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Biomedical subjects

W A Baumgartner

Publications and source records attributed to W A Baumgartner.

At least 163 records · Page 9Linked to original sources
PubMed1985

Heart and heart-lung transplantation: program, development, organization, and initiation.

Since the initiation of cardiac transplantation in 1967, more than 1,000 procedures have been done worldwide. A high percentage of these transplant procedures have been completed in the past few years. In 1983, II centers in the United States performed 173 transplant procedures; by 1984, there were more than 30 heart transplant centers. This sudden increase is due primarily to increasing survival of transplant recipients since the introduction of cyclosporine. However, most transplant surgeons believe that the use of this drug alone will not result in survival results and rehabilitation similar to those obtained in experienced transplant centers. Institutional commitment, adequate resources, attention to detail and most importantly, a dedicated transplant team, are important elements to ensure success. This manuscript will define guidelines for the establishment of a new transplant program and eludicate the organizational details necessary to implement such a program, based on our experience at the Johns Hopkins Hospital over the past two years.

Consumer Behavior↗
PubMed1984

Acute physiological changes following heart-lung allotransplantation in dogs.

The feasibility of clinical heart-lung transplantation requires a better understanding of the physiological consequences of the operation, heart-lung denervation, and the quality of graft preservation. An acute canine model was used to evaluate heart-lung function during the first 24 hours after transplantation. Measurements of cardiopulmonary dynamics were performed in 5 donor animals and compared sequentially after transplantation in the respective recipients. Orthotopic allotransplantation was performed on cardiopulmonary bypass with moderate hypothermia after perfusion of both the heart and lung with a clinical cardioplegic solution (4 degrees C; potassium chloride, 30 mEq/L; mannitol, 20 gm/L). Postoperatively, the animals were ventilated continuously and anesthetized. Hemodynamic variables were monitored, and measurements were made of arterial and venous oxygen, carbon dioxide, saturation, and pulmonary mechanics. Cardiac output and a derived measurement of lung water were determined. Pulmonary vascular resistance, arteriovenous shunt, resistance, and compliance were calculated. At the termination of the experiment, significant differences were observed between donor and recipient lung-water levels (7.7 +/- 0.9 ml/kg versus 12.0 +/- 3.1 ml/kg, respectively; p less than 0.05); 100% arterial oxygen tension (509 +/- 37 mm/Hg versus 227 +/- 114 mm/Hg, respectively; p less than 0.01); and pulmonary compliance (38 +/- 18 ml/cm H2O versus 11 +/- 4 ml/cm H2O, respectively; p less than 0.05). Arteriovenous shunt increased from 12.2 +/- 4 to 16.5 +/- 5% (p = 0.2). This model evaluates the technique currently employed clinically and will be used in the future to compare methods of heart-lung preservation with the goal of allowing distant heart-lung procurement.

Animals↗
PubMed1984

Operative intervention for postinfarction angina.

Thirty-four patients (26 men and 8 women) underwent myocardial revascularization following myocardial infarction (MI) at the Johns Hopkins Hospital during 1980 through 1982. Average age was 59 years. Of the 33 patients with unstable angina, 61% had ischemia in the infarct zone and 39% had "ischemia at a distance." Mean time from MI to operation was 16 days. The MIs were equally divided between a transmural and a subendocardial location. Eleven patients had a history of congestive heart failure. Intraaortic balloon pumping was used preoperatively for anginal stabilization in 14 patients. Mean ejection fraction for the group was 52%. There were 3 operative deaths, all 3 due to myocardial failure. Late follow-up (mean, 13.7 months; range, 6 to 35 months) is complete for 28 patients. There was 1 late death, secondary to cardiac failure. There were no late MIs. Angina had recurred in 5 patients, but only 2 were taking antianginal medication. At the time of follow-up, 52% of patients were in New York Heart Association Functional Class I. This experience suggests that operative intervention for postinfarction angina can be accomplished with an acceptable mortality and thereby increase survival, reduce the later occurrence of MI, and relieve angina in this high-risk group.

Aged↗
PubMed1984

Immediate improvement of dysfunctional myocardial segments after coronary revascularization: detection by intraoperative transesophageal echocardiography.

