Semi-Minimal Invasive Method to Induce Myocardial Infarction in Rats and the Assessment of Cardiac Function by an Isolated Working Heart System

Myocardial infarction (MI) remains the main contributor to morbidity and mortality worldwide. Therefore, research on this topic is mandatory. An easily and highly reproducible MI induction procedure is required to obtain further insight and better understanding of the underlying pathological changes. This procedure can also be used to evaluate the effects or potency of new and promising treatments (as drugs or interventions) in acute MI, subsequent remodeling and heart failure (HF). After intubation and pre-operative preparation of the animal, an anesthetic protocol with isoflurane was performed, and the surgical procedure was conducted quickly. Using a minimally invasive approach, the left anterior descending artery (LAD) was located and occluded by a ligature. The occlusion can be performed acutely for subsequent reperfusion (ischemia/reperfusion injury). Alternatively, the vessel can be ligated permanently to investigate the development of chronic MI, remodeling or HF. Despite common pitfalls, the drop-out rates are minimal. Various treatments such as remote ischemic conditioning can be examined for their cardioprotective potential pre-, peri- and post-operatively. The post-operative recovery was quick as the anesthesia was precisely controlled and the duration of the operation was short. Post-operative analgesia was administered for three days. The minimally invasive procedure reduces the risk of infection and inflammation. Furthermore, it facilitates rapid recovery. The "working heart" measurements were performed ex vivo and enabled precise control of preload, afterload and flow. This procedure requires specific equipment and training for adequate performance. This manuscript provides a detailed step-by-step introduction for conducting these measurements.