Advanced Pulmonary Vascular Disease Research Articles

Non-invasive prediction of pulmonary vascular disease-related exercise intolerance and survival in non-group 1 pulmonary hypertension.

The clinical utility of pulmonary hypertension (PH) risk scores in non-group 1 PH with pulmonary vascular disease (PVD) remains unresolved. We utilized the prospective multicenter PVDOMICS cohort with group 2, 3, 4 or 5 PH-related PVD and calculated group 1 PH risk scores (REVEAL 2.0, REVEAL Lite 2, French registry score and COMPERA 2). The c-statistic to predict death was compared separately in (i) pre-capillary PH groups 3/4/5, and (ii) combined post- and pre-capillary PH group 2. Exercise right heart catheterization reserve, ventricular interdependence and right ventricular-pulmonary artery (RV-PA) coupling were compared across risk categories. Among 449 individuals with group 3/4/5 PH, the REVEAL 2.0 risk score had the highest c-statistic for predicting death (0.699, 95% confidence interval [CI] 0.660-0.737, p < 0.0001) with comparable performance using the simpler REVEAL Lite 2 score (0.695, 95% CI 0.656-0.734, p < 0.0001). The French and COMPERA 2 risk scores were also predictive of mortality, but performance of both was statistically inferior to REVEAL 2.0 (c-statistic difference -0.072, 95% CI -0.123 to -0.020, p = 0.006, and -0.043, 95% CI -0.067 to -0.018, p = 0.0007, respectively). RV function and RV-PA coupling measures were prognostic in isolation, but did not add incremental value to REVEAL (p > 0.50 for all). Findings were similar in patients with group 2 PH (n = 239). Stratification by the REVEAL Lite 2 score non-invasively identified non-group 1 PH with more advanced PVD with worse exercise capacity, RV-PA uncoupling, ventricular interdependence and impaired cardiac output reserve (p < 0.05 for all). Non-invasive REVEAL risk predicts mortality in non-group 1 PH without incremental prognostic value from detailed RV function or RV-PA coupling assessment. Baseline REVEAL Lite 2 risk stratification non-invasively identifies greater pulmonary vascular dysfunction and right heart-related exercise limitation, which may help guide patient selection for targeted pulmonary vascular therapies in non-group 1 PH.

Pulmonary arterial hypertension related to congenital heart disease with a left-to-right shunt: phenotypic spectrum and approach to management.

Patients with pulmonary hypertension associated with a left-right shunt include a wide spectrum of pathophysiological substrates, ranging from those characterized by pulmonary over-circulation to those with advanced pulmonary vascular disease. The former group may benefit from shunt repair in carefully selected cases but, when advanced pulmonary vascular disease has developed, defect closure should be avoided, and pulmonary vasodilators may be used to improve effort tolerance and hemodynamics. There is a paucity of evidence, however, to support decision-making in the care of these patients. We discuss the principles of management in patients with pulmonary hypertension and a predominant left-right shunt. The recommendations and statements made in this paper are based on pathophysiological considerations and expert opinion.

Impact of diabetes mellitus on disease severity and patient survival in idiopathic pulmonary arterial hypertension: data from the Polish multicentre registry (BNP-PL)