To ascertain the immediate effects of coronary artery bypass grafting on regional myocardial function, intraoperative transesophageal two-dimensional echocardiograms were obtained in 20 patients using a 3.5 MHz phased array transducer at the tip of a flexible gastroscope. Cross-sectional images of the left ventricle were obtained at multiple levels before skin incision and were repeated serially before and immediately after cardiopulmonary bypass. Using a computer-aided contouring system, percent systolic wall thickening was determined for eight anatomic segments in each patient at similar loading conditions (four each at mitral and papillary muscle levels). Of the 152 segments analyzed, systolic wall thickening improved from a prerevascularization mean value (+/- SEM) of 42.7 +/- 2.9% to a postrevascularization mean value of 51.6 +/- 2.6% (p less than 0.001). Thickening improved most in those segments with the worst preoperative function (p less than 0.001). Chest wall echocardiograms obtained 8.4 +/- 2.3 days after operation showed no deterioration or further improvement in segmental motion compared with transesophageal echocardiograms obtained after revascularization. Thus: regional myocardial function frequently improves immediately after bypass grafting, with increases in regional thickening being most marked in those segments demonstrating the most severe preoperative dysfunction, and this improvement appears to be sustained; and in some patients, chronic subclinical ischemic dysfunction is present which can be improved by revascularization.

Aged↗
PubMed1984

Serum thyroglobulin, a monitor of differentiated thyroid carcinoma in patients receiving thyroid hormone suppression therapy: concise communication.

Serum thyroglobulin levels were obtained in 86 patients who had undergone thyroidectomy and I-131 ablation for differentiated thyroid cancer, and who were receiving or had recently discontinued thyroid hormone suppression therapy. Excellent correlation was observed between serum thyroglobulin levels in patients receiving thyroid hormone suppression therapy and I-131 imaging studies. Serum thyroglobulin levels equal to or below 20 ng/ml indicate the absence of thyroid carcinoma, and values exceeding 60 ng/ml were indicative of active thyroid cancer but may include some patients without clinical evidence of disease. Intermediate serum thyroglobulin levels were observed in a small number of patients with postsurgical thyroid remnants or active disease. Serum thyroglobulin levels are of considerable value in monitoring the activity of thyroid cancer in patients who are receiving thyroid hormone suppression therapy.

Antithyroid Agents↗
PubMed1983

Diagnosis and treatment of allograft rejection in heart-lung transplant recipients.

Six patients received heart-lung transplants between March, 1981, and January, 1982. There were four women and two men between 26 and 45 years of age, three with primary pulmonary hypertension and three with congenital heart disease and pulmonary hypertension (Eisenmenger's syndrome). Immunosuppression was primarily with cyclosporin-A, with additional corticosteroid, azathioprine, and rabbit antihuman thymocyte globulin. Six episodes of allograft rejection in four patients (10, 11, 21, 24, 53, and 86 days after transplantation) were detected by means of transvenous endomyocardial biopsy. All patients experienced pulmonary edema early after transplantation (reimplantation response), and two patients required mechanical ventilatory support for allograft rejection at 10 and 11 days. Treatment of rejection consisted of intravenous methylprednisolone (four episodes) or augmented oral prednisone (two episodes), with resolution. No episode thought to be pulmonary rejection has occurred in the absence of cardiac findings. Four patients are alive from 6 to 15 months after transplantation and are functionally normal. Early experience with heart-lung transplantation suggests (1) that allograft rejection can be detected by cardiac findings and successfully treated by augmented corticosteroids, (2) that lung rejection does not occur in the absence of cardiac findings, (3) that the frequency and severity of rejection episodes are not greater than with standard cardiac transplantation, and (4) that the frequency of rejection episodes is highest within the first 60 days after transplantation.

Adult↗
PubMed1983

Discriminant analysis of the changing risks of coronary artery operations: 1971-1979.

