[Animal modeling] - Comparison of two minimally invasive Beagle dog models of myocardial infarction

  Objective: to establish a beagle dog model of myocardial infarction by two methods and compare their effects.

  Methods: 30 Beagle dogs were randomly divided into three groups, 10 in each group. ① In sham operation group, the pericardium was cut after thoracotomy without coronary artery ligation. In the other two groups, the anterior descending branch of the left coronary artery of dogs was clamped with titanium clips under the assistance of video-assisted thoracoscope. ② In the minimally invasive direct vision group, a 3.0 cm small incision was made between the third rib on the left edge of the sternum, through which the light source and operating instruments entered the chest. ③ In the thoracoscopic group, the left third intercostal lock midline was opened with a 1.0 cm hole as the detection hole, and the video video-assisted thoracoscope entered the thoracic cavity from here. The third intercostal sternal sideline and the fourth intercostal lock midline were opened with 0.5 cm holes respectively as the operation holes, and the surgical instruments entered the thoracic cavity from here. After modeling, ECG and serum creatine kinase isoenzyme (CK-MB) and troponin I (cTnI) content were measured, and HE staining was used to understand the myocardial lesions in each group. The success rate of the operation, the time from skin incision to chest closure and the wound healing time were recorded.

  Results: Compared with the sham operation group, the animals in the two groups showed significant changes in myocardial infarction (st segment elevation of ECG, increase of serum CK-MB and cTnI levels, myocardial ischemia, necrosis and fibrosis, and decrease of myocardial cells). The survival rate of dogs with the two methods was 90%, the time required for minimally invasive direct vision method was significantly less, and the healing time of thoracoscopic incision was shorter.

  Conclusion: The model of myocardial infarction established by minimally invasive surgery is an ideal model for studying the pathophysiological mechanism of myocardial infarction.