Biomedical subjects
Publications and source records attributed to J S Chaffin.
As the results of organ transplantation show steady improvement, we have seen a marked increase in the number of potential organ recipients. During this time however, the number of donor organs becoming available has remained little changed. The reasons for this phenomenon and some potential solutions for improving the supply of donor organs are reviewed.
Brain death is associated with neuroendocrine changes, in particular with a significant reduction of plasma-free triiodothyronine (T3) that results in impaired aerobic metabolism. Myocardial energy stores are reduced and tissue lactate increased. Cardiac function deteriorates. Similar metabolic changes are seen in patients undergoing open-heart surgery on cardiopulmonary bypass, including those undergoing heart transplantation. Therapy with T3 leads to a reversal of these metabolic changes, resulting in improved cardiac function. One hundred and sixteen consecutive potential donors have been so treated, as have 70 of the recipients. Immediate posttransplant cardiac function was good in all but 3, and these hearts recovered to normal within a maximum of 24 hr of mechanical support. In 2 small randomized trials in patients undergoing myocardial revascularization on cardiopulmonary bypass, postoperative T3 therapy was associated with a reduced need for inotropic support and diuretic therapy in the first study and improved cardiac output in the second study.
During the 2-year period 1987 through 1988, 124 patients were assessed for heart or heart-lung transplantation. Sixty were accepted for heart transplantation, of whom 49 received transplants. Nine required pretransplant intra-aortic balloon pump support (+/- positive-pressure ventilation) for periods ranging from 2 to 15 days (mean 5 days). One patient was supported successfully by a pneumatic biventricular assist device for 70 days pretransplant. The 30-day survival in this group of 10 critically unstable patients was 100% and the 6-month survival 90% (one death). This experience compares well with survival rates of 100% at 30 days and 92% at 6 months in the 39 patients who required no form of pretransplant circulatory support. The biventricular assist device also has been used in 2 other patients; one did not survive to transplant and the other was deemed unsuitable by virtue of cerebral injury. Extracorporeal membrane oxygenation supported 2 posttransplant patients (one heart and one heart-lung) with grossly impaired pulmonary function for periods of 5 and 2 days respectively, but both died before lung function had recovered.
In the 33-month period April 1985 to December 1987, endomyocardial biopsy was performed 314 times in 23 patients with orthotopic (21) or heterotopic (2) heart transplants at Baptist Medical Center. The technique is described. Adequate tissue was obtained in 99% of cases and there was only one complication from the procedure. Mild to severe acute rejection was seen in 105 specimens (33%). The histopathological interpretation has proved invaluable in the care of patients with heart transplants.
Experience with mitral valve replacement over a nine-year period is reviewed. Hospital mortality was 8.9%, with an additional late mortality of 18.5% during a mean follow-up period of 4.34 years. Study of the factors influencing the results of valve replacement revealed a direct correlation between long-term survival and New York Heart Association (NYHA) Functional Class, as judged preoperatively, as well as left ventricular end-diastolic pressure, cardiac index, type of valve lesion, and presence of associated coronary artery disease. Hospital mortality was 32% (p less than 0.01) for those patients in NYHA Functional Class IV before operation, compared with 3% for Class III patients. Untreated concomitant coronary artery disease was associated with a significantly higher perioperative mortality of 28% (p = 0.002) compared with an 8% mortality in patients with coronary artery disease treated by vein bypass at the time of mitral valve replacement. Patients with normal coronary arteries documented angiographically before operation had a 1% hospital mortality. Seventy-two percent of all patients are still alive at a maximum follow-up of nine years. Eighty-three percent of those survivors who were in Functional Class III or IV before operation are now considered to be in Class I or II. We conclude that patients should undergo mitral valve replacement before the development of the advanced functional stage of valve disease. In addition, coronary arteriograms should be performed on all patients who are more than 40 years old at the time of cardiac catheterization, and revascularization considered at the time of mitral valve replacement for those patients with significant coronary disease.
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The presence of an anomalous right subclavian artery in a patient was a cause of dysphagia and ill-defined upper back pain. Her problem was ideally managed by the median sternotomy approach. With this exposure, the artery is divided and its origin from the aortic arch oversewn. Relocating the artery into the right upper mediastinum and anastomosis with or without a segmental graft to the aortic arch restores extremity circulation and eliminates the dysphagia.