The evolution of techniques and indications for lung transplantation

History of Lung Transplantation

Lung transplantation remains the only available therapy for many patients with end-stage lung disease. The number of lung transplants performed has increased significantly, but development of the field was slow compared with other solid-organ transplants. This delayed growth was secondary to the increased complexity of transplanting lungs; the continuous needs for surgical, anesthetics, and critical care improvements; changes in immunosuppression and infection prophylaxis; and donor management and patient selection. The future of lung transplant remains promising: expansion of donor after cardiac death donors, improved outcomes, new immunosuppressants targeted to cellular and antibody-mediated rejection, and use of xenotransplantation or artificial lungs.

Clamshell thoracotomy for en bloc resection of a 3-level thoracic chordoma: technical note and operative video

The clamshell thoracotomy is often used to access both hemithoraxes and the mediastinum simultaneously for cardiothoracic pathology, but this technique is rarely used for the excision of spinal tumors. We describe the use of a clamshell thoracotomy for en bloc excision of a 3-level upper thoracic chordoma in a 20-year-old patient. The lesion involved T2, T3, and T4, and it invaded both chest cavities and indented the mediastinum. After 2 biopsies to confirm the diagnosis, the patient underwent a posterior spinal fusion followed by bilateral clamshell thoracotomy for 3-level en bloc resection with simultaneous access to both chest cavities and the mediastinum. To demonstrate how the clamshell thoracotomy was used to facilitate the tumor resection, an operative video and illustrations are provided, which show in detail how the clamshell thoracotomy can be used to access both hemithoraxes and the mediastinum.

The Bronchial Arterial Circulation in Lung Transplantation: Bedside to Bench to Bedside, and Beyond

Chronic allograft dysfunction (CLAD) remains a major complication, causing the poor survival after lung transplantation (Tx). Although strenuous efforts have been made at preventing CLAD, surgical approaches for lung Tx have not been updated over the last 2 decades. The bronchial artery (BA), which supplies oxygenated blood to the airways and constitutes a functional microvasculature, has occasionally been revascularized during transplants, but this technique did not gain popularity and is not standard in current lung Tx protocols, despite the fact that a small number of studies have shown beneficial effects of BA revascularization on limiting CLAD. Also, recent basic and clinical evidence has demonstrated the relationship between microvasculature damage and CLAD. Thus, the protection of the bronchial circulation and microvasculature in lung grafts may be a key factor to overcome CLAD. This review revisits the history of BA revascularization, discusses the role of the bronchial circulation in lung Tx, and advocates for novel bronchial-arterial-circulation sparing approaches as a future direction for overcoming CLAD. Although there are some already published review articles summarizing the surgical techniques and their possible contribution to outcomes in lung Tx, to the best of our knowledge, this review is the first to elaborate on bronchial circulation that will contribute to prevent CLAD from both scientific and clinical perspectives: from bedside to bench to bedside, and beyond.

Lung transplantation and organ allocation in Brazil: necessity or utility

The philosophy of organ allocation is the result of two seemingly irreconcilable principles: utilitarianism and distributive justice. The process of organ donation and transplantation in Brazil reveals large inequalities between regions and units of the Federation, from the harvesting of organs to their implantation. In this context, lung transplantation is performed in only a few centers in the country and is still a treatment with limited long-term results. The allocation of the few organs harvested for the few procedures performed is defined mainly by chronology, a criterion that is not linked to necessity, which is a criterion of distributive justice, and neither to utility, a criterion of utilitarianism. This article reviews the organ allocation philosophy focusing on the case of lung transplantations in Brazil.

Pathophysiology and Predictors of Bronchial Complications After Lung Transplantation

Bronchial anastomotic breakdown was a major complication in the early days of lung transplantation. Their solution, achieved through an understanding of airway ischemia from the laboratory, was key to the initial clinical success. Subsequently, risk factors, such as prolonged ventilation in both donor and recipient, primary graft dysfunction, and recipient age, have emerged. Innovations, such as local tissue wrapping, telescoping the anastomosis, and bronchial artery revascularization, have not stood the test of time. The short donor bronchus, with a suture line at the level of the lobar bronchus carina, is a proven technique that should be adopted by surgeons.

Lung transplantation

Lung transplantation is a globally accepted treatment for some advanced lung diseases, giving the recipients longer survival and better quality of life. Since the first transplant successfully performed in 1983, more than 40 thousand transplants have been performed worldwide. Of these, about seven hundred were in Brazil. However, survival of the transplant is less than desired, with a high mortality rate related to primary graft dysfunction, infection, and chronic graft dysfunction, particularly in the form of bronchiolitis obliterans syndrome. New technologies have been developed to improve the various stages of lung transplant. To increase the supply of lungs, ex vivo lung reconditioning has been used in some countries, including Brazil. For advanced life support in the perioperative period, extracorporeal membrane oxygenation and hemodynamic support equipment have been used as a bridge to transplant in critically ill patients on the waiting list, and to keep patients alive until resolution of the primary dysfunction after graft transplant. There are patients requiring lung transplant in Brazil who do not even come to the point of being referred to a transplant center because there are only seven such centers active in the country. It is urgent to create new centers capable of performing lung transplantation to provide patients with some advanced forms of lung disease a chance to live longer and with better quality of life.

