Pulmonary Vascular Reactivity and Prognosis in Patients With Chronic Thromboembolic Pulmonary Hypertension

Monographic Issue on Pulmonary Hypertension: Medical and Interventional Treatment for Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of acute pulmonary embolism. The reasons why clots do not resorb are incompletely understood, but the result is partial or complete fibrothrombotic obstruction of pulmonary arteries. A secondary microvasculopathy aggravates the pulmonary hypertension (PH) as a consequence of high flow and shear stress in the nonoccluded arteries. The treatment of CTEPH has long been purely surgical, but many patients were inoperable because of inaccessible lesions or severe comorbidities. Alternatives were developed, including medical therapy and more recently balloon pulmonary angioplasty (BPA). Depending on the generation of the obstructed vessels, the treatment will be surgical, up to the (sub)segmental level, or by BPA for more distal vessels. PH drugs are used to treat the microvasculopathy. The current paper describes the therapeutic management of inoperable patients: the medical approach with PH drugs used in mono- or combination therapy; the proper use of anticoagulants in CTEPH; the technique, indications, and results at short- and long-term of BPA; the multimodal approach for inoperable patients combining PH drugs and BPA; and the effects of rehabilitation. It shows the importance of a multidisciplinary approach to the disease.

Chronic thromboembolic pulmonary hypertension: realising the potential of multimodal management

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of acute pulmonary embolism. Important advances have enabled better understanding, characterisation, and treatment of this condition. Guidelines recommending systematic follow-up after acute pulmonary embolism, and the insight that CTEPH can mimic acute pulmonary embolism on initial presentation, have led to the definition of CTEPH imaging characteristics, the introduction of artificial intelligence diagnosis pathways, and thus the prospect of easier and earlier CTEPH diagnosis. In this Series paper, we show how the understanding of CTEPH as a sequela of inflammatory thrombosis has driven successful multidisciplinary management that integrates surgical, interventional, and medical treatments. We provide imaging examples of classical major vessel targets, describe microvascular targets, define available tools, and depict an algorithm facilitating the initial treatment strategy in people with newly diagnosed CTEPH based on a multidisciplinary team discussion at a CTEPH centre. Further work is needed to optimise the use and combination of multimodal therapeutic options in CTEPH to improve long-term outcomes for patients.

Chronic thromboembolic pulmonary hypertension and the post-pulmonary embolism (PE) syndrome

Over a third of patients surviving acute pulmonary embolism (PE) will experience long-term cardiopulmonary limitations. Persistent thrombi, impaired gas exchange, and altered hemodynamics account for aspects of the postpulmonary embolism syndrome that spans mild functional limitations to debilitating chronic thromboembolic pulmonary hypertension (CTEPH), the most worrisome long-term consequence. Though pulmonary endarterectomy is potentially curative for the latter, less is understood surrounding chronic thromboembolic disease (CTED) and post-PE dyspnea. Advances in pulmonary vasodilator therapies and growing expertise in balloon pulmonary angioplasty provide options for a large group of patients ineligible for surgery, or those with persistent postoperative pulmonary hypertension. In this clinical review, we discuss epidemiology and pathophysiology as well as advances in diagnostics and therapeutics surrounding the spectrum of disease that may follow months after acute PE.

Acute vasoreactivity testing during right heart catheterization in chronic thromboembolic pulmonary hypertension: Results from the pulmonary vascular disease phenomics study

Chronic thromboembolic pulmonary hypertension (CTEPH) is believed to involve both vascular obstruction and vasoconstriction; hence, pulmonary vasodilators such as riociguat may be beneficial. Acute vasoreactivity testing (AVT) is seldom performed routinely in CTEPH patients, so there is limited understanding of the frequency and significance of an acute vasodilator response. Systematic vasodilator testing with oxygen (O₂) and oxygen plus inhaled nitric oxide (O₂ + iNO) was performed as part of the Pulmonary Vascular Disease Omics (PVDOMICS) NHLBI project, providing an opportunity to examine AVT responses in CTEPH. Patients with CTEPH enrolled in PVDOMICS (n = 49, 40 with prevalent CTEPH [82%]) underwent right heart catheterization including AVT with O₂ and O₂ + iNO. Hemodynamics were obtained at baseline and with each challenge. Fourteen of 49 patients (29%) had >20% drop in pulmonary vascular resistance (PVR) with O₂. With O₂ + iNO, 30/49 (61%) had >20% drop in PVR, 20% had >20% drop in mean pulmonary artery pressure (mPAP) and PVR, and 8% had >10 mmHg decline in mPAP to mPAP < 40 with normal cardiac output. Patients on riociguat had less response to O₂ + iNO than patients on phosphodiesterase-5 inhibitors. Our findings shed light on the significant variability in vascular tone that is present in CTEPH, confirming that CTEPH represents a combination of mechanical obstruction and vasoconstriction that appears similar to that observed with Group 1 PAH. Additional study regarding whether results of acute vasodilator testing predict response to therapy and relate to prognosis is warranted.

