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Preservation of myocardial ATP during cardioplegia: comparison of techniques
Insights
Multidose blood cardioplegia and continuous blood cardioplegia best preserve myocardial ATP levels during aortic crossclamping, maintaining heart function. Other methods showed significant ATP depletion.
Area of Science:
- Cardiology
- Cardiac Surgery
- Biochemistry
Background:
- Myocardial adenosine triphosphate (ATP) preservation is crucial for cardiac function post-aortic crossclamping (AXC).
- Different cardioplegia delivery techniques impact high-energy substrate preservation.
Purpose of the Study:
- To evaluate and compare the preservation of myocardial ATP levels using four cardioplegia delivery techniques against continuous coronary perfusion.
- To determine the optimal cardioplegia strategy for maintaining myocardial energy stores during cardiac surgery.
Main Methods:
- Thirty-one dogs underwent cardiopulmonary bypass with left ventricular biopsies for ATP measurement.
- Five groups were studied: continuous coronary perfusion (CCP), multidose blood cardioplegia (MBC), multidose crystalloid cardioplegia (MCC), single-dose blood cardioplegia (SBC), and continuous perfusion blood cardioplegia (CBC).
- Biopsies were taken at intervals during AXC and post-procedure to measure ATP levels.
Main Results:
- Multidose blood cardioplegia (MBC) and continuous perfusion blood cardioplegia (CBC) groups showed the greatest ATP preservation (1.1% and 1.8% increase, respectively).
- MBC group exhibited a significant ATP increase (23%) immediately post-injection.
- Continuous coronary perfusion (CCP) and crystalloid cardioplegia (MCC) groups showed ATP decreases (15.6% and 18%, respectively), while single-dose blood cardioplegia (SBC) showed the poorest preservation (26% decrease).
Conclusions:
- Multidose blood and continuous blood cardioplegia techniques effectively maintain normal myocardial ATP stores during AXC.
- These blood-based cardioplegia methods offer superior myocardial energy preservation compared to continuous coronary perfusion.
- The findings support the use of blood cardioplegia for optimizing myocardial protection during cardiac surgery.
Abstract:
Preservation of myocardial ATP enhances the heart's ability to resume normal function following aortic crossclamping (AXC). Preservation of this high energy substrate during 4 cardioplegia delivery techniques was evaluated and compared with changes occurring during 4 hours of continuous coronary perfusion. Dogs (31) were placed on cardiopulmonary bypass and transmural left ventricular biopsies obtained for control ATP measurements. Animals were then divided into five groups: Group I (n = 6): 4 hrs. of continuous coronary perfusion (CCP); Group II (n = 6): 3 hrs. continuous AXC, multidose blood cardioplegia (MBC); Group III (n = 6): 3 hrs. continuous AXC, multidose crystalloid cardioplegia (MCC); Group IV (n = 6): 2 hrs. intermittent AXC, single dose BC (SBC); Group V (n = 7): 2 hrs. continuous AXC, continuous perfusion BC (CBC). In each group, where applicable, myocardial biopsies were taken at 30 minute intervals during AXC, before and after cardioplegia injection, and 30 minutes following final unclamping and rewarming. Hearts in Group II (MBC) and V (CBC) showed greatest preservation of ATP stores (increases 1.1 +/- 1.2%, increases 1.8 +/- 0.9% respectively; p greater than .05) ATP levels rose as high as 23 +/- 2% (p less than .005) above control immediately following cardioplegia injection in Group II (MBC). Group IV showed poorest preservation of ATP (decreases 26 +/- 5%, p less than .01) with levels falling as much as 37 +/- 10% (p less than .01) during the period of AXC. Hearts in Group I (CCP) demonstrated a 15.6 +/- 7.5% decrease in ATP from control (p less than .05). Group III (MCC) also showed a steady decline in ATP declining 18 +/- 3% (p less than .005) from control. These data indicate that multidose blood and continuous-blood cardioplegia techniques will maintain normal myocardial ATP stores throughout the period of AXC. These groups actually show a slight rise in ATP as compared to 4 hrs. of continuous coronary perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)