Comparison of extracorporeal membrane oxygenation versus cardiopulmonary bypass for lung transplantation

OBJECTIVE

This study compared differences in patient outcomes and operative parameters for extracorporeal membrane oxygenation (ECMO) versus cardiopulmonary bypass (CPB) in patients undergoing lung transplants.

METHODS

Between January 1, 2008, and July 13, 2013, 316 patients underwent lung transplants at our institution, 102 requiring intraoperative mechanical cardiopulmonary support (CPB, n=55; ECMO, n=47). We evaluated survival, blood product transfusions, bleeding complications, graft dysfunction, and rejection.

RESULTS

Intraoperatively, the CPB group required more cell saver volume (1123±701 vs 814±826 mL; P=.043), fresh-frozen plasma (3.64±5.0 vs 1.51±3.2 units; P=.014), platelets (1.38±1.6 vs 0.43±1.25 units; P=.001), and cryoprecipitate (4.89±6.3 vs 0.85±2.8 units; P<.001) than the ECMO group. Postoperatively, the CPB group received more platelets (1.09±2.6 vs 0.13±0.39 units; P=.013) and was more likely to have bleeding (15 [27.3%] vs 3 [6.4%]; P=.006) and reoperation (21 [38.2%] vs 7 [14.9%]; P=.009]. The CPB group had higher rates of primary graft dysfunction at 24 and 72 hours (41 [74.5%] vs 23 [48.9%]; P=.008; and 42 [76.4%] vs 26 [56.5%]; P=.034; respectively). There were no differences in 30-day and 1-year survivals.

CONCLUSIONS

Relative to CPB, the ECMO group required fewer transfusions and had less bleeding, fewer reoperations, and less primary graft dysfunction. There were no statistically significant survival differences at 30 days or 1 year.

Short-term Placement of Multiple Self-expandable Metallic Stents for the Treatment of Bilateral Bronchial Dehiscences Complicating Lung Transplantation

Bronchial dehiscence after lung transplantation is a rare complication yet has high morbidity and mortality. The majority of the patients are not surgical candidates. We present the case of a 59-year-old man with bilateral lung transplantation for interstitial pulmonary fibrosis who was readmitted with symptoms of acute rejection and severe hypoxemic respiratory failure on day 14. Bronchoscopy showed bilateral bronchial anastomotic dehiscences. A computerized tomography scan showed evidence of significant peribronchial air collection in the pleural space and the mediastinum. Owing to a high predictive operative mortality, endobronchial management was planned, and 3 uncovered self-expanding metallic stents (Ultraflex, Boston Scientific Corp) were placed (in the left main stem bronchus, the anterior segment of the right upper lobe, and the right intermediate bronchus). At 5 weeks bronchoscopy showed complete healing of the dehiscences with granulation. The stents were then removed by rigid bronchoscopy. Three weeks after the stent removal a bronchoscopic examination showed a normal tracheobronchial tree except for a slightly narrowed right anastomosis. We conclude that short-term placement of uncovered self-expanding metallic stents provides a safe and minimally invasive option in the management of bilateral dehiscences.

Minor and intermediate surgeries in lung transplant recipients

BACKGROUND

Only limited data exist regarding the incidence and outcome of surgical procedures following lung transplantation (LTX).

METHODS

A retrospective analysis of surgical procedures performed in all LTX patients (n = 250) between 1997 and 2008.

RESULTS

Of 250 patients who underwent LTX, 68 (27.2%) required 154 surgical procedures. Mean age was 53 ± 13 yr. Mean interval between LTX and surgery was 41 ± 40 months. Mean follow-up was 21 ± 9.4 months. Fourteen (9.1%) emergency operations were performed. Sixty patients (39%) underwent general anesthesia, 12 (7.8%) regional anesthesia, and 82 (53%) local anesthesia. Two patients required a major surgical procedure, while 76 of the procedures (49.4%) were intermediate, and 76 were minor surgeries. Only two patients (0.8%) developed complications (one infectious and one bronchospasm). One patient (0.4%) died following surgery as a result of septic shock.

CONCLUSIONS

Minor and intermediate procedures can be performed safely in LTX patients without associated morbidity or mortality.

Pediatric lung transplantation: perspectives for the pathologist

Lung transplantation offers life-saving and life-extending treatment for children and adolescents with congenital and acquired forms of pulmonary and pulmonary vascular disease, for whom medical therapy is ineffective or insufficient for sustained response. This review summarizes the pathology related to lung transplantation for the practicing pediatric pathologist and also highlights aspects of lung transplantation unique to the pediatric population. Clinical issues related to availability of organs, candidate eligibility, surgical technique, and postoperative monitoring are discussed. Pathologic evaluation of routine surveillance transbronchial biopsies requires attention to acute cellular rejection, opportunistic infection, and other forms of acute and resolving lung injury. These findings are correlated in some cases with endobronchial biopsies and bronchoalveolar lavage as adjunctive tools in surveillance. Open or thoracoscopic biopsies also have diagnostic utility in cases with acute or chronic graft deterioration of uncertain etiology. Future challenges in pediatric lung transplantation are similar to those in the adult population, with continued efforts focused on prolonging graft survival, prevention of bronchiolitis obliterans syndrome due to chronic cellular rejection, and evaluation of humoral rejection.

Induction Therapy in Lung Transplantation: Initial Single-Center Experience Comparing Daclizumab and Antithymocyte Globulin

Acute and chronic rejection remain unresolved problems after lung transplantation, despite heavy multidrug immunosuppression. Because acute rejection is associated with inferior outcomes in lung transplantation, we have routinely employed antithymocyte globulin (ATG) or daclizumab as adjuncts to reduce the incidence of rejection episodes.