Brazilian Thoracic Society recommendations for the diagnosis and treatment of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a serious and debilitating disease caused by occlusion of the pulmonary arterial bed by hematic emboli and by the resulting fibrous material. Such occlusion increases vascular resistance and, consequently, the pressure in the region of the pulmonary artery, which is the definition of pulmonary hypertension. The increased load imposed on the right ventricle leads to its progressive dysfunction and, finally, to death. However, CTEPH has a highly significant feature that distinguishes it from other forms of pulmonary hypertension: the fact that it can be cured through treatment with pulmonary thromboendarterectomy. Therefore, the primary objective of the management of CTEPH should be the assessment of patient fitness for surgery at a referral center, given that not all patients are good candidates. For the patients who are not good candidates for pulmonary thromboendarterectomy, the viable therapeutic alternatives include pulmonary artery angioplasty and pharmacological treatment. In these recommendations, the pathophysiological bases for the onset of CTEPH, such as acute pulmonary embolism and the clinical condition of the patient, will be discussed, as will the diagnostic algorithm to be followed and the therapeutic alternatives currently available.

Evaluation of the effect of nitric oxide inhalation in the patients with chronic thromboembolic pulmonary hypertension or pulmonary disease during balloon pulmonary angioplasty

Balloon pulmonary angioplasty (BPA) for chronic thromboembolic pulmonary hypertension (CTEPH) or pulmonary disease (CTEPD) is performed worldwide. High mean pulmonary arterial pressure (mPAP) during BPA is associated with aggravation of procedure‐related complications. Inhaled nitric oxide (NO) acts as a pulmonary vasodilator in CTEPH patients. The aim of this retrospective observational study was to evaluate the effects of inhaled NO in CTEPH/CTEPD patients during BPA. We assessed hemodynamic changes and the frequency of procedure‐related complications with or without NO inhalation. We performed 338 consecutive BPA in 72 CTEPH/CTEPD patients between April 2016 and November 2020. Since December 2019, all 16 patients (72‐BPA sessions) inhaled NO during the procedure as a routine. Inhaled NO significantly reduced mPAP from 31.3 ± 8.5 to 27.2 ± 6.8 mmHg (p < 0.001) without lowering systemic blood pressure (systolic: 139.9 ± 19.9 vs. 135.3 ± 21.8 mmHg; p = 0.247, diastolic: 82.8 ± 13.0 vs. 79.0 ± 9.3 mmHg; p = 0.085, before vs. after NO inhalation, respectively). Procedure‐related complications were observed in 46 sessions (13.6%). The incidence of hemoptysis was significantly higher in the NO group than in the non‐NO group (20.8% vs. 10.9%; p = 0.031). In contrast, all fatal complications (death and use of positive pressure ventilation) occurred in the non‐NO group, but the difference was not statistically significant (0 sessions [0.0%] vs. 7 sessions [2.6%], p = 0.353). Inhaled NO acts as a selective pulmonary vasodilator in CTEPH/CTEPD patients during the BPA procedure.

ERS statement on chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of acute pulmonary embolism, either symptomatic or not. The occlusion of proximal pulmonary arteries by fibrotic intravascular material, in combination with a secondary microvasculopathy of vessels <500 µm, leads to increased pulmonary vascular resistance and progressive right heart failure. The mechanism responsible for the transformation of red clots into fibrotic material remnants has not yet been elucidated. In patients with pulmonary hypertension, the diagnosis is suspected when a ventilation/perfusion lung scan shows mismatched perfusion defects, and confirmed by right heart catheterisation and vascular imaging. Today, in addition to lifelong anticoagulation, treatment modalities include surgery, angioplasty and medical treatment according to the localisation and characteristics of the lesions.This statement outlines a review of the literature and current practice concerning diagnosis and management of CTEPH. It covers the definitions, diagnosis, epidemiology, follow-up after acute pulmonary embolism, pathophysiology, treatment by pulmonary endarterectomy, balloon pulmonary angioplasty, drugs and their combination, rehabilitation and new lines of research in CTEPH.It represents the first collaboration of the European Respiratory Society, the International CTEPH Association and the European Reference Network-Lung in the pulmonary hypertension domain. The statement summarises current knowledge, but does not make formal recommendations for clinical practice.

2018 TSOC guideline focused update on diagnosis and treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized as a progressive and sustained increase in pulmonary vascular resistance, which may induce right ventricular failure. In 2014, the Working Group on Pulmonary Hypertension of the Taiwan Society of Cardiology (TSOC) conducted a review of data and developed a guideline for the management of PAH.⁴ In recent years, several advancements in diagnosis and treatment of PAH has occurred. Therefore, the Working Group on Pulmonary Hypertension of TSOC decided to come up with a focused update that addresses clinically important advances in PAH diagnosis and treatment. This 2018 focused update deals with: (1) the role of echocardiography in PAH; (2) new diagnostic algorithm for the evaluation of PAH; (3) comprehensive prognostic evaluation and risk assessment; (4) treatment goals and follow-up strategy; (5) updated PAH targeted therapy; (6) combination therapy and goal-orientated therapy; (7) updated treatment for PAH associated with congenital heart disease; (8) updated treatment for PAH associated with connective tissue disease; and (9) updated treatment for chronic thromboembolic pulmonary hypertension.

