Ischemic preconditioning

Ischemic preconditioning The concept of ischemic preconditioning is that multiple short episodes of ischemia can protect the heart from a later sustained ischemia later [1]. In an experimental study, 4 episodes of 5 minutes each, separated by 5 minutes of reperfusion followed by 40 minutes of occlusion showed 75% reduction in infarct size compared to controls. But this benefit was not there when the final occlusion time was 3 hours. Authors suggested that multiple pre-infarction anginal episodes may have a similar effect on limiting infarct size if myocardial infarction occurs subsequently. Others have suggested that similar mechanism might operate in warm-up phenomenon in angina [2]. Intermittent ischemia during aortic cross clamping in fibrillating heart during coronary artery bypass surgery is also a clinical model of ischemic preconditioning. Ischemic preconditioning has also been studied during percutaneous coronary intervention. Clinical, ECG and coronary hemodynamic responses to sequential 90 second balloon occlusions of left anterior descending coronary artery was assessed in 12 patients [3]. Compared to the initial balloon occlusion, anginal discomfort was less in the second occlusion. Similarly, ST segment shift and mean pulmonary artery pressure was significantly lower in the second occlusion. Myocardial lactate production was also significantly lower during the second balloon occlusion. It has been shown that ischemic preconditioning during coronary angioplasty i...
Source: Cardiophile MD - Category: Cardiology Authors: Tags: Cardiology Source Type: blogs