Low chloride solutions were proved to be better in resuscitation of emergency cases and decrease the resulting hyperchloremic metabolic acidosis in the last decade. In ringers' acetate solutions, there is acetate, which is metabolized in muscles to produce bicarbonate molecules, so neutralizing the ongoing lactic and hyperchloremic metabolic solutions. Both solutions were proved to be superior to normal saline as a fluid therapy plan in most studies with much less ongoing hyperchloremic metabolic acidosis and inflammatory response. In this protocol, modified Del Nido formula will be involved using ringers' acetate instead of plasmalyte solutions and comparing the effects on myocardial protection versus HTK solutions

First, fulfilling all inclusion criteria and consent acceptance for study are to be confirmed. Preoperative evaluation is done for full laboratory investigations including CBC, coagulation, renal and liver functions, CRP and troponin, full clinical examination for chest and heart, coronary angiography, Echocardiography, carotid doppler and upper and lower venous and arterial doppler are to be done. All patients will be scheduled for on pump CABG surgery. Low dose of midazolam will be given before surgery. Intraoperative monitoring will involve invasive blood pressure, ECG, peripheral pulse oximetry, capnogram.

After induction of anaesthesia and median sternotomy, patients will be randomly allocated into two groups:

Group (D) will receive modified Del Nido cardioplegia (Ringer acetate 1000ml, mannitol 20% 17 ml, magnesium sulphate 10% 20ml, sodium bicarbonate 8.4% 16ml, potassium chloride 7.5% 13ml and lidocaine 2% 8 ml). Crystalloid to blood ratio will be 80% to 20% respectively. Dose will be 15 - 20 ml/kg in first dose then 8 - 10 ml/kg every 60 minutes.

Group (C ) will receive HTK (Histidine, Tryptophan and Ketoglutarate solution) consisting of (1000ml distilled water, sodium 15mmol/L, potassium 9mmol/L, magnesium 4mmol/L, calcium 0.015 mmol/L, histidine 129mmol/L, tryptophan 2mmol/L, ketoglutarate 1mmol/L, mannitol 30mmol and pH 7.02 - 1.2). Dose will be 10 - 20 ml/kg and can be repeated once after 120 minutes.

All patients will receive hypothermia 29 - 32 ℃ and cardioplegia will be injected between the aortic valve and aortic cross clamp in a pressure not less than 50 mmHg above systolic pressure. After removal of aortic cross clamping, the heart will be monitored for ventricular arrhythmias, early recovery, and postoperative 24 hours serum troponin and new changes in echocardiography.

Inclusion Criteria:

1. ≥ 18 years old
2. Any gender
3. Surgery demands cardiopulmonary bypass and cardioplegia.
4. CABG surgeries

Exclusion Criteria:

1. < 18 years old
2. Emergency surgeries
3. Off pump CABG surgeries
4. Taking cardioplegia other than Del Nido or HTK cardioplegia