Chronic Thromboembolic Pulmonary Hypertension: Epidemiology, Diagnosis, and Management

Chronic thromboembolic pulmonary hypertension (CTEPH), classified as World Health Organization (WHO) group 4 pulmonary hypertension (PH), is an interesting and rare pulmonary vascular disorder secondary to mechanical obstruction of the pulmonary vasculature from thromboembolism resulting in PH. The pathophysiology is complex, beginning with mechanical obstruction of the pulmonary arteries, which eventually leads to arteriopathic changes and vascular remodeling in the nonoccluded arteries and in the distal segments of the occluded arteries mediated by thrombus nonresolution, abnormal angiogenesis, endothelial dysfunction, and various local growth factors. Based on available data, CTEPH is a rare disease entity occurring in a small proportion (0.5-3%) of patients after acute pulmonary embolism with an annual incidence ranging anywhere between 1 and 7 cases per million population. It is often underdiagnosed or misdiagnosed as idiopathic pulmonary arterial hypertension due to a lack of clinical suspicion or the under-utilization of radionuclide ventilation/perfusion scan. Although the current standard remains planar ventilation/perfusion scintigraphy as the initial imaging study to screen for CTEPH, and invasive pulmonary angiography with right heart catheterization as confirmatory modalities, they are likely to be replaced by modalities that can provide both anatomic and functional data while minimizing radiation exposure. Surgery is the gold standard treatment and offers better improvements in clinical and hemodynamic parameters compared with medical therapy. The management of CTEPH requires a multidisciplinary team, operability assessment, experienced surgical center, and the consideration of medical PH-directed therapies in patients who have inoperable disease, in addition to supportive therapies. Although, balloon pulmonary angioplasty is gaining interest to improve pulmonary hemodynamics and symptoms in CTEPH patients not amenable to surgery, further investigative randomized studies are needed to validate its use. It is very important for the present-day physician to be familiar with the disease entity and its appropriate evaluation to facilitate early diagnosis and appropriate management.

Usefulness of thrombosis and inflammation biomarkers in chronic thromboembolic pulmonary hypertension-sampling plasma and surgical specimens

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) results from persistent pulmonary vascular obstructions, presumably due to inflammatory thrombosis. Because estimates of thrombus volume at diagnosis have no predictive value, we investigated the role of the thrombosis marker, D-dimer, and the inflammation marker, C-reactive protein (CRP), for predicting outcomes in CTEPH.

METHODS

A total 289 consecutive patients with CTEPH were followed for 57 (median 45 to 69) months. One hundred fifty-seven of these patients underwent surgical pulmonary endarterectomy (PEA). D-dimer and CRP were collected at the time of CTEPH diagnosis and their impact on outcome was analyzed using Cox and logistic regression models. Their association with thrombus composition was analyzed utilizing HistoQuest.

RESULTS

D-dimer and CRP levels were separately and independently predictive of death or need for lung transplantation (p = 0.012 and p = 0.025, respectively). For example, 5-year survival was 90% (confidence limits 84% to 96%) in patients with D-dimer levels <0.5 µg/ml and CRP <1 mg/dl at diagnosis, as compared with 50% (36% to 64%) for patients with D-dimer ≥0.5 µg/ml and CRP ≥1 mg/dl (p < 0.001). D-dimer and CRP both decreased significantly after PEA (p < 0.01). The amount of fresh red thrombus in thrombendarterectomy specimens correlated positively with D-dimer levels at diagnosis (r = 0.37, p = 0.003).

CONCLUSIONS

D-dimer and CRP at the time of diagnosis are independent and significant predictors of outcome in CTEPH, available at the time of diagnosis. This observation suggests an important role for fibrin turnover and inflammation in the pathogenesis of CTEPH and the associated complications.

Acute hemodynamic effects of intravenous adenosine in patients with associated pulmonary arterial hypertension: Comparison with intravenous epoprostenol

Exogenous intravenous (IV) adenosine and epoprostenol are effective vasodilator agents, causing a substantial reduction in pulmonary vascular resistance in patients affected by idiopathic pulmonary arteriolar hypertension (PAH). Their action, in patients with PAH associated with other pathological conditions, is not well defined. In the present paper the authors retrospectively analyzed the acute hemodynamic effects of intravenous adenosine and epoprostenol in 30 consecutive patients (mean age: 58 ± 15 years; 21 females, and 9 males) affected by PAH associated with other pathological conditions, as determined by changes from baseline in systemic and pulmonary hemodynamic parameters. Acute IV administration of adenosine decreased pulmonary vascular resistance index (PVRI) by 3 Wood U/m² (- 20%) compared to baseline (p = 0.02). We noted a slight, not significant, decrease in mean pulmonary artery pressure (mPAP) of 4 mmHg. Cardiac index (CI) increased by 0.5 L/min/m² (15% increase respect to baseline; p = 0.03). The heart rate and mean systemic blood pressure (BP) did not change significantly. Acute IV administration of epoprostenol decreased PVRI by 6 mmHg (- 40%) respect to baseline (p < 0.0001). CI increased by 1.4 L/min/m² (p < 0.0001); while mPAP decreased by 5 mmHg (nearly 10%) (p = 0.04). This decrease of mPAP was accompanied by a mean BP decrease of 11 mmHg compared to baseline (p = 0.003). Our results indicates that, in patients with PAH associated with other pathological conditions, adenosine is predominantly a positive inotropic agent; and epoprostenol a potent vasodilator of both pulmonary and systemic vessels, and a strong positive inotropic agent.

