Chronic Thromboembolic Pulmonary Hypertension: An Update

Endothelial Features Along the Pulmonary Vascular Tree in Chronic Thromboembolic Pulmonary Hypertension: Distinctive or Shared Facets?

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of pulmonary embolism, characterized by the presence of organized fibro-thrombotic material that partially or fully obstructs the lumen of large pulmonary arteries, microvasculopathy, and enlargement of the bronchial systemic vessels. The precise mechanisms underlying CTEPH remain unclear. However, defective angiogenesis and altered pulmonary arterial endothelial cell (PAEC) function may contribute to disease progression. Despite the observation of differences in histological features, shear stress and ischemia along the pulmonary vascular tree, the potential contribution of PAEC phenotype and function to these disparate aspects remains unexplored. Based on these observations, we postulated that angiogenic capacities and endothelial barrier function may contribute to disparities in histological features observed along the pulmonary vascular tree. We thus explored the histological characteristics of the pulmonary vascular tree using pulmonary arterial lesions obtained during pulmonary endarterectomy (PEA). We focused on the angiogenic vascular endothelial growth factor (VEGF)-A/VEGF receptor-2 (VEGFR2) axis and collagen 15A1 (COL15A1), a potential marker of endothelial cells of the systemic circulation. Concurrently, we examined In Vitro angiogenic properties and barrier function of PAECs derived from large and (sub)-segmental pulmonary arterial lesions. (Sub)-segmental pulmonary arterial lesions were abundantly recanalized by neovessels, paralleled by an enriched expression of VEGFR2. VEGF-A expression was more pronounced in large pulmonary arterial lesions. Nevertheless, no significant difference was discerned in In Vitro angiogenic capacities and barrier integrity of PAECs isolated from large and (sub)-segmental pulmonary arterial lesions. Importantly, our findings revealed the presence of endothelial cells (CD31+) expressing COL15A1, as well as CD31+ cells that did not express COL15A1. This suggests that endothelial cells from both systemic and pulmonary circulation contribute to lesion recanalization. Despite disparate in situ angiogenic cues in VEGF-A/VEGFR2 axis between large and (sub)-segmental pulmonary arterial lesions in CTEPH, In Vitro angiogenic capacities and barrier function remain unaltered.

Molecular Pathophysiology of Chronic Thromboembolic Pulmonary Hypertension: A Clinical Update from a Basic Research Perspective

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare but severe condition characterized by persistent obstruction and vascular remodeling in the pulmonary arteries following an acute pulmonary embolism (APE). Although APE is a significant risk factor, up to 25% of CTEPH cases occur without a history of APE or deep vein thrombosis, complicating the understanding of its pathogenesis. Herein, we carried out a narrative review discussing the mechanisms involved in CTEPH development, including fibrotic thrombus formation, pulmonary vascular remodeling, and abnormal angiogenesis, leading to elevated pulmonary vascular resistance and right heart failure. We also outlined how the disease's pathophysiology reveals both proximal and distal pulmonary artery obstruction, contributing to the development of pulmonary hypertension. We depicted the risk factors predicting CTEPH, including thrombotic history, hemostatic disorders, and certain medical conditions. We finally looked at the molecular mechanisms behind the role of endothelial dysfunction, gene expression alterations, and inflammatory processes in CTEPH progression and detection. Despite these insights, there is still a need for improved diagnostic tools, biomarkers, and therapeutic strategies to enhance early detection and management of CTEPH, ultimately aiming to reduce diagnostic delay and improve patient outcomes.

Notch ratio in pulmonary flow predicts long-term survival after pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension

BACKGROUND

Assessment of the pattern of the RV outflow tract Doppler provides insights into the hemodynamics of chronic thromboembolic pulmonary hypertension (CTEPH). We studied whether pre-operative assessment of timing of the pulmonary flow systolic notch by Doppler echocardiography is associated with long-term survival after pulmonary endarterectomy (PEA) for CTEPH.

METHODS

Fifty-nine out of 61 consecutive CETPH patients (mean age 53 ± 14 years, 34% male) whom underwent PEA between June 2002 and June 2005 were studied. Clinical, echocardiographic and hemodynamic variables were assessed pre-operatively and repeat echocardiography was performed 3 months after PEA. Notch ratio (NR) was assessed with pulsed Doppler and calculated as the time from onset of pulmonary flow until notch divided by the time from notch until end of pulmonary flow. Long-term follow-up was obtained between May 2021 and February 2022.

