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Biomedical subjects

W A Baumgartner

Publications and source records attributed to W A Baumgartner.

At least 109 records · Page 6Linked to original sources
PubMed1990

Leukocyte depletion ameliorates free radical-mediated lung injury after cardiopulmonary bypass.

Activated leukocytes and oxygen free radicals have been implicated in the pathogenesis of lung injury associated with cardiopulmonary bypass. To determine whether leukocyte depletion could prevent this injury, we used a dog model simulating routine cardiac operations. Mongrel dogs (11 to 17 kg) were subjected to cardiopulmonary bypass with a bubble oxygenator and cooled to 27 degrees C. After aortic crossclamping and cardioplegic arrest for 90 minutes, control animals (n = 5) were rewarmed and weaned from bypass, and their condition was then stabilized for 90 minutes. Leukocyte-depleted animals (n = 5) had a leukocyte filter incorporated in the bypass circuit. During bypass, circulating leukocyte counts decreased by 60% in control dogs, and by 97% in leukocyte-depleted animals. Free radical generation (estimated by spectrophotometric assay of plasma conjugated dienes) was significantly reduced by leukocyte depletion during and after bypass. Total hemolytic complement activity and the titer of C5 decreased markedly immediately after the onset of bypass in both the control and leukocyte-depleted animals. Pulmonary function after bypass was better preserved in leukocyte-depleted animals. These data suggest that depletion of circulating leukocytes contributes to lung injury during cardiopulmonary bypass and is associated with increased oxygen radical activity, pulmonary edema, and vasoconstriction. Leukocyte depletion substantially reduced the pulmonary injury seen after cardiopulmonary bypass.

Animals↗
PubMed1989

Unique aspects of heart and lung transplantation exhibited in the 'domino-donor' operation.

During the past 2 decades various refinements in heart and lung transplantation procedures have taken place. Improved preservation methods, new immunosuppressive medications, and advances in technical capabilities have allowed innovative procedures to be performed. In May 1987 the first "domino-donor" operation was performed in the United States. A 28-year-old man with cystic fibrosis and end-stage lung disease received the heart and lungs of an anonymous donor after he donated his heart to a 38-year-old man with end-stage ischemic cardiomyopathy. The technical and logistical aspects of this transplantation procedure are described herein. Other unusual features of this case that are discussed include heart-lung transplantation for a patient with cystic fibrosis, the use of cardiopulmonary bypass to allow lung procurement and transplantation across long distances, and the current role of heterotopic cardiac transplantation.

Adult↗
PubMed1989

Exploratory analysis of time-dependent risk for infection, rejection, and death after cardiac transplantation.

Data from 95 heart transplantations performed at The Johns Hopkins Hospital from July 1983 to October 1988 were analyzed to detect patterns of morbidity and mortality. Using nonparametric techniques, hazard functions were determined for all deaths and for deaths due to infection or rejection. The rates of rejection and infection (episodes per patient-month) were determined within each of ten intervals following transplantation. A total of 19 deaths, 281 rejection episodes, and 180 distinct infections were available for analysis during a follow-up of 1 to 62 months. The hazard function for rejection appeared biphasic, with a rapidly decelerating early phase during the first year followed by a constant late phase. The hazard function for infection was triphasic, with a delayed, decelerating early phase, a period of increased risk approximately 2 years after operation, and finally a late constant phase. Both infection and rejection rates (episodes per patient-month) were biphasic, with rapidly decelerating early phases and constant late phases. Multiple regression analysis demonstrated that eventually nonsurviving patients had significantly higher rates of rejection and infection during both the early and late phases compared with survivors. The increased rate of rejection among nonsurvivors was evident throughout follow-up, although no deaths were attributable directly to rejection after the first 8 months. These data suggest that a complex interrelationship between infection and rejection determines late survival after cardiac transplantation and that aggressive treatment of late rejection predisposes toward death from infection.

Actuarial Analysis↗
PubMed1989

Implantable electrical left ventricular assist system: bridge to transplantation and the future.

