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BACKGROUND The United States Chronic Thromboembolic Pulmonary Hypertension Registry (US-CTEPH-R) was designed to characterize the demographic characteristics, evaluation, clinical course, and outcomes of surgical and nonsurgical therapies for patients with chronic thromboembolic pulmonary hypertension. RESEARCH QUESTION What are the differences in baseline characteristics and 1-year outcomes between operated and nonoperated subjects? STUDY DESIGN AND METHODS This study describes a multicenter, prospective, longitudinal, observational registry of patients newly diagnosed (< 6 months) with CTEPH. Inclusion criteria required a mean pulmonary artery pressure ≥ 25 mm Hg documented by right heart catheterization and radiologic confirmation of CTEPH. Between 2015 and 2018, a total of 750 patients were enrolled and followed up biannually until 2019. RESULTS Most patients with CTEPH (87.9%) reported a history of acute pulmonary embolism. CTEPH diagnosis delays were frequent (median, 10 months), and most patients reported World Health Organization functional class 3 status at enrollment with a median mean pulmonary artery pressure of 44 mm Hg. The registry cohort was subdivided into Operable patients undergoing pulmonary thromboendarterectomy (PTE) surgery (n = 566), Operable patients who did not undergo surgery (n = 88), and those who were Inoperable (n = 96). Inoperable patients were older than Operated patients; less likely to be obese; have a DVT history, non-type O blood group, or thrombophilia; and more likely to have COPD or a history of cancer. PTE resulted in a median pulmonary vascular resistance decline from 6.9 to 2.6 Wood units (P < .001) with a 3.9% in-hospital mortality. At 1-year follow-up, Operated patients were less likely treated with oxygen, diuretics, or pulmonary hypertension-targeted therapy compared with Inoperable patients. A larger percentage of Operated patients were World Health Organization functional class 1 or 2 at 1 year (82.9%) compared with the Inoperable (48.2%) and Operable/No Surgery (56%) groups (P < .001). INTERPRETATION Differences exist in the clinical characteristics between patients who exhibited operable CTEPH and those who were inoperable, with the most favorable 1-year outcomes in those who underwent PTE surgery. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov; No.: NCT02429284; URL: www.clinicaltrials.gov.

ISHLT members have recognized the importance of a consensus statement on the evaluation and management of patients with chronic thromboembolic pulmonary hypertension. The creation of this document required multiple steps, including the engagement of the ISHLT councils, approval by the Standards and Guidelines Committee, identification and selection of experts in the field, and the development of 6 working groups. Each working group provided a separate section based on an extensive literature search. These sections were then coalesced into a single document that was circulated to all members of the working groups. Key points were summarized at the end of each section. Due to the limited number of comparative trials in this field, the document was written as a literature review with expert opinion rather than based on level of evidence. (C) 2021 International Society for Heart and Lung Transplantation. All rights reserved.

Background Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare sequela of acute pulmonary embolism that is treatable when recognized. Awareness of this disease has increased with recent advancements in therapeutic options, but delays in diagnosis remain common, and diagnostic and treatment guidelines are often not followed. Data gathered from international registries have improved our understanding of CTEPH, but these data may not be applicable to the US population owing to differences in demographics and medical practice patterns. Objective The US CTEPH Registry (US-CTEPH-R) was developed to provide essential information to better understand the demographics, risk factors, evaluation, and treatment of CTEPH in the United States, as well as the short- and long-term outcomes of surgical and nonsurgical therapies in the modern treatment era. Methods Thirty sites throughout the United States enrolled 750 subjects in this prospective, longitudinal, observational registry of patients newly diagnosed with CTEPH. Enrollment criteria included a mean pulmonary artery pressure ≥25 mmHg by right heart catheterization and radiologic confirmation of CTEPH by a multidisciplinary adjudication committee. Following enrollment, subjects were followed biannually until the conclusion of the study. Quality of life surveys were administered at enrollment and biannually, and all other testing was at the discretion of the treating clinician. Details regarding surgical therapy, balloon pulmonary angioplasty, and medical therapy were collected at enrollment and at follow-up, as well as information related to health care utilization and survival. Results Data from this registry will improve understanding of the demographics, risk factors, and treatment patterns of patients with CTEPH, and the longitudinal impact of therapies on quality of life, health care utilization, and survival. Conclusions This manuscript details the methodology and design of the first large, prospective, longitudinal registry of patients with CTEPH in the United States. Trial Registration ClinicalTrials.gov NCT02429284; https://www.clinicaltrials.gov/ct2/show/NCT02429284 International Registered Report Identifier (IRRID) DERR1-10.2196/25397

Background Hypodense filling defects within the pulmonary veins on computed tomography described as pulmonary vein sign (PVS) have been noted in acute pulmonary embolism and shown to be associated with poor prognosis. We evaluated venous flow abnormalities in chronic thromboembolic pulmonary hypertension (CTEPH) to determine its usefulness in the computed tomography assessment of CTEPH. Methods and Results Blinded retrospective computed tomography analysis of 50 proximal CTEPH cases and 3 control groups—50 acute pulmonary embolism, 50 nonthromboembolic cohort, and 50 pulmonary arterial hypertension. Venous flow reduction was assessed by the following: (1) presence of a filling defect of at least 2 cm in a pulmonary vein draining into the left atrium, and (2) left atrium attenuation (>160 Hounsfield units). PVS was most prevalent in CTEPH. Compared with all controls, sensitivity and specificity of PVS for CTEPH is 78.0% and 85.3% (95% CI, 64.0–88.5 and 78.6–90.6, respectively) versus 34.0% and 70.7% (95% CI, 21.2−48.8 and 62.7–77.8) in acute pulmonary embolism, 8.0% and 62% (95% CI, 2.2–19.2 and 53.7–69.8) in nonthromboembolic and 2.0% and 60% (95% CI, 0.1−10.7 and 51.7−67.9) in pulmonary arterial hypertension. In CTEPH, lobar and segmental arterial occlusive disease was most commonly associated with corresponding absent venous flow. PVS detection was highly reproducible (Kappa=0.96, 95% CI, 0.90–1.01, P Conclusions PVS is easy to detect with higher sensitivity and specificity in CTEPH compared with acute pulmonary embolism and is not a feature of pulmonary arterial hypertension. Asymmetric enhancement of pulmonary veins may serve as an additional parameter in the computed tomography assessment of CTEPH and can be used to differentiate CTEPH from pulmonary arterial hypertension.

