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

Subendocardial ischemia develops in hearts that are fibrillated during cardiopulmonary bypass when: (1) the normal ventricle is fibrillated with a sustained electrical stimulus, (2) the hypertrophied ventricle is allowed to fibrillate spontaneously, (3) the fibrillating heart becomes distended, or (4) the perfusion pressure is reduced to approximately 50 mm Hg. Myocardial hypothermia reduces cardiac oxygen requirements during fibrillation but does not prevent ischemia when perfusion pressure falls to levels frequently attained during clinical open-heart operations. The ischemia occurs because flow cannot rise sufficiently to meet the metabolic demands of ventricular fibrillation. The forces interacting to impede adequate flow to the subendocardium during ventricular fibrillation are: (1) the compressive forces exerted on subendocardial muscle by the strength of fibrillation, (2) the compressive forces resulting from raised intracavitary pressure due to occlusion or malfunction of the ventricular vent, and (3) the evolution of myocardial edema as ischemia is prolonged. We have abandoned the use of ventricular fibrillation in clinical open-heart operations and now allow the heart to beat continually with adequate perfusion pressure. We have not needed to use inotropic drugs postoperatively after aortic or mitral valve replacement since adopting this technique.
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PMID:Ventricular fibrillation. Its effect on myocardial flow, distribution, and performance. 80 60

The late consequences of induced ventricular fibrillation electrically non maintained have been analysed in a series of 547 operations under extracoporeal circulation and moderate hypothermia in the adult; the length of the intraoperative period of fibrillation has been found to have no effect upon the mean postoperative left atrial pressure -- itself a sure indicator of left ventricular function. This is equally true of the variations of the factor both in the operated cases taken together, and between the various groups of operated cases. There is no evidence that ventricular fibrillation has a harmful effect when, in addition, a study is made of the postoperative myocardial complications and of the early deaths. The mean duration of ventricular fibrillation does not differ significantly statistically between the group with complications and deaths, and the group with uncomplicated operations and no mortality.
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PMID:[Is ventricular fibrillation during cardiac surgery a hasard?]. 82 Mar

Twenty-eight dogs were subjected to 90 minutes of hypothermic (30 degrees C) cardiopulmonary bypass with moderate hemodilution. In 6 dogs the heart was vented and beating for 60 minutes. Eight dogs underwent ventricular fibrillation with coronary perfusion (VF + CP). In 14 dogs the aorta was cross-clamped for 60 minutes while the myocardium was protected by local cardiac hypothermia (ICA + LCH). Eighteen animals survived. Hemodynamic studies at seven weeks revealed no major differences among the three groups. At postmortem examination, no gross scarring was noted in any heart. Microscopical examination of 14 hearts was completely-normal. In the VF + CP group, 2 hearts had isolated microscopical scars. Similar linear subendocardial scars (less than or equal to 1.5 X 0.5 mm) were noted in 2 hearts subjected to ICA + LCH. Survival after 60 minutes of VF + CP or ICA + LCH did not result in long-term morphological injury to or functional impairment of the myocardium.
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PMID:Does local cardiac hypothermia during cardiopulmonary bypass protect the myocardium from long-term morphological and functional injury? 90

The paper is based on the authors' personal experience in the employment of general and craniocerebral hypothermia in 90 patients operated on for brain tumours. The most rational level of hypothermia is that of 30-31 degrees C body temperature. Craniocerebral hypothermia induced by the "Holod-2F" apparatus permits to reduce the cortical temperature to 26-28 degrees C, maintaining that of the body within 30-32 degrees C. Such temperature gradient permits to avoid the danger of ventricular fibrillation. In the majority of cases, surgery under craniocerebral hypothermia is free of brain oedema. The postoperative course is also free of brain oedema and pneumonia. Tabulated statistical processing presents the data on the speed and degree of cooling in different parts of the body with reference to the age and body weight of the patient, to the method of cooling, and to the temperature of the cooling fluid.
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PMID:[Total and cranio-cerebral hypothermia in patients subjected to surgery for brain tumors]. 95 50

The technique of preferential cerebral hypothermia is reported in its application to a patient with a "giant" anterior communicating artery aneurysm. The method utilizes elective ventricular fibrillation and differential or "preferential" hypothermia induced by a combination of external skin cooling and perfusion of core organs with 0 degree buffered electrolyte solution. The value of the technique lies in its provision of a period of safe circulatory arrest approaching one hour without the need for anticoagulation, heart-lung bypass, open chest resuscitation or major vessel clamping. Because of the absence of blood flow and because of the clear fluid washout of the cerebral vessels, it was possible to open the aneurysm, evacuate its contents and resect it in several sections. It was not necessary to clip the feeding arteries until all dissection and total removal of the aneurysm were completed. The application of the technique to neurosurgery and cardiovascular surgery is discussed.
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PMID:Preferential cerebral hypothermia with elective cardiac arrest: resection of "giant" aneurysm. 95 90

Intraoperative myocardial protection was evaluated in two groups of patients undergoing coronary surgery in whom different techniques for cardiac arrest were utilized. In group A, profound selective myocardial hypothermic (15 to 18 C) arrest was achieved by perfusing a coolant (7 to 10 C) into the left ventricular cavity and the coronary circulation. The average anoxic arrest time was 82.5 +/- 27 minutes. In group B, ventricular fibrillation and moderate hypothermia were used. Group A patients showed rapid physiologic recovery, low average myocardial creatinine phosphokinase (MB-CK) isoenzyme levels (7.8 IU) , and a well-preserved myocardial ultrastructure. In group B, three patients showed abnormal physiologic recovery; six patients needed postoperative inotropic support; and in seven patients, electron-microscopy revealed irreversible focal changes. The average MB-CK isoenzyme level was 85.6 IU. Analysis of our data demonstrates that when myocardial protection during coronary bypass grafting is achieved by selective profound intracavitary and coronary cooling, there is physiological, ultrastructural, and biochemical evidence of less intraoperative myocardial damage than when ventricular fibrillation is applied.
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PMID:Selective intracavitary and coronary hypothermic cardioplegia for myocardial preservation.Clinical, physiologic, and ultrastructural evaluation. 98 67

