健常人の起立位における左室後壁収縮期奇異性運動に関する研究 心エコー図法による検討

Abstract

Paradoxical motion of the posterior wall of the left ventricle (LV) in the standing position was studied in 70 healthy subjects using echocardiography. Echocardiographic studies were performed in two body positions: supine and standing. Paradoxical motion (PM) of the posterior wall was defined as outward systolic motion for longer than 50% of systolic duration. Studies in the supine position showed normal systolic motion (NL) in all 70 subjects. However, studies in the standing position showed PM of the posterior LV wall in 46 subjects (66%) (PM group), and NL in 24 subjects (NL group). In the standing position, peak outward motion was much greater (4.8 +/- 1.7 mm vs 2.7 +/- 1.1 mm) in the PM group. Duration of the outward motion was also much greater in the PM group (67.4 +/- 11.9% vs 45.4 +/- 6.4%). PM was significantly more frequent in male subjects, in taller subjects and in subjects with lower body weight. At the time of the peak outward motion, there were strong correlations between posterior wall excursion and septal excursion, and between posterior wall excursion and mitral ring excursion. In the PM group, the % increase in heart rate from the supine to standing position was greater, and the % decrease in LV end-diastolic dimension, LV end-diastolic volume, stroke volume and cardiac index were greater. Standing calf venous volume measured by plethysmography was also much greater in the PM group. We conclude that this phenomenon presumably relates to an enhanced posterior motion of the entire heart in systole and to an altered contraction pattern of the posterior wall in the standing position. It is seen as having an important role in the interpretation of tests of LV function carried out in the standing position.