New trends in combined transplantation of the heart and lungs

Heart-lung transplantation is a surgical alternative for patients with end-stage lung disease with associated right heart failure. While the procedure is very promising, the morbidity and mortality remain high. The current understanding of the proper selection of candidates, procurement and preservation of donor organs, operative procedure and postoperative care continues to evolve. At the University of Pittsburgh, 70 heart-lung transplantations have been performed since 1982. Early infection and chronic rejection are the major factors influencing survival. Early (less than 2 weeks) intrathoracic infection occurred in 43% of heart-lung transplant recipients, with pneumonia being the most frequent infection. The incidence of pneumonia in heart-lung transplant recipients is twice that in a comparable group of heart recipients. Subclinical pneumonitis in the donor lung, abnormal muco-ciliary clearance and altered allogenic response in the transplanted lung are significant factors associated with the increased incidence of early infections. Chronic rejection, manifested as bronchiolitis obliterans, has occurred in 54% of heart-lung transplantation recipients. Infection caused by cytomegalovirus, Epstein-Barr virus and Pneumocystis carinii have been shown to increase the incidence of bronchiolitis obliterans, as have episodes of acute rejection. Recent reports of a 61% 2-year survival rate represent a substantial improvement over earlier trials. With a better understanding of the pathogenesis of infection in the transplanted lung as well as improved immunosuppressive agents, further improvements in survival can be expected.     

Obliterative bronchiolitis after lung transplantation

Despite marked improvements in early survival, long-term outcome after lung transplantation is still threatened by obliterative bronchiolitis (OB). Thought to be a manifestation of chronic allograft rejection, OB affects up to 65% of patients at 5 years after surgery and produces a relentless airflow obstruction. Early and late acute rejection are the primary risk factors for OB, but cytomegalovirus infection and airway ischemia may also play a role. In most patients, OB responds poorly to augmented immunosuppression and eventually leads to infectious complications and terminal respiratory failure. Because early diagnosis is associated with better prognosis, every effort should be made to detect OB in a preclinical stage. This may be best achieved by combining several techniques, such as surveillance transbronchial biopsy and bronchoalveolar lavage, measurements of ventilation distribution and exhaled nitric oxide, and expiratory computed tomography.     

Bronchiolitis obliterans syndrome complicating lung or heart-lung transplantation

Lung transplantation is a therapeutic option for patients with end stage lung diseases, but long-term survival remains poor, primarily due to chronic allograft rejection. Bronchiolitis obliterans (BO), a fibrotic process resulting in progressive narrowing of bronchiolar lumens and airflow obstruction, is a manifestation of chronic allograft rejection. The term obliterative bronchiolitis ( OB) is synonymous. Once bronchiolitis obliterans syndrome (BOS) develops, progressive decline in pulmonary function is typical; most patients die of respiratory failure within 5 years of onset. The diagnosis of BOS is usually made by clinical, physiological, and radiographic parameters. The dominant risk factor for BOS is acute allograft rejection, but additional factors play contributory roles [e.g., infections; human leukocyte antigen (HLA) mismatching; and injury to the allograft or airways]. The pathogenesis of BOS is complex and involves myriad cell types (both immune and nonimmune) and release of diverse cytokines and chemokines. Unfortunately, current therapies for BOS are of unproven value. A greater understanding of the pathogenic mechanisms operative in BOS are critical to developing novel strategies to treat and prevent this devastating complication.     

Immune mechanisms of lung allograft rejection

Extended survival after lung transplantation is primarily limited by progressive airflow obstruction and fibrotic obliteration of the small airways, termed bronchiolitis obliterans syndrome (BOS) and bronchiolitis obliterans (BO), respectively. BO is thought to represent the pulmonary-specific manifestation of chronic allograft rejection and the end result of a spectrum of different immunological insults to the allograft. Historically, research has focused on the adaptive immune system and its cellular-based rejection as the driving factor in the development of BO. Recent research in animal lung transplant models and human lung transplant recipients has identified that chemokines, humoral immunity, autoimmunity, and innate immunity also contribute to lung allograft rejection and BO. This review explores the complex immunological mechanisms that promote the high rate of pulmonary allograft failure and significantly impair survival after lung transplantation. We also identify areas for further research critical to improving transplant outcomes.     

