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Effects of pulsatile and nonpulsatile coronary perfusion on performance of the canine left ventricle
Insights
Pulsatile coronary perfusion significantly improved myocardial performance during ventricular fibrillation compared to nonpulsatile flow. This method maintained diastolic compliance and reduced ischemic damage, highlighting its benefit for cardiac surgery.
Area of Science:
- Cardiovascular Physiology
- Cardiac Surgery
- Myocardial Protection
Background:
- Ventricular fibrillation during cardiac procedures poses risks to myocardial performance.
- Normothermic ventricular fibrillation requires effective myocardial protection strategies.
Purpose of the Study:
- To compare the effects of pulsatile versus nonpulsatile coronary perfusion on myocardial function during prolonged normothermic ventricular fibrillation.
- To evaluate diastolic ventricular compliance, myocardial oxygen consumption, lactate extraction, blood flow, and histology.
Main Methods:
- Three groups of hearts were studied: beating hearts with nonpulsatile perfusion (BH/NP), hearts in ventricular fibrillation with nonpulsatile perfusion (Fib/NP), and hearts in ventricular fibrillation with pulsatile perfusion (Fib/P).
- Measurements included diastolic ventricular compliance, myocardial oxygen consumption, lactate extraction, regional myocardial blood flow, and histology after 120 minutes.
Main Results:
- Pulsatile perfusion (Fib/P) maintained normal ventricular diastolic compliance, unlike nonpulsatile perfusion (Fib/NP) which caused a 50% decrease.
- Fib/P showed significantly greater lactate extraction and a higher endocardial/epicardial flow ratio, with minimal subendocardial histologic damage.
- Fib/P resulted in reduced left ventricular myocardial blood flow due to increased oxygen extraction, maintaining near-constant resistance.
Conclusions:
- Pulsatile coronary perfusion effectively minimizes the detrimental effects of prolonged ventricular fibrillation on myocardial performance.
- The findings suggest pulsatile flow is superior to nonpulsatile flow for myocardial protection during cardiac arrest scenarios.
Abstract:
This study compares the effect of pulsatile (Group C, Fib/P) and nonpulsatile (Group B, Fib/NP) coronary perfusion on myocardial performance during 2 hours of normothermic ventricular fibrillation. Group A (BH/NP), used as a base-line observation, consisted of 2 hours of nonpulsatile coronary perfusion in beating hearts. The assessment of ventricular performance included diastolic ventricular compliance, myocardial oxygen consumption and lactate extraction, regional myocardial blood flow, and histology. After 120 minutes of ventricular fibrillation, Group C showed normal ventricular diastolic compliance as compared to a 50 per cent decrease in Group B (p less than 0.01). Myocardial oxygen consumption was not significantly different from that in Group B. Because of a 70 per cent increase in oxygen extraction above Group B (p less than 0.05), total left ventricular myocardial blood flow was reduced (103 +/- 23 versus 260 +/- 36 ml. per 100 Gm. per minute, p less than 0.05) and had near-constant resistance. Lactate extraction was significantly greater and more stable as compared to Group B (9.28 +/- 1.33 versus 1.8 +/- 1.08, p less than 0.05). Left ventricular endocardial/epicardial flow ratio was greater in Group C (1.21 +/- 0.08 versus 1.06 +/- 0.06, p less than 0.05). Minimal subendocardial histologic changes were present as compared to the marked patchy subendocardial ischemic changes seen in Group B. The results demonstrate that the addition of pulsatile flow to coronary perfusion minimized the deleterious effects of prolonged ventricular fibrillation on myocardial performance.