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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypothermic synchronized retroperfusion was applied during coronary artery occlusion to determine its ability to alleviate junctional derangements of reperfusion and to reduce infarct size. The proximal left anterior descending coronary artery was occluded in 25 closed chest dogs for 3 hours and then reperfused for 7 days. Thirteen dogs with no reperfusion pretreatment served as a control group (Group A). In 12 dogs, hypothermic retroperfusion was applied from 30 minutes up to 3 hours of the occlusion period (Group B). Sequential two-dimensional echocardiographic and hemodynamic as well as metabolic measurements were performed. Compared with untreated control dogs, dogs with hypothermic synchronized retroperfusion had significantly reduced heart rate and rate-pressure product, decreased left ventricular volumes and improved ejection fraction during the occlusion period. Two-dimensional echocardiographically-derived ischemic zone systolic fractional area change and systolic wall thickening indicated significantly improved function as a result of retroperfusion. During the reperfusion period, untreated control dogs (group A) had more severe derangements in hemodynamics and wall motion than dogs treated by hypothermic retroperfusion (group B). Mortality was 30.7% in group A, 16.7% in group B and 7th day infarct size as percent of the left ventricle was 12.0 +/- 6.5 (mean +/- standard deviation) and 4.2 +/- 5.9, respectively (p less than 0.02). It is concluded that hypothermic synchronized retroperfusion applied after coronary occlusion and before reperfusion significantly improves cardiac function during occlusion, minimizes complications of reperfusion and reduces the ultimate infarct size. Because this form of circulatory assistance helps maintain cardiac function and delays the evolution of myocardial necrosis, its application may be beneficial during an evolving acute myocardial infarction before achievement of surgical or nonsurgical reperfusion.
J Am Coll Cardiol 1983 Apr
PMID:Prevention of ischemic injury and early reperfusion derangements by hypothermic retroperfusion. 683 45

An isolated rat heart preparation was used to characterize the temperature dependence of the calcium paradox and also to assess the validity of various indices of hypothermic protection. Hearts were subjected to 10-min periods of calcium depletion at various degrees of hypothermia followed by 20 min of normothermic calcium repletion. Using enzyme or protein leakage during calcium repletion as an index of hypothermic protection during calcium depletion, paradox injury was reduced extensively by relatively moderate hypothermia. Thus, depletion at 29 degrees C reduced total creatine kinase leakage by 57 +/- 4% from 1585 +/- 24 IU/g dry wt to 677 +/- 63 IU/g dry wt and at 25 degrees C leakage was reduced by 85 +/- 4% from 1585 +/- 24 IU/g dry wt to 237 +/- 71 IU/g dry wt. However, upon calcium repletion there was no recovery of contractile function. It was not until the myocardial depletion temperature was reduced to 20 degrees C that some functional recovery occurred. Under these circumstances cumulative creatine kinase leakage was reduced to below 88 IU/g dry wt, 6% of its normothermic value and protein leakage was undetectable. Functional recovery was not complete until the temperature was reduced to 15 degrees C or below. Correlation of cumulative enzyme leakage with functional recovery suggested a narrow release threshold (50 to 100 IU/g dry wt) above which no recovery occurred and below which a full recovery could be confidently predicted. Morphological assessments an all-or-none phenomenon; thus although increasingly severe hypothermia progressively reduced the percent of cells that sustained damage (as opposed to the degree of damage in all cells), it was not until 100% of cells appeared ultrastructurally undamaged that functional recovery was observed. Calcium-free perfusion at 4 degrees C protected the intercalated discs from gross lesions and prevented the separation of the external lamina from the surface coat. Our results also stress the heterogeneity of tissue injury and hypothermic protection and in addition shed further light upon the component mechanisms contributing to calcium injury.
J Mol Cell Cardiol 1983 Jun
PMID:The temperature dependence of the calcium paradox: enzymatic, functional and morphological correlates of cellular injury. 687 88