Heart-lung transplantation: an overview

Heart-lung transplantation is in a state of evolution, but for selected patients with end-stage cardiopulmonary and pulmonary disease, it can offer long-term rehabilitation. In the 8 years since heart-lung transplantation was begun at Stanford, much experience has accrued and significant improvements have been made. Advances that have made heart-lung transplantation feasible include better immunosuppression, particularly the triple-drug protocol of cyclosporine, azathioprine, and corticosteroids which decreases the incidence of obliterative bronchiolitis. Techniques of improved lung preservation have made distal donor procurement a reality, and increasing numbers of lung and heart-lung transplantations are now being performed. More importantly, better recipient and donor selection has occurred such that the perioperative mortality has been reduced from 35 to 16 per cent. Currently, the major threat facing survivors of heart-lung transplantation is the insidious development of restrictive airway disease. Our impression is that the development of obliterative bronchiolitis results from repeated rejection episodes or possibly an injury mechanism following severe viral pneumonia. The common pathway seems to be repeated injury and repair mechanism, with the end-stage being obliterative bronchiolitis by scar formation. As suggested, the injury mechanism is probably that of repeated or chronic rejection. To further support the hypothesis of an immunerelated etiology, obliterative bronchiolitis has occurred in recipients of bone marrow transplants if they develop graft-versus-host disease. In an attempt to ameliorate the effects of rejection on airway function, we have increased our maintenance immunosuppression by adding azathioprine. Consequently, patients with early obliterative bronchiolitis on enhanced immunosuppression have had stabilization of the airway disease, and we have noted a significant reduction in the occurrence of obliterative bronchiolitis from 62 per cent in Group 1 patients to 20 per cent in Group 2 patients. Since obliterative bronchiolitis may be reversed by early recognition and treatment of rejection, we have aggressively used bronchoscopy with transbronchial lung biopsy and bronchoalveolar lavage for surveillance of both rejection and infection in our recent patients. Open lung biopsy has not been used since 1986 to diagnose rejection, and we are encouraged that bronchoscopic surveillance is sensitive and effective. The primary goal of the bronchoscopic evaluation protocol was to monitor the patients closely and to treat both rejection and infection early and effectively. Concurrently, we are also measuring pulmonary function parameters, which includes FEV1, FEF 25-75, PaO2, total lung capacities, and profusion gradients. The desired outcome was the maintenance of normal airway dynamics by reversing airway disease at a reversible stage.(ABSTRACT TRUNCATED AT 400 WORDS)     

Late pulmonary haemodynamic changes in heart-lung transplantation.

As survival improves following heart-lung transplantation (HLT) the importance of obliterative bronchiolitis (OB) as a cause of late death increases. Whilst coronary occlusive disease (COD) may be less common in heart-lung transplant recipients than in patients receiving heart transplants, COD associated with OB can be lethal. We have studied 22 long-term survivors of heart-lung transplantation at an average of 25 months following transplantation during rest and at 50 W supine exercise and with prostacyclin induced vasodilation. Cardiac index increased less with exercise as the physiological measurement of OB using forced expiratory volume in one second (FEV1) fell (P = 0.018). Although resting pulmonary vascular resistance increased with falling FEV1, this increase was still within the normal range. We conclude that a fall in cardiac reserve on exercise accompanies the fall in FEV1 which characterizes OB and may reflect cardiac vascular disease.     

Lung immunogenicity, rejection, and obliterative bronchiolitis

Evidence suggests that obliterative bronchiolitis (OB) following human heart-lung transplantation is a form of allograft rejection related to augmented expression of class II major histocompatibility complex antigens (MHCII) on airway epithelium and mediated by activated T cells. Other forms of OB, including those related to viral infection and autoimmune disease, may reflect a similar mechanism.     

