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Biomedical subjects

B Reichart

Publications and source records attributed to B Reichart.

At least 415 records · Page 23Linked to original sources
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Size matching in heart transplantation.

After heart transplantation, problems may arise from hearts that are either too small or too large. Although the "classic" rule requires that the donor/recipient weight ratio mismatch measure not less than 0.8, the chronic organ shortage led to a challenge of that margin. In selected cases donor/recipient weight mismatches of up to 0.5 may be accepted. In these circumstances, heterotopic heart transplantation may be an alternative. In pediatric heart transplantation, disproportionately large hearts (donor/recipient weight mismatches of 2.0 to 3.0) may create the so-called "big-heart syndrome," with coma and general convulsions. Treatment consists of peripheral pressure control with nifedipine.

Adult↗
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Histopathology of hyperacute rejection of the heart: experimental and clinical observations in allografts and xenografts.

The histologic findings in a total of 112 experimental heart transplants comprising allografts (baboon to baboon: n = 37), concordant xenografts (vervet monkey to baboon: n = 52), and discordant xenografts (pig to baboon: n = 23), in which the roles of ABO blood group incompatibility, corcordance, and immunosuppression were evaluated, are described. Hyperacute (vascular, humoral) rejection was characterized by disruption of the microcirculation, with interstitial hemorrhage and edema, rather than by intravascular thrombosis; the features were basically similar whether hyperacute rejection occurred in an ABO-incompatible allograft, concordant xenograft, or discordant xenograft. Hyperacute rejection was noted in all 23 discordant xenografts, in 12 to 52 concordant xenografts, and in four of 17 ABO-incompatible allografts. A unique mixture of acute and hyperacute rejection was observed in three ABO-incompatible allografts and in 10 concordant xenografts. Intensive antirejection therapy was associated with a reduced incidence of hyperacute rejection in corcordant xenografts but also with a significant number of fatal treatment-related complications.

ABO Blood-Group System↗
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Heterotopic heart transplantation: mid-term hemodynamic and echocardiographic analysis--the concern of arteriovenous-valve incompetence.

To assess the hemodynamic contribution of both hearts after heterotopic heart transplantation, we examined recipients by cardiac catheterization and Doppler echocardiography. Since September 1984, immunosuppression consisted of cyclosporine, azathioprine, methylprednisolone, and antithymocyte globulin. In this time interval, 55 orthotopic and 14 heterotopic transplants have been performed. The indications for heterotopic transplant were elevated pulmonary vascular resistance (greater than 4 Wood units), in 10 patients, or gross (greater than 20%) donor-recipient weight mismatch, in six patients. Two patients belonged to both groups. The 1-year survival rate was 63%; currently seven of the 14 patients are alive. Cardiac output (as measured by dye dilution curves and by the Fick method) increased from 4.2 L/min preoperatively to 6.1 L/min in both groups postoperatively (mean follow up, 5.3 months; p less than 0.0005); the transpulmonary gradient fell from 18.5 to 12.3 mm Hg, the pulmonary vascular resistance from 4.4 to 2.4 Wood units (p less than 0.01). The echocardiographic findings were as follows: left ventricular end-diastolic diameter (mm) in the recipient heart was 67.4 +/- 12 and in the donor heart, 42.6 +/- 8.7. Fractional shortening (%) in the recipient heart was 7.1 +/- 2.9 and in the donor heart, 30.4 +/- 10.4. The Doppler technique revealed a cardiac output contribution-ratio (CO donor/CO recipient) of 3.0 +/- 0.61 on average. In all recipient hearts mild and moderate mitral and tricuspid regurgitation was discovered. In the donor heart all mitral and tricuspid valves were found to be incompetent; this was severe in 66% and 11% of the mitral and tricuspid valves, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
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Cytoimmunologic monitoring after heart and heart-lung transplantation.

The ability of cytoimmunologic monitoring to detect acute rejection in heart and heart-lung transplant recipients was assessed. Seventeen heart and nine heart-lung transplant patients treated with cyclosporine as the primary immunosuppressive agent were monitored after operation. Seventeen acute rejection episodes occurred in the heart-only recipients and 12 in the combined heart-lung recipients. These acute rejection reactions were accompanied by increased numbers of "activated" lymphocytes in all but one case, providing cytoimmunologic monitoring a sensitivity of 100% in the heart-lung recipients and 94% in the heart recipients. The specificity was, however, low (68% in the heart recipients and 55% in the heart-lung recipients). Seventy-two percent of the false-positive results were associated with viral infections, particularly cytomegalovirus infections.