METHODS

We performed a controlled clinical trial of the two therapies to evaluate differences in postoperative rejection, infection, bronchiolitis obliterans syndrome (BOS) and host survival. Twenty-five consecutive lung transplant patients received ATG (n = 12; group 1) or daclizumab (n = 13; group 2) as an induction agent. The groups showed similar demographics and immunosuppression protocols, differ only in induction agent.

RESULTS

No differences were observed in the immediate postoperative outcomes, such as length of hospitalization, ICU stay, or time on ventilator. There were no significant differences in the number of episodes of acute rejection, freedom from BOS, or infections. Freedom from acute rejection was significantly greater with daclizumab than with ATG (P = .037). The 1-year survival for group 1 was 67% and for group 2, 77% (P = .584).

CONCLUSIONS

Daclizumab constitutes a safe and effective form of induction immunosuppressive therapy. Using a two-dose administration schedule, daclizumab prolonged the time without acute rejection compared to ATG. The differences in the incidence of infectious complications, acute rejection, or BOS as well as the short-term or long-term results were not significantly different. The results of the study justify the further use of daclizumab as an induction agent in patients following lung transplantation.

Bronchoalveolar lavage fluid characteristics in acute and chronic lung transplant rejection

BACKGROUND

The detection of graft rejection by bronchoalveolar lavage remains controversial.

METHODS

To assess the value of bronchoalveolar lavage fluid in acute and chronic rejection after lung transplantation we analyzed bronchoalveolar lavage fluid cellular differential characteristics, lymphocyte sub-types and interleukin-6 (IL-6) and interleukin-8 (IL-8) cytokine levels in patients with exclusively either acute rejection (n = 37) or bronchiolitis obliterans (BO; n = 48). Both groups were compared with a control group of lung transplantation patients without rejection or infection, matched for the time the lavage was performed after lung transplantation.

RESULTS

The bronchiolitis obliterans group showed marked neutrophilia, high IL-8 and higher CD4(+)CD25(+) and CD8(+)CD45(+) bronchoalveolar lavage fluid levels when compared with their stable controls. When using a cut-off point of >3% neutrophils in the lavage, the sensitivity for BO is 87.0%, the specificity 77.6%. The sensitivity of IL-8 for BO when using a cut-off point of >71.4 pg/ml is 74.5%, the specificity 83.3%. Bronchoalveolar lavage fluid in acute rejection was characterized by marked lymphocytosis, but showed no difference when compared with stable controls in any of the lymphocyte sub-types studied. When using a cut-off point of <==1% lymphocytes in the lavage, the sensitivity for acute rejection (AR) is 40.4%, the specificity 95.6%. The marked neutrophilia, high IL-8 cytokine level and more activated lymphocyte population in bronchiolitis obliterans may indicate ongoing local allograft rejection.

CONCLUSIONS

In the present study we were not able to show any difference in lymphocyte sub-types when comparing acute rejection and control subjects. Cellular and soluble parameters in bronchoalveolar lavage fluid appear useful for diagnosing bronchiolitis obliterans.

Survival benefit of cardiopulmonary bypass support in bilateral lung transplantation for emphysema patients

BACKGROUND

This study is designed to examine a possible association of cardiopulmonary bypass (CPB) support and outcome of lung transplantation in a well-balanced group of emphysema patients.

METHODS

We performed a retrospective analysis of 62 consecutive primary bilateral lung transplantations for emphysema. Risk factors for their possible association with patient survival were analyzed by multivariate logistic regression.

RESULTS

The use of CPB support was associated with improved survival (odds ratio=0.25; P=0.038). The actuarial survival at 1 year was 97% for patients treated with CPB and 77% for patients treated without CPB support. In 28 patients (45%), 2 human leukocyte antigen (HLA)-DR mismatches between donor and recipient occurred, whereas 34 patients had 0 or 1 HLA-DR mismatches. The use of CPB support in the group with two HLA-DR mismatches was associated with improved survival (odds ratio=0.06; P=0.020). This association was not present in the group with 0 or 1 HLA-DR mismatches.

CONCLUSIONS

These results demonstrate a significant survival benefit of CPB support during bilateral lung transplantation in emphysema patients. The difference in survival benefit of CPB support between the patients with 0 or 1 HLA-DR mismatches and the patients with 2 HLA-DR mismatches indicates that the immunosuppressive effect of CPB support might be responsible for this survival benefit. The underlying immunological mechanism might be important in the future treatment of organ transplantation.

Longitudinal profile of bronchoalveolar lavage cell characteristics in patients with a good outcome after lung transplantation

Bronchoalveolar lavage fluid (BALF) analysis is used in patients after lung transplantation (LTX) to obtain more insight into pathological conditions such as acute and chronic allograft rejection. Information on the normal course of BALF cell characteristics in patients with "good outcome" after LTX is limited. Therefore we analyzed 169 BALF samples from 63 well-defined "good outcome" patients after LTX (no acute or chronic transplant dysfunction, bacterial, fungal, or viral infections at the time of BAL). Total cell count decreased from the first months: median (range) 234 x 10(3) (70-610) cells/ml to 103 x 10(3) (10-840) cells/ml during the second year posttransplantation (p < 0.001). Cell differential counts did not change during the 2-yr study period. The CD4/CD8 ratio increased significantly from 0.32 (0.11-0.46) just posttransplantation to 0.62 (0.16-4.27) the second year after LTX. This increasing ratio was mainly due to a sharp decreasing CD8(+) cell count. Thus, characteristics of BAL cellular patterns in patients with good outcomes after LTX show important changes over time. We have defined control values for the BALF cellular profile in patients without pathological airway conditions after LTX. We propose to use these control values as a tool for diagnosing patients with pulmonary complications after LTX and for the follow-up of treatment regimens.