BackgroundRecent studies revealed that alterations in glucose and lipid metabolism in idiopathic pulmonary arterial hypertension (IPAH) are associated with disease severity and poor survival. However, data regarding the impact of diabetes mellitus (DM) on the prognosis of patients with IPAH remain scarce. The aim of our study was to determine that impact using data from a national multicentre prospective pulmonary hypertension registry.MethodsWe analysed data of adult patients with IPAH from the Database of Pulmonary Hypertension in the Polish population (BNP‑PL) between March 1, 2018 and August 31, 2020. Upon admission, clinical, echocardiographic, and haemodynamic data were collected at 21 Polish IPAH reference centres. The all-cause mortality was assessed during a 30-month follow-up period. To adjust for differences in age, body mass index (BMI), and comorbidities between patients with and without DM, a 2-group propensity score matching was performed using a 1:1 pairing algorithm.ResultsA total of 532 patients with IPAH were included in the study and 25.6% were diagnosed with DM. Further matched analysis was performed in 136 patients with DM and 136 without DM. DM was associated with older age, higher BMI, more advanced exertional dyspnea, increased levels of N-terminal pro–brain natriuretic peptide, larger right atrial area, increased mean right atrial pressure, mean pulmonary artery pressure, pulmonary vascular resistance, and all-cause mortality compared with no DM.ConclusionsPatients with IPAH and DM present with more advanced pulmonary vascular disease and worse survival than counterparts without DM independently of age, BMI, and cardiovascular comorbidities.

Macitentan in the Young-Mid-term Outcomes of Patients with Pulmonary Hypertensive Vascular Diseasetreated in a Pediatric Tertiary Care Center.

Pulmonary hypertension (PH) is a severe hemodynamic condition with high morbidity and mortality. Approved targeted therapies are limited for pediatric subjects, and treatments are widely adopted from adult algorithms. Macitentan is a safe and effective drug used for adult PH, but data on pediatric patients are limited. In this prospective single-center study, we investigated mid- and long-term effects of macitentan in children with advanced pulmonary hypertensive vascular disease. Twenty-four patients were enrolled in the study for treatment with macitentan. Efficacy was determined by echo parameters and brain natriuretic peptide levels (BNP) at 3months and 1year. For detailed analysis, the entire cohort was subgrouped into patients with congenital heart disease-related PH (CHD-PH) and non-CHD-PH patients, respectively. Mean age of the patients was 10.7±7.6 years; median observation period was 36months. Twenty of 24 patients were on additional sildenafil and/or prostacyclins. Two of 24 patients discontinued because of peripheral edema. Within the entire cohort, BNP levels and all echo measures such as right ventricular systolic pressure (RVSP), right ventricular end-diastolic diameter (RVED), tricuspid annular plane systolic excursion (TAPSE), pulmonary velocity time integral (VTI), and pulmonary artery acceleration time (PAAT) improved significantly after 3months (p ≤ 0.01), whereas in the long term significant improvement persisted for BNP levels (-16%), VTI (+14%) and PAAT (+11%) (p<0.05). By subgroup analysis, non-CHD PH patients showed significant improvements in BNP levels (-57%) and all echo measures (TAPSE +21%, VTI +13%, PAAT +37%, RVSP -24%, RVED -12%) at 3months (p≤0.01), whereas at 12months, improvements persisted (p<0.05) except for RVSP and RVED (nonsignificant). In CHD-PH patients, none of the measures changed (nonsignificant). 6-MWD (distance walked in 6 minutes)slightly increased but was not statistically evaluated. Data presented herein account for the largest cohort of severely affected pediatric patients receiving macitentan. Overall, macitentan was safe and associated with significant beneficial effects and sustained positive signals after 1year, albeit in the long term disease progression remains a major concern. Our data suggest limited efficacy in CHD-related PH, whereas favorable outcomes were mainly driven by improvements in patients with PH not related to CHD. Larger studies are needed to verify these preliminary results and to prove efficacy of this drug in different pediatric PH entities.

Exercise-Induced Left Atrial Hypertension in Heart Failure With Preserved Ejection Fraction

