Thrombotic Microangiopathy after Lung Transplantation

BACKGROUND

Thrombotic microangiopathy (TMA) is a well-recognized complication after transplantation. The purpose of this study was to describe our center's experience with this complication after lung transplantation.

METHODS

We retrospectively reviewed cases of TMA among patients who underwent lung transplantation between January 1, 1999 and December 31, 2003 (n = 257). The cases were characterized and the outcomes were analyzed. Univariate and multivariate Cox regression models were constructed to identify potential risk factors for TMA.

RESULTS

Twenty-four cases of TMA developed in 20 recipients. Thirteen cases occurred in the setting of another illness and 11 cases were isolated complications. Multivariate Cox regression models identified female gender, history of TMA, and the immunosuppressive regimen as independent predictors of TMA. Maintenance immunosuppression with the combination of a calcineurin inhibitor and sirolimus carried a significantly higher risk of TMA than a calcineurin inhibitor alone. After the diagnosis of TMA, calcineurin inhibitors were stopped in 18 cases; however, in 6 cases in which the onset of TMA coincided with the addition of sirolimus to a calcineurin inhibitor, only sirolimus was discontinued. Plasmapheresis was performed for severe cases (n = 10). TMA remitted in all cases, and an alternate calcineurin inhibitor was introduced in 14 cases. TMA recurred in 4 recipients, a median 253 days after the initial episode. The median survival after the onset of TMA was 377 days.

CONCLUSION

TMA is a serious complication after lung transplantation, and the risk is highest when sirolimus is used in combination with a calcineurin inhibitor.

The significance of a single episode of minimal acute rejection after lung transplantation

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) remains the leading obstacle to better long-term outcomes after lung transplantation. Acute rejection has been identified as the primary risk factor for BOS, but the impact of minimal acute rejection, especially a solitary episode, has usually been discounted as clinically insignificant.

METHODS

We performed a retrospective cohort study of 259 adult lung transplant recipients to determine the risk of BOS associated with a single episode of A1 rejection, without recurrence or subsequent progression to a higher grade. The cohort was divided into 3 groups based on the severity of acute rejection (none, single episode of A1, and single episode of A2). We determined the risks of BOS stages 1, 2, 3, and death for each group using univariate and multivariate Cox regression analyses.

RESULTS

A solitary episode of A1 rejection was a significant risk factor for BOS stages 1 and 2, but not stage 3 or death, in the univariate analysis. Multivariate Cox regression models confirmed that the risk of BOS attributable to a single episode of A1 rejection was independent of other potential risk factors, such as community acquired respiratory viral infections, number of HLA mismatches, and cytomegalovirus pneumonitis. Likewise, univariate and multivariate analyses demonstrated that a single episode of A2 rejection was a significant risk factor for all stages of BOS but not death.

CONCLUSIONS

A single episode of minimal acute rejection without recurrence or subsequent progression to a higher grade is a significant predictor of BOS independent of other risk factors.

Outcome of lung transplantation for patients requiring concomitant cardiac surgery

BACKGROUND

The clinical results of lung transplantation and concomitant cardiac surgery are unclear. The effect of cardiopulmonary bypass on the pulmonary allograft is controversial, and the effect of cardiac arrest and cardiac surgery in this setting is unknown. Our aim was to review the operative results and long-term survival in this group of patients.

METHODS

A retrospective review of all lung transplantations between 1988 and 2003 was performed. Patients who had concomitant cardiac surgery during lung transplantation were compared with those who underwent lung transplantation alone. The variables analyzed included allograft ischemic times, use of cardiopulmonary bypass, early graft dysfunction, postoperative morbidity, survival, length of mechanical ventilation, length of stay in the intensive care unit, and overall hospital stay.

RESULTS

During this period, 35 of 700 lung transplant recipients (15 single and 20 bilateral transplantations) underwent concomitant cardiac surgery. The cardiac procedures were for patent foramen ovale (n = 18), atrial septal defect (n = 9), ventricular septal defect (n = 2), coronary bypass (n = 4), and "other" (n = 2). Allograft ischemic time, use of extracorporeal membrane oxygenation, length of hospital stay, operative mortality, and survival were not significantly different between the 2 groups. Ventilator time and intensive care unit stay were longer in the cardiac surgery group.

