Stroke volume calculated from the mitral valve echogram in patients with and without ventricular dyssynergy

Abstract

A formula was derived for calculating mitral valve stroke volume (MVSV) using the rate of mitral valve (MV) opening (DE slope on the MV echogram), the vertical disease between the mitral leaflet echoes early in diastole (EE), the electrocardiographic PR interval and heart rate. The formula was tested prospectively on 80 consecutive patients from whom 95 simultaneous MV echograms and either thermodilution (45) or Fick (50) cardiac outputs were obtained. Sixteen patients were normal; 54 had coronary artery disease; three had cardiomyopathy; and seven had nonrheumatic mitral regurgitation (MR). Linear regression for stroke volume was r = 0.90, SEE +/- 6, and for cardiac output r = 0.83, SEE +/- 0.5 liter for the 73 patients without MR. The presence or absence of ventricular dyssynergy did not alter statistical findings. MVSV consistently overestimated forward stroke volume for the seven patients with MR. This study shows that the MV echogram provides an accurate, widely applicable method for calculating MVSV.