The treatment of chronic thromboembolic pulmonary hypertension has expanded considerably. The ability to endarterectomize chronic thromboembolic material, the availability of pulmonary hypertension medical therapy to treat inoperable chronic thromboembolic pulmonary hypertension and/or residual pulmonary hypertension, and the rebirth of pulmonary balloon angioplasty have changed the management landscape. Patient selection requires a multidisciplinary evaluation at an experienced center. What is inoperable chronic thromboembolic pulmonary hypertension to one group may be operable chronic thromboembolic pulmonary hypertension to another. The ultimate challenge then becomes which intervention provides the optimal long-term outcome for any individual patient.

The past four decades have witnessed considerable advancements in our understanding of the pathophysiology, and the diagnosis and treatment of patients with chronic thromboembolic pulmonary hypertension (CTEPH). The development of an effective surgical treatment for this disease has been one of the most remarkable achievements to realize a cure for many afflicted with this form of pulmonary hypertension. For those patients with inoperable CTEPH, the past 8 years have been similarly marked by new developments. Studies demonstrating effective pulmonary hypertension-targeted medical therapy and the advancement of balloon pulmonary angioplasty (BPA) now provide patients who are not candidates for surgery beneficial treatment options. However, long-term efficacy of these treatment modalities and the selection of patients appropriate for BPA are topics of ongoing debate and research. This report provides an overview of the current, state-of-the-art therapeutic approach to the CTEPH patient.

Uterine fibroids have been described as an associate to acute venous thromboembolism (VTE), with case reports showing an association between large uterine fibroids, acute deep venous thrombosis (DVT), and acute pulmonary embolism (PE). However, there is little known about the association or causation between uterine fibroids, chronic thromboembolic disease (CTED), and chronic thromboembolic pulmonary hypertension (CTEPH). We report on six women with uterine fibroids and CTEPH, as well as one woman with CTED, all of whom presented with exertional dyspnea, lower extremity swelling, and in the cases of CTEPH, clinical, echocardiographic, and hemodynamic evidence of pulmonary hypertension and right heart failure. Compression of the pelvic veins by fibroids was directly observed with invasive venography or contrast-enhanced computed tomography in five cases. All seven women underwent pulmonary thromboendarterectomy (PTE) followed by marked improvement in functional, clinical, and hemodynamic status.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a progressive pulmonary vascular disease with significant morbidity. It is a result of an alternate natural history in which there is limited resolution of thromboemboli with pulmonary artery obstruction leading to pulmonary hypertension (PH). CTEPH requires a thorough clinical assessment including pulmonary hemodynamics and radiologic evaluation in addition to consultation with an expert center. Surgical intervention remains the optimal management strategy. Select patients may be candidates for catheter-based intervention with balloon pulmonary angioplasty in centers with clinical expertise. Inoperable patients or those with post-intervention PH are treated with pulmonary hypertension-targeted medical therapy.

Background: Left ventricular dyssynchrony has been studied extensively, but this is not the case with right ventricular (RV) dyssynchrony. Our aim was to investigate RV dyssynchrony through 2D speckle strain imaging in patients with chronic thromboembolic pulmonary hypertension (CTEPH) before and after pulmonary thromboendarterectomy (PTE).Methods: We measured 2D peak RV strain (%) of the RV free-wall and time to peak strain (ms) of its three freewall segments (base, mid, and apex) in 127 consecutive CTEPH patients (51 ± 14 years, 59% female) with adequate images pre- and post-PTE. RV strain was calculated using Epsilon Imaging EchoInsight® software. RV dyssynchrony was measured using two methods: the standard deviation of peak systolic strain and the standard deviation of time (ms) to peak strain (RVDT) between the three RV free-wall segments.Results: Mean RV free wall strain did not change significantly after PTE (−11.4 ± 5.7 to −11.2 ± 5.6%, p = 0.67). However, RV dyssynchrony improved dramatic...

Treatment options for patients with inoperable chronic thromboembolic pulmonary hypertension have expanded with the availability of balloon pulmonary angioplasty and pulmonary hypertension targeted medical therapy. Often, both options are appropriate for the provision of care for those patients who are not deemed candidates for PTE surgery. As illustrated by this case, the task of selecting patients suitable for balloon pulmonary angioplasty can be a difficult one, typically requiring input from diagnosticians, radiologists, and surgeons experienced in the evaluation and treatment of patients with CTEPH.

While pulmonary hypertension, an abnormal VQ scan and angiographic evidence of thrombus in the pulmonary arteries are necessary to diagnose chronic thromboembolic pulmonary hypertension, an atrial septal defect with Eisenmenger’s syndrome may present with similar findings. Clues to the presence of an ASD include digital clubbing and scintigraphic evidence of right-to-left shunt with uptake of technetium macro aggregated albumin seen in the brain and kidneys. An echocardiogram with bubble study can also demonstrate a right-to-left shunt. Patients with Eisenmenger’s syndrome should have pulmonary hypertension medically managed. There is no benefit to pulmonary thromboendarterectomy for chronic in situ thrombosis frequently seen in these patients.

There are a number of clinical conditions that mimic the radiographic findings in CTEPH, but few are as difficult to distinguish from CTEPH as pulmonary arteritis. However, as the presented case will demonstrate, there are often hints in the evaluation of patients with pulmonary hypertension to suggest large vessel arteritis as the principal diagnosis.

Perfusion defects on standard lung scintigraphy can be due to many causes, though typically from occlusion or partial obstruction of the pulmonary arteries. This case presentation highlights that outflow obstruction due to large pulmonary venous disease may result in perfusion abnormalities, and should be considered in the differential when a clinician is presented with an abnormal lung ventilation-perfusion scan.

The transition from acute to chronic thromboembolic disease can occur to an unpredictable degree in patients who survive an acute pulmonary embolism. In the vast majority of such patients on anti-thrombotic therapy, near complete resolution of the thrombus occurs. In 2–3% of patients, chronic thromboembolic pulmonary hypertension will develop. However, in an unknown percentage of pulmonary embolic survivors, organized thrombotic residua can involve enough of the pulmonary vascular bed to cause cardiopulmonary symptoms in the absence of pulmonary hypertension or right heart dysfunction. This is referred to as chronic thromboembolic disease or CTED, and the case presentation to follow illustrates some of challenges in treatment recommendations for this unique disease.

Establishing the diagnosis and operability of chronic thromboembolic disease in patients with pulmonary hypertension are the critical first steps in determining surgical candidacy for thromboendarterectomy. However, whether or not a CTEPH patient is ultimately a surgical candidate requires a complete overview of comorbidities, a realistic prediction that a PTE will result in a clinical benefit, and patient acceptance. This case presentation explores the decision-making challenges often faced during an evaluation of patients with chronic thromboembolic disease and multiple comorbidities.

