Comparison of a Heart with HCM in Relaxation and in Contraction

An illustration of the obstructive form of HCM during relaxation (diastole, left) and active contraction (systole, right). The thickened septum and the mitral valve leaflets come in close proximity, effectively narrowing the pathway that blood must travel to get out of the heart. Additionally, the forces on the mitral valve can lead to variable degrees of backward leakage (regurgitation) that can also lead to symptoms.