Effects of induced psychological stress on click and rhythm in mitral valve prolapse.

Our clinical observations suggested that anxiety accentuated the click in patients with mitral valve prolapse. In order to evaluate this systematically, a psychological stress was administered to 30 subjects--15 patients with click murmur syndrome and 15 normal controls. The phonocardiogram was recorded and the electrocardiogram were continuously monitored to assess the effects on arrhythmias. State Anxiety Inventory scores demonstrated an increase in anxiety during the psychological stress. A change in rhythm during psychological stress was noted in five of the 15 patients. No arrhythmias occurred in the control subjects during psychological stress (p less than .025). Amplitude of the click increased during psychological stress in five of the 15 patients, in four associated with arrhythmia. The only patient with auscultatory-electrocardiographic variant developed frequent, multifocal ventricular ectopics with couplets during the psychological stress. Acute psychological stress exerts important effects on the rhythm and click only in some patients with mitral valve prolapse, and may provide a mechanism for intermittence of clicks and episodes of profound unexplained arrhythmias.