CONCLUSIONS

Cardiac surgery at the time of lung transplantation can be performed with acceptable morbidity and mortality. The immediate and long-term survival in these patients is similar to that of other lung transplant recipients. Lung transplantation should continue to be offered to patients with normal ventricular function who require concomitant limited cardiac surgery.

Detection of severe human metapneumovirus infection by real-time polymerase chain reaction and histopathological assessment

BackgroundInfections with common respiratory tract viruses can cause high mortality, especially in immunocompromised hosts, but the impact of human metapneumovirus (hMPV) in this setting was previously unknown

MethodsWe evaluated consecutive bronchoalveolar lavage and bronchial wash fluid samples from 688 patients—72% were immunocompromised and were predominantly lung transplant recipients—for hMPV by use of quantitative real-time polymerase chain reaction (PCR), and positive results were correlated with clinical outcome and results of viral cultures, in situ hybridization, and lung histopathological assessment

ResultsSix cases of hMPV infection were identified, and they had a similar frequency and occurred in a similar age range as other paramyxoviral infections. Four of 6 infections occurred in immunocompromised patients. Infection was confirmed by in situ hybridization for the viral nucleocapsid gene. Histopathological assessment of lung tissue samples showed acute and organizing injury, and smudge cell formation was distinct from findings in infections with other paramyxoviruses. Each patient with high titers of hMPV exhibited a complicated clinical course requiring prolonged hospitalization

ConclusionsOur results provide in situ evidence of hMPV infection in humans and suggest that hMPV is a cause of clinically severe lower respiratory tract infection that can be detected during bronchoscopy by use of real-time PCR and routine histopathological assessment

Minimal acute rejection after lung transplantation: a risk for bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS) is a major cause of lung allograft dysfunction. Although previous studies have identified mild to severe rejection (grade>or=A2) as a risk factor for BOS, the role of minimal rejection (grade A1) remains unclear. To determine if A1 rejection by itself is a risk factor for BOS, we performed a retrospective cohort study on 228 adult lung transplant recipients over a 7-year period. Cohorts were defined by their most severe rejection episode (none, A1 only, and >or=A2) and analyzed for the subsequent development and progression of BOS using univariate and multivariate time-dependent Cox regression analysis. In the univariate model, the occurrence of isolated minimal rejection was a risk factor for all stages of BOS. Similarly, multivariate models that included HLA mismatch, cytomegalovirus pneumonitis, community acquired viral infection, underlying disease and type of transplant demonstrated that A1 rejection was a distinct risk factor for BOS. Furthermore, the associated risk with A1 rejection was slightly greater than the risk from >or=A2 and treatment of A1 rejection decreased the risk for subsequent BOS stage 1. We conclude that minimal rejection is associated with an increased risk for BOS development and progression that is comparable to A2 rejection.

Reliability for Grading Acute Rejection and Airway Inflammation After Lung Transplantation

BACKGROUND

The Lung Rejection Study Group (LRSG) created a scheme for grading acute allograft rejection in 1990 and then revised it in 1996, but virtually no studies have evaluated the reliability of this formulation. This investigation assessed the reliability of the current LRSG system by determining inter- and intrareader agreement for grading transbronchial biopsy samples from lung transplant recipients.

METHODS

Biopsy samples from a cohort of 204 recipients were reviewed and classified by a single pathologist who was blinded to original interpretations. The "A" and "B" rejection grades from this contemporary review were compared with original grades by the kappa statistic.

RESULTS

For "A" grading, weighted kappa was 0.65 (95% confidence interval [CI] 0.60-0.70) for interreader agreement (n = 529 specimens) and 0.65 (95% CI 0.53-0.76) for intrareader agreement (n = 97 specimens). For "B" grading, weighted kappa was 0.26 (95% CI 0.14-0.39) for interreader agreement (n = 164 specimens) and 0.33 (95% CI 0.15-0.51) for intrareader agreement (n = 58 specimens).

