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Surgical revascularization of acute (1 hour) coronary occlusion: blood versus crystalloid cardioplegia
Insights
Blood cardioplegia significantly improved myocardial contractile function recovery after ischemia compared to crystalloid cardioplegia. This suggests blood cardioplegia is more effective in preserving heart function during acute myocardial infarction.
Area of Science:
- Cardiology
- Cardiac Surgery
- Myocardial Protection
Background:
- Coronary artery occlusion leads to myocardial ischemia and impaired contractile function.
- Cardioplegia is crucial for myocardial protection during cardiac surgery.
- Comparing blood and crystalloid cardioplegia is essential for optimizing surgical outcomes.
Purpose of the Study:
- To compare the efficacy of blood versus crystalloid cardioplegia in restoring myocardial contractile function, high-energy phosphate, and tissue water content after ischemia.
- To evaluate the impact of different cardioplegia solutions on post-ischemic myocardial recovery.
Main Methods:
- Anesthetized dogs underwent a 1-hour coronary artery occlusion model.
- Myocardial contractile function was assessed using ultrasonic crystals.
- Left ventricular and aortic pressures were monitored.
- Adenosine triphosphate (ATP) levels and tissue water content were measured post-ischemia.
- Myocardial segments were treated with either crystalloid or blood cardioplegia during bypass.
Main Results:
- Both cardioplegia solutions comparably depleted postischemic subendocardial adenosine triphosphate levels.
- Subendocardial water content increases were similar between crystalloid and blood cardioplegia groups.
- Recovery of segmental shortening was significantly greater with blood cardioplegia (31.5% of control) compared to crystalloid cardioplegia (4.9% of control).
Conclusions:
- Blood cardioplegia demonstrated superior restoration of myocardial contractile function compared to crystalloid cardioplegia in this model of acute evolving myocardial infarction.
- The composition and delivery of blood cardioplegia appear to be more beneficial for post-ischemic cardiac function recovery.
Abstract:
This study compares blood versus crystalloid cardioplegia in restoring contractile function, and high-energy phosphate and tissue water content in a myocardial segment after 1 hour of coronary artery occlusion. Anesthetized dogs underwent instrumentation with the chest open to measure left ventricular and aortic pressures, and systolic shortening in the myocardium perfused by the left anterior descending coronary artery (LAD) was measured with ultrasonic crystals. In 21 dogs, the LAD was occluded for an hour, thereby replacing systolic shortening with passive lengthening averaging -28.7 +/- 6.2% of control shortening in both groups. The dogs were then placed on total bypass, and arrest was achieved with multidose crystalloid (N = 10) or blood cardioplegia (N = 11). The ligatures were released just prior to the second infusion of cardioplegic solution. Postischemic subendocardial levels of adenosine triphosphate were comparably depleted with crystalloid and blood cardioplegia (55.2% and 44.0%, respectively, of control). Subendocardial increases in water content were similar for crystalloid (3.62%) and blood (3.16%) cardioplegia. Recovery of segmental shortening was significantly greater with blood than crystalloid cardioplegia (31.5 +/- 8.2% versus 4.9 +/- 6.6% of control, respectively). We conclude that the composition and the delivery of blood cardioplegia used in this study restore greater postischemic function than crystalloid cardioplegia in acute evolving myocardial infarction.