Florian Wagner

Report from a consensus conference on primary graft dysfunction after cardiac transplantation

Although primary graft dysfunction (PGD) is fairly common early after cardiac transplant, standardized schemes for diagnosis and treatment remain contentious. Most major cardiac transplant centers use different definitions and parameters of cardiac function. Thus, there is difficulty comparing published reports and no agreed protocol for management. A consensus conference was organized to better define, diagnose, and manage PGD. There were 71 participants (transplant cardiologists, surgeons, immunologists and pathologists), with vast clinical and published experience in PGD, representing 42 heart transplant centers worldwide. State-of-the-art PGD presentations occurred with subsequent breakout sessions planned in an attempt to reach consensus on various issues. Graft dysfunction will be classified into primary graft dysfunction (PGD) or secondary graft dysfunction where there is a discernible cause such as hyperacute rejection, pulmonary hypertension, or surgical complications. PGD must be diagnosed within 24 hours of completion of surgery. PGD is divided into PGD-left ventricle and PGD-right ventricle. PGD-left ventricle is categorized into mild, moderate, or severe grades depending on the level of cardiac function and the extent of inotrope and mechanical support required. Agreed risk factors for PGD include donor, recipient, and surgical procedural factors. Recommended management involves minimization of risk factors, gradual increase of inotropes, and use of mechanical circulatory support as needed. Retransplantation may be indicated if risk factors are minimal. With a standardized definition of PGD, there will be more consistent recognition of this phenomenon and treatment modalities will be more comparable. This should lead to better understanding of PGD and prevention/minimization of its adverse outcomes.

Mycophenolate and sirolimus as calcineurin inhibitor-free immunosuppression improves renal function better than calcineurin inhibitor-reduction in late cardiac transplant recipients with chronic renal failure.

Background. Calcineurin-inhibitor-(CNI)-induced renal failure is one major cause of morbidity in cardiac transplantation (HTx). In this prospective, randomized, multicenter trial, the impact of immunosuppressive conversion toward CNI-free (mycophenolate mofetil [MMF] and sirolimus) or a CNI-reduced immunosuppressive regimen on renal function, efficacy, and safety was evaluated. Methods. Since 2004, 63 HTx-patients (0.5–18.4 years after HTx) with CNI-based immunosuppression and reduced creatinine clearance less than 60 mL/min (39±15 mL/min) were included in this trial. Patients in the CNI-free-Group (group 1) were converted to sirolimus that was started with 2 mg/day until target trough levels (8–14 ng/mL) were achieved. Subsequently, CNIs were withdrawn. In CNI-reduction-Group (group 2), CNI target trough levels were reduced by 40%. In both groups MMF was continued and trough level adjusted (1.5–4 &mgr;g/mL). Results. Patients demographics and survival (mean follow-up time: 16.7±9 months) was equal (100%). Renal function improved significantly after complete CNI withdrawal while remaining unchanged with CNI-reduction (Creatinine clearance after 12 months: 53±24 mg/dL [group 1] vs. 38±20 mg/dL [group 2], P=0.01). End-stage renal failure (hemodialysis) was avoided by CNI-withdrawal and occurred only after CNI reduction (n=6; P=0.01). Acute rejection episodes were more common in group 2 (4 vs. 2). Graft function remained stable (echocardiography) within both groups. Adverse events were more common in group 1 (65%) than in group 2 (n=40%) and were responsible for discontinuation in 4 and 0 cases, respectively. Conclusions. Conversion toward a CNI-free immunosuppression (Mycophenolate, sirolimus) is superior to CNI-reduced immunosuppression in improving renal failure in late HTx-recipients. However, this benefit is relativized by the increased incidence and severity of sirolimus/MMF-associated side effects.

Interpenetrating Al2O3-TiAl3 alloys produced by reactive infiltration

Dense alumina-TiAl 3 composites with interpenetrating networks have been fabricated by reactive gas-pressure infiltration and squeeze casting of Al into sintered porous preforms containing 30 vol% TiO 2 and 70 vol% Al 2 O 3 . Strength of up to 543±21 M Pa with corresponding fracture toughness of 8.6±0.4 M Pa√m and hardness of H V10 = 565±27 have been obtained. The present paper discusses processing parameters such as particle size of oxide precursor and preform porosity which control microstructural development and mechanical properties of the composites.

Concomitant implantation of Impella® on top of veno‐arterial extracorporeal membrane oxygenation may improve survival of patients with cardiogenic shock

Veno‐arterial extracorporeal membrane oxygenation (VA‐ECMO) support stabilizes patients with cardiogenic shock. Despite improved oxygenation and peripheral circulation, LV unloading may be impeded due to the increased afterload, resulting in a failing static left ventricle and in high mortality.