Lung scintigraphy is an invaluable screening tool in the evaluation of the pulmonary hypertensive patient. The absence of perfusion defects is properly interpreted to exclude occlusive pulmonary vascular disease such as CTEPH. However, unmatched perfusion defects are due to a number of disease states, and as illustrated with this presented case, extensive precapillary, small vessel pulmonary vascular disease needs to be considered among the possibilities.

Large-vessel pulmonary artery sarcomas are rare tumors of the pulmonary vasculature, accounting for only a fraction of primary lung cancers and with a very poor prognosis. They arise proximally from within the pulmonary artery and spread within the arterial lumen, causing obstruction of the vasculature that may result in right ventricular failure. Although they may have a similar presentation to chronic thromboembolic pulmonary disease and CTEPH, there are subtle indicators in history and imaging that can help with their differential diagnosis, with the confirmation usually resulting from tissue biopsy. This case presentation focuses on this CTEPH mimic.

Perfusion defects on ventilation-perfusion scan and eccentric thrombus lining major pulmonary vessels on CT pulmonary angiography in a patient with severe chronic obstructive airways disease and pulmonary hypertension may not represent CTEPH. This case presentation emphasizes the diagnostic treatment challenges in an emphysema patient with CT evidence for chronic thrombus.

Chronic thromboembolic disease can lead to significant exercise limitations even in the absence of pulmonary hypertension. The decision to proceed with pulmonary thromboendarterectomy is complex, but as in this case, can lead to significant improvements in lung perfusion and exercise tolerance. Though speculative, intervention at this stage of the disease may also prevent the development of significant pulmonary hypertension.

Chronic thromboembolic pulmonary hypertension (CTEPH) is an important consequence of pulmonary embolism that is associated with abnormalities in haemostasis. We investigated the ADAMTS13–von Willebrand factor (VWF) axis in CTEPH, including its relationship with disease severity, inflammation, ABO groups and ADAMTS13 genetic variants. ADAMTS13 and VWF plasma antigen levels were measured in patients with CTEPH (n=208), chronic thromboembolic disease without pulmonary hypertension (CTED) (n=35), resolved pulmonary embolism (n=28), idiopathic pulmonary arterial hypertension (n=30) and healthy controls (n=68). CTEPH genetic ABO associations and protein quantitative trait loci were investigated. ADAMTS13–VWF axis abnormalities were assessed in CTEPH and healthy control subsets by measuring ADAMTS13 activity, D-dimers and VWF multimeric size. Patients with CTEPH had decreased ADAMTS13 (adjusted β −23.4%, 95% CI −30.9– −15.1%, p, The ADAMTS-13–VWF axis is dysregulated in chronic thromboembolism with and without pulmonary hypertension and is implicated in the pathogenesis http://ow.ly/J9SC30nh5T0

Right ventricular function is impaired in chronic thromboembolic pulmonary hypertension (CTEPH). Tricuspid annular plane systolic excursion (TAPSE) and right ventricular fractional area change (RVFAC) have been shown to help assess right ventricular function in pulmonary hypertension. Our goal was to (1) assess TAPSE and RVFAC before and after PTE, and (2) assess correlation of these variables with right heart catheterization data and PVR.We evaluated 67 consecutive patients with CTEPH for pulmonary thromboendarterectomy (PTE). Of these 67 patients, 48 were deemed surgical candidates. Preoperative right heart catheterization was performed within 1.3±1.2 days of the preoperative echocardiogram. All postoperative right heart catheterizations were performed on the first postoperative day.TAPSE dropped from 18±6 to 10±3 mm after PTE (P.0001). RVFAC remained the same (25%±10% vs 30%±12%). Mean pulmonary artery (mPAP) pressure dropped from 45±12 to 28±6 mm Hg after PTE, and pulmonary vascular resistance (PVR) decreased from 757±406 to 306±147 dyne-s/cmIn patients with CTEPH, TAPSE paradoxically decreased by 50% early after PTE. TAPSE correlated inversely with PVR prior to PTE, but this correlation was lost completely after PTE. Thus, despite the immediate and marked decrease in afterload postoperatively, TAPSE did not improve; thus, TAPSE cannot be used as an early marker for surgical success.

Chronic thromboembolic pulmonary hypertension is a progressive and life-threatening condition that is believed to be related to inadequate dissolution of acute pulmonary thromboemboli, followed by fibrotic organization. Without appropriate treatment, progressive pulmonary hypertension, right ventricular failure, and death may occur. While the disorder was initially described nearly a century ago in autopsy studies, antemortem diagnosis became feasible with the advent of cardiac catheterization and angiography techniques in the 1940s, while surgical thromboendarterectomy was not attempted until the 1960s. However, this procedure initially had high mortality rates until refinements in management and surgical techniques resulted in much improved outcomes starting in the 1980s. Many questions remain about the pathophysiology and epidemiology of this condition, with unclear contributions of genetics and environmental exposures. The optimal approach to diagnosis also continues to evolve, with improvements in preoperative imaging and hemodynamic assessment. Treatment of chronic thromboembolic pulmonary hypertension has not remained static, as surgical techniques continue to improve and newer pharmacological treatments and percutaneous catheter-based interventions may play therapeutic roles in selected patients. This is the introductory article of a series that provides a state-of-the-art review of chronic thromboembolic pulmonary hypertension.

Pulmonary hypertension due to chronic thromboembolic disease is potentially curable with pulmonary thromboendarterectomy surgery. As a result, it is important for clinicians to recognize and appropriately diagnose this form of pulmonary hypertension. Advances in this field with changes in surgical technique, the availability of PH-targeted medical therapy for select patient subgroups, and the development of balloon pulmonary angioplasty have broadened therapeutic options for patients. This review will examine what is known about the epidemiology and medical conditions placing patients at risk of developing this disease, will present an approach to evaluation of patients with suspected chronic thromboembolic disease, and will describe the surgical and non-surgical management of this unique patient population.