An implantable left ventricular assist system (LVAS) utilizing an electromechanically driven dual pusher-plate blood pump has been employed in a multiinstitutional trial as a bridge to cardiac transplantation. Under development for permanent circulatory support in patients with end-stage heart disease, the LVAS, in this application, derives power and control from an external console via a percutaneous lead. The LVAS was implanted in 20 patients (16 men, 4 women) who were hemodynamically unstable or in refractory cardiogenic shock. The mean age was 44.9 years (range, 25 to 63 years). Preoperative diagnosis was evenly divided between end-stage ischemic disease, cardiomyopathy, and acute myocardial infarction. Implanted in the left upper quadrant within the anterior abdominal wall, the blood pump was connected between the left ventricular apex and ascending aorta. Total support of the systemic circulation and substantial left ventricular unloading were achieved with synchronous counterpulsation for periods up to 90 days (mean, 22.7 days). All patients were stabilized hemodynamically. The mean preoperative cardiac index of 1.5 L/min/m2 increased by a factor of 2. Pulmonary arterial pressures decreased substantially. Serious complications occurred in 16 patients, precluding cardiac transplantation in 10. Most complications (greater than 70%) were in patients who did not receive transplants; the most common complication was bleeding. Twelve of 13 patients with LVAS implants for more than seven days were mobilized, and 4 were fully ambulatory and completely rehabilitated. Orthotopic cardiac transplantation was performed in 10 patients after implants ranging from two to 90 days (mean, 30.3 days).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Cardiopulmonary bypass with profound hypothermia. An optimal preservation method for multiorgan procurement.

Numerous techniques have been devised for the harvesting of individual organs during a multiorgan procurement operation. Cardiopulmonary bypass with profound hypothermia (PH) has been employed in successful harvesting of heart-lung, kidney, pancreas, and liver grafts. This report summarizes our experience using CPB-PH for the harvesting of multiple organs from 10 brain-dead donors during the period from July 1983 to January 1988. Organs harvested included 10 heart-lungs, 17 kidneys (3 kidneys were not harvested due to anatomy and elevated creatinine), 1 liver, and 1 pancreas. Mean ischemic time for the distantly procured heart-lung grafts was 281 +/- 10 min. Adequate pulmonary function, as assessed by arterial blood gases, was observed in each heart-lung recipient (mean PO2 was 119 +/- 46 mmHg, 164 +/- 47 mmHg, 130 +/- 30 mmHg, 114 +/- 26 mmHg at immediate post-CPB, 6 hr postop, 24 hr postop, and postextubation, respectively). Mean length of intubation was 34 +/- 8 hr. Mean creatinines of kidney recipients at days 2, 7, and current creatinine were 7.4 +/- 3.6 mg%, 3.6 +/- 2.4 mg%, and 1.6 +/- 0.66 mg%, respectively. Eight kidney recipients (47%) required dialysis, (2 patients required only a single dialysis). Ninety-four percent of the kidney transplant patients are alive, and 88% (15/17) have functioning kidneys. One liver and 1 pancreas were harvested during this time period. Preservation was satisfactory in both the pancreas (Johns Hopkins Hospital) and liver (Dr. Thomas Starzl, personal communication). The technique of CPB-PH has resulted in excellent function of heart-lung grafts. Follow-up of the transplanted kidneys, liver, and pancreas utilizing this technique shows equal or better function compared with standard techniques. This technique offers other advantages in addition to satisfactory multiorgan preservation. Placement of an unstable patient on CPB ensures adequate organ perfusion and allows for a gradual yet uniform cooling of all organ systems. Cooling to a core temperature of 10-15 degrees C requires 30 min, during which time preliminary intraabdominal and mediastinal dissection can be carried out. Following cessation of CPB and subsequent exsanguination, organs can be more easily dissected in a near-bloodless field. This technique does not preclude additional crystalloid organ flushing. Since multiorgan procurement occurs with virtually every donor, this technique may be the optimal method providing excellent preservation, ease of dissection, and better control of hemodynamics during the operation.

Cardiopulmonary Bypass↗
PubMed1989

The risk of coronary bypass surgery for patients with postinfarction angina.

Three hundred consecutive patients who developed unstable postinfarction angina requiring isolated coronary artery bypass from 1982 through 1987 were analyzed. Hospital mortality was 5%; 15 (5.5%) additional late deaths occurred during the 69-month follow-up period (mean follow-up, 23.3 months). Significant independent predictors of perioperative mortality by univariate analysis were ejection fraction (p = 0.004); existence of an anterior, transmural infarction (p = 0.0001); and the requirement for preoperative intra-aortic balloon counterpulsation (p = 0.001). By multivariate analysis, only the occurrence of an anterior, transmural infarction (p = 0.001) and the preoperative use of an intra-aortic balloon pump (p = 0.004) were significant independent predictors of mortality. Actuarial survival in this group ranged from 96 +/- 1% at 1 year to 88 +/- 4% at 5 years.

