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

The continuous measurement of intramyocardial pH was used to follow the progression of ischemia and was correlated to the recovery of left ventricular function following normothermic (38 degrees C) and hypothermic (25 degrees C) global ischemia. New miniature myocardial transducers, which incorporate fiberoptic technology and dual pH- and temperature-sensing capability, were placed into the left ventricular free wall and septum of 52 sheep undergoing cardiopulmonary bypass. Left ventricular stroke work as a function of mean left atrial pressure curves were generated before and after cardiopulmonary bypass by volume loading with whole blood. Functional recovery was determined by the ratio of the integrals of the preischemic and postischemic function curves. Control sheep (N = 11) did not undergo ischemia. Three groups (N = 41) underwent aortic cross-clamping until pH reached 7.0, 6.8, or 6.6. The preischemic myocardial pH averaged 7.42 +/- 0.01. Following both normothermic and hypothermic global ischemia, no significant difference was demonstrated in recovery of function between control (pH 7.4) and pH 7.0 groups at either temperature. However, recovery of function of the pH 6.8 and pH 6.6 groups was significantly decreased (p less than 0.01) versus control and pH 7.0 groups at both temperatures. No significant difference in recovery of function was demonstrated at any pH level when normothermic versus hypothermic groups were compared. However, hypothermia provided increased time (p less than 0.001) before each level of function was reached with a slower rate of change of pH (p less than 0.01) compared with the corresponding same pH group in sheep undergoing normothermic (38 degrees C) cardiopulmonary bypass.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Continuous measurement of intramyocardial pH: correlation to functional recovery following normothermic and hypothermic global ischemia. 372 14

The behavioral performance of rats subjected in the neonatal period to hypoxia-ischemia at either 37 degrees C or 21 degrees C was compared to that of sham-ligated animals. Performance on complex motor tests was significantly delayed only in the hypoxic-ischemic 37 degrees C rats. However, cognitive testing disclosed significant delay of spatial learning in animals subjected to hypoxia-ischemia at 21 degrees C and those with gross infarction at 37 degrees C. There was enhanced avoidance learning in the animals with gross infarction in the hypoxia-ischemia 37 degrees C group. Hypoxic-ischemic damage in the neonatal rat at 37 degrees C results in transient delay of complex motor skills, but longer lasting cognitive changes. Hypoxia-ischemia during hypothermia produces no motor deficits, although there may be similar alterations in learning.
Stroke
PMID:Behavioral performance of rats following neonatal hypoxia-ischemia. 381 Jul 35

Coronary revascularization that is neurologically uneventful in patients with bilateral totally occluded internal carotid arteries has not been previously reported. We performed saphenous vein coronary artery bypass grafting on three such patients and observed them for 6 to 23 months. Preoperatively two of our patients had chronic stable symptoms of cerebrovascular insufficiency, and one had received cerebral revascularization via a superficial temporal-to-middle cerebral artery bypass. Controversy exists regarding proper cerebral protective maneuvers during coronary revascularization for patients with advanced cerebrovascular disease. Cerebral protection for our patients during cardiopulmonary bypass included hypothermia and high perfusion flows and pressures. Two patients also received prophylactic sodium thiopental. None of these three patients had a stroke perioperatively or during the follow-up period. We believe that these case histories strongly suggest that the functional state of the cerebral collateral circulation, as judged by preoperative neurological symptoms, predicts neurological outcome after coronary revascularization better than the specific occlusive anatomy of the extracranial carotid arteries.
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PMID:Coronary revascularization in patients with bilateral internal carotid occlusions. 387 50

Analysis of 16 synchronous with 26 sequential combined carotid coronary reconstructions showed no statistical advantage of either approach. Sequential operations are more convenient but increase the total operating time by an hour or so. Synchronous operations can be carried out without carotid shunting despite hypotension provided hypothermia is established. In other circumstances the internal carotid back pressure is used to indicate the need for carotid shunting. In the 42 patients there were three strokes (7%) including one fatal stroke (2%) and two myocardial infarctions, both fatal (5%).
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PMID:Combined carotid coronary reconstructions--synchronous or sequential? 387 22

Cardiopulmonary arrest is a test of the brain's tolerance to global ischemia. New insights into the pathophysiology of global ischemia have led to the potential use of early prophylactic anticonvulsants, hypothermia, barbiturate coma, glucose manipulations, calcium-blocking agents, and hemodilution. A wide spectrum of neurologic sequelae may follow global ischemia, ranging from brain death, vegetative states, and impairment of higher intellectual function to syndromes of amnesia and cortical blindness, post-anoxic myoclonus, delayed leukoencephalopathy, and spinal stroke. The distinctive features of these sequelae and their pathophysiologic aspects are discussed. Special attention is given to brain death and prognostication.
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PMID:Cardiopulmonary arrest. Pathophysiology and neurologic complications. 390 62

