Lung transplantation for pulmonary vascular disease

Pediatric Lung Transplantation for Pulmonary Vascular Diseases: Recent Advances and Challenges

Pediatric lung transplantation for pulmonary vascular diseases has seen notable advancements and trends. Medical therapies, surgical options, and bridging techniques like extracorporeal membrane oxygenation and different forms of transplants have expanded treatment possibilities. Current challenges include ensuring patient adherence to post-transplant therapies, addressing complications like primary graft dysfunction and rejection, and conducting further research in less common conditions like pulmonary veno-occlusive disease and pulmonary vein stenosis. In this review article, the authors will explore the advancements, emerging trends, and persistent challenges in pediatric lung transplantation for pulmonary vascular diseases.

Lung Transplantation in Pulmonary Arterial Hypertension: The Portuguese Experience

BACKGROUND

In patients with pulmonary arterial hypertension (PAH), refractory to medical therapy, lung transplantation emerges as an option. This study describes the outcomes of 8 PAH patients who underwent lung transplantation.

METHODS

A retrospective, single-center study was conducted among patients with PAH who underwent lung transplantation in our center.

RESULTS

Patients had a median age of 46 years, with female sex predominance (75%). Causes of HAP were pulmonary veno-occlusive disease (n = 5, 62.5%), idiopathic PAH (n = 2, 25%), and heritable PAH (n = 1, 12.5%). Pre-transplant hemodynamics revealed a median mean pulmonary artery pressure of 58.5 mm Hg (48-86). All patients received bilateral lung transplants with extracorporeal membrane oxygenation support, displaying immediate post-transplant hemodynamic improvement. Primary graft dysfunction grade 3 (PGD 3) was observed in 75% of patients. Five patients (62.5%) died, with a 72.9% survival at 12 months and 29.2% at 24 months post-transplantation.

CONCLUSION

Our study reveals the complexity and challenges of lung transplants in patients with PAH. Despite notable immediate hemodynamic improvements, high rates of PGD 3 and the survival rate remain a concern. Further research to define optimal peri and post-transplant management to improve survival is required.

Explanatory deep learning to predict elevated pulmonary artery pressure in children with ventricular septal defects using standard chest x-rays: a novel approach

Objective

Early risk assessment of pulmonary arterial hypertension (PAH) in patients with congenital heart disease (CHD) is crucial to ensure timely treatment. We hypothesize that applying artificial intelligence (AI) to chest x-rays (CXRs) could identify the future risk of PAH in patients with ventricular septal defect (VSD).

Methods

A total of 831 VSD patients (161 PAH-VSD, 670 nonPAH-VSD) was retrospectively included. A residual neural networks (ResNet) was trained for classify VSD patients with different outcomes based on chest radiographs. The endpoint of this study was the occurrence of PAH in VSD children before or after surgery.

Results

In the validation set, the AI algorithm achieved an area under the curve (AUC) of 0.82. In an independent test set, the AI algorithm significantly outperformed human observers in terms of AUC (0.81 vs. 0.65). Class Activation Mapping (CAM) images demonstrated the model's attention focused on the pulmonary artery segment.

Conclusion

The preliminary findings of this study suggest that the application of artificial intelligence to chest x-rays in VSD patients can effectively identify the risk of PAH.

Single Lung Transplant for Secondary Pulmonary Hypertension: The Right Option for the Right Patient

Introduction: The optimal treatment for Secondary Pulmonary Hypertension from End-Stage Lung Disease remains controversial. Double Lung Transplantation is widely regarded as the treatment of choice as it eliminates all diseased parenchyma and introduces a large volume of physiologically normal allograft. By comparison, the role of single lung transplantation for pulmonary hypertension (PAH) is less clear. The remaining diseased lung will limit clinical improvements and permit downstream sequelae; including residual cough, recurrent infection, and continued pulmonary hypertension. But not every patient can undergo DLT. Advanced age, frailty, co-morbid conditions, and limited availability of organs will all affect surgical candidacy and can offset the benefits of double lung procedures. Studies that compare SLT and DLT do not commonly explore the utility of single lung procedures even though multiple theoretical advantages exist; including reduced waiting times, less waitlist mortality, fewer surgical complications, and lower operative mortality. Worse, multiple forms of publication and selection bias may favor DLT in registry-based studies. In this review, we present the prevailing literature on single and double lung transplants in patients with secondary pulmonary hypertension and clarify the potential utility of these procedures. Materials and Methods: A PubMed search for English-language articles exploring single and double lung transplants in the setting of secondary pulmonary hypertension was conducted from 1990 to 2023. Key words included "single lung transplant", "double lung transplant", "pulmonary hypertension", "rejection", "complications", "extracorporeal membranous oxygenation", "death", and all appropriate Boolean operators. We prioritized research from retrospective studies that evaluated clinical outcomes from single centers. Conclusions: The question is not whether DLT is better at resolving lung disease; instead, we must ask if SLT is an acceptable form of therapy in a select group of high-risk patients. Further research should focus on how best to identify recipients that may benefit from each type of procedure, and the clinical utility of perioperative VA ECMO.