After cardiac catheterization a 53-year old patient developed widespread myocardial ischemia that produced electromechanical dissociation and cardiogenic shock. The administration of methylprednisolone, the initiation of cardiopulmonary bypass and hypothermia within 40 min of the onset of ischemia, and reperfusion within 90 min of the onset of ischemia were sufficient to salvage a major portion of the ischemic myocardium.
Clin Cardiol 1980 Aug
PMID:Salvage of acutely ischemic myocardium by emergency coronary artery bypass grafting. 696 63

Femoral artery perfusion for cardiopulmonary bypass is still employed for reoperation, procedures involving the thoracic aorta, and partial bypass in critical patients. Retrograde aortic dissection is the most significant complication of femoral perfusion. The reported incidence is from 0.6% to 14% with a mortality of 66%. Most of the deaths occurred in patients in whom the dissection was not recognized , or in whom the dissection was recognized but not treated appropriately. Our experience with retrograde dissection totals six patients of 640 (0.9%) in whom femoral inflow was used. Four of the six patients survived the dissection. Sudden increase in extracorporeal line pressure shortly after beginning cardiopulmonary bypass associated with decreased venous return, dampened radial arterial pressure, and the abrupt appearance of a bluish, bulging ascending aorta establishes the diagnosis. Survival is enhanced if cardiopulmonary bypass is promptly discontinued, aortic cannulation established, and bypass reinstituted with the induction of profound hypothermia. Circulatory arrest may then be employed to repair the false passage. In this series the proposed operation was completed in all six patients.
Clin Cardiol
PMID:Retrograde aortic dissection during cardiopulmonary bypass. 697 67

These data would suggest that hypothermia combined with potassium cardioplegia enhances protection of the ischemic myocardium over other available techniques. The ideal conduct of this myocardial protection is not yet apparent but certain aspects are worthy of emphasis. (1) With the onset of ischemia cardioplegia should be immediately induced to abolish contractile activity and conserve energy. An advantage of blood cardioplegia is that there is no ischemia or it is trivial priorto cardioplegia. (2) The greater the degree of myocardial cooling the better. Although a myocardial temperature of 20 degrees C can commonly be achieved with perfusion hypothermia and topical hypothermia, it is possible to reduce myocardial temperature to 10 degrees C or lower with these same modalities. Because perfusion hypothermia provides fairly uniform rapid myocardial cooling, this should be maximally utilized by cooling of the systemic perfusate to 20 degrees C and cooling the cardioplegic infusate to 4-10 degrees C. Cardiac hypothermia should be maintained with crushed ice made from electrolyte solution or irrigation of the pericardial sac with cold electrolyte solution. The greater the degree of systemic hypothermia the less tendency for the myocardium to warm. (3) The ideal concentration of potassium is unknown at this time with a range of 15-40 mEq/l having been utilized without apparent potassium injury. (4) The ideal composition of the vehicle may never be defined and may not be of great importance. Whole blood would appear to offer physiological and pragmatic advantages over asanguinous vehicles. (5) The safe duration of ischemia has been moderately well defined. 1 h is well tolerated in the dog using profound cardiac hypothermia, whereas 30-45 min with lesser degrees of hypothermia is acceptable. When the interval of ischemia is to be 2 or 3 h reinfusion of potassium every 20-30 min has proven safe both experimentally and clinically.
Adv Cardiol 1980
PMID:Does myocardial protection work? 700 27

Significant advances in five areas of cardiac surgery have contributed to better short and long term results. These include: the use of hypothermia and cardioplegic solutions for intraoperative myocardial protection. Improvement in design and hemodynamic characteristics of prosthetic valves. Refinements in electrosurgical techniques for the treatment of arrhythmias refractory to medical therapy. Improvement in circulatory assist devices including the total artificial heart, and significantly better results in heart transplants due to a better understanding of immunosuppression and infection control. Current information on these five areas is summarized.
Arch Inst Cardiol Mex
PMID:[Advances and perspectives in heart surgery]. 701 37

