EFFECT OF AMYL NITRITE ON MITRAL-VALVE PROLAPSE AND MITRAL REGURGITATION - A TRANSESOPHAGEAL ECHOCARDIOGRAPHIC STUDY

To test the hypothesis that amyl nitrite (AN) increases the degree of prolapse by reducing the left ventricular size and making the mitral apparatus relatively more redundant in patients with mitral valve prolapse (MVP), transesophageal echocardiography was performed in 23 patients with MVP before and after AN inhalation. The heart rate increased from 84 +/- 20 to 104 +/- 25 beats/min (p < 0.001), and the left ventricular end-diastolic dimension decreased from 40 +/- 6 to 37 +/- 5 mm (p < 0.001) after AN administration. The MVP area, the area between each mitral leaflet and a line connecting the mitral anulus and the leaflets' coaptation point, increased significantly after AN inhalation from 0.49 +/- 0.32 to 0.62 +/- 0.39 cm2 (p < 0.01) for the anterior mitral leaflet and from 0.22 +/- 0.20 to 0.29 +/- 0.21 cm2 (p < 0.001) for the posterior mitral leaflet. In contrast, the mitral regurgitant signal area measured using color-coded Doppler flow imaging decreased significantly from 1.10 +/- 1.25 to 0.65 +/- 1.23 cm2 (p < 0.001). Thus, AN in patients with MVP does increase the degrees of the prolapse, but decreases the degree of mitral regurgitation. The former may be explained by a reduction in left ventricular size and the latter by a decrease in left ventricular systolic pressure. Therefore, when evaluating the effects of various maneuvers on the dynamics of MVP, pressure as well as volume of the left ventricle should be taken into consideration.