Murmurs in valvular heart disease result when there is valvular insufficiency or regurgitation (the valves fail to close completely) or stenosis (narrowing of the valves). The aortic or mitral valves are most commonly involved in valvular disease.
For most of ventricular systole, the mitral valve should be closed and the aortic valve should be open, so that '' common systolic valvular defects '' include mitral insufficiency and aortic stenosis. For most of ventricular diastole, the mitral valve should be open and aortic valve should be closed , so that '' common diastolic valvular defects '' include mitral stenosis and aortic insufficiency.
A heart murmur is heard downstream from the valve. Thus, stenosis is orthograde direction from valve and insufficiency is retrograde direction from valve.
Auscultation sites for mitral and aortic murmurs are shown in figure