RESULTS

Pre-operative mean pulmonary artery pressure (mPAP) was 45 ± 15 mmHg and pulmonary vascular resistance (PVR) was 646 ± 454 dynes.s.cm-5. Echocardiography before PEA showed that 7 patients had no notch, 33 had a NR < 1.0 and 19 had a NR > 1.0. Three months after PEA, echocardiography revealed a significant decrease in sPAP in long-term survivors with a NR < 1.0 and a NR > 1.0, while a significant increase in TAPSE/sPAP was only observed in the NR < 1.0 group. Mean long-term clinical follow-up was 14 ± 6 years. NR was significantly different between survivors and non-survivors (0.73 ± 0.25 vs. 1.1 ± 0.44, p < 0.001) but no significant differences were observed in mPAP or PVR. Long-term survival at 14 years was significantly better in patients with a NR < 1.0 compared to patients with a NR > 1.0 (83% vs. 37%, p =  < 0.001).

CONCLUSION

Pre-operative assessment of NR is a predictor of long-term survival in CTEPH patients undergoing PEA, with low mortality risk in patients with NR < 1.0. Long-term survivors with a NR < 1.0 and NR > 1.0 had a significant decrease in sPAP after PEA. However, the TAPSE/sPAP only significantly increased in the NR < 1.0 group. In the NR < 1.0 group, the 6-min walk test increased significantly between pre-operative and at 1-year post-operative follow-up. NR is a simple echocardiographic parameter that can be used in clinical decision-making for PEA.

Quantitative pulmonary perfusion in acute pulmonary embolism and chronic thromboembolic pulmonary hypertension

Current methods for quantifying perfusion from computed tomography pulmonary angiography (CTPA) often rely on semi-quantitative scoring systems and requires an experienced evaluator. Few studies report on absolute quantitative variables derived from the images, and the methods are varied with mixed results. Dual-energy CTPA (DE-CTPA) enables automatic quantification of lung and lobar perfusion with minimal user interaction by utilizing machine learning based software. We aimed to evaluate differences in DE-CTPA derived quantitative perfusion variables between patients with acute pulmonary embolism (PE) and chronic thromboembolic pulmonary hypertension (CTEPH). This retrospective, single-center, observational study included 162 adult patients diagnosed with PE (n = 81) or CTEPH (n = 81) and scanned using dual-energy CT between 2020 and 2023. Mann-Whitney U tests and permutational analysis of variance (PERMANOVA) were used for comparative analyses. We found whole lung perfusion blood volume to be lower (p < 0.001) in PE patients (median 3399 mL [2554, 4284]) than in CTEPH patients (median 4094 mL [3397, 4818]). The same was observed at single lung and lobar level. PERMANOVA encompassing all perfusion variables showed a difference between the two groups (F-statistic = 13.3, p = 0.002). Utilizing logistic regression, right and left lower lobe perfusion blood volume showed some ability to differentiate between PE and CTEPH with area under the receiver operation characteristics curve values of 0.71 (95% CI: 0.56; 0.84) and 0.72 (95% CI: 0.56; 0.86). Pulmonary perfusion is lower in patients with PE than patients with CTEPH, highlighted by differences in DECT-derived perfusion blood volume. Quantitative perfusion variables might be useful to differentiate between the two diseases.

Diagnosis and Management of Pulmonary Hypertension and Right Ventricular Failure in the Cardiovascular Intensive Care Unit

Pulmonary hypertension (PH) encompasses a broad range of conditions, including pulmonary artery hypertension, left-sided heart disease, and pulmonary and thromboembolic disorders. Successful diagnosis and management rely on an integrated clinical assessment of the patient's physiology and right heart function. Right ventricular (RV) heart failure is often a result of PH, but may result from varying abnormalities in preload, afterload, and intrinsic myocardial dysfunction, which require distinct management strategies. Consideration of an individual's hemodynamic phenotype and physiologic circumstances is paramount in management of PH and RV failure, particularly when there is clinical instability in the intensive care setting.