Cardiothoracic surgery after heart and heart-lung transplantation

OBJECTIVE: We sought to examine our management and the outcomes of cardiothoracic procedures after heart and heart lung transplantation. METHODS: We performed a retrospective review of cardiothoracic surgical procedures carried out between 1990 and 2004 in patients who had previously undergone heart or heart-lung transplantation at our institution. RESULTS: Twenty-one out of 340 patients (6.2 %) were identified. Cardiothoracic surgery was performed 44.4 +/- 33 months (range 1 - 115 months) after transplantation. Predominant types of surgery were coronary artery bypass grafting due to allograft vasculopathy (n = 5), aortic surgery due to acute dissection (n = 3), biventricular assist device implantation due to acute rejection (n = 1), tricuspid valve repair (n = 1), multiple cardiac surgical procedures including coronary artery bypass grafting, retransplantation, and tricuspid valve replacement (n = 2), explantation of a functionless heterotopic transplanted heart (n = 1). Lung surgery was performed in six patients due to pneumonia (n = 2), primary lung carcinoma (n = 3), lung torsion following heart-lung transplantation (n = 1). All patients underwent either lobectomy or segmental lung resection. Single lung retransplantation (n = 2) after prior heart-lung transplantation due to bronchiolitis obliterans was performed. In one patient a pneumonectomy (n = 1) due to severe chronic rejection of the contralateral lung was performed. Six subsequent deaths after cardiothoracic procedures were recorded after 1, 4, 78, 163, 205, and 730 days, respectively. Causes of death were advanced carcinoma (n = 1), multi-organ failure due to sepsis (n = 2), sudden heart death (n = 2), and advanced heart failure (n = 1). Fifteen out of 21 patients having undergone cardiothoracic procedures (71.4 %) survived the observation period of 56.6 +/- 34 months (range 1 - 114). CONCLUSIONS: Reasons for cardiothoracic procedures after prior heart or heart-lung transplantation were allograft vasculopathy, aortic dissections years after transplantation, chronic rejection, and either lung infections or malignancies. Surgical repair can be performed with an acceptable operative risk and good long-term survival rates.     

A pathologic analysis of the outcome following heart-lung transplantation: an autopsy study of 22 recipients

Summary Between 1987 and 1989, twenty-two patients who received combined heart-lung transplantation were autopsied at La Pitie Salpetriere Hospital in Paris. With the exception of two recipients who survived for 2 months and 4 months, respectively, the majority of the patients died in the early post-operative period (the mean survival was 20.1 days). At autopsy, five patients showed acute cardiac rejection of a minor grade. Perivascular and peribronchiolar mononuclear cell infiltrates suggesting acute pulmonary rejection were seen in three patients. Obliterating bronchiolitis, which might be indicative of chronic rejection, was observed in four patients who had longer survival rates, and one of these four had died of obliterating bronchiolitis. Rather than allograft rejection, the major causes of death were (1) perioperative hemorrhage, (2) infections (mainly respiratory infections and occasionally mediastinitis), (3) diffuse alveolar damage (the so-called adult respiratory distress syndrome and/or pulmonary organizing edema), and (4) multiple organ failure.The present study suggested some of the reasons why the survival rate following heart-lung transplantation is much poorer than after isolated heart transplantation. Hemodynamic or respiratory problems causing perioperative multiple organ failure as well as pre-existing complications of the recipients, such as cardiac cirrhosis, may play an important role in the prognosis of heart-lung transplantation.     

