Criteria for diagnosis of exercise pulmonary hypertension

The Right Heart International Network (RIGHT-NET): Rationale, Objectives, Methodology, and Clinical Implications

The Right Heart International Network is a multicenter international study aiming to prospectively collect exercise Doppler echocardiography tests of the right heart pulmonary circulation unit (RHPCU) in large cohorts of healthy subjects, elite athletes, and individuals at risk of or with overt pulmonary hypertension. It is going to provide standardization of exercise stress echocardiography of RHPCU and explore the full physiopathologic response.

Forgotten No More: A Focused Update on the Right Ventricle in Cardiovascular Disease

In the last decade, there has been renewed interest in the study of the right ventricle. It is now well established that right ventricular function is a strong predictor of mortality, not only in heart failure but also in pulmonary hypertension, congenital heart disease, and cardiothoracic surgery. The right ventricle is part of a cardiopulmonary unit with connections to the pulmonary circulation, venous return, atria, and left ventricle. In this context, ventriculoarterial coupling, interventricular interactions, and pericardial constraint become important to understand right ventricular adaptation to injury or abnormal loading conditions. This state-of-the-art review summarizes major advances that occurred in the field of right ventricular research over the last decade. The first section focuses on right ventricular physiology and pulmonary circulation. The second section discusses the emerging data on right ventricular phenotyping, highlighting the importance of myocardial deformation (strain) imaging and assessment of end-systolic dimensions. The third section reviews recent clinical trials involving patients at risk for or with established right ventricular failure, focusing on beta blockade, phosphodiesterase inhibition, and mechanical support of the failing right heart. The final section presents a perspective on active areas of research that are most likely to translate in clinical practice in the next decade.

Intravenous sildenafil acutely improves hemodynamic response to exercise in patients with connective tissue disease

Background

Hemodynamic assessment during exercise may unmask an impaired functional reserve of the right ventricle and the pulmonary vasculature in patients with connective tissue disease. We assessed the effect of intravenous sildenafil on the hemodynamic response to exercise in patients with connective tissue disease.

Methods

In this proof-of-concept study, patients with connective tissue disease and mean pulmonary arterial pressure (mPAP) >20 mm Hg were subjected to a supine exercise hemodynamic evaluation before and after administration of intravenous sildenafil 10 mg.

Results

Ten patients (four with moderately elevated mPAP 21–24 mm Hg; six with mPAP >25 mm Hg) underwent hemodynamic assessment. All of them showed markedly abnormal exercise hemodynamics. Intravenous sildenafil was well tolerated and had significant hemodynamic effects at rest and during exercise, although without pulmonary selectivity. Sildenafil reduced median total pulmonary resistance during exercise from 6.22 (IQR 4.61–8.54) to 5.24 (3.95–6.96) mm Hg·min·L^-1 (p = 0.005) and increased median pulmonary arterial capacitance during exercise from 1.59 (0.93–2.28) to 1.74 (1.12–2.69) mL/mm Hg (p = 0.005).

Conclusions

In patients with connective tissue disease who have an abnormal hemodynamic response to exercise, intravenous sildenafil improved adaption of the right ventricular-pulmonary vascular unit to exercise independent of resting mPAP. The impact of acute pharmacological interventions on exercise hemodynamics in patients with pulmonary vascular disease warrants further investigation.

Trial registration

Clinicaltrials.gov NCT01889966.

Exercise unmasks distinct pathophysiologic features in heart failure with preserved ejection fraction and pulmonary vascular disease

Aims

Pulmonary hypertension (PH) and pulmonary vascular disease (PVD) are common and associated with adverse outcomes in heart failure with preserved ejection fraction (HFpEF). Little is known about the impact of PVD on the pathophysiology of exercise intolerance.