BackgroundMany patients with heart failure and preserved ejection fraction have no overt volume overload and normal resting left atrial (LA) pressure. ObjectivesThis study sought to characterize patients with normal resting LA pressure (pulmonary capillary wedge pressure [PCWP] <15 mm Hg) but exercise-induced left atrial hypertension (EILAH). MethodsThe REDUCE LAP-HF II (A Study to Evaluate the Corvia Medical, Inc. IASD System II to Reduce Elevated Left Atrial Pressure in Patients With Heart Failure) trial randomized 626 patients with ejection fraction ≥40% and exercise PCWP ≥25 mm Hg to atrial shunt or sham procedure. The primary trial outcome, a hierarchical composite of death, heart failure hospitalization, intensification of diuretics, and change in health status was compared between patients with EILAH and those with heart failure and resting left atrial hypertension (RELAH). ResultsPatients with EILAH (29%) had similar symptom severity, but lower natriuretic peptide levels, higher 6-minute walk distance, less atrial fibrillation, lower left ventricular mass, smaller LA volumes, lower E/e′, and better LA strain. PCWP was lower at rest, but had a larger increase with exercise in EILAH. Neither group as a whole had a significant effect from shunt therapy vs sham. Patients with EILAH were more likely to have characteristics associated with atrial shunt responsiveness (peak exercise pulmonary vascular resistance <1.74 WU) and no pacemaker (63% vs 46%; P < 0.001). The win ratio for the primary outcome was 1.56 (P = 0.08) in patients with EILAH and 1.51 (P = 0.04) in those with RELAH when responder characteristics were present. ConclusionsPatients with EILAH had similar symptom severity but less advanced myocardial and pulmonary vascular disease. This important subgroup may be difficult to diagnose without invasive exercise hemodynamics, but it has characteristics associated with favorable response to atrial shunt therapy. (A Study to Evaluate the Corvia Medical, Inc. IASD System II to Reduce Elevated Left Atrial Pressure in Patients With Heart Failure [REDUCE LAP-HF TRIAL II]; NCT03088033)

Left atrial enlargement is associated with pulmonary vascular disease in heart failure with preserved ejection fraction.

Elevated left atrial (LA) pressure is a pathophysiologic hallmark of heart failure with preserved ejection fraction (HFpEF). Chronically elevated LA pressure leads to LA enlargement, which may impair LA function and increase pulmonary pressures. We sought to evaluate the relationship between LA volume and pulmonary arterial haemodynamics in patients with HFpEF. Data from 85 patients (aged 69 ± 8 years) who underwent exercise right heart catheterization and echocardiography were retrospectively analysed. All had symptoms of heart failure, left ventricular ejection fraction ≥50% and haemodynamic features of HFpEF. Patients were divided into LA volume index-based tertiles (≤34 ml/m2 , >34 to ≤45 ml/m2 , >45 ml/m2 ). A subgroup analysis was performed in patients with recorded LA global reservoir strain (n=60), with reduced strain defined as ≤24%. Age, sex, body surface area and left ventricular ejection fraction were similar between volume groups. LA volume was associated with blunted increases in cardiac output with exercise (padjusted <0.001), higher resting mean pulmonary artery pressure (padjusted =0.003), with similar wedge pressure (padjusted =1). Pulmonary vascular resistance (PVR) increased with increasing LA volume (padjusted <0.001). Larger LA volumes featured reduced LA strain (padjusted <0.001), with reduced strain associated with reduced PVR-compliance time (0.34 [0.28-0.40] vs. 0.38 [0.33-0.43], p=0.03). Increasing LA volume may be associated with more advanced pulmonary vascular disease in HFpEF, featuring higher PVR and pulmonary pressures. Reduced LA function, worse at increasing LA volumes, is associated with a disrupted PVR-compliance relationship, further augmenting impaired pulmonary haemodynamics.

A Clinical Approach to Multimodality Imaging in Pulmonary Hypertension.

