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Intermittent aortic cross-clamping versus St. Thomas' Hospital cardioplegia in extensive aorta-coronary bypass
Insights
St. Thomas
Area of Science:
- Cardiovascular Surgery
- Cardiology
- Biochemistry
Background:
- Myocardial preservation is critical during extensive myocardial revascularization.
- Assessing myocardial protection strategies is essential for improving surgical outcomes.
Purpose of the Study:
- To compare the efficacy of intermittent aortic cross-clamping at different temperatures versus St. Thomas' Hospital cardioplegia for myocardial protection.
- To evaluate intraoperative markers of ischemic damage, functional recovery, and long-term clinical outcomes.
Main Methods:
- Randomized trial of 72 patients undergoing myocardial revascularization.
- Three groups: aortic cross-clamping at 32°C, 25°C, and St. Thomas' cardioplegia.
- Biochemical analysis of myocardial biopsy specimens, ultrastructural studies, and assessment of creatine kinase isoenzyme release.
Main Results:
- Cardioplegia group showed better preservation of high-energy phosphates, glycogen, and ultrastructure.
- No significant difference in creatine kinase isoenzyme release or severe myocardial damage across groups.
- Improved immediate functional recovery in the cardioplegia group, but higher incidence of atrioventricular conduction problems.
Conclusions:
- All three techniques provide good myocardial protection during extensive aorta-coronary bypass.
- St. Thomas' cardioplegia effectively prevents ischemia-induced cardiac metabolism deterioration.
- Clinical outcomes, including survival and event-free follow-up, were similar across all groups.
Abstract:
Myocardial preservation was assessed in 72 patients undergoing extensive myocardial revascularization. The patients were allocated at random to three surgical techniques: Group 1, intermittent aortic cross-clamping at 32 degrees C; Group 2, intermittent aortic cross-clamping at 25 degrees C; and Group 3, St. Thomas' Hospital cardioplegia. As intraoperative markers of ischemic damage, adenosine triphosphate, creatine phosphate, and glycogen contents were determined in transmural left ventricular biopsy specimens taken at the beginning and at the end of cardiopulmonary bypass. Ultrastructure was studied in a similar pair of biopsy specimens. Release of myocardium-specific creatine kinase isoenzyme was determined intraoperatively and postoperatively. Functional recovery was assessed before and after weaning from cardiopulmonary bypass. The incidence of low cardiac output, myocardial infarction, and rhythm disturbances was compared between groups. Finally, actuarial survival and event-free curves were studied after 18 months' follow-up. The results show a better preservation of high-energy phosphates, glycogen, and ultrastructure in the cardioplegia group as compared to the two cross-clamp groups. However, severe myocardial damage was never observed. Release of MB creatine kinase isoenzyme was the same in all three groups. Functional recovery of the hearts immediately after cessation of cardiopulmonary bypass was better in the cardioplegia group, but the incidence of rhythm disturbances (atrioventricular conduction problems) was higher in the cardioplegia group than in the other two groups (p less than 0.05). Clinical outcome in terms of incidence of perioperative infarction, survival, and event-free follow-up was not different between groups. It is concluded that both techniques (aortic cross-clamping at 32 degrees C or 25 degrees C and St. Thomas' Hospital cardioplegia) offer good myocardial protection in extensive aorta-coronary bypass operations. St. Thomas' cardioplegia, however, in contrast to intermittent aortic cross-clamping, prevents the onset of ischemia-induced deterioration of cardiac metabolism, i.e., destruction of the adenine nucleotide pool.