Midsystolic clicks originiating from tricuspid valve structures: a sequela of heroin-induced endocarditis.

In two patients who had been heroin users, loud midsystolic clicks developed during infective endocarditis involving the tricuspid valve. The sounds were loudest along the left sternal border, exhibited an increase in intensity during inspiration and were associated with right atrial gallop sounds and with murmurs of tricuspid regurgitation. This constellation of clinical events suggests that the midstystolic clicks emanated from tricuspid valve structures as a result of disordered function of the chordae tendineae. Prolapse of the tricuspid valve has recently been demonstrated angiographically to accompany similar abnormalities of mitral valve motion in certain patients with the click-murmur syndrome. The participation of the tricuspid valve in the generation of the auscultatory finding is unclear, but the cases herein reported suggest that the tricuspid valve is capable of producing these findings.