Abnormalities in position of left ventricular papillary muscles in congenital aortic stenosis.

ABSTRACT

Subclinical structural abnormalities may accompany some congenital cardiovascular abnormalities. Echocardiographic observations led us to hypothesize that the positions of the left ventricular papillary muscles are abnormal in hearts with aortic valvar stenosis. To test this hypothesis, we examined 6 normal heart specimens and hearts with congenital cardiovascular malformations, including 5 with pulmonary atresia and an intact ventricular septum, 6 with tetralogy of Fallot and 5 with aortic valvar stenosis. We marked the papillary muscles and the mitral commissures, X-rayed the hearts, and measured the angular positions of the papillary muscles using the midpoint of a chord drawn between the mitral commissures as a reference point. The direction from the midpoint to the lateral commissure was designated as 0 degrees. The data (mean +/- SEM) were analyzed using a computer program (ANOVA). In normal hearts, the anterolateral and posteromedial papillary muscles were positioned, respectively, at 43 +/- 19 degrees and 126 +/- 26 degrees. The positions of the papillary muscles were similar to normal in the hearts with pulmonary atresia (62 +/- 38 degrees and 128 +/- 27 degrees) and tetralogy of Fallot (40 +/- 13 degrees and 130 +/- 37 degrees). In aortic stenosis, the locations of the papillary muscles (-76 +/- 42 degrees and 71 +/- 25 degrees) were significantly different from normal (P less than 0.05). The arc between the papillary muscles was 83 +/- 16 degrees in normals and 147 +/- 45 degrees in aortic stenosis (P less than 0.05). The length of the arc was similar to normal in other heart specimens. Thus, the papillary muscles were abnormally positioned in aortic stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)