Onset of altered interventricular septal motion during cardiac surgery. Assessment by continuous intraoperative transesophageal echocardiography.

Abstract

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 hypokinesis that was observed (4.9 +/- 4.7% [SD]) was accompanied by lateral hyperkinesis (65.2 +/- 4.1%, p less than 0.0001). 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 translation. Quantitative curvature analysis supported this conclusion, with preservation of baseline regional curvature seen throughout the procedure. The mean length of individual translational vectors (reflecting systolic movement of the endocardial centroid) remained minimal (less than or equal to 1.0 mm) through stage 4 but increased more than fourfold at stage 5, continuing in a medial direction after chest closure (5.2 +/- 3.0 mm and 271 +/- 6 degrees from anterior). Thus, abnormal postoperative septal motion is not caused by removal of restraining forces of the pericardium or anterior mediastinum but rather appears to be directly related to events occurring during cardiopulmonary bypass.

Left ventricular strain and strain rate by 2D speckle tracking in chronic thromboembolic pulmonary hypertension before and after pulmonary thromboendarterectomy

“…post-operative septal movement and hypokinesis is commonly observed in patients undergoing open heart surgery, and can affect tissue Doppler imaging of the septum as well [17-19]. A recent study, however, has shown normal septal strain rate after bypass graft surgery [20].…”

Center of volume and total heart volume variation in healthy subjects and patients before and after coronary bypass surgery

“…The cause of this paradoxical septal movement is not fully understood. Proposed explanations include exaggerated cardiac mobility explained by the lack of restraint of the pericardium (Feneley et al , 1987), events during cardiopulmonary bypass (Lehmann et al , 1990) and systolic translation of the ventricle (Force et al , 1983). In the present study paradoxical movement of the septum could be seen in all patients after coronary bypass surgery and the largest increase in COVV after surgery occurred in a direction similar to this movement (towards the right side of the heart).…”

Five‐dimensional MRI incorporating simultaneous resolution of cardiac and respiratory phases for volumetric imaging

“…This strong interventricular interaction explains the acute changes in LV function seen with abrupt pressure overload of the RV (e.g., from pulmonary embolism), as well as the chronic alterations seen in patients with long‐term RV volume overload (e.g., from pulmonary valve insufficiency) (2). Interventricular septal motion abnormalities are frequently seen in patients after open‐heart surgery (3), but both the cause and effects of this remain unclear (4, 5). In‐depth studies of how the anatomical or functional alternations of one ventricle affect the other have focused on the influence of respiration on cardiac chamber dimensions, and the shape and motion of the interventricular septum.…”