Oxygen-derived free radical scavengers for amelioration of reperfusion damage in heart transplantation.

In this study we tried to define the possible benefits of the oxygen-derived free radical scavengers after 3 hours of cold myocardial global ischemia, as required in the setting of cardiac transplantation. Twenty-one pig hearts were harvested after preservation with a cold cardioplegic solution (St. Thomas' Hospital solution) and topical cooling. Normothermic reperfusion with blood was achieved with a special heart-lung machine preparation, which allows the heart to beat in a working or nonworking mode. Twelve hearts served as control hearts (group I), and nine (group II) were subjected to superoxide dismutase and catalase. Superoxide dismutase was applied at a dose of 40 U/ml of cardioplegic solution and 1500 U/kg body weight with the start of reperfusion. Catalase was added to the cardioplegic solution in a dose of 100 U/kg and 3500 U/kg body weight with the start of reperfusion. After 15 minutes of retrograde reperfusion, both left ventricular developed pressure and its first derivative were significantly higher in group II (137 +/- 7.6 mm Hg, 2467 +/- 162 mm Hg/sec) than in group I (105 +/- 6 mm Hg, 1676 +/- 231 mm Hg/sec, p less than 0.05 for each). In addition, a considerably higher coronary blood flow was observed in group II throughout the 180-minute period of reperfusion (p = 0.047). We therefore conclude that the combined administration of superoxide dismutase and catalase during the initial period of cardioplegic arrest and during early reperfusion of donor hearts submitted to 3 hours of cold ischemia has a beneficial effect on myocardial performance.

Lung growth after experimental pulmonary transplantation.

Replacement of the heart and both lungs or single lung transplantation has been performed in a few cases of terminal (cardio) pulmonary disease in childhood. It remains unclear whether pulmonary allografts will meet the demands of a growing organism. Six domestic pigs (mean body weight, 24 kg) underwent left lung transplantation from donors of equal weight. Immunosuppression consisted of cyclosporine, azathioprine, and corticosteroids. After the pigs doubled their body weight, growth of the lung was assessed by bronchography and pulmonary angiography. In transplant animals it took 11 weeks (normal animals, 6 weeks) for their weight to double. At that time, the bronchial tree showed similar growth when compared with nontransplant animals of equal weight. The diameter of the left lower lobe bronchus (9.2 +/- 0.4 mm) was significantly greater than that of animals of 24 kg body weight (7.5 +/- 0.3 mm; p less than 0.01) but comparable to that of normal pigs of similar weight (9.0 +/- 0.5 mm). The same applied for length of the left lower lobe bronchus (transplants, 95 +/- 6.7 mm; controls 24 kg, 67 +/- 2 mm [p less than 0.01]; controls 48 kg, 93 +/- 3 mm). Similar growth tendencies were observed in the pulmonary vascular tree. The diameter of the left lower lobe artery was 9.4 +/- 98 mm in 48 kg transplant pigs, compared with 9.7 +/- 1.2 mm in 24 kg control pigs and 8.5 +/- 0.8 mm in 48 kg control pigs. In one case of recurrent severe pulmonary rejection, the lung did not grow. We conclude from this study that growth is retarded by immunosuppression.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement of currently used methods for lung preservation with prostacyclin and University of Wisconsin solution.

After 6 hours of cold ischemia the quality of lung preservation was assessed in a canine heart-lung transplant model comparing three clinically used methods for lung preservation: donor core cooling by means of extracorporeal circulation (group I); pulmonary artery flush perfusion with either Euro-Collins solution after prostacyclin application (group II); or University of Wisconsin solution after donor pretreatment with prostacyclin (group III). In all cases St. Thomas Hospital solution was used for myocardial protection. Heterotopic heart and orthotopic left lung allotransplantation was performed in three groups of six mongrel dogs each according to the method of lung preservation. After transplantation cardiorespiratory function was assessed at FiO2 of 0.4 for a maximum of 12 hours. After surgery, significantly improved oxygenation of the donor lung was observed in groups II and III, compared to group I (p less than 0.01). Between groups II and III, no significant differences were found in the oxygenation during the first 5 hours, but in the later postoperative course pO2 values decreased in group II although they remained stable on a higher level during the entire postoperative course in group III (p less than 0.05). University of Wisconsin solution for lung preservation in combination with prostacyclin donor pretreatment provides superior postoperative oxygenation of the transplanted lung compared to currently used clinical standards represented by donor core cooling and Euro-Collins flush perfusion.