Surgical techniques for pulmonary metastasectomy

The surgical approaches to pulmonary metastasectomy have evolved during the past 20 years. Important principles include the complete resection of all gross disease, the use of parenchyma-sparing resections, and the simultaneous resection of bilateral metastases wherever technically feasible. Video-assisted thoracic surgery resection has become popular, but is still not standard because it can lead to an incomplete resection. Stapled and precision electrocautery wedge resections remain the most common techniques for parenchymal resection.

Extracorporeal membrane oxygenation before induction of anesthesia in critically ill thoracic transplant patients

Cardiorespiratory failure just before surgery in critically ill thoracic transplant patients can have catastrophic consequences. We judged the cardiorespiratory condition in three of 160 thoracic transplant procedures performed in our center too unstable for a safe induction of anesthesia. In these 3 patients, extracorporeal membrane oxygenation support was installed before induction of anesthesia to maintain an adequate cardiorespiratory state. This strategy was successful for all 3 patients, and long-term survival was achieved with a good quality of life. Guidelines for indications to follow this strategy are discussed.

Bronchial artery revascularization improves tracheal anastomotic healing after lung transplantation

The study aimed to clarify the role of direct bronchial artery revascularization (BAR) after en bloc double-lung (DLT) and heart-lung transplantation (HLT). Group I comprised eight patients with en bloc DLT or HLT and successful BAR, while group II included 14 DLT or HLT cases without BAR or with failed BAR. From these groups, 2 subgroups were extracted: group III, including 6 cases of en bloc DLT with successful BAR and group IV 10 HLT cases without or with failed BAR. Airway healing was evaluated at bronchoscopy and patency of BAR with angiography. Pulmonary viral, bacterial and fungal infections, rejections and bronchiolitis obliterans syndrome (BOS) were registered. Tracheal healing at 2 weeks and 3 months was better in group I than in group 1 (p = 0.003 and p = 0.05, respectively). Compared with group IV, tracheal anastomotic healing at 2 weeks was better in group III (p = 0.007) and tended to be better also after 3 months (p = 0.07). The incidence of infections, rejection or BOS did not differ between groups I and II. BAR thus improved healing of tracheal anastomosis.

Eosinophilic granulocytes and interleukin-6 level in bronchoalveolar lavage fluid are associated with the development of obliterative bronchiolitis after lung transplantation

In a prospective cohort study, we assessed whether changes in total cell counts and differentiation and interleukin-6 (IL-6), IL-8, and monocyte chemoattractant protein-1 (MCP-1) concentrations in bronchoalveolar lavage fluid (BALF) are associated with a higher risk to develop obliterative bronchiolitis (OB). We investigated 60 lung transplant patients (follow-up of 2 to 8 yr) with either histologic evidence of OB within 1 yr after lung transplantation (n = 19) or no pathology, good outcome (GO) for at least 24 mo and well-preserved lung function, i.e., FEV > or = 80% of baseline (n = 41). Median time between lung transplantation and the first BAL was 42 d for the GO group and 41 d for the OB group (p > 0.05). In the bronchial fraction, median total cell counts (0.06 x 10(3)/ml versus 0.04 x 10(3)/ml), lymphocyte (9 x 10(3)/ml versus 2 x 10(3)/ml), and eosinophilic granulocyte counts (1 x 10(3)/ml versus 0) were significantly higher in the OB group than in the GO group (p < 0.05). In the alveolar fraction, this was the case for the median value of neutrophilic granulocyte counts (19 x 10(3)/ml versus 4 x 10(3)/ml), respectively. Median values of IL-6 and IL-8 concentrations in both bronchial (IL-6: 23 versus 6 pg/ml, IL-8: 744 versus 102 pg/ml) and alveolar fractions (IL-6: 13 versus 3 pg/ml, IL-8: 110 versus 30 pg/ml) of the BALF were significantly higher in the OB group than in the GO group. By means of logistic regression, we showed that higher total cell, neutrophilic granulocyte, and lymphocyte counts, the presence of eosinophilic granulocytes, and higher concentrations of IL-6 and IL-8 were significantly associated with an increased risk to develop OB. We conclude that monitoring cell counts, neutrophilic and eosinophilic granulocytes, IL-6, and IL-8 in BALF within 2 mo after lung transplantation in addition to the transbronchial lung biopsy (TBB) pathology will contribute to a better identification and management of the group of patients at risk for developing OB within a year.