Pulmonary hypertension (PH) is a clinical condition characterized by progressive elevations in mean pulmonary artery pressures and right ventricular dysfunction, associated with significant morbidity and mortality. For resting PH to develop, ~50–70% of the pulmonary vasculature must be affected, suggesting that even mild hemodynamic abnormalities are representative of advanced pulmonary vascular disease. The definitive diagnosis of PH is based upon hemodynamics measured by right heart catheterization; however this is an invasive and resource intense study. Early identification of pulmonary vascular disease offers the opportunity to improve outcomes by instituting therapies that slow, reverse, or potentially prevent this devastating disease. Multimodality imaging, including non-invasive modalities such as echocardiography, computed tomography, ventilation perfusion scans, and cardiac magnetic resonance imaging, has emerged as an integral tool for screening, classifying, prognosticating, and monitoring response to therapy in PH. Additionally, novel imaging modalities such as echocardiographic strain imaging, 3D echocardiography, dual energy CT, FDG-PET, and 4D flow MRI are actively being investigated to assess the severity of right ventricular dysfunction in PH. In this review, we will describe the utility and clinical application of multimodality imaging techniques across PH subtypes as it pertains to screening and monitoring of PH.

Diagnosis and Treatment of Right Heart Failure in Pulmonary Vascular Diseases: A National Heart, Lung, and Blood Institute Workshop.

Right ventricular dysfunction is a hallmark of advanced pulmonary vascular, lung parenchymal, and left heart disease, yet the underlying mechanisms that govern (mal)adaptation remain incompletely characterized. Owing to the knowledge gaps in our understanding of the right ventricle (RV) in health and disease, the National Heart, Lung, and Blood Institute (NHLBI) commissioned a working group to identify current challenges in the field. These included a need to define and standardize normal RV structure and function in populations; access to RV tissue for research purposes and the development of complex experimental platforms that recapitulate the in vivo environment; and the advancement of imaging and invasive methodologies to study the RV within basic, translational, and clinical research programs. Specific recommendations were provided, including a call to incorporate precision medicine and innovations in prognosis, diagnosis, and novel RV therapeutics for patients with pulmonary vascular disease.

Pulmonary Hypertension Roundtable: New Invasive Technologies in Pulmonary Hypertension

This spring, Guest Editor Richard A. Krasuski, MD, Professor of Medicine at Duke University School of Medicine in Durham, North Carolina, convened a group of experts to discuss the present and future of invasive technologies in the diagnosis and treatment of pulmonary hypertension. The guests included Jamil A. Aboulhosn, MD, Professor of Medicine at the University of California Los Angeles David Geffen School of Medicine in Los Angeles, California; Raymond Benza, MD, Director of the Division of Cardiovascular Medicine and Professor of Medicine at The Ohio State University College of Medicine in Columbus, Ohio; and J. Eduardo Rame, MD, FACC, Louis R. Dinon MD Professor of Cardiovascular Medicine and Physiology and Chief for Advanced Cardiac and Pulmonary Vascular Disease at Thomas Jefferson University Hospital in Philadelphia, Pennsylvania.

Summary of recommendations for the haemodynamic and angiographic assessment of the pulmonary circulation. Joint statement of the Polish Cardiac Society's Working Group on Pulmonary Circulation and Association of Cardiovascular Interventions.

Right heart catheterisation (RHC) is the 'gold standard' for haemodynamic assessment of the pulmonary circulation. For the diagnosis of pulmonary hypertension (PH), the guidelines of the European Society of Cardiology require a mean pulmonary arterial pressure ≥ 25 mm Hg to be confirmed by direct haemodynamic measurement. Additionally, RHC provides a lot of valuable information about the differential diagnosis and severity of PH, and also helps determine the patient's prognosis. Acute vasoreactivity testing performed in patients with pulmonary arterial hypertension is intended to identify the group of patients who should be treated with calcium channel blockers. Patients referred for heart transplantation require advanced pulmonary vascular disease to be ruled out either on resting examination or during vasoreactivity testing. RHC is a component of such interventional procedures as balloon atrial septostomy, closure of intracardiac shunts in congenital heart and great vessel defects, valvuloplasty for pulmonary valve stenosis, and pulmonary angioplasty. Pulmonary angiography is an examination recommended when selecting patients for pulmonary endarterectomy or balloon pulmonary angioplasty in thromboembolic PH. Due to the dynamic growth in the number of patients diagnosed with and treated for PH in Poland, the Boards of the Polish Cardiac Society's Working Group on Pulmonary Circulation and Association of Cardiovascular Interventions have undertaken a joint project to develop recommendations to standardise guidelines for RHC procedure, acute vasoreactivity testing and pulmonary angiography at cardiac wards and haemodynamic laboratories in Poland. This document has been prepared by experts delegated by the Working Group on Pulmonary Circulation and the Association of Cardiovascular Interventions, and subsequently approved by the Boards of both organs of the Polish Cardiac Society.