It is reported on the successful treatment of a 60-year-old female patient with extreme accidental hypothermia (body temperature 24 degrees C). Cardiac and pulmonary complications could be commanded by intensiv-therapeutic measures. As interesting findings at the time of hospitalisation are exhibited the Osborn-wave in the ECG (first description in a clinical case), the alkalosis (pH 7.52) and a good diuresis (60 ml/min). The prognosis of the accidental hypothermia depends on the duration of the chilling, the rapid transfer under control of a physician into an intensive therapy facility, optimal control and therapy of cardio-vascular and respiratory system, the time of re-warming and the previous injuries as well as the concomitant diseases. The time of re-warming is of importance especially in asystolia and in ventricular fibrillation, in order to reach the defibrillation threshold of 26.6 degrees C. The forms of re-warming (combination of inner and outer re-warming) are to be chosen individually and according to the possibilities. They do not play the role expected for the prognosis. A repeated examination of the patient described after 14 months showed normal according to age organic functions without late lesions.
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PMID:[Accidental hypothermia--case contribution to the clinical aspects and therapy]. 106 95

Anoxic cardiac arrest, as opposed to induced ventricular fibrillation, greatly facilitates accurate distal anastomosis in aortocoronary bypass surgery. In order to diminish the anoxic insult, general and topical hypothermia may be used. In an attempt to establish the value of moderate hypothermia during anoxic cardiac arrest two groups of patients were compared. In group I coronary artery bypass procedures were performed under normothermic conditions with anoxic cardiac arrest. Patients in group II underwent similar procedures but under hypothermic conditions. General body hypothermia to an esophageal temperature of 30 degrees C and topical hypothermia with iced saline lavage were used. Using these techniques, the average intramyocardial temperature was 26 degrees C. Nonfatal cardiac complications did not occur more frequently in the hypothermic group. Operative mortality was decreased from 6.3% in the normothermic group to 1.5% in the hypothermic group. However, in group II, in addition to hypothermia, a second factor in the reduction of mortality was the completeness of the revascularization procedure: 58.5% of the patients had three or more bypass grafts in the hypothermic group. The mean anoxic arrest time was over 50 min for all patients--those who survived as well as those who died with postoperative low cardiac output or myocardial infarction. Therefore, anoxic arrest time should be kept as short as possible and certainly less than 50 min. Intermittent aortic occlusion and performance of the proximal anastomoses using a partial occluding clamp on the aorta are currently being used and, together with moderate hypothermia, provide a further reduction in postoperative myocardial complications.
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PMID:The value of moderate hypothermia during anoxic cardiac arrest for coronary artery surgery. 108 39

Experiments were made using 47 mongrel dogs under normo-and hypothermic perfusion employing the DeWall-Lillehei and Kay-Cross oxygenator. The purpose of this study is to find the ideal method of extracorporeal circulation as an adjunct of cardiac surgery. In this report, the changes of acid-base balance, serum electrolytes and S-GOT during perfusion were investigated. The results obtained were as follows. 1) In spite of the hypothermia, the changes of pH and buffer base in 10 degrees C hypothermic circulatory arrest indicated the gradual progress of the tissue metabolism. After the circulation restarted uncompensated metabolic acidosis without decrease of H2CO3 ensued. The circulatory arrest for 30 minutes in 10 degrees C hypothermia was thought to be hazardous to the preservation of life. 2) In case of ventricular fibrillation, hyperkalemia in the systemic venous blood was often found. It was also observed in the coronary venous blood. In accordance with the fact of hyperkalamia during anoxia, it is presumed that the cardiac anoxia is the important factor for the development of ventricular fibrillation. 3) The value of S-GOT in the arterial blood was not influenced by perfusion time, cardiac arrest and temperature, so far as the perfusion was performed smoothly. S-GOT was elevated when cardiotomy was carried out.
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PMID:[Studies on the extracorporeal circulation. Especially on changes in acid-base balance, serum electrolytes and S-GOT during rapid perfusion cooling (author's transl)]. 110 58

The influence of halothane, ether, carbon dioxide, and perfusion rewarming on the electrocardiogram was studied in 37 dogs subjected to surface-induced deep hypothermia. Significant anesthetic-related differences in P-R, QRS, Q-T and R-R intervals during cooling were not apparent; however, reduced arterial pressure, ventricular fibrillation, and a greater tendency for bradycardia requiring supportive measures were noted at low temperatures with halothane anesthesia. The use of 95% O2/5% CO2 significantly reduced the QTc at low temperatures; Other phenomena, including the occurrence and significance of J waves, are discussed. The relationship of the electrocardiogram to clinical and pathological results was evaluated and indicates that (1) properly managed resuscitation (manual massage and defibrillation) is not a serious hazard, (2) ether in 100% oxygen is the agent of choice for surface-induced deep hypothermia with prolonged circulatory arrest, and (3) halothane may be used in a procedure combining surface cooling and perfusion rewarming if given in a mixture of oxygen and carbon dioxide.
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PMID:Electrocardiographic changes during surface-induced deep hypothermia. The influence of ether, halothane, carbon dioxide, and perfusion rewarming. 112 62


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