949-100 Sigmoid Interventricular Septum in the Aged Causes Hypotension During Dobutamine Stess Echocardiography

Abstract

Hypotension during dobutamine stress echocardiography is caused by ischemia as well as non-ischemic causes. To assess if sigmoid interventricular septum seen in the aged can cause hypotension during dobutamine echo, dobutamine echo was performed in 12 subjects with sigmoid interventricular septum (age: 53 to 76 yrs, 8 men and 4 women). At peak dobutamine dose, 7 subjects (group H) showed a hypotensive response (>5 mmHg decrease in systolic blood pressure from the peak systolic blood pressure; mean = –17 ± 13 mmHg) while 5 subjects (group N) did not. No subject showed regional wall motion abnormalities. Atrest, group H had smaller LV systolic dimension (LVOs) (26 ± 3 vs 30 ± 3 mm) than group N, but no difference was found in LV diastolic dimension (44 ± 3 vs 47 ± 4 mm), %FS (40 ± 6 vs 34 ± 7%), aorto-septal angle (93 ± 10 vs 101 ± 11°), or peak LV outflow velocity (1.3 ± 0.2 vs 1.2 ± 0.3 m/s) between group H and group N. During dobutamine stress. despite the lower peak dobutamine doses in group H than in group N (33 ± 8 vs 40 ± 7 μg/kg/min), group H showed smaller LVOs (20 ± 3 vs 26 ± 4 mm), mitral anulus diameter 119 ± 3 vs 23 ± 2 mm) and aorto-septal angle (84 ± 12 vs 100 ± 6°), and higher heart rate (114 ± 10 vs 79 ± 16 bpm), %FS (53 ± 8 vs 43 ± 7%), and peak LV outflow pressure gradient (43 ± 23 vs 12 ± 5 mmHg). In addition, systolic anterior motion of the mitral valve (SAM) with septal contact developed in 86% of group Hand 0% of group N. Thus, about half of the subjects with sigmoid interventricular septum show hyper-response to dobutamine and develop dynamic LV outflow tract obstruction as well as systemic arterial hypotension even without regional LV wall motion abnormalities.