A Case of Chronic Pulmonary Embolism Resulting in Pulmonary Hypertension and Decompensated Right Heart Failure

Chronic thromboembolic pulmonary hypertension is a deadly condition that results from thrombus organization and formation of fibrous tissue in the large and/or middle-sized pulmonary artery; as a result, pulmonary vascular resistance increases resulting in pulmonary hypertension and right heart failure. Untreated chronic pulmonary embolism causes decompensated right heart failure. Early diagnosis and appropriate treatment are crucial for improving survival. Pulmonary endarterectomy (PEA) is the treatment of choice as it reduces pulmonary vascular resistance. For patients who are not a candidate for PEA, alternative treatment options improve quality of life.

Acute on Chronic Thromboembolic Pulmonary Hypertension: Case Series and Review of Management

Chronic thromboembolic pulmonary hypertension (CTEPH) is a distinct form of precapillary pulmonary hypertension classified as group 4 by the World Symposium on Pulmonary Hypertension (WSPH) and should be excluded during an episode of acute pulmonary embolism (PE). Patients presenting to emergency departments with sudden onset of signs and symptoms of acute PE may already have a pre-existing CTEPH condition decompensated by the new PE episode. Identifying an underlying and undiagnosed CTEPH during acute PE, while challenging, is an important consideration as it will alter the patients’ acute and long-term management. Differential diagnosis and evaluation require an interdisciplinary expert team. Analysis of the clinical condition, the CT angiogram, and the hemodynamic situation are important considerations; patients with CTEPH usually have significantly higher sPAP at the time of index PE, which is unusual and unattainable in the context of acute PE and a naïve right ventricle. The imaging may reveal signs of chronic disease such as right ventricle hypertrophy bronchial collaterals and atypical morphology of the thrombus. There is no standard for the management of acute on chronic CTEPH. Herein, we provide a diagnostic and management algorithm informed by several case descriptions and a review of the literature.

Recognizing pulmonary hypertension following pulmonary thromboendarterectomy: A practical guide for clinicians

Chronic thromboembolic pulmonary hypertension (CTEPH) is a form of pulmonary hypertension (PH) arising from pulmonary vascular obstruction at varying levels within the pulmonary vascular bed, due to chronic pulmonary emboli. The cornerstone of treatment for CTEPH is pulmonary thromboendarterectomy (PTE), a specialized surgery to remove the chronic vascular obstruction. At experienced centers, PTE leads to marked hemodynamic improvement and, in many cases, normalization of cardiopulmonary hemodynamics. However, increasing evidence supports the fact that a significant percentage of patients will have persistent PH after PTE. No consensus exists on the optimal approach to post-PTE patient assessment, and often the most experienced CTEPH centers have little experience in the direct follow-up care of the CTEPH patient post PTE. In this article, we will discuss a practical approach to patient assessment after PTE to help guide clinicians on how to recognize significant PH following PTE. In doing so, we identify the true phenotype of persistent PH post PTE so that appropriate patients can be further helped with the evolving therapies for the management of CTEPH.

Higher Incidence of Chronic Thromboembolic Pulmonary Hypertension After Acute Pulmonary Embolism in Asians Than in Europeans: A Meta-Analysis

Aim: To summarize the incidence of right heart catheter diagnosed chronic thromboembolic pulmonary hypertension (CTEPH) after acute pulmonary embolism (PE) in a meta-analysis. Methods: Cohort studies reporting the incidence of CTEPH after acute PE were identified via search of Medline, Embase, China National Knowledge Infrastructure and WanFang databases. Results: Twenty-two cohort studies with 5,834 acute PE patients were included. Pooled results showed that the overall incidence of CTEPH was 2.82% (95% CI: 2.11-3.53%). Subgroup analyses showed higher incidence of CTEPH in Asians than Europeans (5.08 vs. 1.96%, p = 0.01), in retrospective cohorts than prospective cohorts (4.75 vs. 2.47%, p = 0.02), and in studies with smaller sample size than those with larger sample size (4.57 vs. 1.71%, p < 0.001). Stratified analyses showed previous venous thromboembolic events and unprovoked PE were both significantly associated with increased risk of CTEPH (OR = 2.57 and 2.71, respectively; both p < 0.01). Conclusions: The incidence of CTEPH after acute PE is ~3% and the incidence is higher in Asians than Europeans. Efforts should be made for the early diagnosis and treatment of CTEPH in PE patients, particularly for high-risk population.

