Cardioplegia and myocardial protection were performed under cardiopulmonary bypass during open heart surgery with the use of cold Bretschneider´s cardioplegic solution (4°C) for the coronary artery perfusion and normal saline solution (4°C) for the topical cardiac cooling.
To maintain the state of myocardial protection, coronary artery reperfusion was carried out using Bretschneider´s cardioplegic solution at the interval of 30 minutes.
A total number. of patients studied were 30 cases, including 20 cases of correction for congenital cardiac anomalies and 10 cases of valve replacement for acquired heart valvular disease.
Thr average of patients studied was 21.57 years, ranging from 2 1/2 to 54 years, and the average body weight of patients was 37.05 Kg, ranging from 11 to 65.5Kg.
Cardiopulmonary bypass time during the surgery was observed to be average of 87.89 ±47.55 hours, aortic corss-clamping time to be average of 76.68±44.27 hours ranging from 22 to 183 minutes.
In order. to evaluate the effects of myocardial protection in the surgery, serum enzyme . levels were determined, and the electrocardiographic findings and immediate postoperative recovery of the heart were also observed.
To observe the relationship between aortic cross-clamping time and myocardial protection effects, patients studied were divided. into the following 4 groups.
Ⅰ group ; aortic cross-clamping time, 60 minutes
Ⅱ group ; aortic cross-clamping time, 90 minutes
Ⅲ group aortic cross-clamping time, 120 minutes
Ⅳ group ; aortic cross-clamping time, over 120 minutes
The results obtained in the present study were as follows;
1. Changes in serum enzyme levels in postoperative period.
(1) SGOT; The positive value (increased over 200 units) for ischemic myocardial injury during operation was observed in 4 cases (13.3% of the total) of the total patients studied, of .which 1 case (14.3%) in II group, 2 cases (40.0%) in III group, and 1 case (25.0%) in IV group.
(2) LDH; The positive value (increased over 900 units) for ischemic myocardial injury during operation was observed in 13 cases (43.3% of the total) of the total patients studied, of which 3 cases (21.4%) in I group, 4 cases (57.1%) in 11 group, and 3 cases (60.0%) in III group
(3) CPK; The positive value (increased over 800 units) for ischemic myocardial injury during operation was observed in 7 cases (23.3% of the total) of the total patients studies, including 2 cases (14.2%) in I group, 2 cases (28.5%) in II group, 2 cases (40.0%) in III group, and 1 case (33.3%) in IV group.
2. Postoperative electrocardiographic findings. The number of patients detected by electrocardigraphy as subendocardial or subepicardial myocardial injury or both was found to be 5 cases (20.0% of the total), including 4 cases in II group and 1 case in IV group. Two cases out of a total of 5 cases exhibiting abnormal electrocardiographic findings were combined with AV-dissociation or left anterior hemiblock, and the remaining 3 cases had valvular disease showing a severe cardiac failue before the surgery.
3. Immediate postoperative recovery. The number of patients who received defibrillation because of fibrillation or ventricular tachycardia after removing aortic cross-clamping was 14 cases (46.6% of the total) of the total patients studied, but they all returned to normal heart beat. The number of patients who administered Dopamine because of hypotension after the operation was 6 cases (20.0% of the total) of the total patients studied, including 2 cases in II group and 4 cases in IV group.
4. The myocardial protection methods used in the present study was demonstrated to be very effective for the myocardial protection in the surgery with aortic cross-clamping time of up to 60 minutes. A few ischemic myocardial injury were observed in the surgery with aortic cross-clamping time over 60 minutes, but no cardiac dysfunction was noted. The surgery with aortic cross-clamping time of up to. 183 minutes did not appear to give rise any significant interference with postoperative recovery.
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