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

Three clinical techniques providing significant changes in the approach to myocardial protection have been reported recently. These techniques deviate from conventional practice, and they infer that normothermia is superior to hypothermia, retrograde cardioplegia is more advantageous than antegrade administration, and continuous cardioplegic delivery is preferable to intermittent dosage. Encouraging preliminary clinical results with warm-blood cardioplegia are reported, but rigid clinical and experimental testing against conventional methods is not yet available for evaluation. The ideal cardioprotective strategy has yet to be determined, but these preliminary data suggest strongly that incorporation of these techniques with conventional methods will improve intraoperative myocardial protection and provide the cardiac surgeon with an augmented arsenal of strategies that can be employed to provide increased flexibility.
Curr Opin Cardiol 1992 Dec
PMID:New intraoperative cardioprotective strategies for myocardial protection. 1014 36

New information on cardiopulmonary bypass continues to be produced by investigators from many disciplines. Investigations are related to problems and complications resulting from use of the heart-lung machine. The relationship of perfusion and pressure during bypass in brain, kidney, and other organs is the subject of several reports. The studies confirm that low flow and pressure are safe with hemodilution and hypothermia. Investigations related to the pH stat and alpha stat blood gas schemes are sometimes inconclusive, but significant observations favor the use of the alpha stat blood gas scheme. The complications of choreoathetosis in pediatric patients appears to be related to low levels of hypothermia. Studies continue to show the many adverse effects of cardiopulmonary bypass on platelets, leukocytes, and the complement system. The minimum acceptable activated clotting time during cardiopulmonary bypass may be less than 400 seconds. Other authors address the complications of protamine infusion and heparin-induced thrombocytopenia.
Curr Opin Cardiol 1992 Apr
PMID:Cardiopulmonary bypass surgery. 1017 Nov 89

Energy deficiency and disturbances of sodium and water homeostasis are considered as mechanisms of injury during hypothermic preservation of cardiac muscle. The present study attempts to characterize the effect of potassium (K+) and magnesium (Mg2+) cardioplegia on these mechanisms. Cellular parameters were measured by multinuclear NMR spectroscopy in isolated rat hearts during 12 h of ischemia at 4 degrees C and 2 h of normothermic reperfusion with an isoosmotic Krebs-Henseleit (KH) solution. Potassium and magnesium cardioplegia (a) reduced the rate of ATP hydrolysis and cellular acidification during early stages of ischemia; (b) caused an early cessation of the phase of fast sodium influx after 40 min (P<0.001 vs 120 min with KH); (c) reduced intracellular sodium accumulation to 148-165 micromol/gdw after 12 h (P<0.01 vs 268+/-15 micromol/gdw with KH); (d) decreased ischemic volumes to 2.7+/-0.1 and 2.8+/-0.1 ml/gdw after 8 and 12 h of storage, respectively (P<0.005 v 3.0 and 3.3 ml/gdw with KH). Quantitative analysis of these parameters showed that both hypothermia and cardioplegia increased the relative contribution of sodium to intracellular water accumulation by a factor of 2-2.5. In view of the marked reduction in absolute sodium and water contents, the data indicate that cold cardioplegia limits the increase in intracellular osmolarity. Myocardial mechanical and metabolic recoveries, and cellular viability deteriorated during prolongation of the ischemic period from 8 to 12 h in all experimental groups (P<0.005). Reperfusion was efficient in reversing intracellular sodium and water accumulation in hearts stored with cardioplegia, in contrast to hearts stored in KH. Magnesium, but not potassium cardioplegia, lowered interstitial water contents (P<0.01 v KH), increased intracellular magnesium concentrations (P<0.001), improved mechanical and metabolic recoveries (P<0.01) and cellular viability (P<0.001). These results indicate (a) cardioplegia reduces intracellular sodium (by approximately 46%) and water accumulation (by 66%) during cold ischemia; (b) both hypothermia and cardioplegia limit the rise in intracellular osmolarity and increase the contribution of sodium to cellular swelling; (c) intracellular sodium and water contents were dissociated from myocardial viability and recovery from cold ischemia in potassium and magnesium cardioplegic solutions. It is concluded that intracellular sodium and water accumulation are not dominant factors in determination of cardiac outcome from ischemia.
J Mol Cell Cardiol 1999 Oct
PMID:Efficient limitation of intracellular edema and sodium accumulation by cardioplegia is dissociated from recovery of rat hearts from cold ischemic storage. 1052 18

Spinal cord protection is critical for successful outcomes after descending thoracic and thoracoabdominal aortic aneurysm repair. For descending thoracic aneurysms which end above T9, optimum protection is maintained by distal aortic perfusion via a left atrial to distal arterial bypass circuit with a centrifugal pump. In repairs of extensive thoracoabdominal aneurysms, additional measures are required of extensive thoracoabdominaal aneurysms, additional measures are required including hypothermia, intercostal artery implantation into the graft, and spinal fluid drainage.
Cardiol Clin 1999 Nov
PMID:Spinal cord protection for thoracic aortic surgery. 1058 47

The best surgical approach for the treatment of patients with severe cerebral artery disease and simultaneous serious coronary artery disease still remains controversial. In this report we present a case of a 72-year-old female patient admitted to the hospital with unstable angina. Triple coronary artery obstructive disease and severe bilateral carotid artery stenosis were diagnosed. A combined, simultaneous surgical procedure was performed. After total circulatory by-pass with a membrane oxygenator, the patient's body temperature was lowered to 32 degrees C. During the cool-down period, three proximal anastomoses of segments of autologous saphenous veins were performed in the ascending aorta. Immediately afterwards, bilateral carotid endarterectomy was performed, followed by three distal anastomoses to coronary arteries. The patient showed a satisfactory post-operative outcome. It was concluded that the combination of moderate hypothermia, hemodilution with appropriate hemodynamic control, as used in this patient, was an effective method of cerebral protection. The simultaneous approach of carotid endarterectomy and coronary artery by-pass surgery should be seen as a safe option for the treatment of this type of patient.
Arq Bras Cardiol 2000 Apr
PMID:Bilateral carotid endarterectomy combined with myocardial revascularization during the same surgical act. 1096 88