CONCLUSIONS

On the basis of the analysis of the LRSG scheme, "A" grades exhibit very good reliability, but "B" grades have only fair reliability, and steps to improve this shortcoming should be taken.

Primary graft dysfunction and other selected complications of lung transplantation: A single-center experience of 983 patients

OBJECTIVES

We sought to review the incidence and outcome of lung transplantation complications observed over 15 years at a single center.

METHODS

We performed a retrospective review from our databases, tracking outcomes after adult and pediatric lung transplantation. The 983 operations between July 1988 and September 2003 included 277 pediatric and 706 adult recipients. Bilateral (74%), unilateral (19%), and living lobar transplants (4%) comprised the bulk of this experience. Retransplantations accounted for 44 (4.5%) of the operations.

RESULTS

The groups differed by indication for transplantation. The adults included 57% with emphysema and 17% with cystic fibrosis, and the children included no patients with emphysema and 50% with cystic fibrosis. Hospital mortality was 96 (9.8%) of 983, including 46 (17%) of 277 of the children and 50 (7%) of 706 of the adults. The overall survival curves did not differ between adults and children ( P = .56). Freedom from bronchiolitis obliterans syndrome at 5 and 10 years was 45% and 18% for adults and 48% and 30% for children, respectively ( P = .53). The causes of death for adults included bronchiolitis obliterans syndrome (40%), respiratory failure (17%), and infection (14%), whereas the causes of death in children included bronchiolitis obliterans syndrome (35%), infection (28%), and respiratory failure (21%) ( P < .01). Posttransplantation lymphoproliferative disease occurred in 12% of pediatric recipients and 6% of adults ( P < .01). The frequency of treated airway complications did not differ between adults and children (9% vs 11%, P = .48). The frequency of primary graft dysfunction did not differ between children (22%) and adults (23%), despite disparity in the use of cardiopulmonary bypass.

CONCLUSION

These results highlight major complications after lung transplantation. Despite differences in underlying diagnoses and operative techniques, the 2 cohorts of patients experienced remarkably similar outcomes.

Pneumonia in the solid organ transplant patient

As the field of solid organ transplantation has grown, so has the importance of infectious complications in this select group of patients. Chronic immunosuppression compromises the natural host defenses that typically prevent lower respiratory tract infections and makes the solid organ transplant recipient especially susceptible to pneumonia. Evaluation of pneumonia in this population differs owing to the potential for opportunistic infections. Lung transplant recipients are particularly susceptible to pneumonia and pose unique diagnostic dilemmas. An understanding of the time line for the different key pathogens after transplantation aids the initial evaluation and management.

Immune mechanisms in the pathogenesis of bronchiolitis obliterans syndrome after lung transplantation

Lung transplantation is recognized as the only viable treatment option in a variety of end-stage pulmonary diseases. However, the long-term survival after lung transplantation is limited by the development of obliterative bronchiolitis, and its clinical correlate bronchiolitis obliterans syndrome (BOS), which is considered to represent chronic lung allograft rejection. Histopathologically, BOS is an inflammatory process that leads to fibrous scarring of the terminal and respiratory bronchioles and subsequent total occlusion of the airways. The specific etiology and pathogenesis of BOS are not well understood. The current premise is that BOS represents a common lesion in which different inflammatory insults such as ischemia-reperfusion, rejection, and infection can lead to a similar histological and clinical outcome. However, the low incidence of BOS in non-transplanted individuals and the observation that early development of BOS is predicted by the frequency and severity of acute rejection episodes indicate that alloimmune-dependent mechanisms play a crucial role in the pathogenesis of BOS. The evidence presented in this review indicates that BOS is the result of humoral and cellular immune responses developed against major histocompatibility complex molecules expressed by airway epithelial cells of the lung allograft. This process is aggravated by alloimmune-independent mechanisms such as ischemia-reperfusion and infection. Currently, treatment of BOS is frequently unsuccessful. Therefore, a better understanding of the immunopathogenesis of BOS is of paramount importance toward improving long-term patient and graft survival after lung transplantation.