In this experimental work, fertilized chicken eggs were subjected to hypothermia (34.5 degrees) as to inhibit the incorporation of the aortic infundibulum into the left ventricle. This produced a spectrum of biventricular connection of the aorta including double outlet right ventricle (DORV), a cardiopathy seen naturally in man and in chicken. It represents the persistence in the postnatal heart of the spectrum of embryonic aortic dextroposition, a fact which allowed us to establish a precise anatomoembryologic correlation. Pathogenetically, the failure in the connection of the aortic infundibulum with the left ventricle is due to inhibition, in different degrees, of the leftward morphogenetic movement of the infundibular segment, an embryologic process which is discussed in relation to different theories on the origin of DORV. The role played by cell death in normal and pathologic morphogenesis, is emphasized and some methodological aspects on experimental teratogeneses are mentioned.
Arch Inst Cardiol Mex
PMID:[Spectrum of biventricular aortic connection and double outlet chamber of the right ventricle produced experimentally in the chicken heart by hypothermia (34.5 degrees C)]. 710 9

The aim of this study was to investigate the protective efficacy of potassium cardioplegia in general moderate hypothermia, in five pigs, after 90 minutes of myocardial ischemia induced by extracorporeal circulation (ECC) and aortic clamping. The behaviour of subendocardial supply demand ratio (DPTI/TTI), of CSBF (coronary sinus blood flow) and numerous hemodynamic parameters was evaluated in addition to lactate myocardial metabolism changes, at rest, after 90 minutes of total ECC and during a 60 minutes reperfusion period. The reperfusion period included two phases: during the first (15-20 minutes) the animals were in ECC with unclamped aorta; spontaneous circulation was instituted during the second one (40 minutes). A marked increase in CSBF was observed at aortic clamp removal during the first phase (post ischemic reactive hyperemia). Coronary sinus lactate release was also noted, probably due to wash-out of previously sequestered acid metabolites during aortic clamping (90 minutes). At the onset of the second phase a depressed left ventricular performance and low DPTI/TTI values were shown. A rapid return (20 minutes) to normal values of this parameter was then noted. DPTI/TTI normalization results strictly correlated to the progressive improvement in myocardial performance. Hypothermic potassium cardioplegia seems therefore to prevent the irreversible myocardial damage and favour a fast recovery of cardiac function.
G Ital Cardiol 1982
PMID:[Importance of metabolic disorders and endocardial viability ratio in the prognosis of open-heart operations. Experimental study of the pig heart protected by potassium cardioplegia in hypothermia]. 712 92

The relationship between ischemic contracture and no-reflow phenomenon was studied in 59 isolated rat hearts during global ischemia. The contracture was measured by a water-filled balloon catheter placed in the left ventricular lumen. The time of onset of contracture was changed by preischemic infusion with buffer containing 0.5 mmoles/l iodoacetate (IAA) in order to get early contracture, and by hypothermia which delayed the development of contracture. The first signs of contracture were noticed in normothermia (37 degrees C) at 11 minutes, in hypothermia (26 degrees C) at 25 minutes, and in the IAA-infused group at 3 minutes. The completion of contracture occurred in these groups at 25, 90 and 11 minutes, respectively. The myocardial perfusability was tested at the pre- and postcontracture state by infusing 0.1% fluorescein in isotonic saline into the cannulated aortic root. The myocardial area perfused with fluorescein was quantified in colour photographs taken under ultraviolet light of frozen whole-heart sections. The myocardial perfusion - expressed ad percent of myocardial area - was 99% at the precontracture state in normothermia, 95% in hypothermia and 100% in the IAA-infused group. At the postcontracture state, the myocardial perfusion in these groups was 80, 56 and 18%, respectively. It was concluded that the no-reflow phenomenon in isolated rat heart is closely associated with the development of myocardial contracture during global ischemia.
Basic Res Cardiol
PMID:The relationship between ischemic contracture and no-reflow phenomenon in isolated rat heart. 715 Feb 10

An 83-year-old woman was found unconscious several hours after she had fallen and fractured her lower limbs in a very cold cellar. On admission she was in shock and had metabolic acidosis, anemia and hypokalemia; her axillary and rectal temperature was 23 degrees C. Her initial ECG showed atrial fibrillation with slow ventricular response and a prominent J wave on the left precordial leads. These changes reverted to normal when body temperature returned to 37 degrees C. Moreover a transient, hypothermia-associated increase of QRS voltage was noted.
G Ital Cardiol 1982
PMID:[Electrocardiographic changes in accidental hypothermia]. 717 40


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