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

Cold potassium solution (4 C) is used to induce cardioplegia during coronary artery bypass surgery. When 1,000 ml of the cold solution are introduced through the root of the aorta, the temperature of the myocardium drops to about 7 C within a few minutes. At this level of hypothermia, ischemia can be tolerated for at least 2 h, the surgical field is rendered quiet and dry, and the safety and precision of the procedure are increased. This method, however, does not provide uniform cooling of the myocardium and some areas remain less protected than others. The temperatures in the different areas of the myocardium are measured directly with needle thermistors and the "warm" areas are cooled in turn, in descending order of myocardial temperature. Saphenous vein grafts are anastomosed to the arteries in these warm areas and additional cold solution is instilled through the graft until the temperature drops to 7 C. The coronary artery bypass, and any other required surgical procedure, is then performed. To maintain hypothermia, small amounts of cold solution are infused at intervals through the root of the aorta and through the appropriate graft. With this method of cooling, the operative mortality rate in a series of 200 high-risk patients with coronary artery disease in whom there was at least one factor predisposing to perioperative mortality and/or infarction was only 3%.
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PMID:Uniform myocardial protection by cold potassium-induced cardioplegia for coronary artery bypass. 697 Jan 87

Recent reports have suggested that the delivery of cardioplegia to regional myocardium is impaired in patients with severe coronary artery disease. This study was designed to determine whether or not topical hypothermia is a necessary adjunct to systemic hypothermia and potassium cardioplegia to provide adequate cooling in regional myocardium supplied by stenotic or occluded coronary arteries. Twenty-two patients ranging in age from 47 to 68 years were included in the study. Patients were placed on bypass and cooled to 28 degrees C. Temperature was measured over the right and left coronary artery distributions. The aorta was then cross-clamped and 1,000 cc of potassium blood cardioplegia, 5.7 degrees to 11 degrees C (mean 8.7 degrees), was infused into the aortic root at a mean pressure of 99 mmHg. Temperature was measured and 6 L of cold electrolyte (Plasma-lyte) solution, 2.3 degrees to 5.1 degrees C (mean 3.5) was poured over the heart into the pericardial well. The temperature measurements were then repeated. Myocardial temperature in regional myocardium supplied by normal coronary arteries after the injection of cardioplegia was less than 15 degrees C. However myocardium distal to a severe stenosis or complete occlusion was significantly warmer (p less than 0.001). Topical hypothermia reduced myocardial temperature to less than 15 degrees C in regional myocardium supplied by severely diseased vessels (p less than 0.001). These data demonstrate that the combination of systemic hypothermia and potassium cardioplegia alone does not provide adequate myocardial cooling in patients with severe coronary artery disease and emphasize the need for intraoperative myocardial temperature monitoring to ensure optimal protection during the ischemic period.
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PMID:Importance of topical hypothermia to ensure uniform myocardial cooling during coronary artery bypass. 697 5

The metabolic effects of combined antegrade/retrograde and antegrade cardioplegia on myocardial protection were evaluated and compared in 30 patients who underwent myocardial revascularization. All patients had three-vessel coronary artery disease, and the revascularization was done with exclusive use of arterial grafts (internal mammary artery, gastroepiploic artery). Myocardial protection consisted of oxygenated crystalloid cardioplegia, topical slushed ice, and moderate systemic hypothermia (34 degrees C). The patients were randomly separated into two groups: group A (n = 15), who received antegrade cardioplegia, and group A/R (n = 15), who received combined antegrade/retrograde cardioplegia. There was no significant difference between the two groups concerning preoperative and intraoperative data. After the first dose of cardioplegia, right ventricular temperature was significantly lower in group A/R (15 +/- 2 degrees versus 19 +/- 5 degrees C; p < 0.05), and there was no significant difference between the two groups in left ventricular temperature. Coronary sinus blood samples were obtained before bypass and 5, 10, and 15 minutes after reperfusion; there was no difference between the two groups concerning lactates, superoxide dismutase, and glutathione peroxidase. After reperfusion, malondialdehyde levels increased significantly in group A and there was no change in group A/R, with a significant difference between the two groups (at 10 minutes after reperfusion, 0.80 +/- 0.20 versus 0.53 +/- 0.16 mumol/L; p < 0.05). Right and left ventricular myocardial biopsies were performed before bypass and 15 minutes after reperfusion; there was no significant difference between the two groups concerning adenosine triphosphate and creatine phosphate myocardial concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Antegrade/retrograde cardioplegia in arterial bypass grafting: metabolic randomized clinical trial. 784 66

