Background: Heart positioning during beating heart surgery produces significant haemodynamic compromise either when a deep pericardial stitch (DPS) or apical suction devices (ApSDs) are used. In this study the two techniques' haemodynamic performance and effect on intracardiac structures were compared through transoesophageal echocardiography (TEE) obtained volume measurements and three-dimensional ventricular and mitral valve computer reconstructions.
Methods: Sequential 0 degrees to 180 degrees TEE images of the left heart were obtained in 10 patients undergoing beating heart surgery. Measurements with both techniques in three different positions were obtained: at baseline, the heart elevated to access its inferior surface and the heart elevated and rotated to access its lateral surface. Three-dimensional computer reconstructions of the mitral valve and the left heart were generated. Ventricular volume measurements were used to calculate stroke volume, ejection fraction and differences from baseline. An analysis of variance between each technique in all three positions was performed.
Results: Central venous, left atrial and pulmonary artery pressures were significantly increased with either technique during positioning. Both techniques significantly affected left ventricular function decreasing stroke volume and ejection fraction. In the vertical and rotated position, the ApSD produced a significant decrease from baseline both in stroke volume (DPS: 32.8+/-18.7 vs ApSD: 55.46+/-21.7; p=0.02) and in ejection fraction (DPS: 19.3+/-10.5 vs ApSD: 40.9+/-24.6; p=0.02). The three-dimensional reconstructions demonstrated significant distortion of the atrioventricular geometry and the mitral valve, which was more pronounced with the DPS.
Conclusion: Both techniques produce variable degrees of deformation with associated cardiac dysfunction and haemodynamic instability. Cardiac function is impeded more with an ApSD with the heart elevated and rotated.