Patients with Congenital Systemic-to-Pulmonary Shunts and Increased Pulmonary Vascular Resistance: What Predicts Postoperative Survival?

BackgroundWe carried out a retrospective data review of patients with systemic to pulmonary shunts that underwent surgical repair between February 1990 and February 2012 in order to assess preoperative pulmonary vascular dynamic risk factors for predicting early and late deaths due presumably to pulmonary vascular disease.Methods and ResultsA total of 1024 cases of congenital systemic-to-pulmonary shunt and advanced pulmonary vascular disease beyond infancy and early childhood were closed surgically. The mean follow up duration was 8.5±5.5 (range 0.7 to 20) years. Sixty-one in-hospital deaths (5.96%, 61/1024) occurred after the shunt closure procedure and there were 46 late deaths, yielding 107 total deaths. We analyzed preoperative pulmonary vascular resistance index (PVRI), pulmonary vascular resistance index on pure oxygen challenge (PVRIO), difference between PVRI and PVRIO (PVRID), Qp∶Qs, and Rp∶Rs as individual risk predictors. The results showed that these individual factors all predicted in-hospital death and total death with PVRIO showing better performance than other risk factors. A multivariable Cox regression model was built,and suggested that PVRID and Qp∶Qs were informative factors for predicting survival time from late death and closure of congenital septal defects was safe with a PVRIO<10.3 WU.m2 and PVRID>7.3 WU.m2 on 100% oxygen.ConclusionsAll 4 variables, PVRI, PVRIO, PVRID and Qp∶Qs, should be considered in deciding surgical closure of congenital septal defects and a PVRIO<10.3 WU.m2 and PVRID>7.3 WU.m2 on 100% oxygen are associated with a favorable risk benefit profile for the procedure.

Interdisciplinary networks for the treatment of childhood pulmonary vascular disease: what pulmonary hypertension doctors can learn from pediatric oncologists.

The pathobiology of pulmonary arterial hypertension (PAH) is complex and multifactorial. None of the current therapies has been shown to be universally effective or able to reverse advanced pulmonary vascular disease, characterized by plexiform vascular lesions, or to prevent right ventricular failure in advanced PAH. It is thus unlikely that only one factor, pathway, or gene mutation will explain all forms and cases. Pediatric oncologists recognized a need for intensified, collaborative research within their field more than 40 years ago and implemented major clinical and translational networks worldwide to achieve evidence-based "tailored therapies." The similarities in the pathobiology (e.g., increased proliferation and resistance to apoptosis in vascular cells and perivascular inflammation) and the uncertainties in the proper treatment of both cancer and pulmonary hypertension (PH) have led to the idea of building interdisciplinary networks among PH centers to achieve rapid translation of basic research findings, optimal diagnostic algorithms, and significant, sustained treatment results. Such networks leading to patient registries, clinical trials, drug development, and innovative, effective therapies are urgently needed for the care of children with PH. This article reviews the current status, limitations, and recent developments in the field of pediatric PH. It is suggested that the oncologists' exemplary networks, concepts, and results in the treatment of acute lymphoblastic leukemia are applicable to future networks and innovative therapies for pediatric pulmonary hypertensive vascular disease and right ventricular dysfunction.

