STROKE VOLUME GENERATION OF THE LEFT-VENTRICLE AND ITS RELATION TO CHAMBER SHAPE IN NORMAL SUBJECTS AND PATIENTS WITH MITRAL OR AORTIC REGURGITATION

The total stroke volume of the left ventricle (LV) is equal to the sum of the regional cavity shrinkage. Since nonuniformity of regional wal l motion in LV has been well documented even in normal subjects, the e xtent of the contribution of each region to total stroke volume cannot be easily determined. To assess the left ventricular regional contrib utions to total stroke volume under normal conditions and in compensat ed chronic mitral or aortic regurgitation, LV cineangiograms were anal yzed in 14 normal subjects (N), 8 patients with mitral regurgitation ( MR) and 10 patients with aortic regurgitation (AR). We assumed that th e LV cavity could be viewed as a stack of 30 half-cylindrical discs, 1 5 in the anterior and 15 in the inferior wall regions. LV chamber shap e was more spherical in MR than in N, but was more conical in AR. Perc ent regional hemichordal shortening was significantly decreased in the anterobasal and anteroapical walls in AR, but was similar between N a nd MR. The regional contribution to total stroke volume showed a signi ficant quadratic correlation with the end-diastolic regional shape ind ex (N, r=0.87; MR, r=0.79; AR, r=0.90), which was defined as the regio nal hemiaxial length divided by the LV long-axis length, but was not c orrelated with percent regional hemichordal shortening. Therefore, str oke volume is generated mainly in the mid-ventricular portion in N and MR, but in the basal portion in AR due to the characteristic change i n cavity shape.