Objectives This study aimed to identify the prevalence of cardiac implantable electronic devices (CIEDs) in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and to describe the associated disease burden. Background CTEPH is a debilitating disease, now potentially curable with pulmonary thromboendarterectomy (PTE). The contribution of CIEDs to thrombosis in this patient population has not been previously studied. Methods The charts of 982 CTEPH patients, who underwent PTE between January 1, 2009, and December 31, 2015 at University of California-San Diego (UCSD) Medical Center, were reviewed for pacemakers or implantable cardioverter defibrillators (ICDs) implanted before surgery. Results Among 982 CTEPH patients who underwent PTE, 14 had pacemakers and 3 had ICDs, giving 17 CIEDs and a prevalence of 1.7%. Of these 17 CIEDs, 6 devices were extracted intraoperatively, and 5 of 6 devices were replaced with epicardial leads. Furthermore, of the 950 patients classified by intraoperative UCSD level, 12 of 17 (70.6%) patients with CIEDs had distal disease versus 241 of 933 (25.8%) patients without CIEDs (p = 0.0002). The prevalence of known venous thromboembolism (VTE) was 50% in CIED patients compared with 78.6% in patients without CIEDs (p = 0.018). Conclusions At 1.7%, the prevalence of CIEDs in the PTE population was higher than previously reported values, which estimated CIED prevalence between 0.16% and 0.47% in the general population. Moreover, CTEPH patients with CIEDs were more strongly associated with distal disease burden and less likely to have had previous VTE, which suggested that CIEDs may be a nidus for small clots that embolize distally in the pulmonary vasculature.

Reperfusion lung injury is a postoperative complication of pulmonary thromboendarterectomy that can significantly affect morbidity and mortality. Studies in other postoperative patient populations have demonstrated a reduction in acute lung injury with the use of a low-tidal volume (Vt) ventilation strategy. Whether this approach benefits patients undergoing thromboendarterectomy is unknown.We sought to determine if low-Vt ventilation reduces reperfusion lung injury in patients with chronic thromboembolic pulmonary hypertension undergoing thromboendarterectomy.Patients undergoing thromboendarterectomy at one center were randomized to receive either low (6 ml/kg predicted body weight) or usual care Vts (10 ml/kg) from the initiation of mechanical ventilation in the operating room through Postoperative Day 3. The primary endpoint was the onset of reperfusion lung injury. Secondary outcomes included severity of hypoxemia, days on mechanical ventilation, and intensive care unit and hospital lengths of stay.A total of 128 patients were enrolled and included in the analysis; 63 were randomized to the low-Vt group and 65 were randomized to the usual care group. There was no statistically significant difference in the incidence of reperfusion lung injury between groups (32%, n=20 in the low-Vt group vs. 23%, n=15 in the usual care group; P=0.367). Although differences were noted in plateau pressures (17.9 cm H2O vs. 20.1 cm H2O, P0.001) and peak inspiratory pressures (20.4 cm H2O vs. 23.0 cm H2O, P0.001) between the low-Vt and usual care groups, respectively, mean airway pressures, PaO2/FiO2, days on mechanical ventilation, and ICU and hospital lengths of stay were all similar between groups.In patients with chronic thromboembolic pulmonary hypertension undergoing pulmonary thromboendarterectomy, intra- and postoperative ventilation using low Vts (6 mg/kg) compared with usual care Vts (10 mg/kg) does not reduce the incidence of reperfusion lung injury or improve clinical outcomes. Clinical trial registered with www.clinicaltrials.gov (NCT00747045).

This study sought to determine the prevalence of coronary artery-pulmonary artery collaterals in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and to correlate their presence with the degree of clot burden. CTEPH is a treatable cause of severe pulmonary hypertension and right heart failure. Bronchopulmonary collateral vessels have been used as a supplementary diagnostic and prognostic tool for this disease. Coronary artery-pulmonary artery collaterals in this population have not been described. The coronary angiograms of 300 consecutive patients with CTEPH evaluated for pulmonary thromboendarterectomy (PTE) between January 1, 2007, and May 1, 2014, were examined. Of these patients, 259 (50% male; mean age, 58.3 ± 10.6 years) had cineangiographic images deemed adequate to definitively assess for the presence of coronary artery-pulmonary artery collaterals and were included in the final analyses. Pulmonary angiogram reports were reviewed for extent of pulmonary artery obstruction. The coronary angiograms of 259 age- and sex-matched control patients were also examined. Among 259 CTEPH patients with definitive imaging, 34 coronary artery-pulmonary artery collaterals were found in 28 patients (10.8%), versus 1 coronary artery-pulmonary artery collateral among control subjects (0.4%; P < 0.001). Compared with CTEPH patients without collaterals, patients with collaterals had a significantly higher prevalence of total occlusion of their right or left main pulmonary artery (P < 0.001) or lobar arteries (P < 0.001). In conclusion, the prevalence of coronary artery-pulmonary artery collaterals in CTEPH patients undergoing coronary angiography for possible PTE is approximately 11%. These vessels are associated with more severe pulmonary artery occlusion.

Although there are several iterations of the same theme, Albert Einstein once proclaimed, “The more I learn, the more I realize how much I don’t know.” An interpretation of this notion is that each step forward in discovery simply leads to more questions to answer. The expanding experience with balloon pulmonary angioplasty worldwide in the treatment of chronic thromboembolic pulmonary hypertension (CTEPH) is reminiscent of Einstein’s assertion. In this month’s issue of Circulation: Cardiovascular Quality and Outcomes , Ogawa et al1 report the combined outcomes from 7 institutions in Japan performing balloon pulmonary angioplasty on patients with inoperable CTEPH. And although the information provided in this article is of considerable value, many unanswered questions remain. See Article by Ogawa et al The aggregate data presented in this multicenter Japanese balloon pulmonary angioplasty (BPA) registry provides a clearer characterization of patients undergoing this intervention—80% were female, medical conditions previously reported to be associated with CTEPH were uncommon, thrombophilic disorders were seen in 8.8% of patients, only 15.3% of patients had a prior episode of acute pulmonary embolism, and 34.7% were with a deep venous thrombosis history. This patient phenotype is distinctly different from that reported in large series of CTEPH patients where the male to female ratio is nearly even and a much higher percentage of patients having been identified as experiencing a previous pulmonary embolic event.2 This raises the issue as to whether the patient type is distinct in this series and, as a consequence, whether the reported outcomes are transferable to other BPA-experienced centers. It might be argued that the patient characteristics in the Japanese Registry may be reflective of those at risk for developing inoperable chronic thromboembolic disease. However, published information from several European BPA centers are more …

Background Obesity is a common comorbidity of patients with chronic thromboembolic pulmonary hypertension referred for pulmonary thromboendarterectomy, yet the effect of obesity on pulmonary thromboendarterectomy outcomes has not been well described. Methods We conducted a retrospective cohort study in which 476 consecutive operations over a 3.5-year period were examined to determine the effects of obesity on outcomes. Patients were grouped into four categories based on body mass index (BMI): less than 22 kg/m 2 , 22 to 30 kg/m 2 , 30 to 40 kg/m 2 , and more than 40 kg/m 2 . Results There were important differences in baseline pulmonary hemodynamics, with obese patients having significantly lower pulmonary vascular resistances than nonobese patients. All patients achieved a significant reduction in pulmonary vascular resistance, although the improvement was greatest in the lower BMI groups. The overall in-hospital mortality was 0.8%, and there were no differences in risk among BMI groups. Among the BMI groups, there were no differences in incidence of postoperative complications, including atrial fibrillation (overall 24.8%), reperfusion lung injury (overall 23.1%), and surgical site infection (overall 4.4%) or in median lengths of stay (including ventilator days, intensive care unit days, and postoperative length of stay). Conclusions Pulmonary thromboendarterectomy outcomes have continued to improve, and this surgery can safely be completed in obese patients, previously deemed to be at high risk for poor outcomes.

