Observation of the Beneficial Effect of Physical Exercise on Improving Chronic Collateral Circulation of Myocardium in Animal Experiment
After physical exercise, the activity of patients with angina pectoris can often increase significantly. The benefits of physical exercise are partly due to the slowdown of heart rate and the decrease of myocardial metabolism after the same sub-maximum exercise, which can balance the oxygen supply and consumption of myocardium. At the same time, exercise may also improve the blood supply of myocardial ischemic areas. In this study, 28 healthy cats were selected to perform treadmill exercise. After thoracotomy, a catheter was inserted into the aorta through the left internal mammary artery and another catheter into the left atrium through the left atrium. The left anterior descending coronary artery is located at the far end of the origin of the oblique branch. A 1.5 mm Ameroid constrictor is installed. Because Ameroid is hydrophilic, the coronary artery is completely blocked after 5 days. At the same time, ligation of the left circumflex branch resulted in lumen obstruction of 60-90%. An electrode was implanted in the left ventricular myocardium to record the heart rate. Finally, catheters and electrodes were sutured into the subcutaneous tissue of the cat's neck. Fourteen cats died of ventricular fibrillation or myocardial infarction during a two-week rehabilitation period. Fourteen surviving cats were divided into exercise group and control group, 7 in each group. After measuring the basic data (including exercise test data and myocardial blood flow measured by injecting radioisotope labeled particles), the former trained for five days a week, exercised on a flat plate for one hour a day, started at 3 miles 0 per hour, and gradually increased to 6 miles 5 per hour at the sixth week. After six weeks of physical exercise, the heart rate of the experimental cat was 25 times slower at rest than that of the control group (not significant), while the heart rate of the experimental cat was 35 times slower than that of the control group (P < 0.05). Myocardial blood flow in collateral circulation during rest was similar to that in control group. However, the blood flow in the subendocardial part of the collateral circulation area was 39% higher than that in the control group, while that in the subepicardial part was not insufficient and remained unchanged after exercise. The ratio of endocardial: epicardial blood flow was significantly higher than that in the control group. This paper reports the experimental results of cats and proves that physical exercise can improve chronic collateral circulation of myocardium.