Pharmacotherapy of refractory pulmonary arterial hypertension

INTRODUCTION

Treatment of refractory pulmonary arterial hypertension (PAH) is challenging and rarely the focus of reviews. The purpose of this review is to discuss current treatment options of refractory PAH, along with the state of research of several new medications.

AREAS COVERED

We conducted a comprehensive PubMed search on the relevant literature on treating PAH, with a focus on approved and investigational interventions for high-risk patients. Our strategy used keywords 'Treatment' AND 'Pulmonary Hypertension,' without date restrictions, ensuring a thorough survey of available literature for our review.

EXPERT OPINION

By utilizing serial risk assessment to identify patients remaining intermediate or high-risk, more patients are likely to survive longer. This is done by earlier use of combination or triple therapy with prostacyclin drugs. Current medications for PAH are all essentially vasodilators that improve physiology, but do not truly modify the disease process. The potential application of new investigational medications is exciting as they work by novel pathways likely to change the landscape of refractory PAH treatment.

Lung transplantation as an intervention for pediatric pulmonary hypertension

Lung transplantation is a treatment option for selected children with end-stage lung disease and pulmonary vascular disorders. Overall, pulmonary hypertension (PH) is the second most frequent indication for infants and children requiring lung transplants. In pediatric PH patients, timing for listing remains a difficult decision due to patient heterogeneity and varying allocation policies across different countries. Furthermore, perioperative management can be challenging, making interdisciplinary collaboration among surgical, anesthesiology, critical care, and lung transplant teams essential. Because pediatric PH patients typically have preserved cardiac index and exercise tolerance even with advanced disease, they should be referred early even if they do not meet the criteria for listing of primarily adults by International Society for Heart and Lung Transplantation (ISHLT) published in 2015: New York Heart Association (NYHA) functional class III or IV without improvement, cardiac index < 2 L/min/m² , mean right atrial pressure of >15 mmHg. Bridging strategies with extracorporeal support should be determined at the time of listing in anticipation of possible clinical deterioration. Bilateral lung transplantation using cardiopulmonary bypass to provide hemodynamic stability is nowadays the standard surgical approach in pediatric centers. The immediate post-transplant period is characterized by dramatic changes in the right ventricle (RV) and and left ventricle (LV) anatomy and physiology, which can be life-threatening. Induction, immunosuppression, prophylaxis, and surveillance are not different from patients without PH. Overall, outcomes in pediatric lung and heart-lung transplant patients for PH are not different from those children undergoing transplantation for other indications. In fact, long-term survival is superior in children with idiopathic PH compared to other diseases, providing most recipients with improved quality of life.

Transplant Operative Considerations in Pulmonary Hypertension With Severe Right Heart Failure

Over the past several decades, the operation of choice for end-stage lung disease secondary to severe pulmonary hypertension (PH) has shifted from heart-lung transplantation (HLT) to bilateral lung transplantation (BLT). This change has maintained excellent long-term outcomes and is appropriate for the majority of patients presenting with end-stage disease in need of transplantation. However, a distinct subset of patients with severe PH have an excessive early mortality within 90 days of transplantation. Based on the different causes of this early mortality compared to BLT recipients with other indications, right heart failure and refractory primary graft dysfunction appear to play a significant role. It is therefore critical to identify this subset of patient during their evaluation for transplant. This distinction would allow specific patient referral for HLT, which may mitigate those causes of early mortality. Similarly, there is a subgroup of BLT recipients for severe PH that fail to recover right ventricular function, with suboptimal long-term functional status that is independent of early survival. Identification and referral for HLT of these patients may also be important. In this manuscript, we describe our institutional approach and consideration for the risks of early mortality from right heart failure and primary graft dysfunction, as well failure of right ventricular recovery long term. The described evaluation is used to ascertain those patients with severe PH who may benefit from an HLT over BLT.

Left Ventricular Dysfunction After Lung Transplantation for Pulmonary Arterial Hypertension

BACKGROUND

Lung transplantation (LT) is the final treatment option for patients with pulmonary arterial hypertension (PAH). Perioperative challenges after LT are unique and commonly include excessive bleeding, arrhythmias, and primary graft dysfunction. Transient left ventricular dysfunction (LVD) is a known postoperative complication, but not fully explored. We describe our experiences at a single institution.

METHODS

We reviewed our database for patients with PAH who underwent LT from July 2008 to July 2012. The data were analyzed for preoperative inotrope use, intravenous prostacyclin, cardiac catheterization, and imaging. Also measured were perioperative ischemic time, bypass time, primary graft dysfunction, ventilator days, length of stay, and mortality. LVD is defined as acute cardiopulmonary compromise (acute worsening of hypoxia with new bilateral infiltrates on imaging) with a drop in LV systolic function of 15% from baseline. We compared data between patients with LVD and without LVD.