Many modalities are available for monitoring for ischemia. Electrocardiography (ECG) is the most suitable modality for monitoring for perioperative ischemia. The detection and monitoring of myocardial stunning is more difficult. T wave inversion or peaking may be caused by ischemia. However, numerous nonischemic causes may lead to perioperative T wave changes. Inverted T waves may also indicate myocardial stunning. ST deviation is the most commonly used feature of ischemia. ST depression may be indicative of subendocardial ischemia while ST elevation may be associated with transmural ischemia or injury. Perioperatively, ST deviation may be caused by many nonischemic causes. Fixed ST deviation may be caused by left ventricular hypertrophy (LVH), cardiac conduction changes, old MI, coronary artery disease, and other causes such as drugs, including digitalis. New ST deviation may be caused by changes in body position. During cardiopulmonary bypass, ST deviation may be caused by hypothermia and defibrillation. ST deviation may be caused by new cardiac conduction changes and pericarditis. Ischemia may cause changes in other features of the ECG including the R wave, Q wave, U wave, QRS axis, and the angle between QRS axis and T wave axis. However, the specificity of these features for ischemia is even lower than that of the ST segment.
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PMID:Electrocardiographic determination of perioperative myocardial ischemia and stunning. 806 29

To evaluate the behavior of circulating endothelin and atrial natriuretic peptide (ANP) during coronary artery bypass graft (CABG) surgery, blood samples from patients with coronary artery disease (n = 8) were investigated before, during and after operation. Plasma levels of endothelin and ANP were determined using the radioimmunoassay method. Baseline plasma levels were compared to those of normal volunteers (n = 6). Left ventricular function at rest and as a response to isometric exercise was evaluated using radionuclide ventriculography before and after coronary bypass surgery. The mean endothelin value was found to be within normal limits, however the mean ANP value was slightly higher than control. Patients had significantly improved left ventricular systolic and diastolic function after surgery. The mean endothelin level was higher than initial values immediately after extra-corporeal circulation and returned to initial values in two hours. However, ANP values were increased and remained higher than initial values. Baseline endothelin values were negatively correlated with systolic function parameters, whereas endothelin and heart rate had a positive correlation before extra-corporeal circulation. Coronary artery bypass graft surgery may cause an increase in the circulating endothelin level either due to endothelial injury or due to myocardial ischemia and hypothermia. Following surgery, increased endothelin levels returned to normal values immediately.
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PMID:Changes in the circulating endothelin and atrial natriuretic peptide levels during coronary artery bypass surgery. 816 37

Normothermic systemic perfusion in patients undergoing cardiopulmonary bypass may compromise myocardial hypothermia, a mainstay for preservation of ventricular function during iatrogenic cardiac arrest. The right ventricle is the area of the heart most susceptible to rewarming. We prospectively evaluated myocardial rewarming and indexes of right ventricular function in 30 patients undergoing coronary artery bypass grafting randomized to receive moderate hypothermic (bladder temperature 25 degrees C) or normothermic perfusion and multidose cold blood cardioplegia during cardiopulmonary bypass. All patients had significant stenosis (> 70%) of the right coronary artery, and in 27 of 30 the right coronary artery was revascularized. A right ventricular ejection fraction/volumetric catheter was used to assess right ventricular function by right ventricular ejection fraction and a preload (right ventricular end-diastolic volume) normalized right ventricular stoke work index in the prebypass and postbypass periods. Findings included the following: (1) Greater rewarming of all areas of the heart occurs with normothermic bypass, with the mean temperature difference at the end of each intracardioplegic period ranging from 4.0 degrees to 6.3 degrees C warmer than with hypothermic bypass; (2) the right ventricle was not more susceptible to rewarming than the posterior left ventricle or interventricular septum in either group; (3) right ventricular function did not differ between groups at any time in the study, including the immediate postarrest period; and (4) right ventricular function was preserved and equivalent to the prebypass baseline. We conclude that the moderate myocardial rewarming that occurs with normothermic perfusion does not compromise right ventricular preservation in patients with right coronary artery disease undergoing revascularization with multidose cold blood cardioplegia to maintain electromechanical arrest.
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PMID:Right ventricular function after normothermic versus hypothermic cardiopulmonary bypass. 787 27

