Comparison of two minimally invasive myocardial infarction models in Beagle dogs

  Objective: To establish animal models of myocardial infarction in beagle dogs with two methods and compare their effects.

   Method: 30 Beagle dogs were randomly divided into three groups, each with 10 dogs. ① In the sham operation group, the pericardial cavity was cut after thoracotomy without coronary artery ligation. In the other two groups, the canine left anterior descending coronary artery was clamped with titanium clips under the assistance of video-assisted thoracoscopy. In the minimally invasive direct vision group, a small 3.0 cm incision was made in the third intercostal space on the left margin of the sternum. This hole enters the chest cavity. ③ In the thoracoscopy group, an opening of 1.0 cm at the midline of the third intercostal lock on the left was used as a detection hole, through which the video-assisted thoracoscopy entered the thoracic cavity, and 0.5 was opened at the parasternal line of the third intercostal and the midline of the fourth intercostal lock. The cm hole is used as an operating hole, through which surgical instruments enter the chest cavity. After modeling, the electrocardiogram and the changes of serum creatine kinase isoenzyme (CK-MB) and troponin I (cTnI) content were measured, and HE staining was used to understand the cardiomyopathy of each group. The success rate of the operation, the time from the beginning of the skin incision to the closing of the chest and the wound healing time were recorded.

  Result: Compared with the sham operation group, the two groups of animals showed obvious myocardial infarction changes (ECG st-segment elevation, serum CK-MB and cTnI levels increased, myocardial ischemic necrosis, fibrosis, and myocardial cell reduction). The survival rate of dogs with the two modeling methods is 90%, the minimally invasive direct vision method requires significantly less time, and the thoracoscopic method requires shorter incision healing time.

   Conclusion: The myocardial infarction model established by minimally invasive surgery has small animal trauma and low mortality. It is an ideal model for studying the pathophysiological mechanism of myocardial infarction.