The study will be conducted in the Tertiary care hospital. Institute ethical committee clearance certification will be sought and obtained before the study begin. Informed written consent will be obtained from all the study participants before including them in the study after explaining them implications of the study. This study will be conducted on patients planned to undergo coronary artery bypass graft surgery with normal diastolic function.

Standard fasting guidelines will be followed. Upon arrival in the operating room, standard monitoring (five-lead ECG, SpO2 and non-invasive blood pressure) will be commenced. We will insert a 20-G arterial cannula under local anaesthesia in the radial artery, and a triple lumen central venous pressure (CVP) catheter in the right internal jugular vein using full aseptic technique. 

Group A -sevoflurane group: Anaesthesia will be induced using propofol 1-1.5mg/kg and fentanyl 3–5mcg/kg,titrate according to haemodynamics. Will perform Intubation with cisatracurium 0.1 mg/kg. Anaesthesia maintenance will be done using sevoflurane 1 MAC in 50% oxygen and air, and cisatracurium 2 mcg/kg/min. 

Group B -Propofol group: Anaesthesia will be induced using propofol 1-1.5mg/kg and fentanyl 3–5mcg/kg,titrate according to haemodynamics. Will perform Intubation with cisatracurium 0.1 mg/kg. Anaesthesia maintenance with a continuous infusion of propofol 1.5-4.5 mg/kg/h, and cisatracurium 2 mcg/kg/min.

A bispectral index electrode (BIS-Sensor) will be positioned on the patient’s forehead to monitor depth of anaesthesia, and the BIS value maintenance between 45 and 55 in both groups by adjusting the propofol infusion rate or inhaled sevoflurane concentration. We continuously monitor heart rate (HR), systolic, diastolic and mean arterial pressures (SBP, DBP and MAP) along with CVP. 

We will perform a complete transesophgeal echocardiography (TEE) examination using a commercially available multiplane TEE probe according to the American society of Echocardiography/society of Cardiovascular Anaesthesiologist guidelines. Transoesophageal echocardiography evaluation data will be recorded in three stages, as follows:

1.Transmitral diastolic Doppler flow profile: Obtaining the mid oesophageal four chamber view and pulsed wave Doppler examination done by placing the Doppler sample volume at the tips of the mitral valve leaflets in the LV during diastole. The peak flow velocity of early diastolic filling (E), peak flow velocity of late diastolic filling associated with atrial contraction (A), E/A ratio, A wave duration and deceleration time (DT) for early diastolic filling will be recorded.

2. Tissue Doppler imaging by placing the sample at the lateral mitral valve ring in the mid esophageal four chamber view. A typical TDI signal consist of three waves; early (e)’ late (a’) diastolic , and a systolic (Sm) waves.

3. Pulmonary venous flow velocity using pulsed wave Doppler by placing the sample volume in the left upper pulmonary vein, 0.5-1 cm distal to its junction with the left atrium. Values for the peak systolic flow velocity (S), peak diastolic flow velocity (D), S/D ratio, peak reversal atrial flow (Ar) and duration of reverse atrial flow (Ar dur).

All echocardiography data for statistical analysis will be recorded by TEE immediately after tracheal intubation as a baseline(T0); and 15 min after weaning from bypass (T1).whereas hemodynamic data (HR,MAP and CVP) VIS Score will be recorded at T0,T1.

Transthoracic echocardiography will be done in ICU post operative on Day 0 and Day 1 for assessment of diastolic function.