Actuarial Analysis↗
PubMed1989

Immunosuppression after heart transplantation: prednisone and cyclosporine with and without azathioprine.

Fifty-four patients (group I) underwent isolated heart transplantation between July 1983 and January 1987 and were immunosuppressed with oral prednisone and cyclosporine. Twenty-three patients (group II) were transplanted between January 1987 and June 1988 and were immunosuppressed with oral prednisone, azathioprine, and cyclosporine, with lower targeted cyclosporine blood levels. The groups were similar in sex distribution of both donors and recipients. Primary cardiomyopathy was the primary recipient diagnosis in two thirds of patients in both groups. Donor age, graft ischemic time, and length of recipient hospitalization after transplant were similar. There was a trend toward transplantation of older patients in group II, and group II patients were more likely to receive hearts from local donors. Actuarial survival at 24 months was 75% in group I and 92% in group II. Patients who had triple-drug immunosuppression had statistically less early rejection but more early infections that tended to be minor. Hypertension requiring treatment occurred in 63% of group I patients and 62% of group II patients within the first 9 months after transplantation. Elevation of serum creatinine greater than 2.0 mg/dl occurred in 34% of group I patients and 15% of group II patients. A triple-drug immunosuppressive protocol is associated with less early rejection but more early minor infectious episodes. Although the incidence of hypertension is not reduced, there is a trend toward less nephrotoxicity and better survival.

Actuarial Analysis↗
PubMed1988

In vitro studies of isolated supported human hearts.

We developed methods to revive human hearts, obtained at the time of cardiac transplantation, and study them in the physiology laboratory. The hearts were arrested with cardioplegic solution at the time of explanation and transported to the laboratory at 4 degrees C. The hearts were perfused with a human blood based solution whose flow rate, temperature, and ionic concentration were controlled. Six hearts with various endstage cardiomyopathies were revived in this manner. Once perfusion was started, the hearts maintained a steady contractile state for approximately 30 min during which time data could be collected. Within this time period we could measure end-systolic and end-diastolic pressure-volume relations, the time courses of contraction and relaxation, and the influence of heart rate and premature stimulation on contractile state. The results suggest that evidence of specific cellular abnormalities in human heart disease might be obtained from measurements of global ventricular performance. Furthermore, the type of abnormality identified, namely sarcoplasmic reticulum dysfunction, in several forms of cardiomyopathy was in concordance with results obtained in muscle bath studies of similarly diseased human and animal myocardium.

Cardiomyopathy, Dilated↗
PubMed1988

Donor core-cooling provides improved static preservation for heart-lung transplantation.

Twenty-three dairy calves underwent heart-lung allotransplantation after donor organs were procured using either donor core-cooling through cardiopulmonary bypass (CPB) or pulmonary artery flush (PAF) to assess which method provides optimal graft preservation. In Groups 1 (control) and 2, donors were cooled to 15 degrees C on CPB and organs were either immediately transplanted (Group 1) or stored in saline solution (4 degrees C) for 4 hours (Group 2) prior to transplantation. In Group 3, donors were pretreated with prostaglandin E1 prior to PAF with modified Euro-Collins solution. Organs were stored in saline solution (4 degrees C) for 4 hours and were then transplanted. Acute cardiopulmonary function following transplantation was assessed by the ratio of end-systolic pressure to end-systolic dimension, extravascular lung water (EVLW), lung compliance, arterial oxygenation, and lung biopsy. Cardiac function after the transplantation procedure was similar in all groups, but EVLW values and lung biopsy scores were worse after PAF. Arterial O2 tension appeared lower after PAF, but not significantly so. Core-cooling provides superior static preservation and thus improved graft function in the acute bovine model.

Animals↗
PubMed1988

Aortic valve selection in the elderly patient.

