BACKGROUND: Most surgeons prefer delivering cardioplegia alternatively via the aortic root and coronary sinus in patients undergoing coronary artery bypass graft surgery (CABG). Recently, some surgeons have delivered cardioplegia via the grafted vessel to the obstructed right coronary artery in order to preserve right ventricular function whenever retrograde cardioplegia is delivered. Thus, we have compared the effect on right ventricular preservation between the aforementioned two methods after cardiopulmonary bypass in patients undergoing a right CABG. METHODS: Twenty-eight patients undergoing an elective CABG with significant right coronary artery obstructive disease were allocated into 2 groups. In the alternative cardioplegia delivery group (A-group), cold blood cardioplegia was delivered via the aortic root and coronary sinus alternatively. In the simultaneous cardioplegia delivery group (S-group), cold blood cardioplegia was delivered via the coronary sinus and grafted vessel to the obstructed right coronary artery simultaneously. Hemodynamic measurements were obtained pre-bypass, at pericardial closure and at sternal closure. Data recorded included right ventricular ejection fraction, right ventricular volume index and right and left ventricular hemodynamics. RESULTS: There was no significant difference in the right ventricular ejection fraction between the two groups at pre-bypass, pericardial closure and sternal closure. In both groups, the right ventricular ejection fraction and cardiac index were not decreased, and the left ventricular ejection fraction was higher at pericardial closure than pre-bypass. However, in both groups, there was a decrease in the right andleft ventricular stroke work index and right ventricular stroke volume index at sternal closure. CONCLUSIONS: We have concluded that simultaneous cardioplegia delivery via the coronary sinus and grafted vessel to the obstructed right coronary artery was not superior to the alternative cardioplegia delivery via the aortic root and coronary sinus for preservation of right ventricular function in patients undergoing a right CABG.