The Journal of thoracic and cardiovascular surgery
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J. Thorac. Cardiovasc. Surg. · Sep 1995
Desensitization of myocardial beta-adrenergic receptors and deterioration of left ventricular function after brain death.
Brain death often results in a series of hemodynamic alterations that complicate the treatment of potential organ donors before transplantation. The deterioration of myocardial performance after brain death has been described; however, the pathophysiologic process of the myocardial dysfunction that occurs after brain death has not been elucidated. This study was designed to analyze the function of the myocardial beta-adrenergic receptor and the development of left ventricular dysfunction in a porcine model of experimental brain death. ⋯ Significant deterioration of myocardial performance also occurred within the first hour after brain death, represented by a decrease in preload-recruitable stroke work compared with the baseline value. The deterioration of myocardial performance after brain death correlates temporally with desensitization of the myocardial beta-receptor signal transduction system. The mechanism of impairment appears to be localized to the adenylate cyclase moiety itself.
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J. Thorac. Cardiovasc. Surg. · Sep 1995
Comparative Study Clinical Trial Controlled Clinical TrialDilation of the internal mammary artery by external and intraluminal papaverine application.
Three methods for prevention of perioperative spasm of the internal mammary artery were compared in 78 patients undergoing coronary artery bypass grafting. In group 1, internal mammary artery pedicles were divided distally, clamped, and placed under the upper sternum submerged in papaverine solution (1.5 mg/ml). In group 2, as in group 1 but before clamping, 2 ml of heparinized blood with 1.5 mg/ml papaverine added was injected into the vessel lumen. ⋯ Morphometric measurements on the resected distal portion of the dilated internal mammary arteries disclosed less folding of the internal elastic lamina and a larger luminal area in groups 2 and 3 compared with respective findings in group 1 (1.21 mm2 and 1.42 mm2 versus 0.77 mm2; p < 0.02). Mechanical vessel wall injury occurred in 8 of 52 internal mammary arteries treated with intraluminal papaverine. Intraluminal papaverine solution injected once or twice in addition to external papaverine exposure therefore provides a better blood flow rate and distal dilation than mere submersion in papaverine solution, but at a considerable risk of mechanical wall injury.
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J. Thorac. Cardiovasc. Surg. · Sep 1995
In acute lung injury, inhaled nitric oxide improves ventilation-perfusion matching, pulmonary vascular mechanics, and transpulmonary vascular efficiency.
Acute respiratory distress syndrome continues to be associated with significant morbidity and mortality related to ventilation-perfusion mismatch, pulmonary hypertension, and right ventricular failure. It has been suggested that inhaled nitric oxide, which is a selective pulmonary vasodilator, may be effective in the treatment of acute respiratory distress syndrome; however, the effects of nitric oxide on cardiopulmonary interactions are poorly understood. We therefore developed a model of acute lung injury that mimics the clinical syndrome of acute respiratory distress syndrome. ⋯ Although arterial oxygen tension increased, oxygen delivery did not improve significantly. These data suggest that by improving ventilation-perfusion matching and arterial oxygen tension while lowering pulmonary vascular resistance and impedance, nitric oxide may be beneficial in patients with acute respiratory distress syndrome. However, additional measures to enhance cardiac performance may be required.
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J. Thorac. Cardiovasc. Surg. · Sep 1995
Protection against injury during ischemia and reperfusion by acadesine derivatives GP-1-468 and GP-1-668. Studies in the transplanted rat heart.
Acadesine (AICAr: 5-amino-4-imidazole carboxamide riboside) has been shown to afford sustained protection against injury during ischemia and reperfusion. The present studies used the heterotopically transplanted rat heart to assess the protective properties of two new acadesine analogs: GP-1-468 and GP-1-668. ⋯ Both GP-1-468 and GP-1-668 increase the rate and extent of early postischemic recovery, and this protection is sustained for at least 24 hours. These beneficial actions were associated with an increase of the tissue content of adenosine during ischemia, but they appeared to be independent of the status of the high-energy metabolism.
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J. Thorac. Cardiovasc. Surg. · Sep 1995
Tissue oxygenation with graded dissolved oxygen delivery during cardiopulmonary bypass.
Intravascular perfluorochemical emulsions together with a high oxygen tension may increase the delivery of dissolved oxygen to useful levels. The hypothesis of this study is that increasing the dissolved oxygen content of blood with incremental doses of a perfluorochemical emulsion improves tissue oxygenation during cardiopulmonary bypass in a dose-related fashion. ⋯ Graded increases in mixed venous oxygen tension during cardiopulmonary bypass were observed in response to graded increases in the dissolved oxygen delivery. These data suggest that enhancing oxygenation with perfluorochemical-dissolved oxygen is an effective temporary substitute for the use of hemoglobin-bound oxygen during cardiopulmonary bypass. Perfluorochemical-dissolved oxygen may be particularly beneficial in the setting of multiple hypoxic stresses.