Transoesophageal echocardiography Stroke volume, cardiac output, and right ventricular function will be assessed using transoesophageal echocardiography. Four and 5-chamber transgastric views will be obtained in all six patients included for TEE. The velocity time integral at the left ventricular outflow tract (VTI LVOT) was measured using pulsed wave Doppler. The diameter of the aorta will be measured using a mid-oesophageal long axis view at the level of the aortic annulus. Measurement of stroke volume will be made by multiplying the LVOT VTI and the aortic diameter. Cardiac output will be calculated by multiplying stroke volume with heart rate. All images will be recorded in triplicate by the same operator and measurements made off-line in a blinded fashion.