managed by surgically resecting some of this muscle bulge, allowing normal outflow of blood from the left ventricle. This is probably the condition that gets the greatest symptomatic improvement of all cardiac surgeries, and should be strongly considered in all with the appropriate anatomy. The underlying cardiomyopathy will still require medical management but the symptoms can be greatly relieved.