Donor heart-related variables and early mortality after heart transplantation.

Impaired donor heart function after heart transplantation results in the necessity for prolonged catecholamine and ventilatory support of the patient. Subsequently the risk of multiorgan impairment, infection, and rejection will be increased. In this retrospective analysis we tried to identify donor-related risk factors in patients who died early after transplantation. Of 174 patients undergoing heart transplantation from October 1985 through October 1988, 22 (12.6%) died early. Of the total, 39 cases were evaluated retrospectively for donor-related logistic and metabolic factors. All donors were analyzed with respect to the early mortality for age, weight, height, maximum dopamine concentration, thyroid hormone levels, and the duration from brain death until explantation and ischemia. Thirty patients were survivors (group A); nine patients died early (group B). By multiple regression analysis a significant influence (group A vs group B) of donor age, dopamine support, and ischemic time on early mortality could be demonstrated, whereas donor weight and height, hormone levels of triiodothyronine and thyroxine, and duration of brain death showed no correlation. From this limited experience we conclude that use of hearts from older donors with higher catecholamine support and longer ischemic times will result in an increased early mortality. In contrast, no influence of prolonged brain death times and metabolic factors could be demonstrated.

Heterotopic heart-unilateral left lung transplantation in dogs.

A technique is presented for transplantation of the heart and left lung in the canine model. Preservation of the recipient's heart and right lung allowed heterotopic en bloc transplantation of the donor organs, thus preserving the normal respiratory pattern and obviating the need for cardiopulmonary bypass. Four experiments were performed to develop the surgical technique. The mean survival of the remaining 10 dogs studied was 23 +/- 28 days (range 3 to 91 days). The transplanted heart and lung could be investigated as in orthotopic heart-lung transplantation; bronchoscopy with bronchoalveolar lavage and endobrachial biopsy as well as endomyocardial biopsy were performed by standard approaches. This model is suitable for physiological and immunological long-term observations of cardiopulmonary transplantation in dogs.

University of Wisconsin versus modified Euro-Collins solution for lung preservation.

In a canine model, the quality of lung preservation was assessed using pulmonary artery flush after prostacyclin administration with either modified Euro-Collins solution or University of Wisconsin solution. Twelve combined heterotopic heart and orthotopic left lung allotransplantations were performed after 6 hours of cold ischemia. Myocardial preservation was achieved using St. Thomas Hospital solution. Donor organs were anastomosed parallel to the recipient's heart and right lung, and the superior vena cava inflow was directed into the transplanted heart-left lung block after ligation of the recipient's superior vena cava proximal to the caval anastomosis. Postoperatively, cardiorespiratory function was evaluated separately for donor and recipient organs at an inspired oxygen fraction of 0.4 for a maximum of 12 hours. Significantly improved oxygenation and lower pulmonary vascular resistance index of the donor lung was observed in the University of Wisconsin + prostacyclin group, whereas pulmonary artery pressures showed no significant differences in between both groups. It is concluded that superior results in lung preservation can be achieved with pulmonary artery flush perfusion using University of Wisconsin solution and prostacyclin when compared with Euro-Collins solution and prostacyclin.

Pulmonary reperfusion injury: evidence for oxygen-derived free radical mediated damage and effects of different free radical scavengers.

Blood granulocyte-mediated reactions involving generation of oxygen-derived free radicals have recently been shown to be capable of causing injury to the lungs. These findings suggest a similar mechanism also to be involved in the development of pulmonary ischemia/reperfusion injury. In the present study, therefore, the effects of three oxygen-derived free radical scavengers, superoxide dismutase (SOD; 1 mg/kg), catalase (20,000 IU/kg) and allopurinol (45 mg/kg), were evaluated during reperfusion in a rabbit model after 2 h normothermic ischemia of the lung. During reperfusion, ischemic lungs were found to have an elevated pulmonary vascular resistance, increased total and extravascular lung water content, and decreased arterial oxygen tension (PaO2) compared to control animals. SOD and catalase, but not allopurinol, were able to reduce pulmonary injury by lowering the pulmonary vascular resistance, but could not prevent pulmonary damage as shown by total lung water (TLW) or PaO2. It is concluded that oxygen-derived free radicals such as hydrogen peroxide and the superoxide anion may play an important role in precipitating pulmonary injury after ischemia. The failure of xanthine oxidase inhibition (allopurinol) to exert protective effects may suggest that oxygen-derived free radical generation following pulmonary ischemia occurs predominantly via leukocyte-mediated reactions.