Screening for pulmonary arterial hypertension in patients with systemic sclerosis: Clinical characteristics at diagnosis and long‐term survival

Pulmonary arterial hypertension (PAH) is a severe, life-limiting complication of systemic sclerosis (SSc). Guidelines recommend early detection and management of SSc-PAH. However, little is known about the impact of detection programs on patients with SSc-PAH. This study was undertaken to assess the clinical characteristics of patients with SSc-PAH at diagnosis and their long-term outcomes. Two incident cohorts of patients with SSc-PAH from the same management era (2002/2003) were studied. The first cohort (designated the routine practice cohort) included consecutive adult patients with symptomatic SSc in whom a diagnosis of PAH was made by right-sided heart catheterization (RHC) at the time of recruitment into the French PAH Registry. The second cohort (designated the detection cohort) comprised consecutive patients with SSc who entered a systematic PAH detection program and were subsequently found to have PAH on RHC. Clinical characteristics at diagnosis of PAH and subsequent 8-year mortality were compared between the cohorts. There were 16 patients in each cohort. At the time of PAH diagnosis, patients in the detection cohort had less advanced pulmonary vascular disease compared with patients in the routine practice cohort, as evidenced by more patients being in New York Heart Association class I and class II, a lower mean pulmonary artery pressure and pulmonary vascular resistance index, and a higher cardiac output. Patients in the detection cohort were less likely to receive diuretics and warfarin, but there was no difference in exposure to PAH-specific therapies between the cohorts. The 1-, 3-, 5-, and 8-year survival rates were 75%, 31%, 25%, and 17%, respectively, in the routine practice cohort compared with 100%, 81%, 73%, and 64%, respectively, in the detection cohort (P = 0.0037). Compared with patients in routine clinical practice, PAH detection programs in SSc are able to identify patients with milder forms of the disease, allowing earlier management.

Preoperative pulmonary hemodynamics and assessment of operability: Is there a pulmonary vascular resistance that precludes cardiac operation?

Preoperative pulmonary vascular disease remains an important risk factor for death or right-heart failure in selected children undergoing two-ventricle repair, single-ventricle palliation, or heart transplantation. Preoperative criteria for poor outcome after operation remain unclear. The purpose of this review is to critically assess both the historic and current data and make recommendations where appropriate. An extensive literature search was undertaken in October 2009. Data were analyzed by an expert multidisciplinary team and recommendations were made by consensus. PubMed was searched in October 2009. Data were analyzed and recommendations were made by consensus of a multidisciplinary team. In patients with suspected pulmonary vascular disease anticipating a two-ventricle repair, although preoperative testing via cardiac catheterization with vasodilators is reasonable, the preoperative parameters and the precise values of these parameters that best correlate with early and late outcome remain unclear. Further investigation is warranted in selected populations, such as the growing group of children with congenital heart disease complicated by chronic lung disease of prematurity, and in the developing world where patients may be more likely to present late with advanced pulmonary vascular disease. In patients with a functional single ventricle, there is growing evidence that mean pulmonary artery pressure of >15 mm Hg may be associated with both early and late mortality after the Fontan operation. The relationship of preoperative pulmonary hemodynamics to early and late morbidity remains to be defined. There most likely is a level of preoperative pulmonary vascular disease that puts an individual patient at increased risk for death or severe cyanosis after a bidirectional cavopulmonary anastomosis. It remains unclear, however, how to best assess this risk preoperatively. The limitations in obtaining an accurate assessment of pulmonary vascular disease in the complex single ventricle are discussed. In children awaiting cardiac transplantation with elevated pulmonary vascular disease of >6 U.m and/or transpulmonary gradient of >15 mm Hg, heart transplantation is deemed feasible in most transplant centers if the administration of inotropes or vasodilators can decrease the pulmonary vascular disease to <6 U.m or transpulmonary gradient to <15 mm Hg. In patients with preoperative pulmonary vascular disease, there may be contributing factors to the pulmonary vascular disease, such as the specifics of the cardiac lesion (atrioventricular valve regurgitation, low cardiac output), parenchymal and/or airway issues, and/or individual genetic predisposition. Amelioration of any reversible factors before operation and optimization of their management in the preoperative and postoperative period are recommended.