Methods and results

Heart failure with preserved ejection fraction patients (n = 161) with elevated pulmonary capillary wedge pressure (≥15 mmHg) at rest were classified into three groups: non-PH-HFpEF (n = 21); PH but no PVD (isolated post-capillary PH, IpcPH; n = 95); and PH with PVD (combined post- and pre-capillary PH, CpcPH; n = 45). At rest, CpcPH-HFpEF patients had more right ventricular (RV) dysfunction and lower pulmonary arterial (PA) compliance compared to all other groups. While right atrial pressure (RAP) and left ventricular transmural pressure (LVTMP) were similar in HFpEF with and without PH or PVD at rest, CpcPH-HFpEF patients demonstrated greater increase in RAP, enhanced ventricular interdependence, and paradoxical reduction in LVTMP during exercise, differing from all other groups (P < 0.05). Lower PA compliance was correlated with greater increase in RAP with exercise. During exercise, CpcPH-HFpEF patients displayed an inability to enhance cardiac output, reduction in forward stroke volume, and blunted augmentation in RV systolic performance, changes that were coupled with marked limitation in aerobic capacity.

Conclusion

Heart failure with preserved ejection fraction patients with PVD demonstrate unique haemodynamic limitations during exercise that constrain aerobic capacity, including impaired recruitment of LV preload due to excessive right heart congestion and blunted RV systolic reserve. Interventions targeted to this distinct pathophysiology require testing in patients with HFpEF and PVD.

[Pathophysiology of right ventricular hemodynamics]

The right ventricle (RV) plays a key role in the maintenance of an adequate cardiac output whatever the demand, and thus contributes to the optimization of the ventilation/perfusion ratio. The RV has a thin wall and it buffers the physiological increases in systemic venous return without causing a deleterious rise in right atrial pressure (RAP). The RV is coupled to the pulmonary circulation which is a low pressure, low resistance, high compliance system. In the healthy subject at rest, the contribution of the RV to right heart systolic function is surpassed by the contribution of both left ventricular contraction and the respiratory pump. RV systolic function plays a contributory role during exercise and in patients with pulmonary hypertension. The RV compensates better for volume overload than for pressure overload and is more capable of sustaining chronic increases in load than acute ones. An impaired RV-pulmonary artery coupling leads to a major mismatch between RV function and arterial load ("afterload mismatch") and is associated progressively with a low cardiac output and a high RAP. Right ventricular dysfunction is involved in the pathophysiology of both cardiovascular and pulmonary diseases, and may partly explain the deleterious haemodynamic consequences of mechanical ventilation.

Treatment of exercise pulmonary hypertension improves pulmonary vascular distensibility

Exercise pulmonary hypertension (ePH) is an underappreciated form of exertional limitation. Despite normal resting pulmonary artery pressures, patients with ePH demonstrate early pulmonary vascular changes with reduced pulmonary arterial compliance (PAC) and vascular distensibility (α). Recent data suggest that targeted vasodilator therapy may improve hemodynamics in ePH, but it is not well-known whether such medications alter pulmonary vascular distensibility. Thus, we sought to evaluate if vasodilator therapy improved α a marker of early pulmonary vascular disease in ePH. Ten patients performed supine exercise right heart catheterization (exRHC) with bicycle ergometer to peak exercise. Patients diagnosed with ePH were treated with pulmonary vasodilators. A repeat symptom-limited exercise RHC was performed at least six months after therapy. Patients with ePH had evidence of early pulmonary vascular disease, as baseline PAC and α were reduced. After pulmonary vasodilator therapy, a number of peak exercise hemodynamics statistically improved, including a decrease of total pulmonary resistance and pulmonary vascular resistance, while cardiac output increased. Importantly, vasodilator therapy partially reversed the pathogenic decreases of α at the time of repeat exRHC. Pulmonary vascular distensibility, α, a marker of early pulmonary vascular disease, improves in ePH after therapy with pulmonary vasodilators.