The immature myocardium has a greater tolerance for ischemia than does the mature heart. The effect of ischemia when combined with hypothermia on the newborn heart is poorly understood but has important clinical applications. This study examined the metabolic and functional recovery after 90 minutes of global ischemia at 20 degrees C in neonatal (1 week), immature (1 month), and mature (4 month) isolated working rabbit hearts. Following ischemia, aortic flow, cardiac output, heart rate, and stroke work remained at baseline values for neonatal hearts. Only coronary flow was significantly reduced from a control level of 4.5 +/- 1.4 (standard error of the mean) to 3.3 +/- 1.1 ml/min, p less than 0.05. In the immature group, hemodynamic parameters were below baseline, although no statistical differences were noted. Among mature hearts, however, all hemodynamic values were significantly below preischemic control. Water content was significantly higher in immature (73.2% +/- 1.4%) and mature (75.3% +/- 2.5%) hearts when compared with the neonatal group (46.8% +/- 4.6%), p less than 0.001. Coronary sinus creatine kinase was unchanged from baseline at 10 and 30 minutes following ischemia in the neonatal group. Although demonstrating substantial increases from baseline, statistical significance was not seen in the immature group because of the wide variation about the mean. In the mature group, creatine kinase rose significantly from preischemic levels of 15.4 +/- 4.3 IU/L/gm to 184.2 +/- 51.6 IU/L/gm at 10 minutes (p less than 0.01) and 123.7 +/- 31.9 IU/L/gm at 30 minutes (p less than 0.05). This study demonstrated improved tolerance to prolonged hypothermic ischemia in neonatal rabbit hearts when compared with older hearts subjected to the same conditions. The role of cardioplegic solutions in protecting the neonatal heart during cardiac operations when deep hypothermia is used may be of lesser importance than in the older patient.
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PMID:Recovery of left ventricular function after hypothermic global ischemia. Age-related differences in the isolated working rabbit heart. 394 54

Adriamycin (Adriablastine), administered weekly at the dose of 5 mg/kg i.p. for 3 weeks in rats, produced a general decrease of vitality associated with a decrease of body weight, hypothermia, decreases of stroke volume and cardiac output. Hematocrit was decreased. Renal blood flow decreased whereas pulmonary blood flow increased. Mean blood pressure and heart rate remained unaffected. Biochemical evaluations revealed a decrease of blood urea and serum creatinine, which might be related to decreased food intake and protein metabolism. Morphological changes in the heart tissue could not be appreciated. Venoruton (HR), administered at the dose of 300 mg/kg p.o. daily for 28 days (5 days before and 23 days after the first injection of adriamycin), improved adriamycin-induced clinical signs and symptoms (loss of body weight, hypothermia and decreased general vitality). It tended to increase cardiac output and stroke volume.
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PMID:Protective effects of O-(beta-hydroxyethyl)-rutosides (HR) against adriamycin-induced toxicity in rats. 400 21

Nifedipine, a slow calcium-channel blocker, has been used to preserve myocardial function in the ischemic heart. To quantitatively evaluate the effectiveness of nifedipine as a cardioplegic agent during moderate hypothermia (28 degrees C), 15 pigs were evaluated on total and right heart bypass with measurement at normothermia and after 1 hour of hypothermic ischemia of stroke volume, coronary blood flow, myocardial oxygen consumption, and lactate extraction. Myocardial tissue gases (oxygen and carbon dioxide) were continuously monitored. Animals were divided into three groups: hypothermic ischemia, hypothermic ischemia with infusion of nifedipine carrier without nifedipine, and hypothermic ischemia with nifedipine and its carrier. A significant decrease in stroke volume was seen in all three groups; however, the depression was significantly greater following hypothermic ischemia than following cardioplegia with either nifedipine or its carrier. The mean recovery value of stroke volume was highest in the nifedipine group, but this difference between nifedipine and its carrier alone did not reach statistical significance. Coronary blood flow, myocardial oxygen consumption, lactate extraction, and tissue gases failed to substantiate a significant benefit when nifedipine was compared with its carrier alone. We conclude that under these hypothermic conditions, no proven statistically significant advantage was noted in the nifedipine group when compared with the nifedipine carrier group in swine. However, both nifedipine and the carrier were superior as a myocardial preservative when compared with hypothermic ischemic arrest alone.
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PMID:Quantitative evaluation of the myocardial preservative characteristics of nifedipine during hypothermic myocardial ischemia. 406 42

The efficacy of moderate hypothermia with rewarming in attenuating the myocardial and circulatory consequences of acute coronary ligation was studied in open-chest, anesthetized dogs. Thirty minutes after ligation of the proximal left anterior descending coronary artery, 14 dogs were surface-cooled to 27 degrees C, maintained at this temperature for 2 hr, rewarmed to normothermic levels, and monitored for an additional hour. Fifteen dogs were maintained for a corresponding time period after coronary ligation at normothermic levels. Dogs maintained normothermic demonstrated significant depression (from preligation values) of dP/dt, cardiac output (CO), stroke volume (SV), and left ventricular stroke work and power (LVSW, LVSP) at elevated levels of left ventricular end-diastolic pressure (LVEDP). Dogs subjected to the hypothermic procedure demonstrated decreased inotropic status during hypothermia, but with rewarming, exhibited significantly greater values of left ventricular pressure, dP/dt, CO, SV, LVSW, and LVSP at lower values of LVEDP than observed in dogs maintained normothermic. Increased dysrhythmic activity was not observed during hypothermia. Hearts from dogs subjected to the hypothermic protocol demonstrated qualitatively greater dehydrogenase activity both at the periphery and in the center of the nonperfused region. The results suggest that moderate hypothermia during evolving myocardial infarction may preserve left ventricular cardio- and hemodynamics and thus may be useful in delaying morphological and functional deterioration until definitive treatment can be instituted.
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PMID:Salutary effects of moderate hypothermia on the circulatory and myocardial consequences of acute coronary occlusion in dogs. 407 11

One hundred twenty-four patients had 155 carotid endarterectomies for the relief of stroke symptoms. General hypercarbia anesthesia and arterial pco2 monitoring were used, without resort to internal bypass shunt or hypothermia. Significant permanent post-operative complications developed in three patients (1.9 percent) and there were two postoperative deaths, one of which was caused by a massive myocardial infarction.
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PMID:A safe approach to carotid endarterectomy. 513 26


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