Bronchopulmonary collateral vasculature is a significant source of systemic blood flow in patients with chronic thromboembolic pulmonary hypertension (CTEPH).1 We present 2 cases of coronary artery-to-pulmonary artery (PA) collateral vessels, which have not been previously described in patients with CTEPH. A 40-year-old man with a history of deep venous thrombosis after parotidectomy for a benign lesion, recurrent strokes, and right-sided pulmonary embolism was evaluated for 5 years of progressive exertional dyspnea and suspected CTEPH. He had no known hereditary thrombophilia. Preoperative ventilation–perfusion scintigraphy demonstrated absent perfusion to the right lung and small defects in the left lower lobe (Figure 1). Pulmonary angiography confirmed occlusion of the proximal right PA with no distal flow (Figure 2; Movie I in the Data Supplement). His mean PA pressure was 35 mm Hg, pulmonary vascular resistance was 511 dyne/s per cm5, and cardiac index was 2.3 L/min per m2. Coronary angiography revealed a 4.6-mm diameter corkscrew vessel arising from the left circumflex artery and traveling to the right lung (Figure 3; Movie II in the Data Supplement). He had no significant coronary artery disease. The patient underwent bilateral pulmonary thromboendarterectomy (PTE; Figure 4), during which a small atrial septal defect was found and repaired. Collaterals were noted throughout the mediastinum, particularly around the aorta traversing toward the right lung and directly penetrating the right main PA. Final mean PA …

Background Right ventricular (RV) function is significantly impaired in patients with chronic thromboembolic pulmonary hypertension (CTEPH). Two-dimensional speckle tracking RV strain and strain rate are novel methods to assess regional RV systolic function in CTEPH patients before and after pulmonary thromboendarterectomy (PTE). Our goal was to (1) assess baseline longitudinal strain and strain rate of the basal RV free wall in CTEPH and (2) measure early changes in RV strain and strain rate after PTE. Methods We performed echocardiography on 30 consecutive patients with CTEPH referred for PTE with adequate pre- and post-PTE strain imaging. Strain and strain rate were assessed 6.4 ± 4.5 days before and 9.1 ± 3.9 after PTE. Results Basal RV free wall strain and time to peak strain—but not basal RV strain rate and time to peak strain rate—changed significantly after PTE. Unexpectedly, basal RV strain became less negative, from −24.3% to −18.9% after PTE (P = 0.005). Time to peak strain decreased from 356 to 287 msec after PTE (P

UNLABELLED The ratio of tricuspid regurgitation velocity divided by the velocity-time integral of right ventricular outflow tract pulsed-wave Doppler tracing (TRV/VTI(RVOT) ) has been used to estimate pulmonary vascular resistance (PVR). However, this method has not been validated in chronic thromboembolic pulmonary hypertension (CTEPH). We assessed the utility of TRV/VTI(RVOT) in patients with CTEPH and PVR from 2 to 20 WU. All had right heart catheterization (RHC) within 2 days of echocardiography. TRV/VTI(RVOT) was calculated and RHC-derived pressures, PVR, and cardiac outputs were recorded. Mean pulmonary artery pressure was 47 ± 12 mmHg, cardiac output: 4.2 ± 1.1 L/min, PVR: 9 ± 4 WU, right atrial pressure: 12 ± 6 mmHg. Mean VTI(RVOT) was 13 ± 5 cm; mean TRV was 4.2 ± 0.8 m/s, mean tricuspid regurgitation severity was 2.5 ± 0.8 (1 = trace, 2 = mild, 3 = moderate, 4 = severe). Regression analysis demonstrated a correlation between RHC PVR and TRV/VTI(RVOT) : PVR = 19.4 × (TRV/VTI(RVOT) ) + 2.4 (r = 0.74, P < 0.001). However, Bland-Altman analysis found a poor degree of agreement between echo-derived PVR and RHC PVR. We also studied 28 patients with non-CTEPH pulmonary hypertension. Similar analysis revealed a regression equation of PVR = 20.1 × (TRV/VTIR(RVOT) ) + 0.3 (r = 0.57, P < 0.01). CONCLUSION TRV/VTI(RVOT) is only marginally useful for estimating PVR in CTEPH (r = 0.74). Moreover, the regression equation in CTEPH differs significantly from previous studies in pulmonary hypertension. Reasons for this may include the markedly elevated PVR levels in this population and specific effects on VTI(RVOT) from CTEPH.

