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A clinical trial of blood and crystalloid cardioplegia
Insights
Blood cardioplegia offers superior myocardial protection during coronary bypass grafting compared to crystalloid cardioplegia. This method reduces ischemic injury and improves cardiac functional recovery, suggesting better clinical outcomes for high-risk patients.
Area of Science:
- Cardiovascular Surgery
- Cardioplegia Solutions
- Myocardial Protection
Background:
- Clinical studies on blood vs. crystalloid cardioplegia have yielded inconclusive results regarding myocardial protection.
- Experimental data suggest blood cardioplegia may offer superior protection.
- Assessing myocardial protection requires evaluating both biochemical markers and functional recovery.
Purpose of the Study:
- To compare the efficacy of blood cardioplegia versus crystalloid cardioplegia in protecting the myocardium during coronary bypass grafting.
- To assess the impact of cardioplegia type on perioperative myocardial infarction and biochemical markers of injury.
- To evaluate the metabolic and functional recovery of the heart post-aortic occlusion and declamping.
Main Methods:
- Randomized trial of 90 patients undergoing coronary bypass grafting, assigned to blood (n=43) or crystalloid (n=47) cardioplegia.
- Measurement of perioperative myocardial infarction incidence and maximum MB isoenzyme of creatine kinase levels.
- Assessment of coronary sinus blood flow, cardiac lactate production, and cardiac output using thermodilution.
- Determination of myocardial performance, systolic elastance, and diastolic compliance via volume loading studies and nuclear ventriculography.
Main Results:
- Lower incidence of perioperative myocardial infarction (0 vs. 5, p=0.06) and significantly less maximum MB isoenzyme of creatine kinase (26.3 vs. 35.6 U/L, p<0.02) with blood cardioplegia.
- Significantly lower coronary sinus blood flow post-declamping (160 vs. 220 ml/min, p<0.05) and reduced cardiac lactate production during occlusion and post-declamping with blood cardioplegia (p<0.05 and p<0.01, respectively).
- Superior myocardial performance (p<0.01) and systolic elastance (p<0.01) with blood cardioplegia, while diastolic compliance was similar.
Conclusions:
- Blood cardioplegia significantly reduces ischemic injury and anaerobic metabolism during cardiac arrest.
- It facilitates better functional recovery of the myocardium post-surgery.
- Blood cardioplegia provides superior protection for elective coronary bypass grafting and may benefit high-risk patients.
Abstract:
Although experimental studies suggest that blood cardioplegia provides better protection than crystalloid cardioplegia, clinical studies have been inconclusive. Ninety patients undergoing coronary bypass grafting were randomized to receive either blood (n = 43) or crystalloid cardioplegia (n = 47). The incidence of perioperative myocardial infarction was lower with blood cardioplegia (blood, n = 0; crystalloid, n = 5; p = 0.06), and the maximum MB isoenzyme of creatine kinase was significantly less with blood cardioplegia (blood, 26.3 +/- 12.6 U/L; crystalloid, 35.6 +/- 17.0 U/L, mean +/- standard deviation; p less than 0.02.) Sixty patients (blood cardioplegia, n = 28; crystalloid cardioplegia, n = 32) had more sensitive measurements to assess the metabolic response to aortic occlusion and to compare the metabolic and functional recovery from the operation. Coronary sinus blood flow (by the continuous thermodilution technique) was significantly lower after cross-clamp removal with blood cardioplegia (blood, 160 +/- 100 ml/min; crystalloid, 220 +/- 120 ml/min; p less than 0.05), indicating less reactive hyperemia. The cardiac production of lactate was significantly less with blood cardioplegia during aortic occlusion (blood, -0.5 +/- 0.9 mmol/L; crystalloid, -0.9 +/- 0.9 mmol/L; p less than 0.05) and immediately after aortic declamping (blood, -0.2 +/- 0.4 mmol/L; crystalloid, -0.7 +/- 0.7 mmol/L; p less than 0.01). Thermodilution cardiac output measurements permitted calculation of the left ventricular stroke work index, and nuclear ventriculograms permitted calculation of the left ventricular end-diastolic volume index and end-systolic volume index. Myocardial performance, systolic elastance, and diastolic compliance were determined from volume loading studies (250 to 500 ml colloid) performed 2 to 4 hours postoperatively. Myocardial performance (the left ventricular stroke work index-left ventricular end-diastolic volume index relation) and systolic elastance (the systolic blood pressure-left ventricular end-systolic volume index relation) were significantly better with blood cardioplegia (p less than 0.01 by multivariate analysis); diastolic compliance (the left atrial pressure-left ventricular end-diastolic volume index relation) was similar. Blood cardioplegia reduced ischemic injury, decreased anaerobic metabolism during arrest, and permitted better functional recovery. Blood cardioplegia provides superior protection for elective coronary bypass grafting and may improve the clinical results in patients with unstable angina and in other high-risk patients.