Chronic thromboembolic pulmonary hypertension: a review

Chronic thromboembolic pulmonary hypertension (CTEPH) is a unique form of pulmonary hypertension resulting from obstruction of the pulmonary artery by fibrotic thromboembolic material, usually initiated by recurrent or incomplete resolution of pulmonary embolism. This distinct form of pulmonary hypertension is classified under Group 4 of the World Health Organization classification. Further investigations are usually initiated, with transthoracic echocardiography followed by right heart catheterisation and pulmonary angiography as the gold standard. Definitive treatment is usually in the form of surgical pulmonary endarterectomy. Inoperable CTEPH is medically treated with pharmacological agents such as phosphodiesterase Type 5 inhibitors, endothelin receptor antagonists, soluble guanylate cyclase stimulators and prostacyclin. Recent developments have made balloon pulmonary angioplasty a viable option as well.

Advanced Surgical and Percutaneous Approaches to Pulmonary Vascular Disease

Despite progress in modern medical therapy, pulmonary hypertension remains an unremitting disease. Once severe or refractory to medical therapy, advanced percutaneous and surgical interventions can palliate right ventricular overload, bridge to transplantation, and overall extend a patient's course. These approaches include atrial septostomy, Potts shunt, and extracorporeal life support. Bilateral lung transplantation is the ultimate treatment for eligible patients, although the need for suitable lungs continues to outpace availability. Measures such as ex vivo lung perfusion are ongoing to expand donor lung availability, increase rates of transplant, and decrease waitlist mortality.

Evaluation of Diagnostic Accuracy and Radiation Exposure of Dual-Energy Computed Tomography (DECT) in the Course of Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

PURPOSE

 The purpose of this study was to assess the diagnostic accuracy of computed tomography pulmonary angiogram (CTPA) including dual energy and reconstruction of iodine maps for diagnosing CTEPH. This method for detecting embolisms and perfusion failures was compared with V/Q-SPECT. An additional purpose was to compare the applied radiation dose of both techniques.

MATERIALS AND METHODS

 71 patients (49 women) with suspected CTEPH were included in this prospective study. The patients received a V/Q-SPECT and a dual-energy CTPA. Iodine maps were reconstructed from the data set. CTPA and the iodine maps were read by an experienced radiologist unaware of the clinical information as well as the results of the V/Q-SPECT. Results were compared to the V/Q-SPECT. DLP and the applied amount of radionuclides (MAA, Technegas) were obtained for comparison of radiation dose.

RESULTS

 For the diagnosis of CTEPH, the sensitivity of DECT was 1.000, specificity 0.966, PPV 0.867 and NPV 1.000, respectively. There was not a considerable difference in the x-ray exposure between the DECT examination and the V/Q-SPECT (1.892 mSv vs. 1.911 mSv; p = 0.6115). Both examination modalities were highly consistent regarding the classification of pathological segments (1177/1278 segments, 92,09 %, κ = 0,5938).

CONCLUSION

 This study presents the DECT, in combination with reconstructed iodine maps, as a potential alternative to the current imaging technique of first choice, V/Q-SPECT. For creating future prospective diagnostic algorithms, the implementation of DECT screening with iodine maps should be considered.

KEY POINTS

· DECT correctly identified all CTEPH patients.. · There is substantial agreement between DECT and V/Q-SPECT in the classification of pathological segments.. · There is no significant difference in radiation exposure during DECT examination and V/Q-SPECT examination.. · Reduced radiation dose does not negatively impact image quality..

CITATION FORMAT

· Schüßler A, Richter M, Tello K et al. Evaluation der diagnostischen Genauigkeit und der Strahlendosis der Dual-Energy-Computertomografie (DECT) bei chronisch thromboembolischer pulmonaler Hypertonie (CTEPH). Fortschr Röntgenstr 2021; DOI: 10.1055/a-1502-7541.