Pulmonary hypertension is defined by a mean pulmonary artery pressure greater than 25 mm Hg. Chronic thromboembolic pulmonary hypertension (CTEPH) is defined as pulmonary hypertension in the presence of an organized thrombus within the pulmonary vascular bed that persists at least 3 months after the onset of anticoagulant therapy. Because CTEPH is potentially curable by surgical endarterectomy, correct identification of patients with this form of pulmonary hypertension and an accurate assessment of surgical candidacy are essential to provide optimal care. Patients most commonly present with symptoms of exertional dyspnea and otherwise unexplained decline in exercise capacity. Atypical chest pain, a nonproductive cough, and episodic hemoptysis are observed less frequently. With more advanced disease, patients often develop symptoms suggestive of right ventricular compromise. Physical examination findings are minimal early in the course of this disease, but as pulmonary hypertension progresses, may include nonspecific finding of right ventricular failure, such as a tricuspid regurgitation murmur, pedal edema, and jugular venous distention. Chest radiographs may suggest pulmonary hypertension, but are neither sensitive nor specific for the diagnosis. Radioisotopic ventilation-perfusion scanning is sensitive for detecting CTEPH, making it a valuable screening study. Conventional catheter-based pulmonary angiography retains an important role in establishing the presence and extent of chronic thromboembolic disease. However, computed tomographic and magnetic resonance imaging are playing a growing diagnostic role. Innovative technologies such as dual-energy computed tomography, dynamic contrast-enhanced magnetic resonance imaging, and optical coherence tomography show promise for contributing diagnostic information and assisting in the preoperative characterization of patients with CTEPH.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a potentially curable disease when treated with pulmonary thromboendarterectomy (PTE). However, even at experienced surgical centers, nearly one-third of patients with CTEPH will be deemed inoperable for reasons including distal disease, comorbidities, or out-of-proportion pulmonary hypertension. It is in these patients with inoperable CTEPH that pulmonary hypertension (PH)-targeted medical therapy and balloon pulmonary angioplasty have potential therapeutic value. Previous unblinded cohort trials have assessed PH-targeted medical therapy in various subpopulations of CTEPH patients using epoprostenol, treprostinil, sildenafil, bosentan, and iloprost, each demonstrating measurable pulmonary hemodynamic effects. However, riociguat, a soluble guanylate cyclase stimulator, is the first FDA-approved therapy for inoperable CTEPH to demonstrate both an improvement in functional capabilities (6-minute walk time) as well as significant gains in secondary pulmonary hemodynamic end points in a large placebo-controlled trial. Balloon pulmonary angioplasty is an interventional procedure using telescoping catheters placed in the pulmonary arteries, through which wires and balloons are used to mechanically disrupt chronic clot material and relieve pulmonary vascular obstruction. Contemporary case series from multiple centers worldwide have demonstrated pulmonary hemodynamic improvement with this approach. As a result of these advances, patients with inoperable CTEPH who had few options as recently as 5 years ago now have alternatives with emerging evidence of therapeutic efficacy.

Pulmonary hypertension as a result of chronic thromboembolic disease (CTEPH) is potentially curable with pulmonary endarterectomy surgery. Consequently, correctly diagnosing patients with this type of pulmonary hypertension and evaluating these patients with the goal of establishing their candidacy for surgical intervention is of utmost importance. And as advancements in surgical techniques have allowed successful resection of segmental-level chronic thromboembolic disease, the number of CTEPH patients that are deemed suitable surgical candidates has expanded, making it even more important that the evaluation be conducted with greater precision. This article will review a diagnostic approach to patients with suspected chronic thromboembolic disease with an emphasis on the criteria considered in selecting patients for pulmonary endarterectomy surgery.

Over the past 4 decades, chronic thromboembolic pulmonary hypertension has evolved from an autopsy curiosity to a potentially correctable form of pulmonary hypertension. Advances in surgical techniques along with the introduction of pulmonary hypertension disease-modifying therapies provide a therapeutic option for the majority of patients afflicted with the disease. Approximately 5,000 thromboendarterectomy procedures have now been performed worldwide with mortality rates reported by established programs experienced in the management of this disease process falling to a range of 4 to 7%. A mortality rate of 1.3% has been reported in patients at low risk based on their preoperative hemodynamic profile. After a successful pulmonary thromboendarterectomy, substantial improvement and often normalization can be achieved in right ventricular function, gas exchange, exercise capacity, and quality of life. For patients not candidates for thromboendarterectomy, or for those with persistent post-thromboendarterectomy pulmonary hypertension, disease-modifying medical therapies have been demonstrated to stabilize and improve pulmonary hemodynamics, albeit not to the same extent as primary thromboendarterectomy. The current review focuses on the diagnostic approach to chronic thromboembolic pulmonary hypertension and the available surgical and medical therapeutic options. Additional research is necessary to more accurately predict postoperative hemodynamic outcome and to define the optimal therapeutic approach, especially in patients with involvement of the distal vasculature.

Pulmonary vascular remodeling occurs in patients with chronic thromboembolic pulmonary hypertension (CTEPH). One factor contributing to this vascular wall thickening is the proliferation of pulmonary artery smooth muscle cells (PASMC). Store-operated Ca2+ entry (SOCE) and cytosolic free Ca2+ concentration ([Ca2+]cyt) in PASMC are known to be important in cell proliferation and vascular remodeling in pulmonary hypertension. Rapamycin is widely known for its antiproliferative effects in injured coronary arteries. Although several reports have suggested favorable effects of rapamycin in animal models of pulmonary hypertension, no reports have been published to date in human tissues. Here we report that rapamycin has an inhibitory effect on SOCE and an antiproliferative effect on PASMC derived from endarterectomized tissues of CTEPH patients. Cells were isolated from endarterectomized tissues obtained from patients undergoing pulmonary thromboendarterectomy (PTE). Immunohistochemical analysis indicated high deposition of platelet-derived growth factor (PDGF) in tissue sections from PTE tissues and increased PDGF receptor expression. PDGF transiently phosphorylated Akt, mammalian target of rapamycin (mTOR), and p70S6 kinase in CTEPH cells from CTEPH patients. Acute treatment (30 min) with rapamycin (10 nM) slightly increased cyclopiazonic acid (10 μM)-induced Ca2+ mobilization and significantly reduced SOCE. Chronic treatment (24 h) with rapamycin reduced Ca2+ mobilization and markedly inhibited SOCE. The inhibitory effects of rapamycin on SOCE were less prominent in control cells. Rapamycin also significantly reduced PDGF-stimulated cell proliferation. In conclusion, the data from this study indicate the importance of the mTOR pathway in the development of pulmonary vascular remodeling in CTEPH and suggest a potential therapeutic benefit of rapamycin (or inhibition of mTOR) in these patients.

Objectives The purpose of this study was to investigate the cause of abnormal left ventricular (LV) Doppler diastolic filling characteristics in chronic thromboembolic pulmonary hypertension (CTEPH). Background In CTEPH, LV diastolic function often appears abnormal. It is unclear whether this “impaired relaxation” (E Methods We studied 61 patients with an E Results After PTE, mitral E velocity increased (from 54 ± 16 cm/s to 81 ± 20 cm/s, p m ) did not change after PTE (8.0 ± 3.1 cm/s to 8.1 ± 2.0 cm/s, p = ns), whereas the velocity of the lateral mitral annulus increased (9.3 ± 3.2 cm/s to 11.8 ± 3.1 cm/s, p Conclusions The results of this study strongly suggest that the impaired relaxation pattern observed in patients with CTEPH is not solely the result of geometric effects of RV enlargement and LV chamber distortion but is caused in large part by low LV preload and relative underfilling.