Flow-related right ventricular to pulmonary arterial pressure gradients during exercise

Aims

The assumption of equivalence between right ventricular (RV) and pulmonary arterial systolic pressure is fundamental to several assessments of RV or pulmonary vascular haemodynamic function. Our aims were to (i) determine whether systolic pressure gradients develop across the RV outflow tract in healthy adults during exercise, (ii) examine the potential correlates of such gradients, and (iii) consider the effect of such gradients on calculated indices of RV function.

Methods and results

Healthy untrained and endurance-trained adult volunteers were studied using right-heart catheterization at rest and during submaximal cycle ergometry. RV and pulmonary artery (PA) pressures were simultaneously transduced, and the cardiac output was determined by thermodilution. Systolic pressures, peak and mean gradients, and indices of chamber, vascular, and valve function were analysed offline. Summary data are reported as mean ± standard deviation or median (interquartile range). No significant RV outflow tract gradients were observed at rest [mean gradient = 4 (3–5) mmHg], and the calculated effective orifice area was 3.6 ± 1.0 cm2. The increase in right ventricular systolic pressure during exercise was greater than the PA systolic pressure. Accordingly, mean gradients were developed during light exercise [8 (7–9) mmHg] and increased during moderate exercise [12 (9–14) mmHg, P < 0.001]. The magnitude of the mean gradient was linearly related to the cardiac output (r2 = 0.70, P < 0.001).

Conclusions

In healthy adults without pulmonic stenosis, systolic pressure gradients develop during exercise, and the magnitude is related to the blood flow rate.

A Focus on Macitentan in the Treatment of Pulmonary Arterial Hypertension

The approval of macitentan has increased the number of pharmacological treatments of pulmonary arterial hypertension (PAH). Here, we review the effect on PAH of macitentan compared to other endothelin receptor antagonists. Drugs targeting the endothelin (ET) pathway include the selective ET_A receptor antagonist ambrisentan, the ET_A /ET_B receptor antagonists, bosentan and macitentan, which were recently approved for PAH treatment. Macitentan exhibits higher antagonistic potency than bosentan and ambrisentan in pulmonary smooth muscle cells. Compared to ambrisentan and bosentan, macitentan has a longer duration of action, reflected by the longer half-life, as well as pharmacodynamics attributed to its active metabolite, ACT-132577. The efficacy of macitentan on PAH was investigated in the phase III SERAPHIN trial (NCT00660179). Macitentan significantly reduced morbidity and mortality. It improved the 6-min. walk distance (6MWD) among PAH patients. In the AMB-320/321-E (NCT00578786) study, ambrisentan improved exercise capacity. In the EARLY study (NCT00091715), bosentan showed improvements in 6MWD which were not statistically significant. Bosentan had an effect on PAH in patients with Eisenmenger syndrome (ES) in the BREATHE-5 study (NCT00367770), while macitentan did not improve 6MWD in these patients, but there are differences regarding study size and functional class, and that 30% of the patients treated with macitentan were already in treatment with a phosphodiesterase type 5 inhibitor. Macitentan revealed a lower risk of developing peripheral oedema and hepatotoxicity in the SERAPHIN study. In summary, macitentan has an efficiency comparable to bosentan and ambrisentan in the treatment of PAH. Patients treated with macitentan exhibited less adverse effects compared to bosentan and ambrisentan. In patients with PAH associated with ES, the trials with bosentan and macitentan do not seem comparable, and it needs to be clarified whether these drugs are effective when administered as part of a combination treatment in this condition.