Bronchiolitis obliterans syndrome: Pathogenesis and management

Over the past 15 years, lung transplantation has become an established treatment for a variety of end-stage lung diseases, but medium- and long-term success has been limited by a high incidence of bronchiolitis obliterans syndrome (BOS). Immune mediated injury has been recognized as the leading cause of BOS, and the term is synonymous with chronic rejection. But recently, nonimmune mechanisms, such as gastroesophageal reflux, have been recognized as potential culprits. The results of various treatment options have generally been disappointing, and BOS has emerged as the leading cause of late morbidity and mortality after lung transplantation.

Yield of surveillance bronchoscopy for acute rejection and lymphocytic bronchitis/bronchiolitis after lung transplantation

BACKGROUND

Better understanding of the timing and pattern of surveillance bronchoscopy findings after lung transplantation could influence the timing and frequency of surveillance bronchoscopy. We present our surveillance bronchoscopy experience and test the hypothesis that patients not encountering early acute rejection or lymphocytic bronchitis/bronchiolitis are less likely to have subsequent occult occurrences in the 1st year after lung transplantation.

METHODS

We conducted a retrospective study of 204 patients who underword transplantation between 1996 and 2000. Based on contemporary biopsy-specimen grading in the first 100 days, we formed 2 groups: No Early Rejection and Early Rejection. We compared subsequent yields of surveillance bronchoscopy and the incidence of acute rejection or of lymphocytic bronchitis/bronchiolitis.

RESULTS

We reviewed 645 biopsies taken from 204 recipients during the first 100 days to classify patients into a No Early Rejection Group (n=67) or an Early Rejection Group (n=137). Yield of surveillance bronchoscopy for acute rejection or lymphocytic bronchitis/bronchiolitis was 31% with the greatest yield during the first 30 days (45%), and then decreasing to 26% (p <0.001). After Day 100, 71% of occult acute rejection episodes involved minimal (A1) lesions. Yield of surveillance bronchoscopy after Day 100 was 20% in the No Early Rejection Group and was 27% in the Early Rejection Group (p=0.22). Incidence of acute rejection or lymphocytic bronchitis/bronchiolitis after Day 100 was 41% in the No Early Rejection Group and was 50% in the Early Rejection Group (p=0.17).

CONCLUSION

Surveillance bronchoscopy detects occult acute rejection or lymphocytic bronchitis/bronchiolitis in approximately one-third of biopsy specimens during the 1st year, with the majority of late abnormalities being minimal (A1) rejection. The absence of acute rejection or lymphocytic bronchitis/bronchiolitis during the first 100 days does not predict freedom from such events in the remainder of the 1st year.

Interventional and surgical modalities of treatment for pulmonary arterial hypertension

Beyond medical therapy, different interventional and surgical approaches exist for treatment of pulmonary arterial hypertension (PAH). Atrial septostomy has been applied in patients with lack of response to medical therapy in the absence of other surgical treatment options. With growing experience, procedure-related death rates have been reduced to 5.4%, and the most suitable patient group has been identified among patients with a mean right atrial pressure between 10 and 20 mm Hg. Pulmonary endarterectomy is the accepted form of treatment for patients with chronic thromboembolic pulmonary hypertension. Establishing the diagnosis and the classification of the type of lesions by pulmonary angiography is crucial for optimal patient selection. Perioperative mortality rates have been reduced to <10% in experienced centers, and the hemodynamic improvement is dramatic and sustained. Lung and heart-lung transplantation remains the procedure of choice for patients unsuitable for other treatment modalities. Timing of the procedure is difficult because waiting times vary between centers and usually are in a high range. Early referral of patients unresponsive to other treatment forms is therefore of importance to avoid transplantation of patients with established significant comorbidity. The survival rate during the first five years after transplantation for PAH is intermediate among the lung diseases, lower than chronic obstructive pulmonary disease but higher than idiopathic pulmonary fibrosis.

Lung transplantation for lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis is a rare disease in women leading to respiratory failure. We describe a single-institution experience with lung transplantation for end-stage lymphangioleiomyomatosis.

METHODS

We retrospectively reviewed records of patients transplanted for lymphangioleiomyomatosis between 1989 and 2001. Follow-up was complete on all patients (median 3.5 years).