ANMCO Position Paper: long-term follow-up of patients with pulmonary thromboembolism

Venous thromboembolism (VTE), including pulmonary embolism and deep venous thrombosis, is the third most common cause of cardiovascular death. The management of the acute phase of VTE has already been described in several guidelines. However, the management of the follow-up (FU) of these patients has been poorly defined. This consensus document, created by the Italian cardiologists, wants to clarify this issue using the currently available evidence in VTE. Clinical and instrumental data acquired during the acute phase of the disease are the cornerstone for planning the FU. Acquired or congenital thrombophilic disorders could be identified in apparently unprovoked VTE during the FU. In other cases, an occult cancer could be discovered after a VTE. The main targets of the post-acute management are to prevent recurrence of VTE and to identify the patients who can develop a chronic thromboembolic pulmonary hypertension. Knowledge of pathophysiology and therapeutic approaches is fundamental to decide the most appropriate long-term treatment. Moreover, prognostic stratification during the FU should be constantly updated on the basis of the new evidence acquired. Currently, the cornerstone of VTE treatment is represented by both the oral and the parenteral anticoagulation. Novel oral anticoagulants should be an interesting alternative in the long-term treatment.

An Update on the Management of Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare but life-threatening form of pulmonary artery hypertension that is defined as a mean arterial pulmonary pressure greater than 25mmHg that persists for more than 6 months following anticoagulation therapy in the setting of pulmonary emboli. CTEPH is categorized by the World Health Organization as group IV pulmonary hypertension and is thought to be due to unresolved thromboemboli in the pulmonary artery circulation. Among the 5 classes of pulmonary hypertension, CTEPH is unique in that it is potentially curable with the use of pulmonary thromboendarterectomy surgery. Despite an increasing array of medical and surgical treatment options for patients with CTEPH over the past 2 decades, patients commonly present with advanced disease and carry a poor prognosis, thus, the need for early diagnosis and appropriate referral to an expert center. This review article first highlights the epidemiology, pathophysiology, and clinical presentation of CTEPH. The article then provides diagnostic and therapeutic algorithms for the management of the patient with suspected CTEPH.

Chronic thromboembolic pulmonary hypertension: evolution in management

PURPOSE OF REVIEW

Chronic thromboembolic pulmonary hypertension (CTEPH) is an important cause of pulmonary hypertension. Although surgery is potentially curative, some patients present with inoperable disease. In these patients, medical therapies for pulmonary arterial hypertension are increasingly being used.

RECENT FINDINGS

The pathobiology of CTEPH development remains incompletely understood; however, evidence supports both large and small vessel disorder in patients with the disease. Surgical thromboendarterectomy is an increasingly well tolerated and often curative procedure and is the management strategy of choice for most patients. Although excellent outcomes in surgical management have been noted, the role of medical management in selected patients with inoperable or recurrent or persistent disease after surgery is increasing. A recent large, randomized controlled clinical trial of riociguat in CTEPH demonstrated improvements in exercise capacity, functional class, and hemodynamics. A safe, effective angioplasty approach to CTEPH is being pursued in addition.

SUMMARY

The approach to CTEPH management in the operable patient remains surgical, without clear benefit to preoperative pulmonary arterial hypertension-specific therapy at this time. Patients with inoperable disease or pulmonary hypertension following thromboendarterectomy, however, should be considered for medical management, with riociguat currently having the strongest evidence specific to CTEPH.

Pulmonary Vascular Capacitance as a Predictor of Vasoreactivity in Idiopathic Pulmonary Arterial Hypertension Tested by Adenosine

Background:

Acute pulmonary vasoreactivity testing has been recommended in the diagnostic work-up of patients with idiopathic pulmonary arterial hypertension (IPAH). Pulmonary arteriolar capacitance (Cp) approximated by stroke volume divided by pulmonary pulse pressure (SV/PP) is considered as an independent predictor of mortality in patients with IPAH.

Objectives:

We sought to evaluate any differences in baseline and adenosine Cp between vasoreactive and non-vasoreactive IPAH patients tested with adenosine.

Patients and Methods:

Fourteen patients with IPAH and a vasoreactive adenosine vasoreactivity testing according to the ESC guidelines were compared with 24 IPAH patients with nonreactive adenosine test results.

Results:

There were no statistical significant differences between the two groups regarding NYHA class, body surface area, heart rate, and systemic blood pressure during right heart catheterization. Hemodynamic study showed no statistical significant differences in cardiac output/Index, mean pulmonary artery pressure, pulmonary vascular resistance, and baseline Cp between the two groups. There was a statistical significant but weak increase in adenosine Cp in vasoreactive group compared to non-reactive group (P = 0.04). Multivariable analysis showed an association between Cp and vasoreactivity (Beta = 2, P = 0.04, OR = 0.05 (95%CI = 0.003 - 0.9).