Pulmonary arterial hypertension in paediatric and adult patients with congenital heart disease

Pulmonary arterial hypertension (PAH) commonly arises in patients with congenital heart disease (CHD). Greater numbers of patients with PAH associated with CHD (PAH-CHD) are now surviving into adulthood, many with increasingly complex cardiac defects. Patients with cardiac defects which result in left-to-right shunting are at risk of developing PAH, owing to the increased shear stress and circumferential stretch induced by increased pulmonary blood flow, which leads to endothelial dysfunction and progressive vascular remodelling and, thus, increased pulmonary vascular resistance. Although PAH-CHD shares similar lung histology with idiopathic PAH, differences do exist between these aetiologies. Management of PAH-CHD can involve surgical correction of the cardiac defect and/or treatment of the PAH, depending on the underlying cardiac defect and status of disease progression. Transplantation surgery can be curative but is not without limitations. The timing of intervention in patients with PAH-CHD is important, but the optimums are sometimes difficult to define, with limited robust data to inform management decisions. Uncontrolled studies suggest that prostacyclin analogues and phosphodiesterase type-5 inhibitors may have benefits in advanced pulmonary vascular disease. In the only randomised controlled trial dedicated to end-stage PAH-CHD, bosentan significantly reduced pulmonary vascular resistance and significantly increased 6-minute walk distance without compromising peripheral oxygen saturation, in patients with Eisenmenger syndrome. These data suggest that targeted therapies are beneficial in the PAH-CHD population, and warrant further research.

Critical Care Perspective on Immunotherapy in Lung Transplantation

Lung transplantation is now a viable therapeutic option in the care of patients with advanced pulmonary parenchymal or pulmonary vascular disease. Lung transplantation, however, with chronic posttransplant immunosuppression, creates a uniquely vulnerable population of patients likely to experience significant life-threatening complications requiring intensive care. The introduction of several novel immunosuppressive agents, such as sirolimus and mycophenolate mofetil, in conjunction with more established agents such as cyclosporine and tacrolimus, has greatly increased treatment options for lung transplant recipients and likely contributed to improved short-term transplant outcomes. Modern transplant immunosuppression, however, is associated with a host of complications such as opportunistic infections, renal failure, and thrombotic thrombocytopenic purpura. The main focus of this review is to provide a comprehensive summary of modern immunotherapy in lung transplantation and to increase awareness of the serious and potentially life-threatening complications of these medications.

Reversal of experimental pulmonary hypertension by PDGF inhibition

Progression of pulmonary hypertension is associated with increased proliferation and migration of pulmonary vascular smooth muscle cells. PDGF is a potent mitogen and involved in this process. We now report that the PDGF receptor antagonist STI571 (imatinib) reversed advanced pulmonary vascular disease in 2 animal models of pulmonary hypertension. In rats with monocrotaline-induced pulmonary hypertension, therapy with daily administration of STI571 was started 28 days after induction of the disease. A 2-week treatment resulted in 100% survival, compared with only 50% in sham-treated rats. The changes in RV pressure, measured continuously by telemetry, and right heart hypertrophy were reversed to near-normal levels. STI571 prevented phosphorylation of the PDGF receptor and suppressed activation of downstream signaling pathways. Similar results were obtained in chronically hypoxic mice, which were treated with STI571 after full establishment of pulmonary hypertension. Moreover, expression of the PDGF receptor was found to be significantly increased in lung tissue from pulmonary arterial hypertension patients compared with healthy donor lung tissue. We conclude that STI571 reverses vascular remodeling and cor pulmonale in severe experimental pulmonary hypertension regardless of the initiating stimulus. This regimen offers a unique novel approach for antire-modeling therapy in progressed pulmonary hypertension.