Patients with chronic thromboembolic pulmonary hypertension (CTEPH) often have substantial right ventricular dysfunction. The resulting low cardiac index might predispose to sleep disordered breathing (SDB) by increasing ventilatory instability. The prevalence of SDB and potential association with impaired cardiac index was examined in patients with CTEPH. Patients referred for evaluation for pulmonary thromboendarterectomy surgery were recruited. Subjects underwent a sleep study, unless already using positive airway pressure therapy. Hemodynamic data were obtained from contemporaneous right-sided cardiac catheterization. A total of 49 subjects were included. SDB-defined as ongoing positive airway pressure use or apnea-hypopnea index (AHI) ≥5/h-was found in 57% of subjects. SDB was generally mild in severity, with respiratory events mainly consisting of hypopneas. Cardiac index was found to be significantly lower in subjects with SDB than those without (2.19 vs 2.55L/min/m(2); p= 0.024), whereas no differences were observed in other characteristics. Additionally, cardiac index was independently predictive of AHI. In a subgroup of subjects with an elevated percentage of central events, both cardiac index and lung to finger circulation time correlated with AHI. In conclusion, SDB is prevalent in patients with CTEPH and might decrease with treatments that improve cardiac index.

Background Pulmonary endarterectomy is the accepted therapy for thromboembolic pulmonary hypertension. A recognized complication of this surgery is the postoperative development of reperfusion edema, a potentially fatal cause of respiratory failure. Because reperfusion edema can be a reversible process, temporizing support measures may be life saving. Methods We retrospectively reviewed our experience with venovenous extracorporeal life support (V-V ECLS) from July 1990 to February 2006, in 20 adult patients (mean age 50.5 ± 14.5 years) presenting with potentially reversible respiratory failure after pulmonary endarterectomy. This subset of patients comprised 1.12% of our total pulmonary endarterectomy experience during that time (1,790 cases). Results Overall in-hospital survival was 30.0% for patients requiring ECLS support after pulmonary endarterectomy versus 94.2% for patients who underwent pulmonary endarterectomy alone during the same timeframe. V-V ECLS was instituted at a mean of 86.8 hours after surgery. The mean duration of V-V ECLS was 123.4 ± 71.3 hours. The most common cause of death in ECLS patients after pulmonary endarterectomy was pulmonary hemorrhage. Survival was greater in patients cannulated within 120 hours of surgery (46.2% survival; 6 of 13 patients) compared with those cannulated after 120 hours (0 of 7 patients). Multiple logistic regression identified long duration of mechanical ventilation pre-ECLS and severity of preoperative pulmonary hypertension together as predictors of mortality. Conclusions A small subset of patients undergoing pulmonary endarterectomy develop temporary life-threatening respiratory failure secondary to severe reperfusion edema. In those patients with satisfactory hemodynamic outcome, V-V ECLS is a therapeutic option when all other conventional strategies have been exhausted.

Chronic thromboembolic obstruction of the pulmonary vascular bed has been increasingly recognized as a treatable form of pulmonary hypertension, with surgery referred to as a pulmonary endarterectomy. Careful evaluation of patients with pulmonary hypertension and proper selection of those with surgically accessible, chronic thromboembolic disease are critical determinants for a successful outcome from this operation. This article describes the clinical presentation, appropriate evaluation, and an approach to surgical selection for patients with chronic thromboembolic pulmonary hypertension.

Although acute pulmonary embolism is epidemiologically associated with chronic thromboembolic pulmonary hypertension, the factors responsible for resistance to thrombolysis and a shift toward vascular remodeling within the pulmonary arteries of patients with chronic thromboembolic pulmonary hypertension are unknown.Determine whether fibrin from patients is more resistant to plasmin-mediated lysis than fibrin from healthy control subjects.Fibrinogen purified from patients and control subjects was used to prepare fibrin clots, which were subsequently digested with plasmin for various periods of time. The degradation of the alpha-, beta-, and gamma-chains of fibrin and the appearance of peptide fragments over time were assessed by polyacrylamide gel electrophoresis and Western blotting.Densitometry of Coomassie-stained gels revealed significantly slower cleavage of all three polypeptide chains of fibrin from patients compared with control subjects (p0.05). In particular, release of N-terminal fragments from the beta-chain of fibrin, which promote cell signaling, cell migration, and angiogenesis, was retarded in patients compared with control subjects (p0.01).The relative resistance of patient fibrin to plasmin-mediated lysis may be due to alterations in fibrin(ogen) structure affecting accessibility to plasmin cleavage sites. The persistence of structural motifs of fibrin, such as the beta-chain N-terminus, within the pulmonary vasculature could promote the transition from acute thromboemboli into chronic obstructive vascular scars.

Pathophysiological findings in chronic thromboembolic pulmonary hypertension (CTEPH) have suggested that a secondary small vessel arteriopathy may contribute to the haemodynamic impairment observed in these patients. It was hypothesised that this element of the elevated vascular resistance may be responsive to continuous intravenous epoprostenol therapy. Retrospectively, the clinical and haemodynamic responses to continuous intravenous epoprostenol were evaluated in nine CTEPH patients who subsequently underwent pulmonary thromboendarterectomy (PTE). Cardiopulmonary haemodyamics were determined prior to the initiation of epoprostenol, while on epoprostenol, prior to PTE, and after PTE. Six patients, treated for 2-26 months prior to PTE, experienced either clinical stability or improvement that was associated with a mean reduction in pulmonary vascular resistance (PVR) of 28% (median 33%,,, range 0-46%). Three patients, treated for 3-9 months, experienced clinical deterioration during epoprostenol administration, with a significant increase in PVR in two patients. Subsequent PTE resulted in a highly significant improvement of cardiac index, mean pulmonary artery pressure and total pulmonary resistance. To conclude, selected patients with chronic thromboembolic pulmonary hypertension may benefit clinically and haemodynamically from continuous intravenous epoprostenol treatment prior to pulmonary thromboendarterectomy. Factors predictive of a beneficial response, and whether this intervention influences either morbidity or mortality associated with pulmonary thromboendarterectomy, remain to be established

Background The incidence of pulmonary hypertension resulting from chronic thrombotic occlusion of the pulmonary arteries is significantly underestimated. Although medical therapy for the condition is supportive only, surgical therapy is curative. Our pulmonary endarterectomy program was begun in 1970, and 188 patients were operated on in the subsequent 20 years. With the increased recognition of the disease and the success of operative therapy, however, more than 1,400 operations have been done since 1990 at our center. Methods The safety and efficacy of the operation was assessed with changes made through increased experience. We examined in detail the results of our last 500 consecutive patients. Results Median sternotomy, cardiopulmonary bypass, profound hypothermia, and circulatory arrest were found to be essential to the success of the operation. All occluding material could be removed at operation. We currently believe that there is no degree of embolic occlusion within the pulmonary vascular tree that is inaccessible and no degree of right ventricular impairment or any level of pulmonary vascular resistance that is inoperable. With shorter cardiac arrest periods and the use of a cooling jacket to the head, cerebral impairment has been eliminated. The pulmonary artery pressures and pulmonary vascular resistance in a recent cohort of 500 patients is examined. The mortality rate for the operation has been reduced steadily, and was 22 of the last 500 patients operated on (4.4%). Conclusions The operation is considered curative and therefore greatly superior to transplantation for this condition. Current techniques of operation make the procedure relatively safe.