Conclusions:

Cp could be considered as an index for the prediction of vasoreactivity in patients with IPAH. Prediction of long-term response to calcium channel blockers in patients with IPAH and a positive vasoreactive test by this index should be addressed in further studies.

Pulmonary vascular and right ventricular reserve in patients with normalized resting hemodynamics after pulmonary endarterectomy

Background

Patients with normalized mean pulmonary artery pressure (mPAP) after pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (CTEPH) do not always regain normal exercise capacity. We evaluated right ventricular function, its interaction with both pulsatile and resistive afterload, and the effect of sildenafil during exercise in these patients.

Methods and Results

Fourteen healthy controls, 15 CTEPH patients, and 7 patients with normalized resting mPAP (≤25 mm Hg) post‐PEA underwent cardiopulmonary exercise testing, followed by cardiac magnetic resonance imaging with simultaneous invasive mPAP measurement during incremental supine cycling exercise. Peak oxygen consumption and peak heart rate were significantly reduced in post‐PEA and CTEPH patients compared to controls. The mPAP–cardiac output slope was steeper in post‐PEA patients than in controls and similar to CTEPH. Relative to controls, resting right ventricular ejection fraction was reduced in CTEPH, but not in post‐PEA patients. In contrast, peak exercise right ventricular ejection fraction was reduced both in post‐PEA and CTEPH patients. Exercise led to reduction of pulmonary arterial compliance in all groups. Nevertheless, resting pulmonary arterial compliance values in CTEPH and post‐PEA patients were even lower than those in controls at peak exercise. In post‐PEA patients, sildenafil did not affect resting hemodynamics nor right ventricular function, but decreased the mPAP/cardiac output slope and increased peak exercise right ventricular ejection fraction.

Conclusions

Exercise intolerance in post‐PEA patients is explained by abnormal pulmonary vascular reserve and chronotropic incompetence. The mPAP/cardiac output slope and pulmonary arterial compliance are sensitive measures demonstrating abnormal resistive and pulsatile pulmonary vascular function in post‐PEA patients. These abnormalities are partially attenuated with sildenafil.

Prognostic value of acute vasodilator response in pulmonary arterial hypertension: beyond the "classic" responders

BACKGROUND

A "classic" response to acute vasodilator testing (drop of >10 mm Hg in mean pulmonary artery pressure [mPAP] to <40 mm Hg) confers an excellent prognosis in patients with idiopathic pulmonary arterial hypertension (IPAH) and identifies candidates for treatment with calcium channel blockers (CCB). Little is known about vasodilator responsiveness (VR) in other types of PAH, or about outcomes in patients with a significant but "non-classic" decrease in mPAP. We hypothesized that VR occurs in non-idiopathic PAH and non-classic VR portends a better prognosis than no VR in PAH.

METHODS

Acute VR testing with nitric oxide was performed on 155 consecutive patients referred for PH evaluation. Non-classic response was defined as decrease in mPAP >10 mm Hg to >40 mm Hg with preserved cardiac output. Demographics and functional status were assessed at baseline and the first clinic visit after VR testing, and survival was followed over time.

RESULTS

Twenty patients (13%) displayed classic VR. Among classic responders, 12 (60%) had IPAH and 8 (40%) had connective tissue disease-associated PAH (CTD-PAH); however, only responders with IPAH had improved survival compared with non-responders (p = 0.02). Thirteen patients (8%) had a non-classic VR. Non-classic response was not associated with improved survival compared with non-responders (p = 0.86). Acute change in mPAP or pulmonary vascular resistance in the entire cohort did not predict survival.

CONCLUSIONS

Classic acute VR occurs in CTD-PAH as well as IPAH; however, only IPAH patients have improved outcomes. A significant but non-classic VR is not associated with improved survival.

Chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare but debilitating and life-threatening complication of acute pulmonary embolism. CTEPH results from persistent obstruction of pulmonary arteries and progressive vascular remodelling. Not all patients presenting with CTEPH have a history of clinically overt pulmonary embolism. The diagnostic work-up to detect or rule out CTEPH should include ventilation-perfusion scintigraphy, which has high sensitivity and a negative predictive value of nearly 100%. CT angiography usually reveals typical features of CTEPH, including mosaic perfusion, part or complete occlusion of pulmonary arteries, and intraluminal bands and webs. Patients with suspected CTEPH should be referred to a specialist centre for right-heart catheterisation and pulmonary angiography. Surgical pulmonary endarterectomy remains the treatment of choice for CTEPH and is associated with excellent long-term results and a high probability of cure. For patients with inoperable CTEPH, various medical and interventional therapies are being developed.

Riociguat for pulmonary hypertension

Pulmonary hypertension, an elevation of the mean pulmonary artery pressure ≥25 mmHg, ultimately leads to premature death due to right ventricular dysfunction. Ten treatments from three classes of drugs are licensed for the management of pulmonary arterial hypertension. These treatments have improved exercise capacity but median survival is still poor. Additionally there are no licensed therapies for the other groups of pulmonary hypertension. Riociguat is a novel drug that stimulates soluble guanylate cyclase independently of nitric oxide and in synergy with nitric oxide. This review summarises the available evidence for riociguat in the treatment across all groups of pulmonary hypertension with a focus on pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension.

