Onset of Altered Interventricular Septal Motion During Cardiac Surgery Assessment by Continuous Intraoperative

Abnormal motion of the interventricular septum is frequently observed after uncomplicated cardiac surgery. We sought to elucidate the mechanism underlying this phenomenon by using continuous echocardiographic imaging of the heart from a constant transesophageal location in 21 patients undergoing their first cardiac operation. Quantitative global and regional functional analyses were performed in each patient at baseline (stage 1), after median sternotomy (stage 2), after sternal retraction (stage 3), after pericardiotomy (stage 4), after completion of cardiopulmonary bypass (stage 5), and after chest closure (stage 6). During the first four surgical stages, mean left ventricular fractional shortening varied little among regions with a fixed reference system (maximum range, 31.6-39.2%; p=NS) but changed dramatically after the discontinuation of cardiopulmonary bypass (stage 5). The apparent medial hypoki-nesis that was observed (4.9±4.7 % [SD]) was accompanied by lateral hyperkinesis (65.2±4.1%, p<O.OOOl). These regional differences were completely eliminated with a floating reference system (33.6±2.7 % for medial, and 34.8±1.7 % for lateral; p=NS), suggesting cardiac transla-tion. Quantitative curvature analysis supported this conclusion, with preservation of baseline regional curvature seen throughout the procedure. The mean length of individual translationa