Hemodynamic changes with right lateral decubitus body positioning in the tilted porcine heart

Abstract

Background. In beating-heart coronary surgical procedures, exposure of posterior vessels through sternotomy causes cardiac function to deteriorate. We hypothesized that turning the subject to the right lateral decubitus position before cardiac retraction improves exposure of posterior vessels and preserves cardiac pump function on displacement. Methods. Eight 80-kg open-chest pigs were instrumented with catheter-tip manometers. After a stepwise 60-degree turn to the right lateral decubitus position of the body, the heart was retracted anteriorly to 90 degrees with a suction stabilizer. Results. Right lateral body positioning caused an approximately 45-degree right deviation of the apex, thereby exposing the left atrial groove. Stroke volume, mean arterial pressure, right atrial pressure, and right ventricular end-diastolic pressure increased to 106% ± 5% (mean ± standard error of the mean, p = 0.31), 106% ± 3% ( p = 0.01), 129% ± 8% ( p = 0.001), and 171% ± 14% ( p = 0.002), respectively, compared with control values. In contrast, left atrial pressure decreased to 73% ± 6% ( p = 0.007), whereas left ventricular preload remained unchanged (110% ± 8%, p = 0.26). Additional anterior displacement to 90 degrees fully exposed the posterior vessels, and stroke volume decreased to 90% ± 3% ( p = 0.01) and mean arterial pressure to 93% ± 5% ( p = 0.07) at the expense of further increased right ventricular preload (256% ± 28%, p < 0.001). Conclusions. By placing the subject in the right lateral decubitus position, exposure through sternotomy of posterior vessels in the beating porcine heart was facilitated while mean arterial pressure was maintained.