Efficacy and safety of riociguat in the treatment of chronic thromboembolic pulmonary arterial hypertension: A meta-analysis

BACKGROUND

Riociguat is a novel soluble guanylate cyclase stimulator, and has been widely used for the treatment of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension (CTEPH). Some studies found that riociguat had better effects on CTEPH and proved to be safe, but the results were not utterly consistent. Therefore, the purpose of this study was to comprehensively evaluate the efficacy and safety of riociguat in the treatment of CTEPH.

METHODS

Randomized controlled trials on riociguat for the treatment of CTEPH were searched through such electronic databases as PubMed, Embase, Cochrane Library, Web of Science, China national knowledge internet, and Wanfang. The outcomes included exercise capacity, pulmonary hemodynamics, and side effects. The fixed-effects or random-effects models were used to analyze the pooled data, and heterogeneity was assessed by the I2 test.

RESULTS

Four studies involving 520 patients were included in this meta-analysis. Compared with the placebo group, riociguat significantly improved the hemodynamic indexes and increased 6-min walking distance (P < .0001, standardized mean difference (SMD) = -0.24, 95%CI -0.35 to -0.12; P < .00001, SMD = 0.52, 95%CI 0.33 to 0.71), and decreased the Borg dyspnea score (P = .002, SMD = -0.31, 95%CI -0.51 to -0.12). In addition, riociguat could also significantly reduce the living with pulmonary hypertension scores and increase the EQ-5D scores (P = .01, SMD=-0.23, 95%CI -0.42 to -0.05; P < .00001, SMD = 0.47, 95%CI 0.27 to 0.66), but there was no significant difference in the change level of N-terminal pro-hormone B-type natriuretic peptide in patients with riociguat (P = .20, SMD = -0.24, 95%CI -0.61 to -0.13). The common adverse events of riociguat were dyspepsia and peripheral edema, and no other serious adverse reactions were observed.

CONCLUSIONS

We confirmed that riociguat had better therapeutic effects in improving the hemodynamic parameters and exercise capacity in patients with CTEPH without inducing serious adverse events. This will provide a reasonable medication regimen for the treatment of CTEPH.

Characterization of a Cohort of Patients with Chronic Thromboembolic Pulmonary Hypertension from Northeastern Colombia (REHINO Study)

Chronic thromboembolic disease (CTEPH) is one of the causes for developing pulmonary hypertension (PH). PH is characterized by an increase in pulmonary vascular pressure and resistance, ultimately leading to chronic overload. This study describes the clinical, functional, and hemodynamic characteristics as well as the established treatment strategy for a cohort of patients diagnosed with CTEPH in Bucaramanga, Colombia. In Colombia, PH is considered as an orphan disease with limited epidemiological data. We aim to provide useful information in order to help guide future clinical decisions for PH treatment and prevention. We conducted a cross-sectional study, obtaining clinical data from patients under follow-up, over 18 years of age, with hemodynamic confirmation of CTEPH in two pulmonary outpatient centers in Bucaramanga, Colombia between 2012 and 2018. 35 patients with diagnosis of CTEPH were included. Mean age was 52.3 ± 17.9 years. The mean time between the onset of symptoms to diagnosis was 14 months. 71% had a previous thrombotic event and 69% had functional class III and IV according to the world health organization (WHO) criteria. Most of the patients were classified as at high risk of mortality according to the European Society of Cardiology (ESC) and the European Respiratory Society (ERS/ESC) criteria and 60% were referred to undergo thromboendarterectomy. Most of the patients were under monotherapy treatment with Bosentan, the most prescribed medication in both monotherapy and dual therapy. This study identified a high number of patients in advanced stages of CETPH due to late diagnosis, related to health care limitations. This resulted in worse prognosis and quality of life. In addition, low adherence to non-pharmacological interventions was evidenced in patients who were not candidates for thromboendarterectomy despite the onset of pharmacological therapy.

Successful use of intravenous treprostinil as a bridge to pulmonary thromboendarterectomy

Chronic thromboembolic pulmonary hypertension (CTEPH) involves non-resolving thromboemboli in the pulmonary arteries. Treatment for CTEPH includes lifelong anticoagulation and determination of patients who have disease which is operable versus inoperable. Pulmonary arterial hypertension (PAH) targeted therapies are oftentimes used as a bridge to pulmonary thromboendarterectomy (PTE), though riociguat is the only Food and Drug Administration (FDA)-approved therapy for CTEPH. There is a paucity of data regarding the efficacy of other PAH therapies, particularly as a bridge to PTE. Here, we present a case report of severe CTEPH related to ventriculoatrial shunt in which intravenous treprostinil was used as a bridge to PTE.

