Echocardiographic study of significance of left ventricular minor axis shortening during pre-ejection phase of systole.

This study was designed to investigate the changes in dimensions of the left ventricular minor axis that occur during the pre-ejection period of systole. Three groups of subjects were studied: 29 normal subjects (group 1); 16 patients with mitral regurgitation and 2 patients with ventricular septal defect (group 2); 11 patients with left ventricular volume overload (excluding those with mitral regurgitation and ventricular septal defect), 10 with aortic regurgitation, and 1 witharteriovenousfistula (group 3). To define the onset of left ventricular contraction (mitral valve closure), the electrocardiogram and mitral valve echocardiogram were recorded, and to establish the onset of ejection (aortic valve opening), the electrocardiogram and aortic valve were recorded at a paper speed of 50 mm per second, with 40 ms time lines. The left ventricular echogram and electrocardiogram were then recorded, andthedimensions ofthe left ventricular minor axis at the onset of contraction and of ejection were measured. In group 1 the dimension of the left ventricular minor axis either did not change (14 subjects) or increased by 1 to 2 mm (15 subjects) during the pre-ejection period. In group 2, the dimension of the left ventricular minor axis decreased in all the subjects during the pre-ejection period (mean = 3 mm). The decrease in the dimension was the result of posterior motion of the interventricular septum during the pre-ejection peliod; there was no anterior motion of the posterior wall until the onset of ejection except in 1 patient. In group 3 there was no change in the dimension of the left ventricular minor axis during the pre-ejection period except in 1 patient whose dimension increased by 2 mm. We conclude that shortening of the dimension of the left ventricular minor axis during the pre-ejection period occurs in mitral regurgitation and ventricular septal defect, but not in normal subjects or patients with other forms of left ventricular volume overload which are not accompanied by loss of left ventricular volume into another cardiac chamber during the pre-ejection phase of systole. Left ventricular minor axis shortening during the preejection period should be a useful adjunct to the echocardiographic diagnosis of mitral regurgitation and ventricular septal defect.