The human body has four heart valves. In all four valves, the cusps may no longer be able to fully close nor sufficiently open. Arterial calcification, inflammations, congenital disorders or degenerative processes are potential causes for this. The functioning of the heart valves can be thoroughly tested using echocardiography. In addition, a cardiac catheterization test can also be necessary. Valvular heart disease can require a course of drug treatment or an operation. In the case of the most common vascular heart disease, aortic stenosis, a new heart valve can be implanted either via an operation or a new catheter procedure (TAVI).