To determine the influence of valve selection on valve-related morbidity and mortality and patient survival, comparative long-term performance characteristics of mechanical (N = 68) and bioprosthetic (N = 73) heart valves were analyzed for 141 patients more than 70 years old who underwent isolated aortic valve replacement between 1970 and 1985. Cumulative patient follow-up was 491 patient-years (average, 4.3 years per patient). Hospital mortality was 18% and 19% for patients with mechanical valves and bioprosthetic valves, respectively. Survival at 5 years was 61 +/- 7% (+/- the standard error) and 67 +/- 10% for recipients of mechanical valves and bioprosthetic valves, respectively. Male sex (p = 0.014) and urgency of operation (p = 0.006) were independent risk factors for hospital mortality. Atrial fibrillation increased valve-related mortality (p = 0.01). No patient required reoperation or experienced structural valve failure. While anticoagulant-related hemorrhage was increased in recipients of mechanical valves (9.2 +/- 2.1%/patient-year) compared with recipients of bioprosthetic valves (2.3 +/- 1.1%/patient-year), it did not result in a death or lead to permanent disability. There was no difference in freedom from any valve-related complication at 5 years. However, when all morbid events are considered, recipients of bioprosthetic valves experienced fewer valve-related complications than patients receiving mechanical valves (10.7 +/- 2.3%/patient-year versus 17.6 +/- 2.5%/patient-year, respectively; p less than 0.05). The reduced incidence of anticoagulant-related hemorrhage and the infrequent need for warfarin sodium anticoagulation favor selection of a bioprosthetic heart valve in patients older than 70 years.

Aged↗
PubMed1988

Surgical management of renal cell carcinoma with intracaval neoplastic extension above the hepatic veins.

Cardiopulmonary bypass, hypothermia, temporary cardiac arrest and exsanguination represent the next logical step in the evolutionary management of intracaval neoplastic extension with renal cell carcinoma. This method of management provides control of the circulation of the entire body and allows for careful dissection in a bloodless field with less risk of embolization. From 1981 to 1986, 15 patients were treated with intracaval neoplastic extension of renal cell carcinoma above the level of the most inferior hepatic veins. In 6 patients mobilization of the vena cava with division of the hepatic veins to the caudate lobe allowed excision of the tumor and tumor thrombus without cardiopulmonary bypass (group 1). The remaining 9 patients underwent cardiopulmonary bypass and hypothermia (group 2). There was 1 postoperative mortality in the entire group. Most patients had advanced regional disease but the feasibility of this technique has been demonstrated. Survival appeared to be less in the bypass group. Although some of the patients have had metastatic disease, the quality of life and survival have been prolonged in many of these acutely ill patients.

Actuarial Analysis↗
PubMed1988

Neurohumoral modulation of the pulmonary vasoconstrictor response in the autoperfused working heart-lung preparation during cardiopulmonary preservation.

Uncontrolled pulmonary hypertension during autoperfusion of the heart and lungs for preservation has been described, and it may result in extensive pulmonary injury and occasional early failure of the preparation. In order to investigate the neurohumoral mediators of the vasoconstrictor response in the pulmonary circulation of the autoperfused working heart-lung preparation, heart-lung organ blocks were harvested from calves, placed in a normothermic autoperfusion circuit, and studied. Effects of beta-adrenergic stimulation with isoproterenol, nonspecific vasodilatation with nitroglycerin, alpha-adrenergic blockade with phentolamine, phospholipase A2 inhibition with methylprednisolone, cyclooxygenase inhibition with indomethacin, and white blood cell depletion were independently evaluated. Untreated animals, pre- and postexplant, served as controls. Multipoint pulmonary vascular pressure-cardiac output plots were constructed for each animal. An index of pulmonary vascular resistance was obtained from the linear relation: mean pulmonary artery pressure minus pulmonary capillary wedge pressure divided by cardiac output. An intense flow-dependent pulmonary vasoconstrictor response was confirmed to exist in the denervated bovine autoperfused working heart-lung preparation. Isoproterenol afforded better protection against this response than the other agents studied. White blood cell depletion reduced postexplant pulmonary vasoconstriction, implying that circulating polymorphonuclear leukocytes mediate the response in the autoperfused working heart-lung preparation. White blood cell depletion and the administration of selected pharmacologic agents provide modalities for regulating the pulmonary vasoconstrictor response, and thus may enhance lung preservation in the autoperfusion model.

Animals↗