RESULTS

Sixteen patients met the criteria, the majority of patients (10) with World Health Organization (WHO) group 1 PAH. Thirteen received intravenous prostacyclin therapy, and 6 required inotropes before surgery. Five patients (31%) developed LVD after transplantation. Average time to onset of LVD was 4.2 days. Preoperative vasopressors were required in 60% of those developing LVD. Patients with LVD had lower right and left ventricular ejection fraction with higher left ventricular end diastolic volume before surgery. All patients recovered from LVD within 4 months after LT.

CONCLUSIONS

LVD is a phenomenon observed mostly in patients with WHO group 1 PAH receiving LT. Prompt recognition and treatment of this condition reduced morbidity.

Risks and Epidemiology of Infections After Lung or Heart–Lung Transplantation

Nowadays, lung transplantation is an established treatment option of end-stage pulmonary parenchymal and vascular disease. Post-transplant infections are a significant contributor to overall morbidity and mortality in the lung transplant recipient that, in turn, are higher than in other solid organ transplant recipients. This is likely due to several specific factors such as the constant exposure to the outside environment and the colonized native airway, and the disruption of usual mechanisms of defense including the cough reflex, bronchial circulation, and lymphatic drainage. This chapter will review the common infections that develop in the lung or heart–lung transplant recipient, including the general risk factors for infection in this population, and specific features of prophylaxis and treatment for the most frequent bacterial, viral, and fungal infections. The effects of infection on lung transplant rejection will also be discussed.

Pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic and progressive disease leading to right heart failure and ultimately death if untreated. The first classification of PH was proposed in 1973. In 2008, the fourth World Symposium on PH held in Dana Point (California, USA) revised previous classifications. Currently, PH is devided into five subgroups. Group 1 includes patients suffering from idiopathic or familial PAH with or without germline mutations. Patients with a diagnosis of PAH should systematically been screened regarding to underlying mutations of BMPR2 gene (bone morphogenetic protein receptor type 2) or more rarely of ACVRL1 (activine receptor-like kinase type 1), ENG (endogline) or Smad8 genes. Pulmonary veno occusive disease and pulmonary capillary hemagiomatosis are individualized and designated as clinical group 1'. Group 2 'Pulmonary hypertension due to left heart diseases' is divided into three sub-groups: systolic dysfonction, diastolic dysfonction and valvular dysfonction. Group 3 'Pulmonary hypertension due to respiratory diseases' includes a heterogenous subgroup of respiratory diseases like PH due to pulmonary fibrosis, COPD, lung emphysema or interstitial lung disease for exemple. Group 4 includes chronic thromboembolic pulmonary hypertension without any distinction of proximal or distal forms. Group 5 regroup PH patients with unclear multifactorial mechanisms. Invasive hemodynamic assessment with right heart catheterization is requested to confirm the definite diagnosis of PH showing a resting mean pulmonary artery pressure (mPAP) of ≥ 25 mmHg and a normal pulmonary capillary wedge pressure (PCWP) of ≤ 15 mmHg. The assessment of PCWP may allow the distinction between pre-capillary and post-capillary PH (PCWP > 15 mmHg). Echocardiography is an important tool in the management of patients with underlying suspicion of PH. The European Society of Cardiology and the European Respiratory Society (ESC-ERS) guidelines specify its role, essentially in the screening proposing criteria for estimating the presence of PH mainly based on tricuspid regurgitation peak velocity and systolic artery pressure (sPAP). The therapy of PAH consists of non-specific drugs including oral anticoagulation and diuretics as well as PAH specific therapy. Diuretics are one of the most important treatment in the setting of PH because right heart failure leads to fluid retention, hepatic congestion, ascites and peripheral edema. Current recommendations propose oral anticoagulation aiming for targeting an International Normalized Ratio (INR) between 1.5-2.5. Target INR for patients displaying chronic thromboembolic PH is between 2–3. Better understanding in pathophysiological mechanisms of PH over the past quarter of a century has led to the development of medical therapeutics, even though no cure for PAH exists. Several specific therapeutic agents were developed for the medical management of PAH including prostanoids (epoprostenol, trepoprostenil, iloprost), endothelin receptor antagonists (bosentan, ambrisentan) and phosphodiesterase type 5 inhibitors (sildenafil, tadalafil). This review discusses the current state of art regarding to epidemiologic aspects of PH, diagnostic approaches and the current classification of PH. In addition, currently available specific PAH therapy is discussed as well as future treatments.