Preoperative pulmonary artery pressure and mortality after lung transplantation

BACKGROUND

The purpose of this study was to determine the influence of changes in pulmonary artery pressure during the waiting period on survival after lung transplantation for pulmonary fibrosis.

METHODS

We identified 65 patients with pulmonary fibrosis who underwent lung transplantation from 2003 to 2010. Pulmonary artery pressure determined at listing was compared with intraoperative pressure. The primary outcome was overall survival. Co-variates included type of transplantation (single or bilateral), ischemic time, recipient and donor age and sex.

RESULTS

The median age of the 65 patients undergoing transplantation was 58 years, and 27 (43%) underwent bilateral sequential transplantation. Twenty-two (35%) patients presented at transplantation with a mean pulmonary artery pressure increased by at least 10% compared to the initial pressure at the time of listing. Rising pulmonary artery pressure at transplantation was associated with increased mortality (p = 0.022). Other factors including type of operation, ischemic time, age, and sex, were not significantly associated with mortality. Post-transplantation survival was worse among recipients who had pulmonary artery pressure increased by at least 10% at transplantation (p = 0.003, logrank).

CONCLUSIONS

Increasing pulmonary artery pressure while awaiting lung transplantation is associated with worse long-term survival following transplantation, and is a sign of progressively worsening disease for which greater urgency of donor organ allocation should be considered.

Pulmonary vascular diseases

Diseases of the pulmonary vasculature are a cause of increased pulmonary vascular resistance (PVR) in pulmonary embolism, chronic thromboembolic pulmonary hypertension (CTEPH), and pulmonary arterial hypertension or decreased PVR in pulmonary arteriovenous malformations on hereditary hemorrhagic telangiectasia, portal hypertension, or cavopulmonary anastomosis. All these conditions are associated with a decrease in both arterial PO2 and PCO2. Gas exchange in pulmonary vascular diseases with increased PVR is characterized by a shift of ventilation and perfusion to high ventilation-perfusion ratios, a mild to moderate increase in perfusion to low ventilation-perfusion ratios, and an increased physiologic dead space. Hypoxemia in these patients is essentially explained by altered ventilation-perfusion matching amplified by a decreased mixed venous PO2 caused by a low cardiac output. Hypocapnia is accounted for by hyperventilation, which is essentially related to an increased chemosensitivity. A cardiac shunt on a patent foramen ovale may be a cause of severe hypoxemia in a proportion of patients with pulmonary hypertension and an increase in right atrial pressure. Gas exchange in pulmonary arteriovenous malformations is characterized by variable degree of pulmonary shunting and/or diffusion-perfusion imbalance. Hypocapnia is caused by an increased ventilation in relation to an increased pulmonary blood flow with direct peripheral chemoreceptor stimulation by shunted mixed venous blood flow.

Surgical specimens, haemodynamics and long-term outcomes after pulmonary endarterectomy

Background

Chronic thromboembolic pulmonary hypertension is surgically curable by pulmonary endarterectomy (PEA). It is unclear whether PEA impacts primarily steady state right ventricular afterload (ie, pulmonary vascular resistance (PVR)) or pulsatile right ventricular afterload (ie, pulmonary arterial compliance (C_PA)). Our objectives were to (1) quantify PEA specimens and measure the impact of PEA on PVR and C_PA in a structure/function study and (2) analyse the effects of haemodynamic changes on long-term survival/freedom of lung transplantation in an outcome study.

Methods

Thrombi were laid out, weighed, photographed and measured. PVR, C_PA and resistance times compliance (RC-time) were assessed at baseline, within 4 days after PEA (‘immediately postoperative’) and 1 year after PEA, in 110 consecutive patients who were followed for 34.5 (11.9; 78.3) months.

Results

Lengths and numbers of PEA specimen tails were inversely correlated with immediate postoperative PVR (p<0.0001, r=−0.566; p<0.0001, r=−0.580). PVR and C_PA normalised immediately postoperatively while RC-time remained unchanged. Immediate postoperative PVR was the only predictor of long-term survival/freedom of lung transplantation (p<0.0001). Patients with immediate postoperative PVR<590 dynes.s.cm⁻⁵ had better long-term outcomes than patients with PVR≥590 dynes.s.cm⁻⁵ (p<0.0001, respectively).

Conclusions

PEA immediately decreased PVR and increased C_PA under a constant RC-time. However, immediate postoperative PVR was the only predictor of long-term survival/freedom of lung transplantation. Our study confirms the importance of a complete, bilateral surgical endarterectomy. Low PVR measured immediately postoperative predicts excellent long-term outcome.

Nitric oxide deficiency in pulmonary hypertension: Pathobiology and implications for therapy

Nitric oxide (NO) is a diffusible gas with diverse roles in human physiology and disease. Significant progress in the understanding of its biological effects has taken place in recent years. This has led to a better understanding of the pathobiology of pulmonary hypertension (PH) and the development of new therapies. This article provides an overview of the NO physiology and its role in the pathobiology of lung diseases, particularly PH. We also discuss current and emerging specific treatments that target NO signaling pathways in PH.