Lung transplantation: indications, techniques and results

Lung transplantation is proposed for young patients with a severe disease that can be expected to be fatal within less than two or three years. The main indications are chronic respiratory failure induced by chronic obstructive lung disease, cystic fibrosis or pulmonary fibrosis, and severe primary or secondary (Eisenmenger syndrome) pulmonary hypertension. The type of transplantation, determined after an exhaustive work-up ruling out all contraindications, is generally a single lung transplantation if there is no bronchial infection or two-lung transplantation or heart-lung transplantation in case of bronchiectasis or pulmonary artery hypertension. Survival at 1, 3 and 5 years is 72, 57 and 43% respectively. Transplantation improves exercise capacity, quality of life and lung function. It normalizes hematosis in case of chronic respiratory failure and pulmonary hemodynamics in case of pulmonary hypertension. The risk of complications, dominated by infections and rejections, requires careful clinical, functional and endoscopic follow-up. Bacterial infections are frequent during the first weeks. The frequency of opportunistic infections can be reduced by anti-infectious prophylaxis strategies. The rejection can occur as an acute episode, frequent during the first 100 days, or is sometimes asymptomatic. Chronic rejection or obliterating bronchiolitis is the main mid-term complication after lung transplantation and is responsible for the low long-term survival rate with recurrent secondary infections due to frequent bronchial colonization with Pseudomonas aeruginosa. Improved prognosis of lung transplantation requires the development of new immunosuppressive agents with lower risk of infection and chronic rejection observed with current treatments.     

The role of bronchoscopic surveillance monitoring in the care of lung transplant recipients

Fiberoptic bronchoscopy remains the gold standard to establish the presence or absence of acute pulmonary allograft rejection or infection after lung transplantation (LT). Performance of clinically mandated transbronchial lung biopsy enhances diagnostic precision and has a satisfactory risk:benefit ratio in experienced hands. Surveillance transbronchial biopsies have a lower yield but may provide longitudinal insight into immunological events in the allograft that can assist long-term management. Moreover, knowledge about the structural integrity of the bronchial anastomosis is critical to achieve optimum outcomes. Obliterative bronchiolitis (OB) is the most common cause of late graft dysfunction and mortality after LT. Significant OB is invariably associated with reduced graft function, denoted physiologically by the bronchiolitis obliterans syndrome (BOS). Importantly, not all BOS is due to OB. The major risk factor for BOS is thought to be acute cellular rejection but new data support an important role for lymphocytic bronchiolitis. This review examines the role of fiberoptic bronchoscopy after LT as a surveillance tool and discusses indications, risk:benefit, and outcomes, with emphasis on two specific findings on biopsy; namely, minimal acute cellular rejection and lymphocytic bronchiolitis. Findings on follow-up biopsies to assess the outcome of therapies and the natural history of untreated "minimal" rejection events are also discussed.     

Lung transplantation: management and complications

Lung transplantation has become an accepted treatment modality for end stage lung disease including emphysema, fibrosing alveolitis, cystic fibrosis, pulmonary hypertension and bronchiectasis. Despite the use of potent immunosuppressive drugs, acute rejection occurs frequently, especially in the first few weeks and months after transplantation. Bacterial, viral and fungal infections frequently occur in lung transplant recipients. Rapid diagnosis and adequate treatment of infections is needed. The side effects with the use of long term immunosuppressive agents includes renal toxicity, hypertension, neurotoxicity, hyperlipidemia, leucopoenia, hyperglycaemia, weight gain, osteoporosis and malignancy. However, obliterative bronchiolitis (OB) which is regarded as a chronic rejection process remains the dominant cause of morbidity and mortality in the long-term survivors of lung transplantation. This article focuses on the postoperative and long term management of lung transplant recipients.     

Acute and chronic rejection after lung transplantation

Over the last decade, improvements in surgical techniques, lung preservation, immunosuppression, and management of ischemia-reperfusion injury and infections have contributed to increase the 1 year patient survival after lung transplantation to 70 to 80%. However, the incidence of acute rejection remains higher than after other types of solid organ transplantation, and long-term survival is threatened by bronchiolitis obliterans, which is thought to be a form of chronic allograft rejection. This article reviews major aspects of clinical presentation, risk factors, diagnosis, and management of acute and chronic rejection after lung transplantation.     

