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Does interruption of normothermic cardioplegia have adverse effects on myocardium? A retrospective and prospective
J A Rousou1, R M Engelman, J E Flack
1Division of Cardiac Surgery, Springfield, MA 01107, USA.
Insights
Warm cardioplegia interruptions during coronary artery bypass grafting do not harm the heart. This study found no adverse effects on myocardial protection, indicating warm retrograde blood cardioplegia is effective.
Area of Science:
- Cardiovascular Surgery
- Cardiac Anesthesia
- Myocardial Protection
Background:
- Coronary artery bypass grafting (CABG) requires effective myocardial protection.
- Warm cardioplegia is used, but the impact of interruptions is debated.
- Retrograde, near-continuous warm cardioplegia is a specific technique.
Purpose of the Study:
- To evaluate the clinical impact of cumulative cardioplegic interruption during CABG.
- To determine if warm cardioplegia interruptions affect myocardial outcomes.
- To assess the efficacy of warm retrograde cardioplegia.
Main Methods:
- 154 patients undergoing isolated CABG were divided into three groups based on cardioplegic interruption percentage (<20%, 20-39%, >40%).
- Clinical outcomes, cardioplegic interruption/reperfusion data were recorded.
- Intraoperative hemodynamics and metabolic markers were assessed in a subset of patients.
Main Results:
- No significant differences in clinical outcomes (infarction, mortality, length of stay) were observed across groups.
- Creatine kinase-MB (CK-MB) and inotrope use were unexpectedly higher in the lowest interruption group.
- Intraoperative evaluations showed no significant hemodynamic or metabolic differences between <30% and >30% interruption groups.
Conclusions:
- Warm cardioplegia interruption, as clinically applied, does not adversely affect the myocardium during coronary revascularization.
- Warm retrograde near-continuous blood cardioplegia is an effective method for myocardial protection.
Abstract:
A total of 154 patients who underwent isolated coronary revascularization (coronary artery bypass grafting) using retrograde, near-continuous, warm cardioplegia for myocardial protection, were arbitrarily divided into three groups according to the cumulative cardioplegic interruption (i.e. the sum total of all the short cardioplegic interruption periods, expressed as a percentage of the cardiac arrest period). Group 1 (39 patients) had < 20% interruption (mean(s.e.m.) 12.5(0.01)%), group 2 (82 patients) had 20-39% interruption (mean(s.e.m.) 30.1(0.01)%) and group 3 (33 patients) had > 40% interruption (mean(s.e.m.) 45.4(0.01%). The three groups were comparable except for longer clamp time in group 3 and a lower cardiac index in group 1. The mean number and duration of cardioplegic interruptions and reperfusions and multiple clinical outcomes were recorded. Clinical outcomes (Q) wave perioperative infraction, use of an intra-aortic balloon pump, mortality, and length of stay in the intensive care unit and hospital) were the same in all groups despite significant differences in percent, number and duration of interruption and reperfusion as well as cardiac arrest. The only significant differences found were in the level of creatine kinase-MB (CK-MB) and use of inotropes after surgery, both being higher in group 1 than in groups 2 and 3 (which is the opposite of what would be expected). Intraoperative hemodynamic (cardiac index and left ventricular ejection fraction) and metabolic evaluations (CK-MB, lactate production and oxygen extraction) in 22 additional patients who underwent coronary artery bypass grafting showed no significant differences between two groups having < 30% versus > 30% cumulative cardioplegic interruption. It is concluded that warm cardioplegic interruption as used clinically has no adverse effects on the myocardium in patients undergoing coronary revascularization. Warm retrograde near-continuous blood cardioplegia is an effective method of myocardial protection.