Left ventricular function, tricuspid incompetence, and incidence of coronary artery disease late after orthotopic heart transplantation.

Functional results and data concerning the incidence and severity of graft atherosclerosis (GASC) and tricuspid incompetence (TI) in the intermediate term after orthotopic heart transplantation (HTX) are still striking. We examined 92 patients 1, 2, and 3 years after HTX by right and left heart catheterization in order to evaluate pump function, the status of the coronary arteries and the extend of TI, using a double indicator thermodilation technique. Mean left ventricular volumes and ejection fraction were normal 1 and 2 years post-transplant. The incidence of GASC was 8/87 (9.2%) at 1, and 11/92 (12%) at 2 years. It was more frequent (16%) in patients with preexisting coronary artery disease (IHD) than in patients with underlying dilative cardiomyopathy (DCM) (11%). At the end of the 1st postoperative year, 62% of patients were free of TI, whereas only 38% had normal valve function 2 years posttransplant. In 9/14 (64%) of patients, consecutively assessed at 1 and 2 years, TI had increased between both investigations. Preoperative haemodynamics, the number of endomyocardial biopsies and rejection episodes as well as preoperative cardiac size did not correlate with TI. Left ventricular volumes and ejection fraction are normal in the intermediate term after HTX. The incidence of GASC was less than 10% at 1 year and did not significantly increase thereafter. TI is a frequent and yet unexplained finding after HTX showing a considerable tendency to increase with time, but with little or not haemodynamic consequence.

Growth of lung allografts after experimental transplantation.

Heart and lung transplantation has been performed in cases of end-stage cardiopulmonary disease in infants. Nevertheless, it still remains unclear whether lung allografts adjust to a growing organism. In 6 young domestic pigs unilateral left lung allotransplantation was performed. Immunosuppression consisted of a triple drug therapy including cyclosporine, azathioprine, and corticosteroids. Lung growth was studied by using bronchography, pulmonary angiography, and lung histology. After 11 weeks the transplanted animals had doubled their body weight from 24 kg to 48 kg. Non-transplanted animals in contrast doubled their weight within only 6 weeks. The growth retardation was attributed to the immunosuppressive therapy. The bronchial tree and pulmonary vasculature of lung allografts showed a similar growth potential to non-transplanted lungs in animals of equivalent body weight. In one case of recurrent severe rejection of the lung no growth was observed. Therefore it was concluded that lung allografts grow adequately according to the development of the recipient organism. Lung transplantation in children does not seem to be restricted by a limited growth potential of the graft.

Oxygen free radical scavengers to prevent pulmonary reperfusion injury after heart-lung transplantation.

Oxygen free radical scavengers, such as superoxide dismutase (SOD) and catalase (CAT), have been shown to reduce effectively myocardial reperfusion injury. No such data have been reported for cold global pulmonary ischemia, which is required in heart-lung transplantation. Heterotopic heart-left lung allotransplantation was performed in 18 dogs after single-flush perfusion of the lungs with Euro-Collins solution (60 ml/kg), cardioplegic arrest, and 6 hours of cold global ischemia. Six dogs served as controls. In six other dogs prostacyclin (PGI2) was administered both into the pulmonary artery (20 ng/kg/min) and to the Euro-Collins solution (15 mg/L) before explantation (group A). Grafts in six other dogs were preserved with Euro-Collins solution plus SOD (40,000 U/L) and CAT (100,000 U/L)(group B). In addition, SOD (1 mg/kg) and CAT (1.5 mg/kg) were given intravenously during the first 20 minutes of reperfusion. There was no significant difference in cardiac output, right and left atrial pressures, nor pulmonary arteriolar resistance among the groups. In contrast, left atrial oxygen pressure (PO2) values were best in group B. At all times, PO2 values in animals in groups A and B exceeded those in control animals. Compared with control animals with Euro-Collins solution preservation alone, animals with both PGI2 and SOD/CAT preservation had significantly improved pulmonary function after heart-lung transplantation. Better oxygenation in the SOD/CAT group (group B) suggests an important impact of oxygen free radicals during reperfusion.