High prevalence of gastroesophageal reflux in children after lung transplantation

Bronchiolitis obliterans and its clinical correlate bronchiolitis obliterans syndrome (BOS) are a major cause of morbidity and mortality following lung transplantation. Gastroesophageal reflux disease (GERD) may be a contributing factor for the development of BOS. Since 2002, all recipients of lung and heart-lung transplantation at our institution have been routinely investigated for GERD. In this observational study, we report on the prevalence of GERD in this population, including all pediatric patients undergoing single (SLTx) or double (DLTx) lung transplantation or heart-lung (HLTx) transplantation from January 2003-May 2004. GERD was assessed 3-6 months after transplantation by 24-hr pH testing. The fraction time (Ft) with a pH < 4 within a 24-hr period was recorded. Spirometry data, episodes of confirmed acute rejection, and demographic data were also collected. Ten transplant operations were performed: 4 DLTx, 1 SLTx, and 5 HLTx. Nine patients had cystic fibrosis. One patient had end-stage pulmonary disease secondary to chronic aspiration pneumonia and postadenovirus lung damage. Of 10 patients tested, 2 had severe GERD (Ft > 20%), 5 had moderate GERD (Ft 10-20%), 2 had mild GERD (Ft 5-10%), and 1 had no GERD. The only patient in this group with no GERD had a Nissen fundoplication pretransplant. All study patients were asymptomatic for GERD. All patients with episodes of rejection had moderate to severe GERD posttransplant. There was no association between severity of GERD and peak spirometry results posttransplant. Moderate to severe GERD is common following lung transplantation in children.     

Transplantation of the lung

The introduction of cyclosporine as a highly effective immunosuppressive agent and the development of new techniques for heart-lung and lung transplantation have led to a new treatment for a wide range of fatal cardiopulmonary diseases. Indications for surgery are now becoming clear, together with major contra-indications. Suppurative lung disease, such as cystic fibrosis, can be effectively treated by heart-lung transplant (HLT). A whole new field of pulmonary medicine is emerging to provide the physiological monitoring and diagnostic techniques for major complications such as opportunistic lung infection and pulmonary rejection. Obliterative bronchiolitis, a consequence of frequent and severe rejection, still provides a major challenge to the immunological scientist and respiratory physician. Lung transplantation, by disrupting the vascular supply and innervation of the lung, is raising major questions about the generally accepted beliefs of regulation of breathing and pulmonary mechanics. Finally, as the survival rate improves beyond the current 50% at 3 yrs, lung transplantation will perhaps present further challenges to our understanding of the pathogenesis of various diseases such as asthma and cystic fibrosis.     

Heart-lung transplantation: better use of resources

PURPOSE: Our goal was to review the experience at Papworth Hospital, Cambridgeshire, England, with combined heart-lung transplantation. PATIENTS AND METHODS: Since April 1984, 31 patients have undergone heart-lung transplantation. Donors and recipients are carefully matched with regards to serology, morphology, and cytomegalovirus compatibility. A pulmonary preservation fluid has been developed that allows distant organ procurement with a single pulmonary artery flush technique. RESULTS: Acute cardiac rejection has not occurred in these patients. Twenty-three patients are alive between two months and over three years following transplantation. The actuarial survival rate at one year is 78 percent, and 70 percent at two years. Three patients died as a result of cytomegalovirus pneumonitis; in two patients, obliterative bronchiolitis developed, and both died, one after an opportunistic infection developed. Three patients died from other causes. The use of transbronchial biopsy of the lung has provided accurate, early, and safe diagnosis of pulmonary rejection. CONCLUSION: Developments in organ preservation and patient management, as well as careful selection of recipients and donors, have led to the effective use of resources and thereby to these good results. In particular, the incidence of obliterative bronchiolitis has been low, which is attributed to the early treatment of pulmonary rejection following diagnosis by transbronchial biopsy.     

