changing murmurs in infective endocarditis
Last reviewed 01/2018
Heart murmurs are invariably present in infective endocarditis and changing murmurs are characteristic. The valve lesion is always destructive producing progressive incompetence. Two events are common:
- acute aortic incompetence caused by fenestration or inversion of an aortic valve cusp - produces a fall in cardiac output and a shock-like state. Tachycardia occurs with a small pulse volume. The first heart sound is lost owing to premature closure of the mitral valve caused by the very high end-diastolic pressure in the left ventricle. A third heart sound or a mitral diastolic murmur is common because of the brief time available for ventricular filling through the mitral valve.
- acute mitral incompetence caused by rupture of damaged chordae tendinae - produces a systolic murmur which peaks in mid-systole and is best heard at the base of the heart. The patient usually remains in sinus rhythm with little left atrial enlargement.