ECG signs, systemic blood pressure and pulse oximetry were monitored continuously during EMI induction. Arterial oxygen saturation was measured with a pulse oximeter. The skin was clipped and shaved and standard electrocardiography (ECG) electrodes were attached in both the front limbs and bilateral sides of the lower abdomen. Prophylactic antibiotics (cefuroxime 25 mg/kg i.m.) were administered before and after surgery. A standard 22-gauge intravenous catheter was inserted into the marginal auricular vein to establish intravenous access. The rabbits were placed in the supine position. The surgical procedure was performed under aseptic conditions. Group B underwent EMI with a closed-chest method involving transauricular superselective catheterization of the left anterior descending coronary artery and distal percutaneous embolization with the introduction of a micro-coil.Īfter induction of dissociative anesthesia as described previously, subsequent anesthesia was maintained with low doses of propofol. Group A underwent EMI with an open-chest method involving surgical tracheostomy, a mini median sternotomy and left anterior descending coronary artery ligation with a plain suture. The experimental protocol consisted of two groups. All EMI procedures were performed with the animals under dissociative anesthesia with a mixture of ketamine (35 mg/kg) and xylazine (5 mg/kg) i.m. 86-23, revised 1985) and was approved by the local Hospital's Scientific and Ethics Committee. This investigation was carried out in conformity with the "Guide for the Care and Use of Laboratory Animals" published by the National Institutes of Health (NIH publication No. New Zealand White rabbits weighing 2.5-3.5 kg were kept in separate cages in an environmentally controlled animal research facility. This model of percutaneous transauricular EMI in the rabbit was compared with the gold standard of experimental myocardial infarction as induced by coronary ligation with a plain suture. The aim of the present study was to establish a closed-chest, solely percutaneous, minimally invasive technique in order to induce EMI by transauricular embolization of the left coronary artery of the rabbit heart. Most importantly, they may induce more physiologically more clinically relevant myocardial ischemia. Closed-chest models of EMI primarily avoid the major trauma of thoracotomy with its potential influence on cardiac and whole-body physiology and recovery. Alternative closed-chest models of EMI that mainly use endovascular catheterization techniques have been developed, where transcatheter access to the coronaries is typically gained via surgical cutdown and exposure of the carotid or femoral artery. The preceding pericardial incision bears little pathophysiological relevance to human clinical afflictions and may disturb the progression of myocardial remodelling, whereas major surgery alone may affect whole body homeostasis and alter local and systemic immunological and inflammatory responses. However, open-chest EMI is associated with local and systemic side effects of major surgery. Open-chest procedures allow direct access to the heart with visual inspection of procedural results, while immediate contact to the epicardial coronary vessels provides the opportunity for accurate measurements of coronary blood flow and other relevant hemodynamic parameters. Most animal studies on EMI have employed the traditional open-chest platform with thoracotomy and direct surgical ligation of the left coronary artery. Experimental coronary infarction and ischemia of the myocardium may be produced in many animal species and in various ways. A large body of evidence has been amassed regarding the pathophysiology, pharmacological treatment strategies and relevant interventional therapy in the setting of acute and chronic myocardial ischemia and infarction. During the last years, experimental myocardial ischemia (EMI) has been one of the most extensively studied topics in modern cardiovascular research. Appropriate animal models are essential in order to investigate the mechanisms of myocardial infarction and develop new therapeutic interventions. Ischemic coronary artery disease is a major cause of morbidity and mortality.
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