History of clinical transplantation

The emergence of transplantation has seen the development of increasingly potent immunosuppressive agents, progressively better methods of tissue and organ preservation, refinements in histocompatibility matching, and numerous innovations in surgical techniques. Such efforts in combination ultimately made it possible to successfully engraft all of the organs and bone marrow cells in humans. At a more fundamental level, however, the transplantation enterprise hinged on two seminal turning points. The first was the recognition by Billingham, Brent, and Medawar in 1953 that it was possible to induce chimerism-associated neonatal tolerance deliberately. This discovery escalated over the next 15 years to the first successful bone marrow transplantations in humans in 1968. The second turning point was the demonstration during the early 1960s that canine and human organ allografts could self-induce tolerance with the aid of immunosuppression. By the end of 1962, however, it had been incorrectly concluded that turning points one and two involved different immune mechanisms. The error was not corrected until well into the 1990s. In this historical account, the vast literature that sprang up during the intervening 30 years has been summarized. Although admirably documenting empiric progress in clinical transplantation, its failure to explain organ allograft acceptance predestined organ recipients to lifetime immunosuppression and precluded fundamental changes in the treatment policies. After it was discovered in 1992 that long-surviving organ transplant recipients had persistent microchimerism, it was possible to see the mechanistic commonality of organ and bone marrow transplantation. A clarifying central principle of immunology could then be synthesized with which to guide efforts to induce tolerance systematically to human tissues and perhaps ultimately to xenografts.

Bilateral sequential single lung transplantation for pulmonary hypertension and Eisenmenger's syndrome

BACKGROUND

Lung transplantation, with and without intracardiac repair for pulmonary hypertension (PH) and Eisenmenger's syndrome (EIS), has become an alternative transplant strategy to combined heart and lung transplantation (HLT).

METHODS

Thirty-five patients with PH or EIS underwent either bilateral sequential single lung transplantation (BSSLT, group I, n = 13) or HLT (group II, n = 22). Another 74 patients, who underwent BSSLT for other indications, served as controls (group III). Immediate allograft function, early and medium-term outcomes, lung function, and 2-year survival were compared between the groups.

RESULTS

Comparisons between groups I and II showed no significant difference in any variables except percent predicted forced vital capacity. Immediate allograft function was significantly inferior (p < 0.05) and the blood loss was greater (p < 0.01) in group I when compared with those in group III. However, this resulted in no significant difference in early and medium-term outcomes, and 2-year survival between the 2 groups.

CONCLUSIONS

BSSLT for PH and EIS can be performed as an alternative procedure to HLT without an increase in early and medium-term morbidity and mortality. Results are comparable with BSSLT performed for other indications.

Transforming growth factor beta (TGF-beta) and obliterative bronchiolitis following pulmonary transplantation

BACKGROUND

Obliterative bronchiolitis (OB) characterised by small-airway fibrosis is a major cause of morbidity and mortality after lung transplantation. TGF-beta has been implicated in the pathogenesis of fibrosis.

METHODS

We immunohistochemically examined 380 transbronchial biopsies (from 91 pulmonary transplants) using TGF-beta polyclonal antibodies. OB and interstitial fibrosis were diagnosed and graded in all biopsies. Other potential histologic and clinical risk factors for OB were analysed.

RESULTS

Procedures were heart and lung (n = 32), bilateral sequential lung (n = 18), and single lung transplantation (n = 41). The incidence of OB in this group was 28.5%. In all patients with OB, TGF-beta was immunolocalized in the airways and lung parenchyma. TGF-beta expression was greater in OB patients (median score 8, range 5-12) in comparison to patients without OB (median score 4, range 1-13), p < .0001. Positive TGF-beta staining preceded the histologic confirmation of OB by 6 to 18 months. The development of OB was associated with two HLA mismatches at the A locus (p = .02); recurrent acute rejection episodes (p < .0005); lymphocytic bronchiolitis (p = .0001); and tissue eosinophilia, regardless of the rejection grade (p < .0001).

CONCLUSIONS

Increased expression of TGF-beta is a risk factor for the development of OB. Other risk factors are recurrent acute rejection, lymphocytic bronchiolitis, tissue eosinophilia, and two mismatches at the HLA-A locus. This suggests that the pathogenesis of progressive small airway fibrosis characteristic of OB may be inflammatory damage, followed by an aberrant repair process due to excessive TGF-beta production following allograft injury. Hence, modulation of TGF-beta levels or function by antagonists may represent an important approach to control OB.

Transforming growth factor-beta (TGF-beta1) genotype and lung allograft fibrosis

BACKGROUND

TGF-beta1 is a prosclerotic cytokine implicated in fibrotic processes. Fibrosis of the pulmonary parenchyma and airways is a frequent presentation in lung transplant recipients before and after transplantation. There are two genetic polymorphisms in the DNA sequence encoding the leader sequence of the TGF-beta1 protein, located at codon 10 (either leucine or proline) and at codon 25 (either arginine or proline). The codon 25 arginine allele is associated with higher TGF-beta1 production by cells activated in vitro. We tested the hypothesis that inheritance of alleles of the TGF-beta1 gene conferring higher production of TGF-beta1 may be responsible for over-expression of TGF-beta1 in transplant recipients resulting in lung allograft fibrosis.

METHODS

We extracted DNA from leukocytes collected from 91 pulmonary transplants performed at our centre and 96 normal healthy volunteers between May 1990 and September 1995. Part of the first exon was amplified by PCR. Samples were genotyped by using sequence specific oligonucleotide probes.

