Ultrapower; a Minimally Invasive Tool for Evaluation of Total Cardiac Power

The intervention is a comparison between two methods of calculating the heart's energy delivery, cardiac power, measured in watts. A tertiary measurement is calculation of arterioventricular coupling. All patients will have cardiac power output calculated through the use of Doppler echocardiography. The echocardiography based cardiac output will be done through the velocity time integral of the left ventricular outflow tract (LVOT). This will be compared against total power as measured by our Ultrapower approach which involves instantaneous doppler measurement of cardiac output through LVOT multiplied with simultaneous radial artery pressure. This and ejection fraction (for calculation of ventriculoarterial coupling) will be recorded at rest in neutral position preoperatively, directly post operatively and the day after operation. Directly postoperatively the power measurements will also be repeated in Trendelenburg and anti Trendelenburg position.