Effects of Donor Pre-Treatment With Dopamine on Survival After Heart Transplantation A Cohort Study of Heart Transplant Recipients Nested in a Randomized Controlled Multicenter Trial

OBJECTIVES We determined the outcome of cardiac allografts from multiorgan donors enrolled in a randomized trial of donor pre-treatment with dopamine. BACKGROUND Treatment of the brain-dead donor with low-dose dopamine improves immediate graft function after kidney transplantation. METHODS A cohort study of 93 heart transplants from 21 European centers was undertaken between March 2004 and August 2007. We assessed post-transplant left ventricular function (LVF), requirement of a left ventricular assist device (LVAD) or biventricular assist device (BVAD), need for hemofiltration, acute rejection, and survival of recipients of a dopamine-treated versus untreated graft. RESULTS Donor dopamine was associated with improved survival 3 years after transplantation (87.0% vs. 67.8%, p = 0.03). Fewer recipients of a pre-treated graft required hemofiltration after transplant (21.7% vs. 40.4%, p = 0.05). Impaired LVF (15.2% vs. 21.3%, p = 0.59), requirement of a LVAD (4.4% vs. 10.6%, p = 0.44), and biopsy-proven acute rejection (19.6% vs. 14.9%, p = 0.59) were not statistically different between groups. Post-transplant impaired LVF (hazard ratio [HR]: 4.95; 95% confidence interval [CI]: 2.08 to 11.79; p < 0.001), requirement of LVAD (HR: 6.65; 95% CI: 2.40 to 18.45; p < 0.001), and hemofiltration (HR: 2.83; 95% CI: 1.20 to 6.69; p = 0.02) were predictive of death. The survival benefit remained (HR: 0.33; 95% CI: 0.12 to 0.89; p = 0.03) after adjustment for various risks affecting mortality, including pre-transplant LVAD/BVAD, inotropic support, and impaired kidney function. CONCLUSIONS Treatment of brain-dead donors with dopamine of 4 μg/kg/min will not harm cardiac allografts but appears to improve the clinical course of the heart allograft recipient. (Prospective Randomized Trial to Evaluate the Efficacy of Donor Preconditioning With Dopamine on Initial Graft Function After Kidney Transplantation; NCT00115115).

Protection against acute porcine lung ischemia/reperfusion injury by systemic preconditioning via hind limb ischemia

Previous work on various organs and tissues has shown that ischemic preconditioning protects against reperfusion injury in these organs and also against secondary effects in the lung. In contrast, the purpose of this study was to investigate the effects of preconditioning in a remote organ (hind limb ischemia) on an ischemia/reperfusion (I/R) treatment of the lung itself. A porcine model of in situ left lung ischemia (90 min) and reperfusion (5 h) was used. Systemic preconditioning was induced by clamping the left common femoral artery (3 × 5 min). Lung injury was assessed in terms of pulmonary vascular resistance, pulmonary artery pressure, pulmonary venous and arterial pO2, and tissue macrophage counts. The zymosan‐stimulated release of reactive oxygen species (ROS) in whole blood was determined by a chemiluminometric procedure. Inflammatory cytokines (interleukin‐1β and interleukin‐6) were measured in arterial plasma as indicators of a systemic inflammatory reaction. Preconditioning by hind limb ischemia completely prevented the I/R‐induced functional impairment of the lung, the pulmonary hypertension and the reduced oxygenation capacity. The plasma levels of interleukin‐1β and the macrophage counts in preconditioned animals were reduced to control values, whereas the levels of interleukin‐6 and the release of ROS were not affected by preconditioning. In conclusion, systemic preconditioning by repeated hind limb ischemia protects against acute I/R injury of the lung but not against all indices of reperfusion‐associated systemic inflammation.

A novel charcoal-induced model of obliterative bronchiolitis–like lesions: Implications of chronic nonspecific airway inflammation in the development of posttransplantation obliterative bronchiolitis

OBJECTIVES In this study, we describe the development of a nonallogeneic animal model of obliterative bronchiolitis-like lesions. Furthermore, we examined whether chronic rejection alone can lead to the development of obliterative bronchiolitis or whether additional nonspecific airway inflammation is required. METHODS Part I: Rats were intratracheally injected with 0.2 ml of activated charcoal or sorbitol solution (carrier for charcoal control). Animals were put to death beginning at 2 weeks up to 20 weeks. Part II: Animals were divided into three groups: group I, underimmunosuppressed Brown Norway to Lewis lung allografts; group II, charcoal-treated underimmunosuppressed allografts; and group III, charcoal-treated rats. Animals were put to death at 3 months after transplantation. RESULTS Part I: In charcoal-laden bronchioles, subacute nonspecific airway inflammation was detected at 2 weeks. Slow, subclinical fibroproliferation ensued during the following weeks. Obliterative bronchiolitis-like lesions were observed in 80% of charcoal-treated animals at 12 weeks. Part II: Allografts developed extensive vascular lesions consistent with acute and chronic vascular rejection. Obliterative bronchiolitis-like lesions were scarcely detected. Charcoal-treated allografts demonstrated evidence of diffuse and severe obliterative bronchiolitis-like lesions. CONCLUSIONS Transtracheal injection of activated charcoal into native lungs results in slowly progressive airway injury and inflammation leading to obliterative airway lesions. Inadequate immunosuppression primarily results in chronic vascular rejection but not obliterative bronchiolitis. Underimmunosuppressed allografts subjected to nonspecific airway inflammation develop obliterative airway lesions that are more prominent than in native lungs. This suggests that a cofactor to chronic rejection is likely necessary for the development of lung transplant obliterative bronchiolitis.

