Continuous warm versus intermittent cold blood cardioplegia for coronary bypass surgery in patients with left ventricular dysfunction.

Between October 1991 and March 1994, 108 consecutive patients with moderate to severe left ventricular dysfunction underwent non-emergency isolated coronary artery surgery under the care of one surgeon (A.R.). They were prospectively randomised to receiving either intermittent cold (Group 1-50 patients) or continuous warm (Group 2-58 patients) blood cardioplegia for myocardial protection. There were no significant differences in clinical outcome between the two groups, as judged by operative mortality, rates of perioperative myocardial infarction, the serum CKMB isoenzyme level at 2 and 18 h after operation, need for circulatory support, postoperative neurological deficit, or duration of hospital stay. Group 2 patients required significantly more potassium (68 vs 29 mmol, P < 0.001) to maintain diastolic arrest and also had higher serum potassium levels after removal of the cross-clamp (P < 0.001). However, sinus rhythm returned spontaneously with greater frequency (91.2% vs 45.8%, P < 0.001) in Group 2 patients. In conclusion this report suggests that retrograde continuous warm blood cardioplegia provides comparable myocardial protection to that achieved with retrograde intermittent cold blood cardioplegia in patients with moderate to severe left ventricular dysfunction undergoing isolated coronary artery surgery.