The risk of perioperative myocardial infarction (PMI) and operative mortality (OM) associated with coronary artery bypass grafting (CABG) has declined since the introduction of this procedure 15 years ago. Rigorous scientific investigation of the reasons for this trend has been hindered by the complex interactions between changing indications for operation, criteria for patient selection, and management methods. Using univariate and multivariate logistic regression analyses, we investigated the effects of 42 variables on PMI and OM for two cohorts undergoing CABG between 1971 and 1975 (Group A) and 1977 and 1979 (Group B). According to previously identified risk factors, Group B patients were at higher potential risk than those in Group A. Nevertheless, the PMI and OM rates declined from 8.7% +/- 0.9% to 4.6% +/- 0.7% (p = 0.005) and from 2.4% +/- 0.5% to 1.2% +/- 0.4% (p = 0.07), respectively. In calendar year 1979 (N = 438), the PMI and OM rates were 2.8% +/- 0.8% and 0.7% +/- 0.4%. More importantly, the independent determinants of PMI and OM for the two time intervals were distinctly different. Factors which affected the PMI rate in Group A were no longer determinants of PMI in Group B; with the exception of emergency operation and, to a modest extent, congestive heart failure (CHF), predictors of OM in Group A were not determinants of OM in Group B. Thus the adverse impact of multiple patient-related and disease-related determinants of PMI and OM has been neutralized over this decade by the real improvements in patient management. The specific factors and management concepts responsible for these superior results in sicker patients remain uncharacterized; however, in general terms, more sophisticated medical, anesthetic, and nursing management and more refined surgical expertise have essentially nullified the concept of high-risk candidates. Furthermore, the more propitious early results being attained currently may translate directly into parallel long-term improvements in functional benefit and survival.

Coronary Artery Bypass↗
PubMed1983

Reappraisal of cardiopulmonary bypass with deep hypothermia and circulatory arrest for complex neurosurgical operations.

Although cardiopulmonary bypass (CPB) with hypothermia and circulatory arrest is routinely used for certain cardiovascular procedures, its advantages have infrequently been applied for other unusual surgical problems. Fourteen patients (six men and eight women, average age 48 years, range 29 to 74 years) underwent 15 operations over a 4-year period beginning in November 1978. Preoperative diagnosis included giant middle cerebral aneurysm (n = 8), internal carotid aneurysm (3), basilar artery aneurysm (2), and medullary hemangioblastoma (2). All patients had lesions that were considered inoperable by standard neurosurgical techniques. Operative technique consisted of peripheral cannulation with a long and short femoral vein cannula for venous return (24 to 28F) and a single femoral arterial cannula (18 to 24F). CPB flows ranged from 1 to 3.5 L/min, and the total CBP times averaged 146 minutes (range 66 to 282 minutes). Circulatory arrest times averaged 21 minutes (range 5 to 51 minutes), with two patients having no period of circulatory arrest. Lowest core temperature ranged from 16 degrees to 20 degrees C, with cooling and rewarming aided by Brown-Harrison heat exchangers placed in a countercurrent fashion within the venous return line. The heart spontaneously defibrillated in six patients, and external countershock was required in nine patients. No difficulty was encountered with cardiac distention. The intended operation was accomplished in all cases with 13 of 14 patients being discharged from hospital, having had a good neurosurgical result. One patient sustained a hemorrhagic infarction of the cerebellum and pons and is presently recovering. Our experience indicates that peripheral CPB with induced hypothermia and circulatory arrest is a safe technique for approaching otherwise inoperable neurosurgical lesions.

Adult↗
PubMed1982

The durability of porcine xenograft valves and conduits in children.

One hundred four patients younger than 20 years of age underwent intracardiac xenograft valve replacement (n = 41) or extracardiac conduit implantation (n = 63). Long-term follow-up averaged 4.5 and 4.3 years, respectively, and cumulative follow-up totaled 344 patient-years (pt-yr). Thirty patients were followed more than 5 years. Functional results and survival were satisfactory, but valve failure and conduit failure prompted 23 reoperations at linearized rates of 10.1 +/- 2.6% and 4.1 +/- 1.5%/pt-yr, respectively. The rate of valve failure due to leaflet fibrocalcification (primary tissue failure [PTF] was 8.1 +/- 2.4%/pt-yr. Among patients who underwent valve replacement, 52 +/- 13% were free of reoperation at 5 years (59 +/- 13% for PTF only), as were 80 +/- 9% of patients who received an extracardiac conduit. There were no deaths associated with the 22 late reoperations or with the 21 reoperations for PTF. Valve failure was due to PTF in 80% of cases; conversely, isolated valvular PTF was the cause of conduit failure in only one of eight patients. The most common cause of conduit failure was exuberant pseudointimal proliferation in the proximal conduit, which was seen in six of eight patients (75%) with or without other sites of obstruction and responsible for nine of the 15 obstructions (60%). These results underscore the palliative nature of these procedures, militate against indiscriminant use of conduits, prompt consideration of alternative nonconduit techniques where possible, and reemphasize the clinical need for superior valve substitutes and biomaterials for use in the pediatric age group.