Pulmonary hypertension complicated by pericardial effusion: a single center experience

BACKGROUND

Pericardial effusion is an independent predictor of mortality in patients with pulmonary arterial hypertension (PAH). However, the management and outcomes of patients with pulmonary hypertension (PH) and pericardial effusion are not well described.

METHODS

A retrospective, observational study was conducted at Baylor College of Medicine and The Methodist Hospital by screening all patients admitted between 1 June 2005 and 1 June 2010 with the International Classification of Diseases, ninth revision codes for PH and pericardial effusion. A total of 138 patients were identified, and 103 patients were excluded on the basis of valvular heart disease, recent surgery or end-stage renal disease. Thirty-five patients with PH diagnosed by a historical right heart catheterization or echocardiography and with documented pericardial effusion were included in this analysis. Demographic, hemodynamic, laboratory and survival data were collected.

RESULTS

The mean age was 49.5±36 years (mean ± standard deviation), 31 of 35 patients were women (93%) and pulmonary artery systolic pressure was 77 ± 19 mmHg. Mean follow-up period was 20.5 ± 12.9 months. Fifteen patients had PAH associated with connective tissue disease (50%). The majority of the patients (87%) with pericardial effusion were managed conservatively. Four patients (13%) who were hemodynamically unstable underwent pericardial window placement. One of them was started on epoprostenol, and two patients had the doses of PAH-specific medications uptitrated. Three of four pericardial window patients survived to the conclusion of the follow-up period. The overall survival in our cohort was 60%, with three patients lost to follow-up.

CONCLUSIONS

Connective tissue disease associated PAH and female sex were predominant in our cohort of patients with pericardial effusion. Seventy-five percent of patients who were treated with pericardial window for hemodynamically unstable pericardial effusion survived until the end of the study period. Pericardial window may be a therapeutic option in patients with unstable PH with pericardial effusion. Further studies are needed to determine the optimal treatment strategy for such patients.

Current status of lung transplantation

Lung transplantation is a well-established treatment option for selected patients with end-stage lung disease, leading to improved survival and improved quality of life. The last 20 years have seen a steady growth in number of lung transplantation procedures performed worldwide. The increase in clinical activity has been associated with tremendous progress in the understanding of cellular and molecular processes that limit both short- and long-term outcomes. This review gives a comprehensive overview of the current status of lung transplantation for the referring physician. It demonstrates that careful selection of potential recipients, optimisation of their condition prior to transplant, use of carefully assessed donor organs, excellent surgery and meticulous long-term follow-up are all essential ingredients in determining a successful outcome.

Lung transplantation for pulmonary hypertension

Although medical therapies for pulmonary arterial hypertension have greatly improved, it remains a chronic and fatal disease. For patients who are refractory to medical therapy, lung transplantation is an important treatment option. This review discusses issues pertaining to indications for transplant, preparation for transplant and listing, operative issues, and outcomes for patients with pulmonary arterial hypertension.

Lung transplantation in children with idiopathic pulmonary arterial hypertension: an 18-year experience

BACKGROUND

The natural history of idiopathic pulmonary arterial hypertension (IPAH) in patients of all ages is one of relentless progression. For those who fail medical therapy, lung transplantation remains the ultimate palliation. In the USA, IPAH is the second leading indication for lung transplantation in children and first for children 1 to 5 years of age. In this study, we report our 18-year experience with lung transplantation in children with IPAH.

METHODS

We performed a retrospective chart review of children with IPAH listed for lung transplant at our center between 1991 and 2009. Our data reflect a total of 26 children ranging in age from 1.6 to 18.9 years. Nineteen were transplanted and 7 died while waiting (27%). The impact of a number of pre-transplant variables on survival was evaluated.

RESULTS

Median survival for those transplanted was 5.8 years, with 1- and 5-year survival rates of 95% and 61%, respectively. Survival was independent of pre-transplant considerations such as age, weight, need for intravenous (IV) inotropes, use of IV pulmonary vasodilators, year of transplant and severity of right-sided cardiac pressures. There was 1 hospital death. Compared with the transplanted group, children who died waiting had a significantly higher incidence of supra-systemic right heart pressures (p = 0.02) and hemoptysis (p = 0.01).

CONCLUSIONS

Our study is the largest to date to look at outcomes for lung transplantation in children with IPAH. Their median survival compares favorably with that of all pediatric lung transplant recipients, 5.8 years vs 4.5 years, respectively. We did not identify any pre-transplant variables that presaged a poorer outcome. Thus, survival seemed more related to factors that influence long-term outcomes in all transplant recipients such as rejection and infection. Lung transplantation remains a viable option for children with IPAH, especially for those with supra-systemic right heart pressures despite maximal medical therapy.

[Surgical treatment of pulmonary arterial hypertension]

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a severe disease that has undergone a dramatic improvement in therapeutic management over the past 20 years. Among the new therapeutic options, surgery has the potential to dramatically improve or, in some cases, cure PAH.