Adolescent↗
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Optimalization of immunosuppression after xenogeneic heart transplantation in primates.

Xenogeneic heart transplantation is becoming increasingly attractive because of the shortage of suitable donor organs. In small infants and neonates, for whom suitable human grafts are difficult to obtain, this may play a particularly important role. To evaluate the optimal immunosuppressive regimen after xenogeneic transplantation, cervical heterotopic heart transplantation was performed with vervet monkeys as donors and chacma baboons as recipients. The following groups were investigated: group 1 (n = 9): control, no immunosuppressive medication; group 2 (n = 5): cyclosporine in combination with azathioprine and methylprednisolone; group 3 (n = 6): cyclosporine, azathioprine, and methylprednisolone in combination with antithymocyte globulin for postoperative days 0 to 9; group 4 (n = 7): cyclosporine, azathioprine, and methylprednisolone in combination with 15-deoxyspergualin for postoperative days 0 to 9. Because of severe treatment-related side effects that were observed in group 4, further immunosuppression was modified as follows: group 5 (n = 5): 15-deoxyspergualin was combined with cyclosporine and methylprednisolone only. Acute rejection episodes were diagnosed by cytoimmunologic monitoring on alternate days and weekly myocardial biopsies and were treated with 500 mg methylprednisolone intravenously for 3 to 5 consecutive days. The graft survival after xenogeneic heart transplantation was best in group 3 with 43.3 days compared with 10.3 days in the control group. Still 2.3 acute rejections occurred, which in most cases led to graft failure in these animals. In group 4 the graft survival was prolonged to 20.1 days on average. Only 0.5 acute rejections per animal occurred, but severe gastrointestinal complications and infections were observed that made further experiments necessary to minimize these treatment-related complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
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Heterotopic heart transplantation in 1988--recent selective indications and outcome.

Considering a worldwide average 1-year survival rate of nearly 90% after orthotopic heart transplantation, the question arises as to whether there is still an indication for heterotopic heart transplantation. Since 1967, 132 heart transplantations have been performed at our institution. From 1974 to 1983 only heterotopic transplantations were performed. Since 1985, quadruple-drug therapy has been used for immunosuppression. This consists of low dose cyclosporine in combination with azathioprine, methylprednisolone (in lower dosages), and rabbit antithymocyte globulin (for the first 4 to 6 days after operation and as rescue therapy for severe rejections). Fifty-five transplantations have been performed with this therapy (44 orthotopic and 11 heterotopic). The indications for heterotopic transplantations were either elevated pulmonary vascular resistance (4 to 6 Wood units, n = 6), or a gross donor and recipient weight mismatch (more than 20%) in candidates who showed signs of severe cardiac decompensation (n = 6). One patient had both indications. The 1-year survival rate for those patients was 83%. Currently seven of the 11 patients are alive with life spans ranging from 6 months to 2.5 years after operation. Causes of deaths were infections (n = 3) and chronic graft rejection (n = 1). The recipients were restudied with right-sided heart catheterizations performed from 2 months to 2 years after transplantation. In all patients the cardiac output increased significantly from a mean of 4.0 to 5.8 L/min (p less than 0.0005). In patients with elevated pulmonary vascular resistance, this value decreased after heterotopic transplantation from a mean of 4.9 to 2.4 Wood units.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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Triiodothyronine therapy for heart donor and recipient.

Both (1) brain-dead donors and (2) transplant recipients on cardiopulmonary bypass suffer a depletion in plasma-free triiodothyronine (T3), which leads to metabolic changes (from inhibition of mitochondrial function), resulting in myocardial energy store depletion. Replacement therapy with T3 reverses these changes in both donor and recipient. Donor heart energy stores and function will be maintained at optimum levels if T3 therapy is administered to both donor and recipient at the time of transplantation.

Cardiopulmonary Bypass↗
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Anomalous left superior vena cava in combined heart-lung transplantation.

