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Improved myocardial preservation during global ischemia by continuous retrograde coronary sinus perfusion
Insights
Retrograde coronary sinus perfusion significantly improved heart function recovery after ischemia by delivering oxygen and substrates beyond blockages. This method maintained better myocardial oxygen levels and reduced carbon dioxide buildup compared to traditional methods.
Area of Science:
- Cardiovascular Surgery
- Myocardial Preservation
- Ischemic Heart Disease
Background:
- Antegrade cardioplegia delivery can be limited by coronary stenoses.
- Improved myocardial preservation strategies are crucial for reducing ischemia-reperfusion injury.
Purpose of the Study:
- To evaluate retrograde coronary sinus perfusion for delivering cardioplegic solutions, oxygen, and substrates.
- To assess its efficacy in myocardial preservation during ischemia, especially with coronary artery occlusion.
Main Methods:
- 41 canine hearts underwent 90 minutes of ischemia with circumflex artery occlusion.
- Groups received antegrade crystalloid cardioplegia, antegrade plus cooling, continuous retrograde perfusion, or retrograde perfusion with oxygenated perfluorocarbon.
- Intramyocardial PO2, PCO2, temperature, and left ventricular (LV) function were monitored.
Main Results:
- Retrograde perfusion (Groups III and IV) showed significantly better LV function recovery (73-78%) compared to antegrade (36-41%).
- Retrograde perfusion maintained intramyocardial PO2 near pre-ischemic levels or increased it, unlike antegrade methods which caused a significant drop.
- Retrograde perfusion led to more uniform myocardial cooling and reduced intramyocardial PCO2 accumulation.
Conclusions:
- Retrograde coronary sinus perfusion is a superior method for myocardial preservation during cardiac surgery, especially with coronary stenoses.
- It effectively delivers cardioplegic solutions, oxygen, and substrates, improving functional recovery and tissue viability.
- This technique offers advantages over traditional antegrade delivery in compromised coronary circulations.
Abstract:
To investigate whether retrograde continuous low-pressure perfusion of the coronary sinus could deliver cardioplegic solutions with oxygen and substrate beyond stenoses and result in improved myocardial preservation, we subjected 41 canine hearts to 90 minutes of ischemia with an occlusion on the circumflex coronary artery. There were four groups: Group I, antegrade (aortic root) crystalloid cardioplegia every 30 minutes during ischemia; Group II, antegrade plus topical cooling; Group III, continuous retrograde perfusion; Group IV, same as Group III, with an oxygenated perfluorocarbon. All solutions had a PO2 of 400 to 500 mm Hg. Intramyocardial oxygen and carbon dioxide tensions (PO2 and PCO2) and mean myocardial temperatures were monitored during ischemia, and left ventricular (LV) function was assessed before ischemia and after reperfusion. After global ischemia, the circumflex occlusion was released and the hearts reperfused. Following 60 minutes of reperfusion, isovolumic developed pressure returned to 36% +/- 4% and 41% +/- 5% of preischemic levels, respectively, in Groups I and II. By contrast, Groups III and IV (retrograde perfusion) had a significantly greater percent of recovery (78% +/- 5% and 73% +/- 5%). Circumflex area intramyocardial PO2 fell 20 and 25 mm Hg below preischemic levels in Groups I and II during ischemia, whereas in Group III, intramyocardial PO2 in the circumflex region remained near preischemic levels, and in Group IV, it rose 19 mm Hg. Mean myocardial temperature during ischemia in the circumflex area was significantly higher in Group I than in Groups II, III, and IV. Peak intramyocardial PCO2 in the circumflex region was significantly less in the retrogradely perfused hearts. Retrograde coronary sinus perfusion resulted in significant improvement in recovery of LV function, uniform myocardial cooling, normal intramyocardial PO2, and less intramyocardial PCO2 accumulation, despite the presence of a total circumflex coronary artery occlusion.