BACKGROUND

Surgical treatment of PAH includes pulmonary endarterectomy which can cure PAH when the cause is obstruction of the pulmonary arteries by fibrous tissue resulting from pulmonary embolism, by tumours as angiosarcomas, and echinococcus cysts. Transplantation is required in end-stage PAH after failure of medical treatment. Atrial septostomy and Potts procedure are palliative surgical procedures that can delay transplantation.

VIEWPOINT

Extracorporeal cardiopulmonary support is the latest surgical improvement, not only as a bridge to transplantation in end-stage PAH but also during recovery after transplantation or pulmonary endarterectomy.

CONCLUSIONS

Surgery is part of the therapeutic management of PAH. Dialogue between physicians and surgeons is a prerequisite for any reasoned therapeutic decision.

Medical and surgical treatment of acute right ventricular failure

Acute right ventricular (RV) failure is a frequent and serious clinical challenge in the intensive care unit. It is usually seen as a consequence of left ventricular failure, pulmonary embolism, pulmonary hypertension, sepsis, acute lung injury or after cardiothoracic surgery. The presence of acute RV failure not only carries substantial morbidity and mortality, but also complicates the use of commonly used treatment strategies in critically ill patients. In contrast to the left ventricle, the RV remains relatively understudied, and investigations of the treatment of isolated RV failure are rare and usually limited to nonrandomized observations. We searched PubMed for papers in the English language by using the search words right ventricle, right ventricular failure, pulmonary hypertension, sepsis, shock, acute lung injury, cardiothoracic surgery, mechanical ventilation, vasopressors, inotropes, and pulmonary vasodilators. These were used in various combinations. We read the abstracts of the relevant titles to confirm their relevance, and the full papers were then extracted. References from extracted papers were checked for any additional relevant papers. This review summarizes the general measures, ventilation strategies, vasoactive substances, and surgical as well as mechanical approaches that are currently used or actively investigated in the treatment of the acutely failing RV.

Lung transplantation for pulmonary hypertension in children

Lung and heart-lung transplantation are accepted treatments for children with end-stage pulmonary vascular disease. This is a review of the current literature and our own experience with lung and heart-lung transplantation for children with pulmonary hypertension of a variety of causes. I reviewed the pertinent literature and our lung transplant database to acquire information and data regarding this subject. The patients include those at St. Louis Children's Hospital as well as those reported from other institutions. The major operative complications include those related to the surgical procedure itself (vascular and airway anastomotic stenoses) and those related to graft dysfunction. The 3- and 5-yr survival is approximately 60% and 50%, respectively, for children undergoing lung transplantation for pulmonary hypertension.Although these survival statistics are somewhat poor, transplantation remains the only viable alternative for children with end-stage pulmonary vascular disease failing to respond to medical therapy.

Pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a devastating disease with significant disability and mortality, and it has much higher prevalence than previously thought. During the past 15 years, we have witnessed remarkable advances in our understanding of pathogenesis, in diagnostic process and in the development of disease-specific treatments for PAH. Nowadays, the diagnosis is more clearly defined, non-invasive markers of disease severity can be widely applied, and finally we can adopt evidence-based treatment. Newer drugs availability has resulted in radical change in the management of this disease. The article reviews established approaches to evaluation and treatment of this disorder.

[Oxygen therapy in acute and chronic conditions: Indications, oxygen systems, assessement and follow-up]

Oxygen therapy has become a major tool for infants with acute and chronic respiratory failure. Appropriate goals when prescribing supplemental oxygen are reduction and prevention of hypoxemia, prevention and treatment of pulmonary hypertension and decrease in respiratory and cardiac overload. This is commonplace in the acute setting and is also becoming widespread in chronic pathologies. However, there is a lack of consensus on many fundamental issues, such as appropriate indications, desirable targets and outcome measures amongst centres, reflecting a variety of clinical practices. The Techniques Group of the Spanish Society of Pediatric Pneumology undertook to design recommendations for a rational approach to oxygen therapy, reviewing the existing literature in order to establish its indications, benefits and potential risks as well as its cost-effectivenes. General aspects of oxygen treatment are reviewed including physiological mechanisms, indications, delivery systems and assessment methods. Management of patients on home oxygen therapy is also addressed with discussion of benefits and potential risks of supplemental oxygen use.

