The Annals of thoracic surgery
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Randomized Controlled Trial Comparative Study Clinical Trial
Cerebral blood flow during cardiac operations: comparison of Kety-Schmidt and xenon-133 clearance methods.
This study simultaneously compared the standard Kety-Schmidt and the modified xenon-133 (133Xe) clearance techniques for measuring cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) during cardiac operations. The validity of the CBF method is important because our management of the patient during cardiopulmonary bypass (CPB) is based, in part, on our understanding of the cerebral hemodynamics during CPB. In 20 patients undergoing coronary artery bypass grafting, CBF and CMRO2 were determined by both methods. ⋯ The modified 133Xe technique as typically used during cardiac operations does not appear to measure CBF accurately; this leads to corresponding errors in CMRO2 calculations. Determination of CMRO2 and cerebral autoregulatory function during cardiac operations appears to be more appropriate if based on the more direct Kety-Schmidt technique. Accordingly, our management of CPB with respect to cerebral perfusion as it has been determined by the modified 133Xe clearance method may require reassessment.
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Comparative Study Clinical Trial Controlled Clinical Trial
Tranexamic acid significantly reduces blood loss associated with coronary revascularization.
Four hundred fifteen patients undergoing coronary revascularization over a 12-month period were divided into two groups: 209 controls in the first 6 months received no tranexamic acid (TA) before cardiopulmonary bypass and 206 patients in the second 6 months received TA as a hemostatic agent. The demographics and the surgical techniques used were similar in the two groups. With TA there was a significant decrease in blood loss postoperatively, from 1,114.1 mL in the controls to 803.7 mL in those given TA (p < 0.001); in red blood cell use, from 1.7 units/patient in the controls to 0.69 units/patient in those given TA (p < 0.001); in fresh frozen plasma requirements, from 0.23 units/patient in the controls to 0.024 units/patient in those given TA (p < 0.01); and in platelet transfusion, from 1.06 units/patient in the controls to 0.30 units/patients in those given TA (p < 0.01). ⋯ In this study, TA profoundly affected the coagulopathy associated with bypass in patients undergoing coronary revascularization. It significantly reduced blood loss and blood product transfusions. Any potential increased thrombotic complications could not be clearly demonstrated in this study, but should not be ignored.
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Clinical Trial
Resternotomy for bleeding after cardiac operation: a marker for increased morbidity and mortality.
Over a 2-year period from January 1, 1992, to December 31, 1993, of 2,221 patients undergoing cardiac operations in our unit, 85 (3.8%) were reopened for the control of bleeding (9 patients more than once). The incidence of resternotomy in coronary cases was 2.3%, but resternotomy was more than three times as likely in valve cases (odds ratio, 3.4; 95% confidence interval, 2.1 to 5.4). Previous cardiac operation was more common among resternotomy patients than among the remainder (18% versus 9%, respectively; p = 0.018). ⋯ Nineteen resternotomy patients (22%) died in the hospital, a proportion significantly greater than the risk assigned to this group of patients preoperatively (12.8%) (p = 0.008). In contrast, the observed mortality for the other 2,136 patients (5.5%) was significantly less (8.3%) (p < 0.00006). Multiple forward stepwise logistic-regression analysis confirmed resternotomy for excessive bleeding after cardiac operation to be a significant independent predictor of a prolonged stay in the intensive care unit (p < 0.0001), the need for intraaortic balloon counterpulsation (p < 0.0001), and death (p < 0.0001).
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Long-term support on the implantable left ventricular assist device (LVAD) produces structural changes in the recipient's heart. To assess the possibility of heart "recovery" we reviewed the records of 19 HeartMate LVAD recipients to determine structural and left ventricular histologic changes during LVAD support. Intraoperative transesophageal echocardiographic studies were performed in the operating room before LVAD insertion, immediately after LVAD insertion, and at explantation and heart transplantation (mean duration of support, 76 +/- 34 days). ⋯ We conclude that implantable LVAD support is associated with immediate changes in ventricular structure. Histologic markers of acute myocyte damage improve, but fibrosis increases. Because the structural changes occur immediately, they do not indicate "recovery" of left ventricular function, but merely changes in loading conditions.
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Case Reports
Intraoperative prosthetic valve dysfunction: detection by transesophageal echocardiography.
We describe the valuable role of intraoperative transesophageal echocardiography in the detection of immediate prosthetic valve dysfunction. Transesophageal echocardiography accurately diagnosed one leaflet of a St. Jude Medical mitral valve to be stuck. We recommend routine transesophageal echocardiography for mitral valve operations.