Exercise and the right ventricle: a potential Achilles' heel

Exercise is associated with unequivocal health benefits and results in many structural and functional changes of the myocardium that enhance performance and prevent heart failure. However, intense exercise also presents a significant hemodynamic challenge in which the right-sided heart chambers are exposed to a disproportionate increase in afterload and wall stress that can manifest as myocardial fatigue or even damage if intense exercise is sustained for prolonged periods. This review focuses on the physiological factors that result in a disproportionate load on the right ventricle during exercise and the long-term consequences. The changes in cardiac structure and function that define 'athlete's heart' disproportionately affect the right-sided heart chambers and this can raise important diagnostic overlap with some cardiac pathologies, particularly some inherited cardiomyopathies. The interaction between exercise and arrhythmogenic right ventricular cardiomyopathy (ARVC) will be highlighted as an important example of how hemodynamic stressors can combine with deficiencies in cardiac structural elements to cause cardiac dysfunction predisposing to arrhythmias. The extent to which extreme exercise can cause adverse remodelling in the absence of a genetic predisposition remains controversial. In the athlete with profound changes in heart structure, it can be extremely challenging to determine whether common symptoms such as palpitations may be a marker of more sinister arrhythmias. This review discusses some of the techniques that have recently been proposed to identify pathology in these circumstances. Finally, we will discuss recent evidence defining the role of exercise restriction as a therapeutic intervention in individuals predisposed to arrhythmogenic cardiomyopathy.

Right Ventricular Myofilament Functional Differences in Humans With Systemic Sclerosis-Associated Versus Idiopathic Pulmonary Arterial Hypertension

BACKGROUND

Patients with systemic sclerosis (SSc)-associated pulmonary arterial hypertension (PAH) have a far worse prognosis than those with idiopathic PAH (IPAH). In the intact heart, SSc-PAH exhibits depressed rest and reserve right ventricular (RV) contractility compared with IPAH. We tested whether this disparity involves underlying differences in myofilament function.

METHODS

Cardiac myocytes were isolated from RV septal endomyocardial biopsies from patients with SSc-PAH, IPAH, or SSc with exertional dyspnea but no resting PAH (SSc-d); control RV septal tissue was obtained from nondiseased donor hearts (6-7 per group). Isolated myocyte passive length-tension and developed tension-calcium relationships were determined and correlated with in vivo RV function and reserve. RV septal fibrosis was also examined.

RESULTS

Myocyte passive stiffness from length-tension relations was similarly increased in IPAH and SSc-PAH compared with control, although SSc-PAH biopsies had more interstitial fibrosis. More striking disparities were found between active force-calcium relations. Compared with controls, maximal calcium-activated force (Fmax) was 28% higher in IPAH but 37% lower in SSc-PAH. Fmax in SSc-d was intermediate between control and SSc-PAH. The calcium concentration required for half-maximal force (EC50) was similar between control, IPAH, and SSc-d but lower in SSc-PAH. This disparity disappeared in myocytes incubated with the active catalytic subunit of protein kinase A. Myocyte Fmax directly correlated with in vivo RV contractility assessed by end-systolic elastance (R2 =0.46, P=0.002) and change in end-systolic elastance with exercise (R2 =0.49, P=0.008) and was inversely related with exercise-induced chamber dilation (R2 =0.63, P<0.002), which also was a marker of depressed contractile reserve.

CONCLUSIONS

A primary defect in human SSc-PAH resides in depressed sarcomere function, whereas this is enhanced in IPAH. These disparities correlate with in vivo RV contractility and contractile reserve and are consistent with worse clinical outcomes in SSc-PAH. The existence of sarcomere disease before the development of resting PAH in patients with SSc-d suggests that earlier identification and intervention may prove useful.

New insights into the recognition, classification and management of systemic sclerosis-associated pulmonary hypertension

PURPOSE OF REVIEW

Pulmonary hypertension is a common complication of systemic sclerosis (SSc), and remains a leading cause of morbidity and mortality. We will review recent developments in the recognition, classification and treatment of pulmonary hypertension in SSc.

RECENT FINDINGS

Advances in screening for pulmonary arterial hypertension (PAH) and use of exercise haemodynamics may help to identify pulmonary vascular disease earlier in SSc. Recent studies have led to changes in recommendations for adjunct therapy and selection of pulmonary vasodilators for the treatment of SSc-associated PAH.