The role of neutrophils in the pathogenesis of obliterative bronchiolitis after lung transplantation

Abstract: Obliterative bronchiolitis (OB) represents the most important long-term complication after lung transplantation. Elevated numbers of neutrophils within the airways are a hallmark of OB. It is unclear what causes the recruitment and activation of neutrophils in the airways of patients with OB: the process of chronic rejection itself or infection, which may (especially in latent virus infection) often be overlooked by the currently applied diagnostic procedures. It is well known that besides their physiologic functions in the clearance of invading micro-organisms, activated neutrophils have a remarkable potential to cause damage to lung tissue. This is attributable to their capability to generate reactive oxygen species and to release potentially toxic proteases. It has been shown that the increased numbers of neutrophils in bronchoalveolar lavage fluid of patients with bronchiolitis obliterans syndrome (BOS) after lung transplantation are associated with elevated levels of interleukin-8, the predominant neutrophil chemotactic factor in the lung. As evidence for the impact of neutrophils on the pathogenesis of BOS, there is significant oxidative stress within the airways of patients with BOS. In addition, the milieu within the airways is characterized by an imbalance between neutrophil elastase (NE) and molecules that inhibit NE as a result of an increased burden of NE released by neutrophils. A defective antiprotease shield due to the loss of secretory leukoprotease inhibitor could be demonstrated in BOS. These mechanisms may provide possible targets to develop new therapeutic strategies that either prevent neutrophil sequestration and activation, or inhibit neutrophil products in order to prevent or attenuate airway damage.     

Relevance of GERD in Lung Transplant Patients

Lung transplantation has become a valuable treatment for end-stage pulmonary disorders in an attempt to improve quality of life and extend survival. Development of chronic rejection, also known as bronchiolitis obliterans syndrome (BOS), is responsible for the vast majority of deaths after lung transplantation. Up to 50% of lung transplant patients develop BOS within the first 5 years after transplantation. A high prevalence of gastroesophageal reflux and aspiration of gastric components has been described after lung transplantation. Reflux and aspiration have been implicated in the development of BOS and antireflux surgery has been proposed; however, the causal relationship with BOS and the impact of reflux in lung transplantation survival needs to be further elucidated.     

Influence of donor and recipient HLA locus mismatching on development of obliterative bronchiolitis after lung transplantation

Obliterative bronchiolitis (OB) after lung transplantation is the end result of multiple immunologic, virologic, genetic, and environmental effects on the transplanted lung. In this study, we first analyzed risk factors for OB in a single-center population of 152 lung transplant recipients. We then examined the influence of donor and recipient HLA mismatching on progression to OB, and on the identified risk factors for OB. The median time to onset of OB for the entire study population was 2.7 yr. The significant risk factors for OB by multivariate analyses were grade A2 or A3 acute rejection (p = 0.0126) and cytomegalovirus (CMV) pneumonitis (p = 0.0358). The only significant HLA risk factor for OB was mismatching at the HLA-A locus (p = 0.0144). On the basis of Cox proportional hazards modeling, a predictive formula was derived to estimate the risk of OB after lung transplantation. Although mismatching at the HLA-DR locus was a significant risk factor for CMV pneumonitis in recipients exposed to CMV before transplantation (p = 0.0199), and protected against acute rejection, it did not independently protect against OB. These results indicate that HLA mismatches between donors and recipients significantly influence the development of OB both directly, and indirectly, by influencing the major risk factors for OB.     

Bronchiolitis obliterans and airways obstruction associated with graft-versus-host disease

Bronchiolitis obliterans is a nonspecific pathologic lesion seen after fume inhalation and infections, which is associated with connective tissue disorders and is a complication of organ transplantation. Bronchiolitis obliterans with organizing pneumonia is also associated with the connective tissue disorders but is usually idiopathic and has better prognosis with corticosteroid therapy. Bone marrow-related obliterative bronchiolitis is limited to patients who develop chronic graft-versus-host disease. Symptoms begin with cough in 3 to 6 months and progress to dyspnea and severe airflow obstruction. The roentgenogram is normal or shows hyperinflation. Prognosis is poor and most patients develop disabling irreversible airflow obstruction. Bronchiolitis obliterans is the most important clinical complication in heart-lung transplant recipients. It is not preceded by typical features of chronic graft-versus-host disease, but has the same clinical course of dyspnea, airflow obstruction, and poor response to therapy. Bronchiolitis obliterans in transplant recipients may represent a form of allograft rejection.