A 29-year-old man was accidentally exposed to cold and his mild hypothermia uniquely resulted in the transient exaggeration of his normothermic electrocardiographic findings, which were consistent with early repolarization. A unifying concept of clinical entities with similar J wave and ST segment elevation (J-ST syndrome) is proposed.
Int J Cardiol 2001 Jan
PMID:Electrocardiographic issues related to action potential phases 1 and 2 on the occasion of a case of accidental mild hypothermia. 1120 8

We report the case of a patient with a pseudoaneurysm of the ascending aortic clinically diagnosed 5 months after surgical replacement of the aortic valve. Diagnosis was confirmed with the aid of two-dimensional echocardiography and helicoidal angiotomography. The corrective surgery, which consisted of a reinforced suture of the communication with the ascending aorta after opening and aspiration of the cavity of the pseudoaneurysm, was successfully performed through a complete sternotomy using extracorporeal circulation, femorofemoral cannulation, and moderate hypothermia, with no aortic clamping.
Arq Bras Cardiol 2001 Apr
PMID:Surgical repair of a pseudoaneurysm of the ascending aorta after aortic valve replacement. 1132 36

Myocardial contractility depends on temperature. We investigated the influence of mild hypothermia (37-31 degrees C) on isometric twitch force, sarcoplasmic reticulum (SR) Ca2+-content and intracellular Ca2+-transients in ventricular muscle strips from human and porcine myocardium, and on in vivo hemodynamic parameters in pigs. In vitro experiments: muscle strips from 5 nonfailing human and 8 pig hearts. Electrical stimulation (1 Hz), simultaneous recording of isometric force and rapid cooling contractures (RCCs) as an indicator of SR Ca2+-content, or intracellular Ca2+-transients (aequorin method). In vivo experiments: 8 pigs were monitored with Millar-Tip (left ventricle) and Swan-Ganz catheter (pulmonary artery). Hemodynamic parameters were assessed at baseline conditions (37 degrees C), and after stepwise cooling on cardiopulmonary bypass to 35, 33 and 31 degrees C. Hypothermia increased isometric twitch force significantly by 91 +/- 16 % in human and by 50 +/- 9 % in pig myocardium (31 vs. 37 degrees C; p < 0.05, respectively). RCCs or aequorin light emission did not change significantly. In anesthetized pigs, mild hypothermia resulted in an increase in hemodynamic parameters of myocardial contractility. While heart rate decreased from 111 +/- 3 to 73 +/- 1 min(-1), cardiac output increased from 2.4 +/- 0.1 to 3.1 +/- 0.31/min, and stroke volume increased from 21 +/- 1 to 41 +/- 3 ml. +dP/dtmax increased by 25 +/- 8% (37 vs. 31 degrees C; p < 0.05 for all values). Systemic and pulmonary vascular resistance did not change significantly during cooling. Mild hypothermia exerts significant positive inotropic effects in human and porcine myocardium without increasing intracellular Ca2+-transients or SR Ca2+-content. These effects translate into improved hemodynamic parameters of left ventricular function.
Basic Res Cardiol 2001 Apr
PMID:Influence of mild hypothermia on myocardial contractility and circulatory function. 1132 39

In a century of remarkable progress in medicine, one of the outstanding stories is the development of successful treatment of congenital heart malformations. This achievement is the outcome of the ideas and research of many people. Many of the early 'transforming' advances originated in Canada. Maude Abbott catalogued and classified heart malformations in a clinically meaningful manner. Arthur Charles and David Scott in Toronto, Ontario, produced a clinically useful heparin preparation, and the studies of Bill Bigelow led to the application of hypothermia in cardiac surgery. John Keith and Bill Mustard at Toronto's Hospital for Sick Children, and Arnold Johnson and Tony Dobell at the Montreal Children's Hospital, Montreal, Quebec, established the first Canadian programs devoted to the correction of congenital heart defects in childhood. Mustard devised the first widely successful operation for transposition of the great arteries. Flavio Coceani and Peter Olley discovered the role of prostaglandin E in the ductus arteriosus, and applied that knowledge clinically. The turn of the century is an appropriate time to celebrate these Canadian successes.
Can J Cardiol 2001 Jun
PMID:Lest we forget: Early Canadian contributions to the care of children with congenital heart malformations. 1152 19

Observations from finite-element computer models, together with analytic developments based on percolation theory have suggested that subtle fluctuations of ECG morphology might serve as an indicator diminished cardiac electrical stability. With fixed-rate atrial pacing in canines, we have previously observed a pattern of alternation in T wave energy which correlated with cardiac electrical stability. We report here on a series of 20 canine experiments in which cardiac electrical stability (measured via Ventricular Fibrillation Threshold determination) was compared to a non-degenerate, multidimensional measurement of the degree of alternating activity present in the ECG complex morphology. The decrease in cardiac electrical stability brought on by both coronary artery occlusion and systemic hypothermia was consistently accompanied by subtle alternation in ECG morphology, with the absolute degree of alternating activity being significantly (negatively) correlated with cardiac electrical stability.
Comput Cardiol 1985
PMID:Subtle alternating electrocardiographic morphology as an indicator of decreased cardiac electrical stability. 1154 63


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