RESULT

The distribution of codon 10 alleles was similar in a normal healthy control group and in lung transplant recipients, regardless of their pretransplant lung pathology. By contrast, there was a significant difference in the frequency of codon 25 alleles between the control and transplant groups. In the normal control group 81% were codon 25 arginine/arginine (A/A) homozygotes, 19% were arginine/proline (A/P) heterozygotes and none were proline/proline (P/P) homozygotes. The distribution of codon 25 alleles was similar in lung transplant recipients who did not have a significant fibrosis in pretransplant pathology, but in transplant recipients who came to transplantation with lung fibrosis 98% (41 of 42 patients) were homozygous for the codon 25 A/A allele (p < .05). After lung transplantation 39 of 91 patients developed lung allograft fibrosis, and of these 92.3% (36 of 39 recipients) were of homozygous codon 25 A/A high TGF-beta1 producer genotype (p < .001). Lung transplant recipients who were homozygous for both codon 10 L/L and codon 25 A/A showed poor survival compared with all other TGF-beta1 genotypes (p < .03).

CONCLUSION

Homozygosity for arginine at codon 25 of the leader sequence of TGF-beta1 that correlates with higher TGF-b production in vitro, is associated with fibrotic lung pathology before lung transplantation and with the development of fibrosis in the graft. In combination with the codon 10 leucine allele, homozygosity for the codon 25arginine allele is a marker for poor post-transplant prognosis and recipient survival.

Bilateral sequential lung transplantation without sternal division eliminates posttransplantation sternal complications

OBJECTIVE

The objective of this study was to assess the efficacy and safety of an alternative surgical incision for bilateral sequential lung transplantation. The vast majority of these operations worldwide have been performed through an anterolateral thoracosternotomy known as the "clamshell" incision. Recently, we have undertaken most of these operations through bilateral anterolateral thoracotomies without sternal division.

METHODS

Our medical center performed 262 bilateral sequential single lung transplantations from 1989 to April 1998. Between July 1996 and April 1998 we performed 69 bilateral sequential single lung transplantations on 68 recipients with 52 transplantations being conducted without initial sternal division. We retrospectively reviewed the results of these operations to assess the safety of the altered exposure and the efficacy in avoiding sternal wound complications such as malunion, dehiscence, osteomyelitis, and migrating hardware. Comparison was made to a historical control group composed of the last 50 patients in whom the full clamshell incision was used.

RESULTS

Of the 68 patients who underwent transplantations, 52 patients underwent the initial exploratory procedure without sternal division. Two patients required emergency sternal division for institution of cardiopulmonary bypass to control life-threatening bleeding. Eleven of 68 patients were placed on bypass electively to permit transplantation, and the lack of a sternotomy in 8 patients did not present an obstacle to ascending aortic and right atrial cannulation. There were no wound healing complications in the 50 patients for whom the sternum was left intact. In a historical control group of 50 patients who underwent transplantation with sternal division, 34% experienced morbidity or mild disability as a direct result of poor sternal healing.

CONCLUSIONS

We conclude that bilateral anterolateral thoracotomy without sternal division is a safe approach that allows adequate exposure without the risk of commonly observed problems with sternal healing.

Transforming growth factor-beta1 and lung allograft fibrosis

OBJECTIVES

Transforming growth factor beta1 (TGF-beta1) is a potent immunosuppressive cytokine that promotes fibrosis by enhancing the synthesis of extracellular matrix components. The repair process following lung allograft injury is due to rejection or infection replaces lung parenchyma by fibrotic tissue, leading to pulmonary dysfunction. The role of TGF-beta1 in this excessive healing process and increasing the risk of infection is unknown.

METHODS

We analysed our patient data to investigate the relevance of different factors on allograft fibrosis and its correlation with TGF-beta1. Fibrosis was graded in H and E stained sections. TGF-beta1 genotype was determined in all patients.

RESULTS

Patients were aged between 16 and 62 years (mean age of 39.6 years). Procedures were heart/lung (n = 32), double lung (n = 18), and SLT (n = 41). A total of 46 patients had lung allograft fibrosis diagnosed in transbronchial biopsies sections. Patients who had developed interstitial fibrosis had significantly more acute rejection episodes (mean 3.4 +/- 2.8) compared with patients without fibrosis (mean 2.1 +/- 2.2) (P = 0.024). The presence of eosinophils in the interstitium preceded and were associated with the development of fibrosis regardless of the rejection grade (P = 0.0001). TGF-beta1 was heavily expressed in sections with fibrosis with a mean score of 6.8 +/- 2.9 compared with 2.4 +/- 0.6 in sections with no fibrosis (P < 0.0001). TGF-beta1 expression correlated positively with fibrosis grades (P < 0.0001). The mean survival for patients with a fibrosis score > 6 is 892.4 +/- 73 days compared with mean survival 427 +/- 78 in patients with scores < 6 (P = 0.0001). Patients who developed fibrosis had homozygous TGF-beta1 genotype that correlates with excessive TGF-beta1 expression (P = 0.01). The use of cardiopulmonary bypass was associated with the development of excessive fibrosis (P = 0.02), and 7 patients who had severe fibrosis died of septicaemia (17.5%). FEV1 (forced expiratory volume) was significantly higher in patients without fibrosis (1870 +/- 111 ml versus 1590 +/- 160; P = 0.02).

CONCLUSIONS

The risks of lung allograft fibrosis increases with recurrent rejection, tissue eosinophilia, homozygous TGF-beta1 genotype and the use of bypass machine. Fibrosis was associated with higher mortality and morbidity might be explained by the TGF-beta1 immunosuppressive and fibrotic properties. Immunological strategies to down-regulate TGF-beta1 production might improve survival and function of lung allografts.