SUMMARY

Recent advances in the diagnosis, classification and management of pulmonary hypertension in SSc have continued to improve our understanding of this challenging disease. Ongoing investigation in the pathogenesis of this disease will afford the opportunity to develop targeted therapies to improve outcomes for SSc patients with pulmonary hypertension.

[Altitude and the right heart]

INTRODUCTION

Altitude is associated with a decrease in partial pressure of oxygen. Hypoxia induces pulmonary vasoconstriction with subsequent fixed increase in pulmonary artery pressure, and eventual right heart failure.

CURRENT KNOWLEDGE

High altitude exposure is associated with an increase in pulmonary artery pressure that is proportional to initial vasoconstriction. Echocardiographic evaluations on a large number of subjects show that the altitude-induced increase in pulmonary pressure is generally modest and does not exceed the 25mmHg that are diagnostic of pulmonary hypertension. This does not greatly increase right ventricular afterload, so that imaging of the right ventricle only shows some alterations of indices of systolic or diastolic function, but preserved contractile reserve during exercise. In less than 1% of cases, hypoxic vasoconstriction is strong and may be a cause of severe pulmonary hypertension and right heart failure.

PERSPECTIVES

The prognostic relevance of altitude-induced pulmonary hypertension and associated cardiac function alterations is not known. Treatment of hypoxic pulmonary hypertension relies on evacuation to a lower altitude, oxygen and pulmonary vasodilators. These treatment strategies have not been rigorously evaluated.

CONCLUSIONS

Altitude may be a cause of right heart failure. This uncommon complication of altitude exposure requires further epidemiological and therapeutic studies.

Stressing the Cardiopulmonary Vascular System: The Role of Echocardiography

The cardiopulmonary vascular system represents a key determinant of prognosis in several cardiorespiratory diseases. Although right heart catheterization is considered the gold standard for assessing pulmonary hemodynamics, a comprehensive noninvasive evaluation including left and right ventricular reserve and function and cardiopulmonary interactions remains highly attractive. Stress echocardiography is crucial in the evaluation of many cardiac conditions, typically coronary artery disease but also heart failure and valvular heart disease. In stress echocardiographic applications beyond coronary artery disease, the assessment of the cardiopulmonary vascular system is a cornerstone. The possibility of coupling the left and right ventricles with the pulmonary circuit during stress can provide significant insight into cardiopulmonary physiology in healthy and diseased subjects, can support the diagnosis of the etiology of pulmonary hypertension and other conditions, and can offer valuable prognostic information. In this state-of-the-art document, the topic of stress echocardiography applied to the cardiopulmonary vascular system is thoroughly addressed, from pathophysiology to different stress modalities and echocardiographic parameters, from clinical applications to limitations and future directions.

Multicentre observational screening survey for the detection of CTEPH following pulmonary embolism

Chronic thromboembolic pulmonary hypertension (CTEPH) is a severe complication of pulmonary embolism. Its incidence following pulmonary embolism is debated. Active screening for CTEPH in patients with acute pulmonary embolism is yet to be recommended.

This prospective, multicentre, observational study (Multicentre Observational Screening Survey for the Detection of Chronic Thromboembolic Pulmonary Hypertension (CTEPH) Following Pulmonary Embolism (INPUT on PE); ISRCTN61417303) included patients with acute pulmonary embolism from 11 centres in Switzerland from March 2009 to November 2016. Screening for possible CTEPH was performed at 6, 12 and 24 months using a stepwise algorithm that included a dyspnoea phone-based survey, transthoracic echocardiography, right heart catheterisation and radiological confirmation of CTEPH.

Out of 1699 patients with pulmonary embolism, 508 patients were assessed for CTEPH screening over 2 years. CTEPH incidence following pulmonary embolism was 3.7 per 1000 patient-years, with a 2-year cumulative incidence of 0.79%. The Swiss pulmonary hypertension registry consulted in December 2016 did not report additional CTEPH cases in these patients. The survey yielded 100% sensitivity and 81.6% specificity. The second step echocardiography in newly dyspnoeic patients showed a negative predictive value of 100%.