Thioredoxin as a biomarker for graft rejection in lung transplant recipients

Primary graft dysfunction and rejection are common complications in lung transplant recipients. Increased expression of thioredoxin-1 (Trx), a 12-kDa redox-regulatory protein, has been reported in multiple lung pathophysiological conditions involving oxidative and inflammatory mediated injury including graft rejection in canine and rat models of lung transplantation. Our objective was to determine whether increased Trx expression is associated with progression of rejection pathophysiology in human lung transplant recipients. Bronchoalveolar lavage (BAL) fluid and transbronchial biopsy samples were collected as a routine part of post-transplant clinical care from 18 lung transplant patients from our adult lung transplant programme. Lung transplant recipient profile included age/sex, ethnic background, days on ventilator, total ischaemic time, and cytomegalovirus (CMV) status. Based on histopathological grading criteria, patients were divided into two groups, rejecting (A1/A2 or B1) and non-rejecting (A0/B0). Rejecting and non-rejecting group total BAL cell counts and differential cell counts for neutrophils, macrophages, lymphocytes and eosinophils as well as total BAL cell Trx levels were analysed. Total BAL cell counts were significantly (p <0.05) elevated in graft rejecting versus non-rejecting patients. Differential BAL macrophage counts were comparable in rejection and non-rejection groups, whereas there were significant increases in neutrophils and lymphocytes but not eosinophils in patients with rejection versus non-rejection pathology (p <0.05). Total ischaemic time and days on ventilator in rejection and non-rejection groups were comparable. However, Trx levels were significantly elevated in BAL cells from graft-rejecting patients compared with non-rejecting patients (p <0.05). These data suggest that surveillance monitoring of BAL Trx levels after lung transplantation can serve as a biomarker to assess severity of graft rejection.

Priming donor lungs with thioredoxin-1 attenuates acute allograft injury in a rat model of lung transplantation

BACKGROUND

Lung graft dysfunction and rejection are significant causes of morbidity and mortality in transplant recipients. Thioredoxin-1, a redox-regulatory protein, functions as an antioxidant in multiple organs, including lungs. We examined whether priming of the donor lungs with thioredoxin-1 before transplantation attenuates acute lung injury.

METHODS

Orthotopic left lung transplantation was performed from Lewis (donor) to Sprague-Dawley (recipient) rats. Donor lungs were perfused and stored in Perfadex solution (Vitrolife, Uppsala, Sweden), with or without purified thioredoxin-1. Changes in bronchoalveolar lavage (BAL) analysis, allograft oxygen exchange function, nuclear factor kappaB (NF-kappaB)/DNA binding, myeloperoxidase activities, and immunohistologic evaluation of neutrophils, macrophages, and cytotoxic T-cells (CD8(+)) infiltration were examined in post-transplant allograft (left) and native (right) lungs at Days 1 and 5.

RESULTS

BAL cell differential analysis showed significant increases in macrophages and neutrophils in allografts at Day 1 post-transplant. At Days 1 and 5, lymphocyte infiltration was significantly increased and myeloperoxidase and NF-kappaB/DNA binding activities were increased vs basal activities. Immunohistology staining revealed increased infiltration of macrophages, neutrophils, and CD8(+) T cell sub-sets. Pre-transplant priming of donor lungs with thioredoxin-1 improved oxygen exchange and attenuated NF-kappaB/DNA binding activity, and infiltration of macrophages, neutrophils, and CD8(+) T cell sub-sets in allografts at Days 1 and 5 post-transplant.

CONCLUSIONS

Priming of donor lungs with thioredoxin-1 before transplant attenuates acute allograft injury in a rat model of lung transplantation, and appears to be associated with the antioxidant function of thioredoxin-1 that limits early ischemia-reperfusion injury, NF-kappaB activation, and progressive infiltration of inflammatory and immune cells in allografts.

Review: Therapeutic advances in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction, in situ thrombosis, and vascular remodeling of small pulmonary arteries inducing increased pulmonary arterial resistance. Conventional treatment is based on life style modification and nonspecific treatment (warfarine, diuretics, oxygen). Calcium channel blockers are vasodilatators that have been shown to be of great efficacy in a very specific subpopulation of patients with PAH. For the majority of patients, specific PAH therapies are still lacking. Numerous studies evaluating prostacyclin agonists, endothelin-receptor antagonists, and phosphodiesterase type 5 inhibitors are now available to guide therapeutic choices. Despite those important advances there is still no cure for PAH. Fortunately, research is ongoing and many drugs show promises.

Cardiovascular consequences of pulmonary hypertension

Pulmonary hypertension occurs when pulmonary vascular pressures are elevated. Pulmonary arterial hypertension is associated with occlusion of the pulmonary arterial tree, while pulmonary venous hypertension is seen when pulmonary vein outflow is impeded. Cardiovascular consequences are common with pulmonary hypertension, regardless of the underlying pathogenesis and whether management is complex. However, there are a number of interventions that may improve quality of life and survival of pulmonary hypertension. This article discusses current recommendations for diagnosis and management.

Lung transplantation and pulmonary hypertension

The presence of pulmonary hypertension affects lung transplantation in multiple ways, from patient selection, transplant risks, type of transplant, intraoperative management, to transplant outcome. A working knowledge of natural disease progression, the latest medical treatment options, and transplant outcome is critical in patient selection, and a good understanding of the transplant process, including the new transplant allocation system, is important for physicians involved in the care of patients with pulmonary arterial hypertension. The complexity of these factors underscores the importance of good communication between referring physicians and transplant centers.