Chronic thromboembolic pulmonary hypertension (CTEPH): updated Recommendations of the Cologne Consensus Conference 2011

In the 2009 European Guidelines on the diagnosis and treatment of pulmonary hypertension (PH), one section covers aspects of pathophysiology, diagnosis and treatment of chronic thromboembolic pulmonary hypertension (CTEPH). The practical implementation of the guidelines for this disease is of crucial importance, because CTEPH is a subset of PH which can potentially be cured by pulmonary endarterectomy (PEA). Nowadays, CTEPH is commonly underdiagnosed and not properly managed. Any patient with unexplained PH should be evaluated for the presence of CTEPH, and a ventilation/perfusion (V/Q) lung scan is recommended as screening method of choice. If the V/Q scan or CT angiography reveals signs of CTEPH, the patient should be referred to a specialized center with expertise in the medical and surgical management of this disease. Every case has to be reviewed by an experienced PEA surgeon for the assessment of operability. In this updated recommendation, important contents of the European guidelines were commented, and more recent information regarding diagnosis and treatment was added.

Diagnostic evaluation and management of chronic thromboembolic pulmonary hypertension: a clinical practice guideline

BACKGROUND

Pulmonary embolism is a common condition. Some patients subsequently develop chronic thromboembolic pulmonary hypertension (CTEPH). Many care gaps exist in the diagnosis and management of CTEPH patients including lack of awareness, incomplete diagnostic assessment, and inconsistent use of surgical and medical therapies.

METHODS

A representative interdisciplinary panel of medical experts undertook a formal clinical practice guideline development process. A total of 20 key clinical issues were defined according to the patient population, intervention, comparator, outcome (PICO) approach. The panel performed an evidence-based, systematic, literature review, assessed and graded the relevant evidence, and made 26 recommendations.

RESULTS

Asymptomatic patients postpulmonary embolism should not be screened for CTEPH. In patients with pulmonary hypertension, the possibility of CTEPH should be routinely evaluated with initial ventilation/perfusion lung scanning, not computed tomography angiography. Pulmonary endarterectomy surgery is the treatment of choice in patients with surgically accessible CTEPH, and may also be effective in CTEPH patients with disease in more 'distal' pulmonary arteries. The anatomical extent of CTEPH for surgical pulmonary endarterectomy is best assessed by contrast pulmonary angiography, although positive computed tomography angiography may be acceptable. Novel medications indicated for the treatment of pulmonary hypertension may be effective for selected CTEPH patients.

CONCLUSIONS

The present guideline requires formal dissemination to relevant target user groups, the development of tools for implementation into routine clinical practice and formal evaluation of the impact of the guideline on the quality of care of CTEPH patients. Moreover, the guideline will be updated periodically to reflect new evidence or clinical approaches.

Management of massive and submassive pulmonary embolism, iliofemoral deep vein thrombosis, and chronic thromboembolic pulmonary hypertension: a scientific statement from the American Heart Association

Venous thromboembolism (VTE) is responsible for the hospitalization of >250 000 Americans annually and represents a significant risk for morbidity and mortality. Despite the publication of evidence-based clinical practice guidelines to aid in the management of VTE in its acute and chronic forms, the clinician is frequently confronted with manifestations of VTE for which data are sparse and optimal management is unclear. In particular, the optimal use of advanced therapies for acute VTE, including thrombolysis and catheter-based therapies, remains uncertain. This report addresses the management of massive and submassive pulmonary embolism (PE), iliofemoral deep vein thrombosis (IFDVT),and chronic thromboembolic pulmonary hypertension (CTEPH). The goal is to provide practical advice to enable the busy clinician to optimize the management of patients with these severe manifestations of VTE. Although this document makes recommendations for management, optimal medical decisions must incorporate other factors, including patient wishes, quality of life, and life expectancy based on age and comorbidities. The appropriateness of these recommendations for a specific patient may vary depending on these factors and will be best judged by the bedside clinician.

Response to inhaled nitric oxide predicts survival in patients with pulmonary hypertension

OBJECTIVE

To examine the ability of vasodilator response to predict survival in a diverse cohort of patients with pulmonary hypertension (PH).

PATIENTS & METHODS

A total of 214 consecutive treatment-naive patients referred for invasive PH evaluation were enrolled between November 1998 and December 2008. Vasoreactivity was assessed during inhalation of 40 parts per million nitric oxide (iNO) and vasodilator responders were defined as those participants who achieved a mean pulmonary artery pressure (PAP) of ≤ 40 mm Hg and a drop in mean PAP ≥ the median for the cohort (13%). Kaplan-Meier analysis and Cox proportional hazards modeling were used to identify predictors of survival.

RESULTS

There were 51 deaths (25.9%) over a mean follow-up period of 2.3 years. Kaplan-Meier analysis demonstrated that vasodilator responders had significantly improved survival (P < .01). Vasodilator responders had improved survival regardless of whether or not they had idiopathic or nonidiopathic PH (P = .02, P < .01) or whether or not they had Dana Point class 1 or non-Dana Point class 1 PH (P < .01, P = .01). In multivariate modeling, advanced age, elevated right atrial pressure, elevated serum creatinine, and worsened functional class significantly predicted shorter survival (P = .01, P = .01, P = .01, P < .01), whereas vasodilator response predicted improved survival (P = .01).

