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Results for “HEART ARREST”

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PubMed1992

Reduced free radical generation during reperfusion of hypothermically arrested hearts.

Several studies indicate the presence of hydroxyl radical (OH.) as well as its involvement in the myocardial reperfusion injury. A transition metal-like iron is necessary for the conversion of superoxide anion (O2-) to a highly reactive and cytotoxic hydroxyl radical (OH.). In the present study, we have examined the generation of OH. and free iron in reperfused hearts following either normothermic (37 degrees C) or hypothermic ischemia (5 degrees C). Employing the Langendorff technique, isolated rat hearts were subjected to global ischemia for 30 min at 37 degrees C or 5 degrees C and were then reperfused for 15 min at 37 degrees C. The results of the study suggest that both the OH. generation in myocardium and free iron release into perfusate were significantly lower in hearts made ischemic at 5 degrees C as compared to 37 degrees C. Release of myoglobin and lactic acid dehydrogenase into perfusate also followed a similar pattern. Furthermore, in in vitro studies, chemically generated O2- at 5 degrees C caused a significantly lower rate of oxidation of oxymyoglobin as well as generation of OH. and free iron as compared to 37 degrees C. These results suggest that (1) reperfusion of hypothermic ischemic heart is associated with a reduction in the generation of OH. and cellular damage compared to that of normothermic ischemic heart, and (2) myoglobin, an intracellular protein, is a source of free iron and plays a role in the reperfusion injury mediated by free radicals.

Animals↗
PubMed1983

The influence of non-coronary collateral blood supply on the electively arrested heart during ischemia and reperfusion.

To study the influence of non-coronary collateral blood circulation (NCCBC) on the integrity of the ischemic myocardium a right-sided thoracotomy was performed on 15 anesthetized dogs. Following a total cardiopulmonary bypass (CPB), ventricular fibrillation was induced, during which 2,000 ml calcium-free cardioplegic solution LK 352 was given at the aortic root over an 8-10 min period. Precautions were taken to prevent retrograde blood flow into the coronary system via the coronary sinus. After 90 min of ischemia, ten of the dog hearts were reperfused with systemic blood for the next 30 min. Transmural biopsies were taken from the apex of the left ventricle at the following intervals: (1) before CPB, (2) immediately after the infusion of LK 352, (3) following 90 min of ischemia, (4) after 5 min, (5) after 15 min, and finally (6) after 30 min of reperfusion and were then studied ultrastructurally. The presence of NCCBC was documented by the observation of erythrocyte-filled blood vessels in the biopsies corresponding to nos. 2 and 3 of the above. To assess the degree of ischemic injury and the extent of myocardial recovery during reperfusion, a scoring system based on a semiquantitative assessment of the characteristic morphological changes was used. The average result of the separately assessed subendo- and subepicardial layers represented the score, which was plotted on the ischemic injury and the recovery scale, thus making a direct comparison of the hearts possible. All the hearts generously supplied with blood via extracoronary routes during ischemia showed minimal and reversible ischemic injuries. They recovered more quickly and more completely following reperfusion than those hearts without NCCBC. From these results we conclude that despite its warming-up effect on the myocardium and its tendency to wash out the cardioplegic solution, the NCCBC generally protects the myocardium from serious ischemic injuries and shortens the period of recuperation during the reperfusion.

Animals↗
PubMed1963

[HEART ARREST].

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Cell Respiration↗
PubMed1983

[Intraoperative control of the state of the arrested heart].

Monitoring the function of the operated on heart over time based on the principle of recording the effort of the myocardium at rest was tried under the clinical conditions after preliminary experiments on the hearts of rats and dogs. The study included 11 patients operated on for aortal, mitral and multi-valvular prosthetics under pharmacological cardioplegia. Such monitoring enables an objective appraisal of the heart status, Besides, it makes it possible to decide on whether repeated administration of cardioplegic solutions is required, to specify the times of reoxygenation and to prognose the pattern of the heart function recovery after operation is over. The data obtained helped detect some disadvantages of the generally accepted method of pharmacological cardioplegia.

Animals↗