RESULTS

Seven single and 7 bilateral transplants were performed on 14 recipients (mean age 41.8 years). Eleven patients suffered the following intra-operative complications: dysrhythmia (1); blood loss > 1,000 ml (7); extensive pleural adhesions (10); hypothermia (1); phrenic nerve injury (1); and graft dysfunction (2). The following post-operative complications occurred in 11 recipients: dysrhythmia (7); respiratory failure (5); sepsis (3); airway dehiscence (2); vocal cord dysfunction (1); cholecystitis (1); deep vein thrombosis (1); acute renal failure (1); and pericarditis (1). Post-operative chylous fistulas necessitated thoracic duct ligation (1); sclerosis (6); and drainage of ascites (1). There were no peri-operative deaths. Late deaths occurred due to sepsis in 2 patients and obliterative bronchiolitis in 1 patient. Survival rates were 100%, 90% and 69% at (1, 2 and 5 years, respectively.) Mean FEV1 (1.77 +/- 1.06 vs 0.60 +/- 0.91) and 6-minute walk (1,519 +/- 379 vs 826 +/- 293 feet) improved at 1 year as compared with pre-transplant evaluation. Five patients reached criteria for bronchiolitis obliterans syndrome. One recipient has had a documented recurrence of lymphangioleiomyomatosis in the transplanted lung.

CONCLUSIONS

Early and late survival after lung transplant are comparable in lymphangioleiomyomatosis patients versus patients with other diseases. Morbidity is common after transplant for lymphangioleiomyomatosis and is usually due to lymphangioleiomyomatosis-related complications. Lymphangioleiomyomatosis recurrence in the allograft does not pose a substantial clinical problem.

Respiratory viral infections are a distinct risk for bronchiolitis obliterans syndrome and death

Bronchiolitis obliterans syndrome (BOS) is the major obstacle to long-term survival after lung transplantation, in part because its pathogenesis is poorly understood and treatment options are limited. To identify unique risk factors for BOS and death, we performed a retrospective cohort study on 259 consecutive adult lung transplant recipients over a 5-year period. The demographic and clinical characteristics of this population were analyzed for an association between BOS or death and potential risk factors, including community-acquired respiratory viral (CARV) infections, acute rejection, and cytomegalovirus pneumonitis. Respiratory syncytial virus, parainfluenza, influenza, and adenovirus accounted for 21 CARV infections. Univariate and multivariate time-dependent Cox regression analyses demonstrated that this CARV group was more likely to develop BOS, death, and death from BOS. Furthermore, these trends were more pronounced in patients with evidence of lower respiratory tract-CARV (lower-CARV) infections. Notably, the CARV and lower-CARV infections were risk factors for BOS, death, and death from BOS distinct from the risk attributable to acute rejection. Identification of CARV and lower-CARV infections as BOS and mortality risk factors has important clinical implications and may provide insight into disease pathogenesis and accelerate the development of novel treatment strategies to modify post-CARV BOS.

The Predictive Value of Bronchiolitis Obliterans Syndrome Stage 0-p

Bronchiolitis obliterans syndrome (BOS) remains the main cause of graft loss after lung transplantation. Stage 0-p was recently added to the staging criteria to detect early deterioration in allograft function that might presage BOS stage 1. We assessed the predictive value of stage 0-p by retrospectively analyzing spirometric data for 203 adult bilateral lung transplant recipients. The FEV(1) criterion for stage 0-p had a positive predictive value of 79% and a negative predictive value of 82%. In contrast, the FEF(25-75%) criterion for stage 0-p had a positive predictive value of 52% and a negative predictive value of 72%. Fifty-seven percent of subjects who developed stage 0-p by the FEV(1) criterion progressed to stage 1 within 1 year, whereas only 37% of those who developed stage 0-p by the FEF(25-75%) criterion progressed to stage 1 within 1 year. We conclude that the FEV(1) criterion for stage 0-p is a reasonable predictor of BOS stage 1 after bilateral lung transplantation, but the FEF(25-75%) criterion for stage 0-p is not predictive of BOS stage 1 after bilateral lung transplantation.