An anomalous left superior vena cava (SVC) was identified in two recipients during combined heart-lung transplantation. In the first patient an interposition Gore-Tex graft was used to reconstitute the venous drainage from the aberrant left SVC to the right atrium. In the second patient a new method of reconstituting the drainage from the left SVC with the donor innominate vein is described. It is recommended that excision of the donor heart and lung should include the innominate vein, as it may be used to create a venous channel for an aberrant left SVC if present in the recipient.

Adolescent↗
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Regression of Kaposi's sarcoma after reduction of immunosuppressive therapy in a heart transplant patient.

The de novo development of Kaposi's sarcoma, confirmed by lymph node biopsy 17 months after heart transplantation in an 18-year-old patient, is described. Constitutional symptoms and axillary and inguinal lymphadenopathy were the presenting features. Surveillance for systemic involvement was negative, and the tumor seemed to be confined to the lymphoreticular system alone. Chemotherapy with vincristine and cyclophosphamide resulted in severe leukopenia and was discontinued. Immunosuppressive therapy, consisting of cyclosporine and methylprednisolone, was gradually reduced, resulting in regression of symptoms and lymphadenopathy. One year later the patient was symptom free, and only one extremely small inguinal lymph node was palpable. Microscopic examination of this node, however, revealed persistent Kaposi's sarcoma. The patient's immunosuppressed state would now appear to be sufficient to prevent acute rejection and yet insufficient to lead to growth and spread of the tumor.

Adolescent↗
PubMedDate not supplied

Xenogeneic and allogeneic canine heart transplantation: a model for cytologic and immunologic monitoring of rejection mechanisms.

In the model of heterotopic intrathoracic heart transplantation, rejections of the graft are not lethal for the recipient animal. Therefore it is possible to follow the immunologic rejection mechanism to the final stage. Allogeneic dog hearts (n = 6) and xenogeneic fox hearts (n = 6) were transplanted. Immunosuppression therapy included cyclosporine and methylprednisolone. Cytoimmunologic monitoring was done every second day. Due to fluctuations of lymphocyte subpopulations and their immature forms, endomyocardial biopsies were performed. The transplanted allogeneic hearts survived for 53.2 +/- 14.8 days if treated with cyclosporine (historical control group without immunosuppression 6.8 +/- 0.8 days). Xenogeneic fox hearts stopped beating after 20.2 +/- 4.1 days (historical control 8.4 +/- 1.9 days). The allogeneic grafts were all rejected in an acute cellular fashion, whereas xenogeneic transplanted hearts showed humoral and cellular rejection mechanisms. Monitoring of circulating inflammatory cells allowed differentiation between humoral and cellular rejection, which was confirmed by histology. Both types of rejection were accompanied by an increase of lymphocytes and their activated forms. Differentiation of lymphocyte subpopulations revealed a significant increase of surface IgG-positive B-lymphocytes under humoral rejection, whereas acute cellular rejection episodes showed a substantial increase of surface IgG-negative lymphocytes. Humoral rejection that developed even with cyclosporine administration was not influenced, whereas cellular rejections were controlled by increasing methylprednisolone to 250 mg/day for 3 days.

Animals↗
PubMedDate not supplied

Cytoimmunological monitoring in acute rejection and viral, bacterial or fungal infection following transplantation.

This study assessed the ability of immunomonitoring to differentiate between acute cardiac rejection and viral, bacterial or fungal infections, using data of thirty-five cyclosporine treated heart and heart-lung transplant recipients. Peripheral blood samples were analyzed daily for 20 days, then three times weekly until the patient's discharge. Later, peripheral blood was examined every fourteen days on an outpatient basis. White blood cells were counted and differentiated. A mononuclear concentrate was obtained by the Ficoll-Hypaque gradient and centrifugation method, and cytocentrifuged onto slides. The cells were stained by a five minute method. Percentages of lymphocytes, prelymphoblasts, lymphoblasts, large granular lymphocytes and monocytes were calculated. When activated cells were detected, aliquots of the mononuclear concentrate were labeled using monoclonal antibodies. In these thirty-five patients, more than 60 acute rejection episodes were diagnosed by the cytoimmunological method. Acute rejection was characterized by a significant rise of the number of leukocytes, lymphocytes, prelymphoblasts and lymphoblasts. The T-lymphocyte population increased while the B-cells remained normal. Ninety-five percent of all acute rejection episodes were diagnosed using cytoimmunological parameters. During viral infection more than 20% of the mononuclear cells were large granular lymphocytes and the OKT4/OKT8 ratio was less than one. During bacterial and fungal infections the B-lymphocytes increased to 40% of the mononuclear cells. In addition, juvenile polymorphs appeared in the mononuclear concentrate and the OKT4/OKT8 ratio was within normal limits (1.5 to 2.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
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Experimental studies of the anatomical and functional characteristics of kangaroo aortic valve bioprostheses.