Clotting and fibrinolytic disturbance during lung transplantation: effect of low-dose aprotinin. Groningen Lung Transplant Group

Patients undergoing lung transplantation are often confronted with a bleeding problem that may be due in part to the use of cardiopulmonary bypass and its activation of blood clotting and fibrinolysis.

OBJECTIVE

We performed a prospective study to determine whether and to what extent the clotting and fibrinolytic systems are being activated and whether low-dose aprotinin is effective in inhibiting blood activation during lung transplantation.

METHODS

Thirty lung transplantations performed on 29 patients were divided into a group with cardiopulmonary bypass alone (n = 12), a group with cardiopulmonary bypass and 2 x 10(6) KIU aprotinin administered at the beginning of bypass in the pump prime (n = 12), and a group without cardiopulmonary bypass (n = 6). Serial blood samples were taken from the recipient before anesthesia, seven times during the operation, and 4 and 24 hours thereafter.

RESULTS

Results show that in the group having cardiopulmonary bypass alone, the concentration of the clotting marker thrombin/antithrombin III complex increased significantly during the early phase of the operation (p < 0.01) and remained high until the end of the operation. Levels of tissue-type plasminogen activator, a trigger of fibrinolysis released by injured endothelium, also increased sharply in the early phase of the operation in the cardiopulmonary bypass group (p < 0.01), followed by a significant increase in fibrin degradation products (p < 0.01). In the aprotinin group, a significant reduction of thrombin/antithrombin III complex (p < 0.05), tissue-type plasminogen activator (p < 0.05), and fibrin degradation products (p < 0.05) was observed in the early phase of the operation compared with levels in the bypass group, but these markers increased late during bypass associated with a significant drop (p < 0.05) of plasma aprotinin level monitored by plasmin inhibiting capacity. In the nonbypass group, concentrations of thrombin/antithrombin III complex and tissue-type plasminogen activator also rose significantly (p < 0.05) in the early phase of the operation, but the levels were significantly lower than those of the bypass group (p < 0.05). Blood loss during the operation was 2521 +/- 550 ml in the bypass group, 1991 +/- 408 ml in the aprotinin/bypass group, and 875 +/- 248 ml in the nonbypass group.

CONCLUSION

These results suggest that clotting and fibrinolysis are activated during lung transplantation, especially in patients undergoing cardiopulmonary bypass. Aprotinin in a low dose significantly reduced activation of clotting and fibrinolysis in the early phase of the operation but not during the late phase of lung transplantation.

Clamshell Incision for Simultaneous Correction of Aortic Coarctation and Intracardiac Defects

A clamshell incision allows simultaneous correction of aortic coarctation and intracardiac defects. This incision combines the benefits of a single incision with those of excellent exposure of the heart and the entire thoracic aorta as well as a superior cosmetic result.

[Bilateral trans-sternal thoracotomy in the treatment of complicated bilateral pneumothorax]

Transsternal bilateral thoracotomy ("clam shell" incision) is an approach that allows wide access to both sides of the thorax. Its use dates from the earliest period of cardiac surgery, and it fell into disuse in the face of the advantages of a mid-level sternal approach. The "clam shell" incision was revived, however, with the introduction of lung transplantation. We describe 2 cases of bilateral pneumothorax treated by this surgical route.

A model of unilateral pulmonary lobar transplantation

Unilateral lung transplantation has become an accepted treatment for patients with end-stage pulmonary disease. Donor shortage, however, is a major limitation, with up to 87% of patients dying of their pulmonary disease while awaiting transplantation. This is especially true in neonatal and pediatric patient populations. The use of organ segments from cadaveric or living donors may provide a solution. The purpose of this study, therefore, was to evaluate the function and hemodynamic response to pulmonary lobar transplantation using a swine model. Five transplants were performed for acute study, while 10 were performed for 6-week survival. The left lower lobe was harvested from a 70- to 75-kg donor animal. The lobe was then transplanted into a 20 to 25-kg recipient following left pneumonectomy. Graft function was determined by pulmonary arterial and venous blood gas analysis. Cardiac output, pulmonary pressure, and pulmonary vascular resistance were measured under two experimental conditions: (1) baseline and (2) with the right pulmonary artery occluded, forcing the entire cardiac output through the lobar graft. All grafts showed excellent acute and long-term function with regard to gas exchange. The lobar grafts, however, were characterized by high pulmonary vascular resistance both acutely and 6 weeks post-transplant. Contralateral pulmonary artery occlusion resulted in hemodynamic instability and right heart failure. No animal was able to be solely supported by the lobar transplant for more than one hour. These results have prompted a bilateral lobar transplant model and current studies are in progress.