Immunohistochemical characterization of inflammatory and proliferative events during chronic rejection in rat lung allografts.

BACKGROUND Chronic rejection is assumed to be the principle cause of airway injury leading to obliterative bronchiolitis (OB) after lung transplantation (Tx). To better understand the contribution of chronic rejection in the development of OB in allografted lungs, we examined the histopathological changes and cytokine expression in inadequately immunosuppressed rat lung allografts. METHODS Three groups of rats were studied: group I, control nontransplanted Lewis (Lew) rats (n=5); group II, syngeneic Lew-to-Lew isografts (n=25); and group III, Brown Norway-to-Lew allografts (n=25). Groups II and III received two single doses of cyclosporine on postoperative days 2-3. Transplanted animals were killed (n=5) at monthly intervals from 2 months to 6 months after Tx. Resected lungs were stained with hematoxylin and eosin, Massons trichrome, and Van Giesons elastin, and immunostained with antisera to interleukin (IL)-1beta, IL-8, and basic fibroblast growth factor (bFGF). The intensity of immunostaining was graded from 0 to 4 (0=no staining, 4=strong staining). RESULTS In groups I and II, normal airways and vessels were observed. Minimal intensity and distribution of immunostaining for all markers were detected in groups I and II. Group III allografts demonstrated acute grade II-III vascular rejection with mild bronchiolar injury and inflammation at 2 months after Tx. At 6 months after Tx, all allografts demonstrated severe and diffuse chronic vascular rejection. Late airway changes consistent with OB were detected in four of five allografts, however, these lesions were expressed infrequently. Immunohistochemical findings revealed moderate to strong expression for IL-8 and bFGF over the airway epithelium, acute and chronic inflammatory cells, and fibroblasts in allografts at 2 months after Tx. Despite focal development of OB at 6 months, intensity and distribution of immunostaining significantly decreased for all three cytokine markers. CONCLUSIONS Inadequate immunosuppression of rat lung allografts leads primarily to chronic vascular rejection but fails to induce severe and diffuse development of OB. In this animal model, cytokines IL-1beta, IL-8, and bFGF are likely to play an important role in the early inflammatory phase but not during the late proliferative events of chronic rejection.

Growth-differentiation factor-15 improves reclassification for the diagnosis of heart failure with normal ejection fraction in morbid obesity

This study aimed to examine the incremental value of growth‐differentiation factor‐15 (GDF‐15) to N‐terminal pro brain natriuretic hormone (NT‐proBNP) levels for the diagnosis of left ventricular diastolic dysfunction (LVDD) and possible heart failure (HF) in morbidly obese patients.

Prevention of initial perfusion failure during xenogeneic ex vivo liver perfusion by selectin inhibition.

BACKGROUND Endothelial cell activation triggered by xenoreactive antibodies and complement products is the main feature of discordant xenograft rejection. The contribution of early cell-mediated mechanisms to this rejection process is poorly understood, and the function of adhesion molecules in xenogeneic cell interactions in vivo is unclear. The aim of the study was to investigate the role of selectins in mediating cell-dependent initial perfusion failure and functional restrictions in xenoperfused guinea pig (GP) livers. METHODS Isolated GP livers were hemoperfused in a flow-constant, recirculating perfusion system via the portal vein. Microhemodynamic parameters such as sinusoidal perfusion rate and leukocyte flux were analyzed using intravital fluorescence microscopy. Hepatic oxygen consumption and bile production, as well as liver enzymes, potassium level, and numbers of white blood cells and platelets in the perfusate, were determined. The GP livers were perfused either with GP blood (control perfusion), with unmodified rat blood (xenoperfusion), or with rat blood treated with the selectin-blocking polysaccharide Fucoidin. RESULTS A significant sinusoidal perfusion failure was observed in the xenoperfusion group, which was accompanied by distinct signs of a functional restriction-like reduced oxygen consumption, bile production, and increased perfusion pressure. However, there were significantly fewer impairments in the Fucoidin group. Furthermore, fewer platelets were trapped and a smaller number of stagnant leukocytes were observed in this group. CONCLUSION Fucoidin did not suppress complement activation during xenoperfusion. Considering that Fucoidin inhibits the selectin-dependent interactions among white blood cells, platelets, and sulfate-containing proteoglycans on the surface of vascular endothelium, these findings suggest an important role for early cellular interactions in the development of organ failure during xenogeneic rejection.