Aortic dissection with an entrance tear in the transverse aorta is generally considered to have the highest acute fatality rate of any type of dissection and the direction of its extension is the most difficult to predict. In a prospective study, we evaluated 61 consecutive patients (mean age 56.7 years, ranging from 21 to 75 years), presenting with ascending aortic dissection during a 36-month-period and tried to clarify the incidence of retrograde ascending aortic dissection. In 49 patients (80.3%), the intimal tear was located in the ascending aorta, whereas the dissection originated in the transverse aorta in 12 patients (19.7%); in this latter group, extension was strictly retrograde in 5 patients and in both directions in 7 patients. Three patients died before operation; 58 patients underwent aortic replacement/repair under moderate hypothermia; if the primary tear extended into the transverse aorta or was not found in the ascending aorta, the aortic arch was explored during a brief period of deep hypothermic circulatory arrest. The overall operative mortality was 12.1% (7/58); it was 10.4% (5/48) in ascending aortic dissection and 20% (2/10) in dissection of the transverse aorta. Age (P < 0.005), concomitant coronary artery disease (P < 0.01) and the site of intimal tear (P < 0.01) were significant predictive factors of operative risk. A tear in the transverse aorta is almost always associated with retrograde dissection and may simulate dissection with the entrance tear in the ascending aorta. Localization of the entrance tear remains a diagnostic challenge in aortic dissection but Doppler-echocardiography had a high sensitivity in this series (96.7%).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Retrograde ascending aortic dissection: a diagnostic and therapeutic challenge. 846 Nov 47

The effects of retrograde and antegrade delivery of cardioplegic solution on myocardial function were evaluated and compared in 60 patients who underwent myocardial revascularization. All patients had three-vessel coronary artery disease, and the revascularization was done with extensive use of the internal mammary artery. Seventy-five percent of the distal anastomoses were performed with the internal mammary artery. Myocardial protection consisted of St. Thomas' Hospital cardioplegic solution, topical slushed ice, and systemic hypothermia (28 degrees C). The patients were randomly separated into two groups: group A (n = 30), who received antegrade cardioplegia, and group B (n = 30), who received retrograde cardioplegia. With the exception of the total dose of cardioplegic solution (p = 0.02), there was no significant difference between the two groups that concerned septal myocardial temperature at the moment of asystole and after infusion of the total dose of cardioplegic solution. Cardiac function was assessed before and after the patient was weaned from cardiopulmonary bypass. In the immediate postoperative period there was a significant increase in right atrial pressure of the patients who underwent antegrade cardioplegia. For the other registered parameters there was no significant difference either in the immediate postoperative period or 6 hours later. Release of creatine kinase MB isoenzyme was the same in the two groups. Clinical outcome in terms of mortality, prevalence of perioperative infarction, prevalence of low cardiac output, and rhythm and conduction disturbances was similar in both groups. Technical problems related to cannulation and decannulation of the coronary sinus were not encountered. Multivariate analysis showed that occlusion of the left anterior descending coronary artery (p = 0.012) is an essential contraindication of antegrade delivery of cardioplegic solution. Analysis of the patients with an occlusion of the left anterior descending coronary artery who underwent antegrade (n = 9) and retrograde (n = 10) cardioplegia showed a significant difference in the total dose of cardioplegic solution (p = 0.02) and septal myocardial temperature at the moment of asystole (p = 0.008) and after infusion of the total dose of cardioplegic solution (p = 0.015). The mean arterial systolic blood pressure in the antegrade group was significantly lower than in the retrograde group (p = 0.003). Preservation of the left ventricular stroke work index was significantly better in the retrograde group (namely, 85% of its initial value versus 71% in the antegrade group, p = 0.0116).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Retrograde versus antegrade delivery of cardioplegic solution in myocardial revascularization. A clinical trial in patients with three-vessel coronary artery disease who underwent myocardial revascularization with extensive use of the internal mammary artery. 848 64