CTEPH is a rare but treatable disease. A simple and sensitive way for CTEPH screening in patients with acute pulmonary embolism is recommended.

Network Analysis to Risk Stratify Patients With Exercise Intolerance

RATIONALE

Current methods assessing clinical risk because of exercise intolerance in patients with cardiopulmonary disease rely on a small subset of traditional variables. Alternative strategies incorporating the spectrum of factors underlying prognosis in at-risk patients may be useful clinically, but are lacking.

OBJECTIVE

Use unbiased analyses to identify variables that correspond to clinical risk in patients with exercise intolerance.

METHODS AND RESULTS

Data from 738 consecutive patients referred for invasive cardiopulmonary exercise testing at a single center (2011-2015) were analyzed retrospectively (derivation cohort). A correlation network of invasive cardiopulmonary exercise testing parameters was assembled using |r|>0.5. From an exercise network of 39 variables (ie, nodes) and 98 correlations (ie, edges) corresponding to P<9.5e-46 for each correlation, we focused on a subnetwork containing peak volume of oxygen consumption (pVo2) and 9 linked nodes. K-mean clustering based on these 10 variables identified 4 novel patient clusters characterized by significant differences in 44 of 45 exercise measurements (P<0.01). Compared with a probabilistic model, including 23 independent predictors of pVo2 and pVo2 itself, the network model was less redundant and identified clusters that were more distinct. Cluster assignment from the network model was predictive of subsequent clinical events. For example, a 4.3-fold (P<0.0001; 95% CI, 2.2-8.1) and 2.8-fold (P=0.0018; 95% CI, 1.5-5.2) increase in hazard for age- and pVo2-adjusted all-cause 3-year hospitalization, respectively, were observed between the highest versus lowest risk clusters. Using these data, we developed the first risk-stratification calculator for patients with exercise intolerance. When applying the risk calculator to patients in 2 independent invasive cardiopulmonary exercise testing cohorts (Boston and Graz, Austria), we observed a clinical risk profile that paralleled the derivation cohort.

CONCLUSIONS

Network analyses were used to identify novel exercise groups and develop a point-of-care risk calculator. These data expand the range of useful clinical variables beyond pVo2 that predict hospitalization in patients with exercise intolerance.

Pulmonary hemodynamics responses to hypoxia and/or CO2 inhalation during moderate exercise in humans

In this study, we hypothesized that adding CO₂ to an inhaled hypoxic gas mixture will limit the rise of pulmonary artery pressure (PAP) induced by a moderate exercise. Eight 20-year-old males performed four constant-load exercise tests on cycle at 40% of maximal oxygen consumption in four conditions: ambient air, normobaric hypoxia (12.5% O₂), inhaled CO₂ (4.5% CO₂), and combination of hypoxia and inhaled CO₂. Doppler echocardiography was used to measure systolic (s)PAP, cardiac output (CO). Total pulmonary resistance (TPR) was calculated. Arterialized blood pH was 7.40 at exercise in ambient and hypoxia conditions, whereas CO₂ inhalation and combined conditions showed acidosis. sPAP increases from rest in ambient air to exercise ranged as follows: ambient + 110%, CO₂ inhalation + 135%, combined + 184%, hypoxia + 217% (p < 0.001). CO was higher when inhaling O₂-poor gas mixtures with or without CO₂ (~ 17 L min^-1) than in the other conditions (~ 14 L min^-1, p < 0.001). Exercise induced a significant decrease in TPR in the four conditions (p < 0.05) but less marked in hypoxia (- 19% of the resting value in ambient air) than in ambient (- 33%) and in both CO₂ inhalation and combined condition (- 29%). We conclude that (1) acute CO₂ inhalation did not significantly modify pulmonary hemodynamics during moderate exercise. (2) CO₂ adjunction to hypoxic gas mixture did not modify CO, despite a higher CaO₂ in combined condition than in hypoxia. (3) TPR was lower in combined than in hypoxia condition, limiting sPAP increase in combined condition.

