The Annals of thoracic surgery
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Long-term survival at our institution for postcardiotomy cardiogenic shock patients supported with the BioPump is 36% (29/80 patients). A heparin-coated extracorporeal membrane oxygenator (ECMO), first introduced in 1991, may reduce organ injury associated with cardiopulmonary bypass. The device can be employed rapidly because it connects directly to the cardiopulmonary bypass cannula. ⋯ Extracorporeal membrane oxygenation without left ventricular drainage clearly is not effective in patients undergoing mitral valve operations as it does not effectively decompress the left ventricle, but it was highly effective in treating postcardiotomy cardiogenic shock in our coronary artery bypass grafting patients. Extracorporeal membrane oxygenation also proved to be safe as the patient-related complications of stroke, renal failure, and mediastinitis were low. Our preliminary success with heparin-coated ECMO now needs to be confirmed by studies from other centers with larger groups of patients.
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From January 1986 through June 1992, 512 elderly patients (70 years and older) underwent internal mammary artery grafting (IMAG). The operative mortality in these patients was 7.62% (39 of 512), which was significantly higher than that (1.97% [60 of 3,047]; p < 0.0001) in younger patients (under 70 years old). To investigate the risk factors in the elderly, the data from the 512 patients were evaluated by univariate analysis and multiple logistic regression. ⋯ The regression analysis demonstrated that right IMAG, reoperation, history of myocardial infarction, age, left main artery disease, history of smoking, and postoperative complications are the risk factors for the elderly undergoing IMAG. Therefore, particular care should be taken in those patients scheduled to undergo IMAG. The role of right IMAG in the elderly should be further clarified before universal acceptance of the technique in these patients.
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Homograft replacement of the aortic valve has inherent advantages for the patient in terms of decreased incidence of thromboembolism, endocarditis, and anticoagulation-related complications. Limitations in its use stem from a significant incidence of postoperative aortic regurgitation, related to difficulty with consistent commissural and sinotubular geometry when inserted in the subcoronary position. To minimize this complication, we used a homograft as a functional unit in 71 patients between 1986 and May 1993, either as a root replacement (n = 58) or as an intraaortic inclusion cylinder (n = 13). ⋯ Freedom from significant aortic regurgitation was 88% +/- 7% at 6-year follow-up. More consistent maintenance of the sinotubular and commissural geometry of the aortic homograft may be achieved with the root replacement or the inclusion cylinder techniques. This may reduce the incidence of postoperative aortic regurgitation and further benefit the patient by reducing the need for reoperation in the future.
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Clinical Trial
Retrograde warm blood cardioplegia preserves hypertrophied myocardium: a clinical study.
The ability of retrograde warm blood cardioplegia to preserve hypertrophied myocardium remains controversial. This two-part study was undertaken to address this question in patients subjected to aortic valve replacement for calcified aortic valve stenosis complicated with echocardiographically defined left ventricular hypertrophy. Part 1 was designed to assess the intraoperative patterns of myocardial oxidative metabolism in 20 patients in whom the severity of left ventricular hypertrophy was reflected by a mean (+/- standard error of the mean) myocardial mass index of 213 +/- 15 g/m2. ⋯ The results of part II show that the clinical outcomes of warm patients were overall good and not different from those of the cold group. We conclude that retrograde warm blood cardioplegia can adequately preserve hypertrophied myocardium by keeping its metabolism predominantly aerobic during aortic cross-clamping provided that measures are taken to optimize the determinants of the oxygen demand/supply ratio throughout. These measures include avoidance of left ventricular distention, immediate ablation of any recurring activity during arrest, maintenance of high retrograde flow rates, limitation of hemodilution, and uninterrupted mode of cardioplegia delivery.
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To analyze quantitatively the performance of the intravenacaval blood gas exchanger (IVOX), we developed a right atrium-pulmonary artery venovenous extracorporeal bypass circuit. Oxygen transfer and carbon dioxide removal were calculated at different blood flow rates, different hemoglobin levels, and during permissive hypercapnia. Oxygen transfer increased linearly with blood flow up to 41 mL/min. ⋯ Carbon dioxide removal was 45 mL/min at blood carbon dioxide tension of 42 mm Hg but increased to a maximum of 81 mL/min at a carbon dioxide tension of 90 mm Hg. We conclude that IVOX is a diffusion-limited device dependent on blood flow, hemoglobin content, and the gas pressure gradient across the membrane. Further engineering improvements are needed to improve the gas exchange performance of IVOX.