Recent studies suggest that plasma levels of alpha-hANP may reflect the severity of heart failure, but mechanism whereby ANP secretion increase is not known. Changes in alpha-hANP concentration in the arterial (A-ANP) and coronary sinus blood (CS-ANP) during and after the cardiopulmonary bypass (CPB) were measured to investigate the role of ANP in patients undergoing cardiac surgery. Fifteen patients were divided into 2 group; Group I, valvular heart disease (n = 9), Group II, coronary artery disease (n = 6). Both A-ANP and CS-ANP were significantly higher in the Group I than Group II before and during CPB. The difference between two groups decreased and was insignificant after CPB. The CS-ANP was twice as high as A-ANP at simultaneous sampling point. Significant correlations between the changes in PCWP (delta PCWP) and delta A-ANP (p < 0.01), delta RAP and delta A-ANP (p < 0.02) and an inverse linear correlation between CI and A-ANP (p < 0.01) were observed. Not a significant correlation was found between ANP and urine volume, urinary sodium excretion and other renal functional parameters during and after CPB. Hypothermia and the use of mannitol in large quantities were considered to be factors. In the Group I, A-ANPs were also measured in the postoperative follow-up period. A-ANP remained elevated above 100 pg/ml in patients with poor and decreased below 100 pg/ml with good prognostic signs 3 to 6 months postoperatively. From these results, it is suggested that alpha hANP is secreted from the atrial wall to the coronary sinus vein and the levels of alpha-hANP in the perioperative and follow-up period after heart surgery, especially in the valvular heart disease, are considered to reflect the cardiac performance.
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PMID:[Changes of alpha hANP concentration in arterial and coronary sinus blood during and after cardiopulmonary bypass]. 851 51

Fifty patients with drug-resistant, recurrent tachyarrhythmias causing Wolff-Parkinson-White syndrome underwent surgery between 1990 and 1992. All recognized surgical methods for accessory pathway destruction were performed. Epicardial electric shock ablation was first used as a method of surgically destroying an accessory atrioventricular pathway in 1983. This technique avoids the need for cardioplegia and hypothermia during operation. The procedure is based on the application of a series of two to five electrical shocks (50-150 J) to the region of the atrioventricular groove where the accessory pathway has been previously located. Some 32 patients with a left free wall accessory pathway underwent this operation. Cardioplegia and hypothermia were not required in 22 patients with an accessory pathway located in the left lateral position. In the second group comprising ten patients with a left lateral accessory pathway, four were diagnosed as having a second pathway and four had concomitant heart pathology such as coronary artery disease -- one had an atrial septal defect and another had a ventricular septal defect. Accessory pathway ablation was carried out in these ten patients using epicardial electric shock under normothermic cardiopulmonary bypass. Concomitant heart pathology was corrected at the second stage of the operation under cardiopulmonary bypass with cardioplegia and hypothermia. Postoperative electrophysiological studies confirmed that the accessory pathway had been destroyed in all patients. The only side effects of epicardial electric shock application were transient ST elevation < 1 mm in four patients, transient atrioventricular bloc in two and moderate sinus tachycardia in three.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Epicardial electric shock ablation of the left lateral accessory pathway. 857 41


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