A novel minimal invasive closed chest myocardial ischaemia reperfusion model in rhesus monkeys (Macaca mulatta): improved stability of cardiorespiratory parameters.

The aim of this study was to report the cardiorespiratory events observed during coronary artery occlusion and reperfusion in a minimally invasive closed chest myocardial occlusion-reperfusion model in rhesus monkeys. We hypothesized that a minimally invasive technique may lead to fewer cardiac arrhythmias and complications. Eight male rhesus macaques 10-15 kg and 10-15 years old were sedated with ketamine (2 mg/kg), midazolam (1.3 mg/kg), atropine (0.01 mg/kg) and buprenorphine 0.02 mg/kg intramuscularly. Etomidate 1-2 mg/kg was injected intravenously to allow tracheal intubation. Anaesthesia was maintained with isoflurane. Pulse oximetry, electrocardiogram (ECG), heart rate, mean arterial blood pressure (MAP), inspired isoflurane fractions (F(I)ISO) and core temperature were recorded every 10 min. The coronary artery occlusion was induced by a balloon-tipped catheter advanced via the femoral artery into the left anterior descending artery and inflated to completely occlude the vessel for 20-50 min (IT) before reperfusion. Sequences of elevated ST segment, QRS complex prolongation, ventricular premature complexes and ventricular fibrillation were observed with a lower incidence than previously described in the literature. IT was (min: 17; max: 50) min long. F(I)ISO was lower than the minimal alveolar concentration in these species. Hypotension (MAP < 70 mmHg) and hypothermia (T°C < 36°C) were observed in all macaques. This minimally invasive closed chest model was successful in providing better cardiorespiratory physiological parameters than reported in previous models. The benefit (achieving ischaemia) versus risk (lethal arrhythmia) of the duration of the coronary occlusion should be considered.