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

The effect of diltiazem on creatine kinase release and tissue adenosine triphosphate content was investigated during calcium paradox in the isolated perfused rat heart. Creatine kinase loss was minimal during the calcium-free phase, but there was a 100-fold increase in creatine kinase release after reperfusion with normal calcium-containing medium. Diltiazem reduced creatine kinase loss by 35 percent when added to calcium-free medium and by approximately 80 percent when added to both calcium-free and reperfusion media. Adenosine triphosphate content was significantly increased from 2.98 mumol in untreated calcium paradox hearts to 5 mumol/g dry weight in diltiazem-treated hearts. With hypothermia the calcium paradox injury was completely inhibited if the temperature of calcium-free perfusion was maintained at 15 degrees C. Diltiazem appears to exert its protective effect through its ability to prevent the cellular separation and alterations in the gap junctions during calcium deprivation of cells and to limit calcium entry into the cells after reperfusion with calcium-containing medium.
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PMID:Prevention of calcium paradox-related myocardial cell injury with diltiazem, a calcium channel blocking agent. 628 3

Complex hepatic surgery often requires occlusion of the portal triad in order to decrease parenchymal bleeding. This study was undertaken to evaluate the effects of topical hypothermia and intravenous steroids on liver ischemia by measuring adenosine triphosphate (ATP) levels within the hepatic parenchyma. Forty New Zealand white rabbits were divided into four experimental and four control groups. All experimental animals underwent laparotomy and ligation of the porta hepatis. Serial liver biopsy specimens were obtained at predetermined time intervals. Group I received no further intervention. Group II were topically cooled until intrahepatic temperature reached 30 degrees C. Group III received preligation intravenous methylprednisolone (30 mg/kg). Group IV received both steroids and topical hypothermia. The corresponding control groups underwent laparotomy and isolation of the porta without ligation. Adenosine triphosphate was extracted from the liver parenchyma and quantified by high-performance liquid chromatography (HPLC). The data were analyzed using a three-factor mixed analysis of variance (ANOVA). There was a statistically significant protective effect on ATP levels provided by topical hypothermia at 15 and 30 minutes of ischemia (p < 0.01), but not at 60 minutes (p > 0.05). Steroids were not found to have any protective effect on ATP levels at any time point. The combination of steroids and topical hypothermia provided significant preservation of hepatic parenchymal ATP levels, although less than that of hypothermia alone, at 15 and 30 minutes of ischemia (p < 0.01).
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PMID:The effects of topical hypothermia and steroids on ATP levels in an in vivo liver ischemia model. 793 3

One hundred seven patients undergoing coronary artery bypass grafting were randomized to receive warm antegrade (n = 21), warm retrograde (n = 22), cold antegrade (n = 20), cold retrograde (n = 22), or intermittent cold antegrade (n = 22) blood cardioplegia. Myocardial oxygen consumption and lactate production, adenine nucleotides, and adenine nucleotide degradation products were measured during the operation, and creatine kinase-MB release was assessed postoperatively. Warm cardioplegia resulted in greater myocardial lactate production than cold cardioplegia (p = 0.048). Retrograde cardioplegia was associated with greater lactate production than antegrade cardioplegia (p = 0.015). Adenosine triphosphate depletion was similar among groups. However, poorly diffusible metabolites of adenosine triphosphate accumulated to the greatest extent in the intermittent cold group. Levels of hypoxanthine were highest after warm retrograde cardioplegia. Operative mortality and morbidity were low and were not different among groups. In summary, none of the five techniques of cardioplegia evaluated in this study was able to completely prevent myocardial ischemia. Anaerobic lactate production was minimized with cold cardioplegia and with antegrade cardioplegic delivery. Hypothermia may have impaired regeneration of adenosine triphosphate, however, particularly in association with inadequate or intermittent cardioplegic flow.
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PMID:Which techniques of cardioplegia prevent ischemia? 823 94

A 31-year-old male with slow ventricular tachycardia (VT) developed a nonsustained VT with prolongation of the JT intervals after injection of contrast medium and saline into the marginal vein of the coronary sinus. The earliest activation site of the VT existed in the epicardium of the left ventricular base. Adenosine triphosphate prevented induction of VT and prolongation of JT intervals. Ventricular premature contractions showing the same morphology as the VT were also inhibited by nicorandil and verapamil. The mechanism of the VT was suggested to be abnormal automaticity due to an increase in the Ca++ current into cells after prolongation of the action potential duration induced by hypothermia.
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PMID:Slow ventricular tachycardia located in the epicardium of the left ventricular base and characterized by effects of adenosine triphosphate, nicorandil and verapamil. 989 Feb 11

Continuous blood perfusion of donor hearts for transplantation has been the focus of an increasing amount of research, but the optimal preparation and perfusion techniques have not been clearly defined. Therefore, we investigated the effectiveness of different preservation strategies using continuous, normothermic heart perfusion after donor heart harvesting. Hearts of 12 pigs were randomly assigned to two groups receiving a constant pressure perfusion in a modified Langendorff system after different preparation techniques. In Group 1, six hearts were arrested with Bretschneider HTK cardioplegia (4 degrees C) and then reperfused with a circulating pressure of 80 to 90 mmHg using leukocyte depleted autologous blood. In Group 2, beating hearts of six pigs were explanted while being perfused, without cardioplegic arrest. Post-harvesting perfusion was similar to Group 1 except for a lower circulating pressure (40-50 mm Hg). At different time points (baseline and 1, 6, and 12 h after reperfusion), myocardial biopsies were taken, and contractility was assessed by measuring the maximum rate of left ventricular pressure rise (Deltap/Deltat (max)). Adenosine triphosphate (ATP) concentration was measured in all biopsies using a bioluminescence technique. Additionally, ultrastructural alterations were investigated using electron microscopy. Hypothermic cardioplegia and a higher reperfusion pressure (Group 1) were associated with an earlier and sharper decline in contractile function and intracellular ATP concentration. Ultrastructural alterations in Group 1 appeared earlier and were more distinctive than in Group 2. Endothelial ultrastructure, in particular, was better preserved in Group 2. Significant alterations were present in both groups after 12 h of perfusion but were more severe in Group 1. Blood perfusion provides protection against severe ischemic damage for a limited time. The use of a lower perfusion pressure, as well as avoiding cardioplegia and hypothermia, led to significantly better and longer preservation of perfused hearts.
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PMID:Functional, metabolic, and morphological aspects of continuous, normothermic heart preservation: effects of different preparation and perfusion techniques. 1950 81


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