Surgical therapies for pulmonary arterial hypertension

Surgical therapies for the treatment of pulmonary arterial hypertension typically are reserved for patients who are deemed to be refractory to medical therapy and have evidence of progressive right-sided heart failure. Atrial septostomy, a primarily palliative procedure, may stave off hemodynamic collapse from right-sided heart failure long enough to permit a more definitive surgical treatment such as lung or combined heart-lung transplantation. This article discusses indications for and results of atrial septostomy and lung and heart-lung transplantation in patients who have pulmonary arterial hypertension.

A rational approach to home oxygen use in infants and children

The provision of supplemental oxygen for infants and children with hypoxaemia is expensive but advantageous because it facilitates earlier discharge from hospital and enhances quality of life in the home setting. It is seen as potentially cost effective and family friendly. However, the prescription of supplemental oxygen varies greatly between neonatologists, paediatric respiratory physicians and paediatric cardiologists. There is a lack of consensus on appropriate indications for prescribing oxygen, desirable oxygen targets and clinically significant immediate and longer-term outcome measures. Of the limited studies available, most are small studies reporting the treatment of infants with chronic neonatal lung disease with inconsistent outcome measures. Such data are not readily extrapolated to older children, who are also poorly served by existing data in adult studies. Further delineation of the indications for home oxygen therapy is required together with appropriately designed and funded multicentre trials to provide evidence for optimal oxygen therapy.

Reversal of idiopathic pulmonary arterial hypertension and allograft pneumonectomy after single lung transplantation

Prior to the advent of effective medical therapies, the only treatment option for patients with idiopathic pulmonary arterial hypertension (IPAH) was lung transplantation. We present the case of a woman who underwent single-lung transplantation for the treatment of IPAH > 10 years ago in whom chronic rejection developed. Despite complete obliteration of the allograft, it was noted that her PA pressure levels had almost normalized. Therefore, an allograft pneumonectomy was performed. To our knowledge, this is the first reported case of the regression of pulmonary vascular disease following lung transplantation with subsequent successful removal of the allograft.

Public funding of bosentan for the treatment of pulmonary artery hypertension in Australia: cost effectiveness and risk sharing

OBJECTIVES

In Australia, no therapeutic agents were subsidised for the treatment of idiopathic pulmonary artery hypertension (iPAH), a rare progressive and severe disease with short life expectancy, until 1 March 2004, when bosentan (a dual endothelin receptor antagonist of high cost) was listed on the Pharmaceutical Benefits Scheme (PBS). Bosentan, in addition to conventional therapy, has been shown to slow iPAH progression and improve clinical and haemodynamic status and symptomatology, compared with placebo and conventional therapy. The objective of this paper is to describe the process of the Australian Pharmaceutical Benefits Scheme listing for bosentan (Tracleer), which included a health economic model assessing the cost effectiveness of bosentan from a healthcare payer perspective, and a risk-sharing arrangement based on the establishment of a patient registry.

METHODS

The health economic model predicted the cost, hospitalisation and mortality rates of a population of iPAH patients treated with either the conventional therapy regimen used in Australia or bosentan plus the conventional therapy regimen. The model was implemented as a first-order Monte Carlo simulation with mortality modelled directly as the main clinical outcome. The impacts of proposed continuation criteria, restricting the ongoing use of the drug, were evaluated. Costs and outcomes were discounted at 5% and a sensitivity analysis examined the robustness of the key assumptions.

RESULTS

The model predicted that after 5, 10 and 15 years, the difference in average cumulative costs between bosentan plus conventional therapy and conventional therapy alone would be 116,929 Australian dollars (A dollars), A181,808 dollars and A216,331 dollars for each patient, respectively. There would be an associated increase in average life expectancy of 1.39, 2.93 and 3.87 years at 5, 10 and 15 years, respectively, with an incremental cost-effectiveness ratio at 15 years of A55,927 dollars for each life-year gained. Removing the continuation criteria from the model increased the incremental cost-effectiveness ratio to A62,267 dollars (1996-2002 values).

CONCLUSIONS

Economic modelling based on improved survival suggests bosentan to be a potentially cost-effective treatment for iPAH. However, the structure of the model and its inputs should be reviewed and updated as more data become available.