In many tests done in vitro and in vivo on porcine aortic valve grafts, high pressure gradients were found under normal as well as under stress conditions. The transvalvular pressure difference is due to the immobility of the right aortic porcine leaflet that is fixed tightly to the muscular septum of the ventricle. Our own studies of 24 kangaroo hearts show different anatomical features: the right leaflet is practically free in this movement. Thus the maximum orifice area of the kangaroo aortic valve is reduced by only 24.2 per cent, whereas the porcine valve shows a reduction of 36.5 per cent. This difference proved to be highly significant (P less than 0.001). Therefore, in cooperation with Hancock Laboratories, kangaroo aortic valve grafts were tested as xenotransplants, using a pulse duplicator. The first results show that larger orifice areas are achieved by kangaroo valves one or two sizes smaller than their porcine counterparts.

Animals↗
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Toxoplasmosis after heart transplantation: diagnosis by endomyocardial biopsy.

Protozoal infections such as toxoplasmosis are known complications in heart transplant recipients. Diagnosis of the disease is often difficult. This article describes the course of a patient who had a febrile illness with leukocytosis and neurologic disorders after heart transplantation; all microbiologic and serologic tests of the peripheral blood and the cerebrospinal fluid failed to identify the responsible pathogen. Infection with Toxoplasma gondii was finally diagnosed by endomyocardial biopsy. We conclude that in heart transplant recipients with infections of unclear origin and neurologic disorders, endomyocardial biopsy may be helpful in the diagnosis, especially in cases of toxoplasmosis.

Biopsy↗
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One heart transplanted successfully twice.

We report the first successful reuse of a previously transplanted heart after perioperative brain death of the first recipient. The second recipient was a 66-year-old man suffering from end-stage ischemic cardiomyopathy. The intra- and postoperative course of the retransplantation was completely uneventful. At the time of writing, more than 2 years after reuse of the graft, the patient remains in New York Heart Association class I. This procedure, which proved to be possible under certain optimal conditions, should be considered in the case of brain death of a graft recipient, particularly with regard to the ongoing donor shortage.

Adult↗
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How successful is OKT3 rescue therapy for steroid-resistant acute rejection episodes after heart transplantation?

OKT3 is recommended as rescue therapy for cases of steroid-resistant, clinically persistant acute rejection episodes after heart transplantation. In this study we determined the efficacy of such treatment. One hundred thirty-two patients were included in this study. The postoperative immunosuppressive regimen consisted of triple-drug therapy and perioperative antithymocyte globulin. During a follow-up of 10 to 108 weeks (mean, 51 +/- 20 weeks) 281 treatment-requiring acute rejection episodes (International Society for Heart and Lung Transplantation > or = II) were observed. In 29 cases (10.3%) the grade of the acute rejection episodes was either unchanged after two series of intravenous steroid pulse therapy, was worsened after the first steroid course, or the patient experienced clinical deterioration as a result of the acute rejection episodes. These patients were considered to have steroid-resistant acute rejection episodes and received a 10-day rescue therapy with OKT3, followed by control endomyocardial biopsy. In 17 cases, control endomyocardial biopsy revealed normal myocardium (group I). In 10 cases acute rejection episodes remained unchanged (group II); twice a deterioration was found (group III). However, 12 of the 17 patients from group I experienced a rebound of the acute rejection episodes (International Society for Heart and Lung Transplantation > or = II) 1 to 3 weeks later. Side effects of OKT3 treatment were fever, chills, intestinal complications, hemodynamic response, convulsions, and viral infections.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