The Journal of thoracic and cardiovascular surgery
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J. Thorac. Cardiovasc. Surg. · Jul 1996
Comparative StudyMeasurement of heparin concentration in whole blood with the Hepcon/HMS device does not agree with laboratory determination of plasma heparin concentration using a chromogenic substrate for activated factor X.
Measurement of circulating heparin concentration has been suggested to optimize anticoagulation during cardiopulmonary bypass. The Hepcon/HMS device (Medtronic HemoTec, Inc., Parker, Colo.) uses heparin/protamine titration to quantitatively determine heparin concentration. Extensive validation of this instrument is still lacking. ⋯ We conclude that heparin concentrations determined with the Hepcon/HMS instrument do not agree with laboratory determination of heparin concentration. Monitoring of heparin concentrations during bypass with the Hepcon/HMS device cannot be recommended.
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J. Thorac. Cardiovasc. Surg. · Jul 1996
Euro-Collins solution exacerbates lung injury in the setting of high-flow reperfusion.
Single-lung transplantation has been abandoned for the treatment of pulmonary hypertension by many centers because of overperfusion of the graft following implantation. Euro-Collins solution is currently used for lung preservation despite the vasoconstrictive effect of this intracellular-type solution. We hypothesized that high-flow reperfusion, alone or in combination with Euro-Collins-induced vasoconstriction, may cause lung dysfunction. ⋯ Similarly, the wet/dry ratio of the lungs in the high-flow experimental group (13.92 +/- 2.32) was significantly greater than that in the low-flow experimental group (6.27 +/- 0.19, p < 0.01) and than that in the high-flow control group (5.88 +/- 0.23, p < 0.001). These data demonstrate that high-flow reperfusion and preservation with Euro-Collins solution are deleterious to lung function, both individually and in combination, in an ex vivo rabbit lung model. Lung preservation with Euro-Collins solution may not be optimal when high-flow reperfusion is anticipated, as in the setting of unilateral lung transplantation for pulmonary hypertension.
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J. Thorac. Cardiovasc. Surg. · Jul 1996
Preservation of endothelium-dependent vasodilation with low-potassium University of Wisconsin solution.
University of Wisconsin solution has provided excellent myocardial preservation. However, the high potassium content of the currently available University of Wisconsin solution has been implicated in coronary artery endothelial damage. We placed 16 neonatal (age 1 to 3 days) Duroc piglet hearts on an isolated nonworking perfusion circuit. ⋯ The loss of endothelium-dependent coronary blood flow response in group 2 correlated with a decreased capacity to release nitric oxide after arrest (prearrest 8.25 +/- 2.30 nmol/min per gram versus postarrest -2.46 +/- 2.29 nmol/min per gram, p < 0.01). Endothelium-independent vasodilatory response revealed no significant difference between groups before and after arrest. These results suggest that the low-potassium University of Wisconsin solution provides superior protection of the endothelium by preserving the endothelium-dependent vasodilatory response to nitric oxide release.
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J. Thorac. Cardiovasc. Surg. · Jun 1996
Randomized Controlled Trial Comparative Study Clinical TrialAlpha-stat acid-base regulation during cardiopulmonary bypass improves neuropsychologic outcome in patients undergoing coronary artery bypass grafting.
Neuropsychologic impairment in patients undergoing cardiopulmonary bypass may be associated with cerebral blood flow changes arising from different management protocols for carbon dioxide tension during bypass. Seventy patients having coronary artery bypass grafting were randomized to either pH-stat or alpha-stat acid-base management during cardiopulmonary bypass with a membrane oxygenator. In each patient, cerebral blood flow (xenon 133 clearance), middle cerebral artery blood flow velocity (transcranial Doppler sonography), and cerebral oxygen metabolism (cerebral metabolic rate and cerebral extraction ratio) were measured during four phases of the operation: before bypass, during bypass (at hypothermia and at normothermia), and after bypass. ⋯ Cerebral extraction ratio for oxygen demonstrated relative cerebral hyperemia during hypothermic (28 degrees C) bypass in both the pH-stat and alpha-stat groups (0.12 [0.11 to 0.14] and 0.25 [0.22 to 0.28], respectively); however, hyperemia was significantly more pronounced in the pH-stat group, indicating greater disruption in cerebral autoregulation. Neuropsychologic impairment criteria of deterioration in results of three or more tests revealed that a significantly (Fisher's exact test, p = 0.02) higher proportion of patients in the pH-stat group fared poorly than in the alpha-stat group at 6 weeks (17/35, 48.6% [32% to 65.1%], and 7/35, 20% [6.7% to 33.2.2%], respectively). In conclusion, patients receiving alpha-stat management had less disruption of cerebral autoregulation during cardiopulmonary bypass, accompanied by a reduced incidence of postoperative cerebral dysfunction.
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J. Thorac. Cardiovasc. Surg. · Jun 1996
Morphologic determinants favoring surgical aortic valvuloplasty versus pulmonary autograft aortic valve replacement in children.
The pulmonary autograft is being used with increasing frequency to replace the diseased aortic valve in the pediatric population. Attempted surgical aortic valvuloplasty with an unacceptable result and return to cardiopulmonary bypass for aortic valve replacement with a pulmonary autograft results in prolonged bypass time and increased potential for morbidity. Therefore, the ability to predict an unsuccessful outcome for valvuloplasty would be of significant clinical benefit. This issue is addressed in the present study. ⋯ (1) Surgical aortic valvuloplasty should be the preferred approach when the aortic valve is tricuspid. (2) In contrast, aortic valve replacement with a pulmonary autograft should be the preferred strategy in the presence of a nontricuspid aortic valve (especially when the aortic valve is regurgitant) and after failed surgical valvuloplasty.