Antagonisation of platelet activating factor--a new therapeutic concept for improvement of organ quality in lung preservation.

The release of platelet activating factor (PAF) is thought to be one of the most important pathophysiological pathways in the development of ischemic lung injury. We investigated the use of a PAF antagonist (PAF-a) in a canine model in reducing PAF-mediated pulmonary dysfunction following lung preservation and transplantation. Twelve combined heterotopic heart and orthotopic left lung allotransplantations were performed after 6 h of cold ischemia. Following administration of prostacyclin (PGI2), Euro-Collins solution (EC) was used for pulmonary artery flush in all donors, while in six animals the PAF-a, WEB 2170 BS, was administered to the donor (0.15 mg/kg for 30 min), to the storage solution (0.3 mg/kg) and to the recipient during reperfusion for a total of 6 h (0.3 mg/kg per h) EC/PAF-a). In all donors myocardial preservation was achieved using St. Thomas Hospital solution. Postoperatively, cardiorespiratory function was evaluated separately for donor and recipient organs at an FiO2 of 0.4 for a maximum of 12 h. The quality of lung preservation was assessed by means of postoperative oxygenation (pO2), pulmonary artery pressure (PAP) and pulmonary vascular resistance index (PVRI). In the EC/PAF-a group, pO2 of the donor lung was significantly elevated (P < 0.01) and PVRI was significantly lower (P < 0.05) when compared to the EC group, while PAP showed no significant differences between both groups and throughout the entire postoperative course. We concluded that a significant improvement in the current clinical standard for lung preservation could be obtained by the application of WEB 2170 BS in combination with EC flush as demonstrated by improved oxygenation and lower PVRI of the transplantated organs.

Comparison of mononuclear cell subpopulations in bronchoalveolar lavage fluid in acute rejection after lung transplantation and Mycoplasma infection in rats.

Acute lung rejection after orthotopic left lung transplantation and Mycoplasma pulmonis infection were studied immunohistologically by bronchoalveolar lavage (BAL) in inbred rats using monoclonal antibodies differentiating lymphocyte and macrophage subpopulations. Twenty transplants in a major histocompatibility complex (MHC)-different strain combination (Brown-Norway/Lewis) were examined 2, 4, and 6 days after transplantation. Thirty isotransplants (Lewis/Lewis) and normal Lewis rats were used as controls. Eight Lewis rats with acute Mycoplasma pulmonis infection and six Lewis rats with chronic Mycoplasma infection also underwent BAL. Mononuclear cell subpopulations were analyzed using a panel of monoclonal antibodies to MHC and macrophage differentiation antigens: ED1 monocyte/macrophages, ED2 inflammatory tissue macrophages, OX19 T lymphocytes, and OX12 B lymphocytes. The following results were obtained: (1) All allotransplants developed acute rejection on day 2, and it advanced until day 6, demonstrating severe perivascular and peribronchiolar infiltration of inflammatory tissue macrophages (ED1+/ED2+): (2) the proportion and number of inflammatory macrophages (ED2+) in BAL fluid increased on day 6; (3) in BAL the proportion and number of T lymphocytes (OX19+) increased more prominently than B lymphocytes (OX12+) on day 6 of acute rejection; (4) in infection with Mycoplasma pulmonis the increase of T lymphocytes (OX19+) in BAL was more prominent than that of B lymphocytes (OX12+). In conclusion, serial analysis of macrophage, T- and B-lymphocyte antigens was performed. The increase of the proportion of inflammatory macrophages (ED2+) and lymphocytes (OX19+, OX12+) in BAL fluid occurred rather late in the rejection response. This limits the use of BAL as an early diagnostic method of allografted lung rejection.(ABSTRACT TRUNCATED AT 250 WORDS)