Exercise-Induced Pulmonary Hypertension: Translating Pathophysiological Concepts Into Clinical Practice

Exercise stress testing of the pulmonary circulation for the diagnosis of latent or early-stage pulmonary hypertension (PH) is gaining acceptance. There is emerging consensus to define exercise-induced PH by a mean pulmonary artery pressure > 30 mm Hg at a cardiac output < 10 L/min and a total pulmonary vascular resistance> 3 Wood units at maximum exercise, in the absence of PH at rest. Exercise-induced PH has been reported in association with a bone morphogenetic receptor-2 gene mutation, in systemic sclerosis, in left heart conditions, in chronic lung diseases, and in chronic pulmonary thromboembolism. Exercise-induced PH is a cause of decreased exercise capacity, may precede the development of manifest PH in a proportion of patients, and is associated with a decreased life expectancy. Exercise stress testing of the pulmonary circulation has to be dynamic and rely on measurements of the components of the pulmonary vascular equation during, not after exercise. Noninvasive imaging measurements may be sufficiently accurate in experienced hands, but suffer from lack of precision, so that invasive measurements are required for individual decision-making. Exercise-induced PH is caused either by pulmonary vasoconstriction, pulmonary vascular remodeling, or by increased upstream transmission of pulmonary venous pressure. This differential diagnosis is clinical. Left heart disease as a cause of exercise-induced PH can be further ascertained by a pulmonary artery wedge pressure above or below 20 mm Hg at a cardiac output < 10 L/min or a pulmonary artery wedge pressure-flow relationship above or below 2 mm Hg/L/min during exercise.

An official European Respiratory Society statement: pulmonary haemodynamics during exercise

There is growing recognition of the clinical importance of pulmonary haemodynamics during exercise, but several questions remain to be elucidated. The goal of this statement is to assess the scientific evidence in this field in order to provide a basis for future recommendations.

Right heart catheterisation is the gold standard method to assess pulmonary haemodynamics at rest and during exercise. Exercise echocardiography and cardiopulmonary exercise testing represent non-invasive tools with evolving clinical applications. The term “exercise pulmonary hypertension” may be the most adequate to describe an abnormal pulmonary haemodynamic response characterised by an excessive pulmonary arterial pressure (PAP) increase in relation to flow during exercise. Exercise pulmonary hypertension may be defined as the presence of resting mean PAP <25 mmHg and mean PAP >30 mmHg during exercise with total pulmonary resistance >3 Wood units. Exercise pulmonary hypertension represents the haemodynamic appearance of early pulmonary vascular disease, left heart disease, lung disease or a combination of these conditions. Exercise pulmonary hypertension is associated with the presence of a modest elevation of resting mean PAP and requires clinical follow-up, particularly if risk factors for pulmonary hypertension are present. There is a lack of robust clinical evidence on targeted medical therapy for exercise pulmonary hypertension.