Hepatocyte Growth Factor Suppresses Vascular Medial Hyperplasia and Matrix Accumulation in Advanced Pulmonary Hypertension of Rats

Pulmonary hypertension (PH) is a progressive disease characterized by raised pulmonary vascular resistance, thought to be curable only through lung transplantation. Pathophysiologically, proliferation of pulmonary artery smooth muscle cells triggers pulmonary arterial stenosis and/or regurgitation, especially in advanced PH. Using a rat model of advanced pulmonary vascular disease produced by injecting monocrotaline, we show that hepatocyte growth factor (HGF) targets pulmonary arterioles and blocks the progression of PH. In these rats, endogenous HGF production was dramatically downregulated during developing experimental PH, but c-Met/HGF receptor was abundant in the medial layers of pulmonary arterioles. HGF gene transfection 2 weeks after the monocrotaline injection resulted in milder medial hyperplasia in lung arterioles and inhibited overgrowth of pulmonary artery smooth muscle cells. Notably, exogenous HGF reduced lung expression levels of endothelin-1 and transforming growth factor-beta, which are critically involved in PH-linked fibrogenic events. Overall, medial wall thickening of pulmonary arteries was almost completely prevented by HGF, and the total collagen deposition in the lung decreased; both effects contributed to the suppression of pulmonary artery hypertension. Our results suggest that the loss of endogenous HGF may be a feature of the pathogenesis of PH and that HGF supplementation may minimize pathological lung conditions, even advanced PH.

A mathematical framework for group analysis of von Willebrand factor multimeric composition following luminography.

The objective of the present study was to establish a method for quantitative analysis of von Willebrand factor (vWF) multimeric composition using a mathematical framework based on curve fitting. Plasma vWF multimers from 15 healthy subjects and 13 patients with advanced pulmonary vascular disease were analyzed by Western immunoblotting followed by luminography. Quantitative analysis of luminographs was carried out by calculating the relative densities of low, intermediate and high molecular weight fractions using laser densitometry. For each densitometric peak (representing a given fraction of vWF multimers) a mean area value was obtained using data from all group subjects (patients and normal individuals) and plotted against the distance between the peak and IgM (950 kDa). Curves were constructed for each group using nonlinear fitting. Results indicated that highly accurate curves could be obtained for healthy controls and patients, with respective coefficients of determination (r2) of 0.9898 and 0.9778. Differences were observed between patients and normal subjects regarding curve shape, coefficients and the region of highest protein concentration. We conclude that the method provides accurate quantitative information on the composition of vWF multimers and may be useful for comparisons between groups and possibly treatments.

The index of pulmonary vascular disease in children with congenital heart disease: relationship to clinical and haemodynamic findings.

We asked whether a scoring system [index of pulmonary vascular disease (IPVD)] that quantifies the individual pulmonary vascular pathology would relate to postoperative survival in patients with congenital heart disease and pulmonary hypertension (PH). Lung biopsy specimens from 28 patients at a median age of 6 months (1 month to 21 years) were analysed qualitatively and morphometrically. The IPVD and other morphometric parameters were related to haemodynamic findings and survival. Mean pulmonary artery pressure (PAP) was 44 mmHg (15-72 mmHg), and the resistance to pulmonary perfusion was 5 U x m(2) (0.9-14 U x m(2)). There were three early (in-hospital) and three late deaths during the follow-up period of 2.5 years (6 months to 7 years). Incipient plexiform lesions were observed in one infant with trisomy 21 and complete atrioventricular septal defect (cAVSD). An IPVD score above the upper critical limit (>2.2) was not observed during the first year of life. On discriminant analysis, morphometric parameters could not predict mortality ( P=0.08). The IPVD is not helpful to predict surgical mortality during the first year of life. Patients with trisomy 21 and cAVSD may show advanced pulmonary vascular disease in infancy.