Five physicians addressed important issues in the diagnosis and management of patients with pulmonary thromboembolic disease. The roundtable discussion was moderated by Victor F. Tapson, MD, Associate Professor of Medicine, Division of Pulmonary and Critical Care Medicine, Duke University Medical Center, Durham, North Carolina, and included William Auger, MD, Professor of Clinical Medicine, University of California, San Diego, Medical Center, San Diego, California; Peter Fedullo, MD, Clinical Professor of Medicine, University of California, San Diego, Medical Center; Eckhard Mayer, MD, Professor of Thoracic Surgery, Department of Cardio-Thoracic Surgery, University Hospital, Mainz, Germany; and Christopher McGregor, MD, Professor of Surgery, Consultant in Cardio-Thoracic Surgery, and Director of the Mayo Clinic William J von Liebig Transplant Center, Rochester, Minnesota.

In their 1993 report, Moser and Bloor [1] described an array of microvascular “pulmonary hypertensive” lesions in patients with operable chronic thromboembolic disease. Although it was concluded that these findings in any one patient did not “preclude a positive haemodynamic and clinical result”, these early observations became the foundation of our current understanding of the evolution of pulmonary hypertension and right heart failure, following the establishment of proximal vessel, occlusive organised thromboembolic disease [2, 3]. Despite the significance and role of the microcirculation in chronic thromboembolic pulmonary hypertension (CTEPH), our understanding of the histopathology remains rather rudimentary [4] and previously confined to descriptions of the precapillary pulmonary …

Patients with pulmonary hypertension due to chronic thromboembolic disease benefit from pulmonary thromboendarterectomy. A subset of these patients present with concomitant coronary or valvular disease.From July 1990 to July 2000, 90 patients (68 males, 22 females, mean age 68 years) with pulmonary vascular resistance (PVR) ranging from 297 to 2261 dynes x sec x cm(-5) underwent pulmonary thromboendarterectomy in conjunction with coronary bypass grafting (59 patients), coronary artery bypass grafting/foramen ovale closure (24 patients), tricuspid annuloplasty (3 patients), mitral valve repair (2 patients), and aortic valve replacement (2 patients). The perioperative and hemodynamic outcomes of these patients were compared with the cohort of 1,100 isolated pulmonary thromboendarterectomies performed at our institution during this time.Overall perioperative survival (93.3%; 84 of 90 patients) and mean diminution in PVR (521 dynes x sec x cm(-5)) for patients undergoing combined operations were similar to those undergoing pulmonary thromboendarterectomy alone (94.2% survival; 1034 of 1100 patients; 547 dynes x sec x cm(-5) mean PVR reduction). Although patients undergoing combined operations were older (mean age 68 vs 50 years, p0.0001), had longer hospital stays (median 14 vs 9 days), and had worse left ventricular function (mean preoperative cardiac output 3.1 vs 4.4, p0.0001), there was no difference in cross-clamp time, resolution of tricuspid regurgitation, or postoperative systolic function between these two groups.Pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension may be performed safely in conjunction with other cardiac operations. Older patients evaluated for pulmonary thromboendarterectomy should be screened for concomitant coronary and valvular disease.

Pulmonary thromboendartectomy (PTE) for chronic thromboembolic pulmonary hypertension may be complicated by reperfusion lung injury. This has previously been demonstrated to be neutrophil-mediated. We postulated that blocking selectin-mediated adhesion of neutrophils to the endothelium with Cylexin (CY-1503) would prevent reperfusion lung injury in this patient population. In this double-blind, randomized, placebo-controlled, parallel study, 26 patients received Cylexin the day of surgery and 25 received placebo. Significantly fewer patients in the treated group (31%) compared with the placebo group (60%) developed lung injury (p = 0.036). However, the average number of days of mechanical ventilation, days in the intensive care unit (ICU) and hospital, as well as mortality were not significantly different between the treatment groups. Those with reperfusion lung injury had significantly elevated percent neutrophils, total protein, and soluble P-selectin in bronchoalveolar lavage fluid compared with those without lung injury. We conclude that reperfusion lung injury after PTE is a high-permeability lung injury and its incidence can be reduced by the administration of Cylexin on the day of surgery.

We sought to identify imaging features that help predict surgical success in patients undergoing thromboendarterectomy.Thirty-nine consecutive patients who underwent pulmonary angiography and thromboendarterectomy during 1995 and 1996 were included. Thirty-four underwent helical CT angiography. Measurements of postoperative pulmonary vascular resistance were compared with preoperative imaging features and preoperative pulmonary vascular resistance.The best imaging indicators of a relatively high postoperative pulmonary vascular resistance were the extent of small vessel disease identified on CT angiograms as segments with abnormal perfusion but normal segmental arteries (p = 0.005) and the extent of central disease (p = 0.015). Combined with preoperative pulmonary vascular resistance, these features had a strong correlation with postoperative outcome (p = 0.0005). Segmental arterial disease seen on both conventional angiography and CT angiography correlated poorly with surgical outcome.In patients with chronic thromboembolic pulmonary hypertension, CT angiographic evidence of extensive central vessel disease and limited small vessel involvement indicates a favorable surgical outcome.

Obstruction of major pulmonary vessels with organized thromboemboli is a rare sequelae of acute pulmonary embolic disease. Depending on the extent and duration of vascular occlusion, patients experiencing this unusual disorder may develop significant pulmonary hypertension and cor pulmonale. If left untreated, the ultimate clinical outcome is right heart failure and death. Over the past several decades, the description of this clinical entity has evolved from an autopsy curiosity to a recognized cause of chronic pulmonary hypertension. Also, during this same time period, surgical capabilities have greatly advanced, providing these patients a potentially life-saving remedy for this debilitating form of pulmonary vascular disease. This article provides a historical perspective for our current understanding of major vessel chronic thromboembolic pulmonary hypertension as a distinct clinical disorder. It also chronicles the developments in surgical techniques that have made thromboendarterectomy of the pulmonary arterial bed a reality.