Respiratory responses to CO2 rebreathing in lung transplant recipients

To evaluate the respiratory responses after lung transplantation, we studied the hypercarbic ventilatory response in 20 patients with severe obstructive pulmonary disease and compared it with that of 10 normal subjects. Eleven patients underwent bilateral lung transplantation and 9 patients had single-lung transplantation. All patients had preoperative hypercapnia (51.3 +/- 9.7 mm Hg) and blunted slopes of CO2 rebreathing curves for minute ventilation (0.39 +/- 0.20 L.min-1.mm Hg-1) and inspiratory occlusion pressure (0.35 +/- 0.30 s-1). The hypercapnia and blunted ventilatory responses persisted at the initial postoperative test (5.8 +/- 2.0 days) despite improved pulmonary function (preoperative forced expiratory volume in 1 second [FEV1], 0.57 +/- 0.16 L; initial postoperative FEV1, 1.83 +/- 0.65 L; p < 0.001). By the 15th to 30th postoperative day (21.3 +/- 6.0 days), compared with preoperative and initial postoperative values, end-tidal CO2 had normalized (40.6 +/- 6.9 versus 51.3 +/- 9.7 and 49.6 +/- 10.3 mm Hg; p < 0.005) and was coupled with enhanced ventilatory responses for the rebreathing curve for minute ventilation (1.26 +/- 0.7 versus 0.39 +/- 0.20 and 0.32 +/- 0.32 L.min-1.mm Hg-1; p < 0.005) and the inspiratory occlusion pressure curve (0.98 +/- 7.4 versus 0.35 +/- 0.30 and 0.41 +/- 0.29 s-1; p < 0.005). These respiratory responses developed without a change in postoperative pulmonary function (initial postoperative FEV1, 1.83 +/- 0.65 L versus last postoperative FEV1, 1.96 +/- 0.66 L; p = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

The clamshell incision: an improved approach to bilateral pulmonary and mediastinal tumor

Median sternotomy has been the accepted approach for dealing with mediastinal tumors or bilateral pulmonary disease, but exposure to the lower lobes and to mediastinal tumors extensively involving a hemithorax is often limited. Based on the reported experience from double-lung transplantation, we explored the use of clamshell incisions for these difficult problems. From March 1991 to December 1993, we prospectively studied the utility of clamshell incisions in 90 patients for the following indications: bilateral pulmonary metastases (62 patients), primary lung carcinoma with mediastinal involvement (13 patients), primary tumors of the mediastinum (14 patients), and mesothelioma (1 patient). Bilateral anterior thoracotomies with a transverse sternotomy (clamshell incision) were employed in 71 patients and a unilateral anterior thoracotomy with partial or complete median sternotomy (hemiclamshell incision) was used in 19 patients. For closure, we used pericostal sutures and sternal wires, usually augmented by sternal K-wire stents or Steinmann pins to prevent sternal override. Exposure to all areas of the mediastinum, pericardium, pleura, and lung was excellent. Specifically, the clamshell incision afforded markedly better access to lower lobe disease and hemithoracic extension of mediastinal disease than that possible with median sternotomy. There were no deaths or significant morbidity, and all patients tolerated the incisions well without mechanical respiratory difficulties. There was one wound infection. There was no late sternal override and the cosmetic results were found to be excellent during a follow-up of 2 to 33 months. We conclude that clamshell incisions constitute an improved surgical approach for the management of bilateral pulmonary or combined pulmonary and mediastinal disease.

Routine immediate direct bronchial artery revascularization for single-lung transplantation

Ischemia of the donor airway remains a significant cause of morbidity after single-lung transplantation; serious manifestations may occur early (anastomotic dehiscence) or late (stricture). Direct, immediate revascularization of the donor bronchial arteries, using the recipient internal thoracic artery, was performed in 10 consecutive recipients of single-lung transplants for whom we procured the organs. Mean recipient age was 52.6 years (range, 43 to 59 years); 6 were male and 4 female. Recipient diagnoses were emphysema (6), obliterative bronchiolitis (2), pulmonary fibrosis (1), and primary pulmonary hypertension (1). Bronchial artery revascularization initially prolonged the ischemic time by only 15 to 20 minutes; this improved with experience. There was one early death and two late deaths in the series. Internal thoracic arteriography was performed 7 to 10 days postoperatively in all 9 surviving patients. There was excellent perfusion of the donor bronchial arteries in 7 of these 9 patients. Bronchoscopy was performed when clinically indicated. No patient had early or late airway healing complications at a median follow-up of 13 months (range, 6 to 16 months). We conclude that direct, immediate bronchial artery revascularization is feasible on a routine basis for single-lung transplantation, and airway healing has been excellent.

[Lung transplantation at the Barnes Hospital in 1992]

Lung transplantation is a constantly changing form of therapy. The St. Louis Work Group is known for its contributions in the area of single lung transplant, with two highly active programs running at present, one for adults and one for children. The Group is also active in research, in the development of various methods for lung preservation, and in medium-and long-term studies. Finally, this team writes and updates the International Register of Lung Transplants, which brings together the vast majority of operations of this type done worldwide. The Register permits control of results of lung transplant operations as well as the assessment of future alternatives.

Lung transplantation for chemotherapy-induced pulmonary fibrosis

A 26-year-old man cured of childhood acute lymphoblastic leukemia underwent a single lung transplant for drug-induced pulmonary toxicity 9 years after the completion of chemotherapy. It is not known whether patients cured of a malignancy who undergo organ transplantation are at increased risk of malignancy as compared to other organ transplant recipients. There was no evidence of recurrent or secondary malignancy in this case. Since single lung transplantation has been effective for idiopathic pulmonary fibrosis, it should be considered for patients cured of a malignancy who develop chemotherapy-induced pulmonary fibrosis.

Donor lung procurement: assessment and operative technique

Given the relative scarcity of suitable donors and the widespread application of cardiac and pulmonary transplantation, it is imperative that a heart and two lungs be extracted from each donor. From increasing clinical experience and laboratory investigation in lung preservation, more flexible criteria for the assessment of potential lung donors are emerging. In this communication, we present our current criteria of donor lung suitability, and a simple and reliable technique of combined cardiopulmonary extraction that has provided suitable heart and lung grafts with excellent preservation, used in our last 150 donor organ procurements.