Adolescent↗
PubMed1981

Bronchoscopic diagnosis and treatment of bronchial stump suture granulomas.

Eight patients in whom new respiratory symptoms developed following pulmonary resection have been evaluated. The bronchial stumps in all of these patients had been closed with Tevdec suture material. The total number of pulmonary resections using Tevdec suture from January, 1971, to January, 1980, was 180, yielding an incidence of the complication of 4.4%. No patient had empyema or bronchopleural fistula. Symptoms included nonproductive cough (eight patients), hemoptysis (five patients), wheezing (two patients), and coughing up suture material (two patients). The underlying disease necessitating pulmonary resection was carcinoma in five patients, carcinoid adenoma in one patient, tuberculosis in one patient, and bronchiectasis in one patient. The median time interval between resection and development of respiratory symptoms was 18 months, with a range of 8 to 57 months. The chest roentgenograms showed no change from earlier postoperative films. Bronchoscopy under general anesthesia was performed in all eight patients. Granulation tissue around loosened Tevdec sutures was present in all patients so examined. No residual tumor or specific infection was identified. Immediate and sustained relief of symptoms was obtained in seven of eight patients by removal of the loosened sutures. One patient has had recurrence of minor hemoptysis 18 months following suture removal but has refused further endoscopy. Stainless steel staples have been used for bronchial stump closure in over 100 pulmonary resections since 1977 and no such complications have been seen.

Adult↗
PubMed1981

Translocation of the aortic valve for prosthetic valve endocarditis.

Aortic prosthetic valve endocarditis is frequently associated with a perivalvular ring abscess which destroys the normal annulus, so that it is difficult to seat a new prosthesis. Between November, 1974, and January, 1980, we treated four patients with aortic prosthetic endocarditis by translocation of the aortic valve, closure of the native coronary artery ostia, and placement of saphenous vein bypass grafts to the coronary arteries. In each case operation was undertaken because of progressive congestive heart failure resulting from aortic regurgitation; two patients had systemic emboli, and two patients had uncontrolled infection. Infection was due to Enterococcus in three instances and to an unknown organism in one. Total ischemic times averaged 2 hours, 15 minutes; a 25 mm Dacron graft containing a porcine valve was used to replace the ascending aorta and aortic valve, and two or three saphenous vein grafts were placed to distal coronary arteries. One patient died 40 days postoperatively of renal failure and Pseudomonas pneumonia with an intact repair. The other three patients were hospital survivors, with one doing well until dying of chronic active hepatitis 12 months postoperatively. The other two patients are alive at 4 months and 18 months with satisfactory hemodynamic function and are free of infection. Translocation of the aortic valve for prosthetic valve endocarditis is a useful alternative when conventional replacement techniques cannot be utilized.

Adult↗
PubMed1980

The use of thoracoscopy in the diagnosis of pleural disease.

Seventeen patients (ten male and seven female) between the ages of 21 and 76 years underwent thoracoscopy from 1976 through 1978 by the Stanford University University Thoracic Surgical Service. There was no morbidity or mortality. This technique was used when other conventional methods such as thoracentesis and pleural biopsy failed to obtain a diagnosis of suspected thoracic pathology. Thoracoscopy was diagnostic in 16 of 17 cases. The diagnosis of malignancy was made in 11 cases, whereas benign disease was found in the remaining six cases. Of the latter group, there was one false-negative result, which on subsequent thoracotomy was diagnosed as recurrent Hodgkin's disease. The current revival of thoracoscopy as a diagnostic entity is proving to be very valuable in the evaluation of thoracic disease. An increased awareness of the tool and its use should decrease the number of major thoracotomy procedures.

Adult↗
PubMed1980

In vivo evaluation of age-associated changes in delayed-type hypersensitivity.

The effectiveness of a recently developed isotopic in vivo assay for the measurement of delayed-type hypersensitivity (DTH) was compared to that of the conventional skin sensitization assay based on the ear-swelling index. DTH was measured in young and old C57BL/6 mice under conditions of normal health, spontaneous reticular cell sarcoma, Sendai virus infections and under the above conditions, while being treated with a potential immunorestorative agent, mercaptoethanol. A good correlation was observed between the two types of assay. However the reliability and sensitivity of the isotopic assay was found to be superior to the conventional skin sensitization assay. Thus, under optimum conditions, the swelling assay showed a 35% decline in DTH in old mice, and the isotopic assay a 62% decline.

Aging↗