Traitement de l’hypertension artérielle pulmonaire

Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction, in situ thrombosis, and vascular remodeling of small pulmonary arteries. It induces a fixed pulmonary arterial obstruction, persistent elevation of pulmonary arterial resistance, and eventually right heart failure. Conventional therapy is based on simple measures (exercise limitation) and nonspecific treatments (warfarin, diuretics, and oxygen). Pure vasodilators, such as calcium channel blockers, are effective only in a minority of patients who have an acute response to vasodilator testing. Intravenous prostacyclin (epoprostenol) and endothelin receptor blockers have vasodilator and antiproliferative properties. Epoprostenol therapy has significantly improved PAH prognosis and remains the first-line treatment for patients with the most severe disease. Bosentan is an interesting first-line treatment for NYHA functional class III patients. Availability of novel specific drugs (endothelin receptor type A antagonists, prostacyclin analogues, type 5 phosphodiesterase inhibitors) is opening new perspectives in PAH treatment. The long-term benefit of these drugs remains to be evaluated and their respective place in treatment of these patients is still uncertain. The evolution of therapy from vasodilators to antiproliferative agents reflects the advancement in our understanding of the mechanisms mediating pulmonary arterial hypertension.

The right ventricle in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a term used to classify a variety of conditions that share in common an injury to the pulmonary vasculature that produces elevations in pulmonary arterial pressure. However, it is the integrity of right ventricular function, rather than the degree of vascular injury, that is the major determinant of symptoms and survival in PAH. The article will review the normal structure and function of the right ventricle and summarize the impact of PAH and its treatments on right ventricular function.

[Treatments for pulmonary arterial hypertension]

PURPOSE

Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction, in situ thrombosis and vascular remodeling of small pulmonary arteries inducing a fixed pulmonary arterial obstruction and persistent elevation of pulmonary arterial resistance. Conventional treatment is based on simple measures (exercise limitation) and non-specific drugs (warfarine, diuretics, oxygen).

CURRENT KNOWLEDGE AND KEY POINTS

Pure vasodilators like calcium channel antagonists have little or no effect on the vast majority of patients, presumably because fixed pulmonary arteriopathy predominate over vasoconstriction. Intravenous prostacyclin (epoprostenol) and endothelin receptor antagonists have vasodilator and antiproliferative properties. Epoprostenol therapy has resulted in significant improvements in prognosis of this disease and this drug remains the first-line treatment of the most severe patients. Bosentan is an interesting first-line treatment for NYHA functional class III patients. Availability of novel specific drugs (endothelin receptor type A antagonists, prostacyclin analogues, type 5 phosphodiesterase inhibitors) open new perspectives in treatment of PAH. The long-term benefit of these drugs remains to be evaluated and their respective place in treatment of these patients is still uncertain. We here present the different therapeutic alternatives available in the PAH and propose an algorithm for treatment of these patients.

FUTURE PROSPECTS AND PROJECTS

The evolution of therapy from vasodilators to antiproliferative agents reflects the advancement in our understanding of the mechanisms mediating pulmonary arterial hypertension.

The transplant recipient for nontransplant surgery

The transplant recipient has traded a life-threatening illness for a chronically immunosuppressed state. Subsequent anesthetic management for non-transplant surgical procedures may be challenging. The anesthesia provider must be aware of the degree of post-transplant organ dysfunction and alter anesthesia techniques accordingly. This article reviews the anesthetic concerns for patients who have undergone a variety of organ transplants.

Pulmonary capillary haemangiomatosis in children and adolescents: report of a new case and a review of the literature

Pulmonary capillary haemangiomatosis (PCH) in childhood is a rarity, characterised by the uncontrolled proliferation of pulmonary microvessels which may invade pulmonary, bronchial and vascular structures, resulting in diffuse alveolar haemorrhage, manifesting clinically in haemoptysis, dyspnoea and symptoms of pulmonary hypertension (PH). A 14-year-old boy with some particular features (pericardial effusion and thrombocytopenia) is presented and 14 paediatric/adolescent cases from the literature are surveyed. The diagnostic problems and difficulties are discussed, including the importance of imaging (high-resolution CT) and histopathological studies, with the aim of providing a clear-cut distinction of PCH from other conditions such as primary PH (PPH). The literature data can be regarded as ambiguous: both similarities and relatively sharp distinctions between PCH and PPH are to be found. New developments in the field of genetics are also discussed. The early coexistence of PCH and other (vascular) disorders and associations, involving focal or diffuse, disseminated forms is summarised briefly. Conclusion. The diagnosis of this progressive disorder may lead to effective therapy. Treatment possibilities include the rapidly evolving field of anti-angiogenic therapy, but at present lung transplantation is universally accepted as the final definitive treatment for pulmonary capillary haemangiomatosis.

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.

Surgical Treatments/Interventions for Pulmonary Arterial Hypertension

While considerable advances have been achieved in the medical treatment of pulmonary arterial hypertension (PAH) over the past decade, surgical and interventional approaches continue to have important roles in those patients for whom medical therapy is unavailable or has been unsuccessful. These techniques include pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension, thoracic transplantation, and atrial septostomy. This chapter will provide evidence-based recommendations for the selection and timing of surgical and interventional treatments of PAH for physicians involved in the care of these complex patients.