CONCLUSIONS

Vasodilator responsiveness to iNO is an important method of risk stratifying PH patients, with results that apply regardless of clinical etiology.

Pulmonary thromboembolic disease. Clinical management of acute and chronic disease

Pulmonary thromboembolism falls between the areas of pulmonology and cardiology, internal medicine and intensive care, radiology and nuclear medicine, and hematology and cardiothoracic surgery. Depending on their clinical background, physicians faced with a patient with a pulmonary thromboembolism may speak different languages and adopt different treatment approaches. Now, however, there is an opportunity to end the Tower of Babel surrounding pulmonary thromboembolism. There is a growing acknowledgement that the key clinical problems in both acute pulmonary embolism and chronic thromboembolic pulmonary hypertension are linked to right ventricular pressure overload and right ventricular failure. As a result, cardiologists and cardiac intensive care specialists are taking an increasing interest in understanding and combating these conditions. The European Society of Cardiology was the first to elaborate comprehensive clinical practice guidelines for pulmonary thromboembolism and chronic thromboembolic pulmonary hypertension. The task forces involved in producing these guidelines included radiologists, pulmonologists, hematologists, intensive care physicians and surgeons, which ensured that the final document was universally acceptable. The aim of this article was to provide an overview of the epidemiology, risk factors, diagnosis, treatment, prognosis and prevention of acute pulmonary thromboembolism and chronic thromboembolic pulmonary hypertension, while taking into account European Society of Cardiology guidelines and incorporating new evidence where necessary.

Clinical and haemodynamic evaluation of chronic thromboembolic pulmonary hypertension patients scheduled for pulmonary thromboendarterectomy: Is schistosomiasis hypertension an important confounding factor?

INTRODUCTION

Chronic thromboembolic pulmonary hypertension is a disease affecting approximately 4,000 people per year in the United States. The incidence rate in Brazil, however, is unknown. The estimated survival for patients with chronic thromboembolic pulmonary hypertension without treatment is approximately three years. Pulmonary thromboendarterectomy for select patients is a potentially curative procedure when correctly applied. In Brazil, the clinical and hemodynamic profiles of chronic thromboembolic pulmonary hypertension patients have yet to be described.

OBJECTIVES

To evaluate the clinical and hemodynamic characteristics of chronic thromboembolic pulmonary hypertension patients scheduled for pulmonary thromboendarterectomy in a referral center for chronic thromboembolic pulmonary hypertension treatment in Brazil.

METHODS

From December 2006 to November 2009, patients were evaluated and scheduled for pulmonary thromboendarterectomy. The subjects were classified according to gender, age and functional class and were tested for thrombofilia and brain natriuretic peptide levels.

RESULTS

Thirty-five consecutive chronic thromboembolic pulmonary hypertension patients were evaluated. Two patients tested positive for schistosomiasis, and 31 were enrolled in the study (19 female, 12 male). The majority of patients were categorized in functional classes III and IV. Hemodynamic data showed a mean pulmonary vascular resistance (PVR) of 970.8 ± 494.36 dynas·s·cm-5 and a low cardiac output of 3.378 ± 1.13 L/min. Linear regression revealed a direct relation between cardiac output and pulmonary vascular resistance. Paradoxical septal movement was strongly correlated with pulmonary vascular resistance and cardiac output (p=0.001). Brain natriuretic peptide serum levels were elevated in 19 of 27 patients.

CONCLUSIONS

In a referral center for pulmonary hypertension in Brazil, chronic thromboembolic pulmonary hypertension patients evaluated for pulmonary thromboendarterectomy had a hemodynamically severe status and had elevated brain natriuretic peptide serum levels. There was a predominance of females in our cohort, and the prevalence of hematological disorders and schistosomiasis was low (less than 10%).

Diagnosis and vasculopathy in chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by pulmonary hypertension caused by nonresolving thromboemboli of the pulmonary artery. However, up to 40% of CTEPH patients have had no clinically apparent acute pulmonary embolic episodes. In addition, both a female predominance and an association of HLA with CTEPH unrelated to deep vein thrombosis are observed in Japan, thus suggesting this condition to be a type of pulmonary vasculopathy. The key for making an accurate diagnosis is to consider CTEPH in any patients with dyspnea on exertion. Perfusion scans provide an excellent noninvasive tool for distinguishing between pulmonary arterial hypertension (PAH) and CTEPH, while CT angiography is useful for differentiating arteritis, tumor, and a congenital anomaly of the pulmonary artery from CTEPH. Pulmonary angiography (PAG) is still considered the gold standard for evaluating CTEPH. No subpleural perfusion in any segments by PAG with high pulmonary vascular resistance is might be related to small vessel disease, thus resulting in a poor outcome after surgery. Recent data suggest a potential therapeutic benefit of antiproliferative therapy for cells isolated from endarterectomized tissue.