Pulmonary Hypertension: A Brief Guide for Clinicians

Pulmonary hypertension (PH) is classified into 5 clinical subgroups: pulmonary arterial hypertension (PAH), PH due to left-sided heart disease, PH due to chronic lung disease, chronic thromboembolic PH (CTEPH), and PH with an unclear and/or multifactorial mechanisms. A range of underlying conditions can lead to these disorders. Overall, PH affects approximately 1% of the global population, and over half of patients with heart failure may be affected. Cardiologists are therefore likely to encounter PH in their practice. Routine tests in patients with symptoms and physical findings suggestive of PH include electrocardiography, chest radiography, and pulmonary function tests. Transthoracic echocardiography is used to estimate the probability of PH. All patients with suspected or confirmed PH, without confirmed left-sided heart or lung diseases, should have a ventilation-perfusion scan to exclude CTEPH. Right-sided heart catheterization is essential for accurate diagnosis and classification. All patients with PAH or CTEPH must be referred to a specialist center. Surgical pulmonary endarterectomy is the treatment of choice for eligible patients with CTEPH. Targeted treatments (phosphodiesterase type 5 inhibitors, soluble guanylate cyclase stimulators, endothelin receptor antagonists, prostacyclin analogues, and prostacyclin receptor agonists) are licensed for patients with PAH. The soluble guanylate cyclase stimulator riociguat is the only licensed targeted therapy for patients with inoperable or persistent/recurrent CTEPH. Management of PH resulting from left-sided heart disease primarily involves treatment of the underlying condition.

Research progress on the pathogenesis of CTEPH

Chronic thromboembolic pulmonary hypertension (CTEPH) is an established long-term complication of pulmonary thromboembolism (PTE). However, studies have shown that many patients with a definitive CTEPH diagnosis have no history of symptomatic PTE, suggesting that PTE is not the only cause of CTEPH. Despite extensive progress in research on pulmonary hypertension in recent years, due to a lack of relevant studies on the pathophysiology of CTEPH, implementing pulmonary endarterectomy (PEA) in patients has many challenges, and the prognosis of patients with CTEPH is still not optimistic. Therefore, revealing the pathogenesis of CTEPH would be of great significance for understanding the occurrence and development of CTEPH, developing relevant drug treatment studies and formulating intervention strategies, and may provide new preventive measures. This article summarizes the current research progress in CTEPH pathogenesis from the perspective of risk factors related to medical history, abnormal coagulation and fibrinolytic mechanisms, inflammatory mechanisms, genetic susceptibility factors, angiogenesis, in situ thrombosis, vascular remodeling, and other aspects.

CTPA, DECT, MRI, V/Q Scan, and SPECT/CT V/Q for the noninvasive diagnosis of chronic thromboembolic pulmonary hypertension: A protocol for systemic review and network meta-analysis of diagnostic test accuracy

BACKGROUND

To determine the diagnostic accuracy of techniques with chronic thromboembolic pulmonary hypertension (CTEPH) patients via a protocol for systemic review and network meta-analysis.

METHODS

We will search PubMed, EMBASE, Web of Science, and Google Scholar from inception to October 1, 2018. The reference lists of the retrieved articles are also consulted. Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) will be used to assess the risk of bias in each study. The direct meta-analyses, network meta-analyses, and ranking of competing diagnostic tests will be used by STATA 12.0 and WINBUGS 1.4. Heterogeneity and inconsistency are assessed.

RESULTS

This study is ongoing, will be submitted to a peer-reviewed journal publication once completed.

CONCLUSION

This study will provide a comprehensive evidence summary of diagnostic test accuracy in detecting the CTEPH, and can help patients and clinicians to select appropriate or best diagnostic test.

ETHICS AND COMMUNICATION

No ethical approval and patient consent are required, because it is based on published researches.

PROSPERO REGISTRATION NUMBER

CRD42019121279.