Open chest cardiopulmonary bypass,cardioplegia perfusion on aortic root by ascending aorta occlusion:a new experimental rat model on cardiac surgery study

Qiu Bingmei; Wang Lei; Ding Peicheng; Zhang Xing; Xu Rukun; Hu Lanxin; Wang Anli

doi:10.13498/j.cnki.chin.j.ecc.2024.04.13

Abstract：Objective To establish the process of cardiac arrest and resuscitation in rats with median thoracotomy to simulate cardiopulmonary bypass(CPB)by injecting cardioplegic solution from the ascending aorta root.Methods 10 adult male SD rats were selected(weight ranging from 350 g to 450 g).Inhalation induced and intraperitoneal injection anesthesia was followed with endotracheal intubation and small animal ventilator-assisted ventilation.The right internal jugular vein was inserted by a self-made drainage tube with lateral holes serving as venous drainage while the tail artery was intubated as arterial perfusion to establish CPB,the femoral artery was intubated and monitored for blood pressure.At the beginning of CPB,median thoracotomy was performed,the heart was exposed,and the ascending aorta was clamped.Cardioplegia was perfused through the root of the ascending aorta root.After 30 minutes of clamping,the ascending aorta was re-opened,and calcium chloride,small doses of epinephrine and furosemide were administered.Blood samples were collected before CPB,at the beginning of CPB,10 min after CPB,at the beginning of aortic clamping,10 and 20 minutes after clamping,aorta re-open,CPB weaned off and 2 hours after CPB weaned off for blood gas analysis.Additionally hemodynamics of rats were observed after CPB weaned off.Results 7 rats successfully underwent modeling,while one suffered cardiac arrest during the thoracotomy procedure,one died of hemorrhagic shock due to faild internal jugular vein intubation,another died of cardiac arrest because of arrythmia due to jugular vein intubation.CPB time was 72±12 min,post-resuscitation parallel circulation time was 21±6 min.Hematocrit level during CPB was significantly lower than baseline,the results of blood gas analysis at each measurement point remained acceptable as CPB standard.Conclusion The CPB with median thoracotomy and ascending aorta occlusion model in rats is a low-cost,stable and reliable experimental model,which can be used as an alternative study tool of organ impairment and myocardial protection in patients undergoing cardiac surgery.