Left ventricular midwall dynamics in the right anterior oblique projection in intact unanesthetized man

Abstract

The presence of nonuniform, asymmetric, asynergic left ventricular contraction is usually taken as indicative of segmental disease. In order to assess the uniformity, symmetry, and synergy of left ventricular contraction in patients with normal left ventricular function, we measured the dynamics of implanted radiopaque midwall markers silhouetting the left ventricle in the 30° right anterior oblique projection in eight patients post-cardiac surgery having normal left ventricular volumes, ejection fraction, heart rate, cardiac output, circumferential fiber shortening velocity and subjectively normal wall motion in all left ventricular regions. Systolic excursion (range 0.98–1.16 cm) and velocity (range 3.6–5.4 cm/sec) of posterior wall sites were greater ( P < 0.05) than those of their counterparts in the anterior wall (excursion 0.66–0.98 cm, velocity 2.8–4.0 cm/sec). Along both walls excursion and velocity of basal segments were greater ( P < 0.05) than those of other segments in the same wall. Apical sites moved inward and toward the aortic valve, midbaseapex sites moved almost directly inward, and basal sites moved inward and toward the apex, with anterior sites having a greater apical component than posterior sites ( P < 0.05). These data are consistent with myocardial fiber distribution and orientation in the wall of the heart and the location of the papillary muscles relative to the 30° right anterior oblique view of the left ventricle. We conclude that contraction can be nonuniform, asymmetric, and asynergic even in the left ventricle with normal function.