Annals of cardiac anaesthesia
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Two features of off-pump coronary artery bypass (OPCAB) can lead to hemodynamic instability: transient occlusion of coronary arteries during distal anastomosis construction and displacement of the heart to provide access to distal coronary arteries. The position of the heart during OPCAB trans-esophageal echocardiography (TEE) can often provide an indication as to how much compression of the right or left ventricle has occurred. If either chamber is not filling, repositioning of the heart will be necessary. ⋯ This, along with distal anastomosis causing transient occlusion of coronary arteries, may cause transient hypotension with increased filling pressures. TEE is more helpful in this scenario. In these patients, TEE helps differentiate between cardiac dysfunction and secondary to myocardial ischemia in which regional wall motion abnormalities will be present from a much more common scenario where the increase in filling pressure is secondary to extra cardiac compression and provides the ability to detect mitral regurgitation (MR) with a color-flow Doppler, as well as assess right heart function.
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Propofol and isoflurane may be used during fast track anesthesia for off-pump bypass, where transient ischemia is common. The purpose of this study was to compare the effects of propofol vs isoflurane in a porcine model of acute coronary occlusion. Twenty five pigs were randomized to receive general anesthesia with either isoflurane, 1 MAC (n = 13), or propofol, 3 mg/kg bolus followed by 200 microg/ kg/min infusion (n = 12). ⋯ There was a significant difference in Emax between isoflurane and propofol during early and late reperfusion [3.4 (0.5) and 4.0 (0.3) vs 2.6 (0.4) and 3.2 (0.5) mmHg/sec, respectively; P < 0.05]. Postreperfusion ventricular fibrillation occurred in 54% animals in the propofol group vs none in the isoflurane group ( P 0.05). Isoflurane administration was found to be cardioprotective against ventricular depression and arrhythmias compared to propofol.
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Letter Case Reports
Intravenous ondansetron causing severe bradycardia: two cases.