Hemodynamic Phenotyping of Pulmonary Hypertension in Left Heart Failure

Increased pulmonary venous pressure secondary to left heart disease is the most common cause of pulmonary hypertension (PH). The diagnosis of PH due to left heart disease relies on a clinical probability assessment followed by the invasive measurements of a mean pulmonary artery pressure (PAP) ≥25 mm Hg and mean wedged PAP (PAWP) >15 mm Hg. A combination of mean PAP and mean PAWP defines postcapillary PH. Postcapillary PH is generally associated with a diastolic pulmonary pressure gradient (diastolic PAP minus mean PAWP) <7 mm Hg, a transpulmonary pressure gradient (mean PAP minus mean PAWP) <12 mm Hg, and pulmonary vascular resistance ≤3 Wood units (WU). This combination of criteria defines isolated postcapillary PH. Postcapillary PH with elevated vascular gradients and pulmonary vascular resistance defines combined post- and precapillary PH (Cpc-PH). Postcapillary PH is associated with a decreased survival in proportion to increased pulmonary vascular gradients, decreased pulmonary arterial compliance, and reduced right ventricular function. The Cpc-PH subcategory occurs in 12% to 13% of patients with PH due to left heart disease. Patients with Cpc-PH have severe PH, with higher diastolic pulmonary pressure gradient, transpulmonary pressure gradient, and pulmonary vascular resistance and more pronounced ventilatory responses to exercise, lower pulmonary arterial compliance, depressed right ventricular ejection fraction, and shorter life expectancy than isolated postcapillary PH. Cpc-PH bears similarities to pulmonary arterial hypertension. Whether Cpc-PH is amenable to therapies targeting the pulmonary circulation remains to be tested by properly designed randomized controlled trials.

Modern diagnosis of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) should be suspected in patients presenting persistent dyspnea three months after a pulmonary embolism or in patients presenting with acute pulmonary embolism and suggestive images on the CT-scan. For these patients, a specific diagnostic work-up should be performed. First step consists of the ventilation/perfusion (V/Q) scan which is a good screening test due to its high sensitivity and high negative predictive value. Pulmonary angiography remains the gold standard approach for the confirmation of the diagnosis and pre-surgical evaluation of CTEPH. New emerging technologies such as Dual-Energy Computed Tomography angiography (DECT) and Computed Tomography angiography (CTA) are developing and broadly available. These non invasive methods provide diagnostic information similar to conventional pulmonary angiography and surgical operability information. They are to be considered as an alternative in the diagnostic approach of patients with CTEPH as presented in the ESC/ERS guidelines. Haemodynamic measurement whiles exercising during right heart catheterization may improve diagnostic sensitivity of CTEPH and could therefore be used as a diagnostic test in patient with normal haemodynamic at rest.

Long-term outcomes of dasatinib-induced pulmonary arterial hypertension: a population-based study

This study aimed to describe the long-term outcomes of pulmonary arterial hypertension (PAH) induced by dasatinib.

21 incident, right heart catheterisation-confirmed cases of dasatinib-induced PAH were identified from the French Pulmonary Hypertension Registry. Clinical and haemodynamic variables were compared from baseline to last follow-up (median (range) 24 (1–81) months).

Median age was 52 years and 15 patients were female (71%). 19 patients received dasatinib for chronic myelogenous leukaemia for a median (range) duration of 42 (8–74) months before PAH diagnosis. No bone morphogenic protein receptor-2 (BMPR2) mutations were found in the 10 patients tested. Dasatinib was uniformly discontinued and 11 patients received PAH medications. Four patients died during follow-up. New York Heart Association functional class improved from 76% in class III/IV to 90% in class I/II (p<0.01). Median (range) 6-min walk distance improved from 306 (0–660) to 430 (165–635) m (p<0.01). Median (range) mean pulmonary arterial pressure improved from 45 (30–70) to 26 (17–50) mmHg (p<0.01) and pulmonary vascular resistance from 6.1 (3.2–27.3) to 2.6 (1.2–5.9) Wood units (p<0.01). Patients treated with PAH medications had worse baseline haemodynamics but similar long-term outcomes to untreated patients. PAH persisted in 37% of patients.

Dasatinib-induced PAH frequently improves after discontinuation but persisted in over one-third of patients, therefore systematic follow-up is essential.

Changes in pulmonary exercise haemodynamics in scleroderma: a 4-year prospective study

Pulmonary arterial hypertension (PAH) is a feared complication of systemic sclerosis. In this prospective cohort study, we monitored the changes in resting and exercise pulmonary haemodynamics of scleroderma patients without initial PAH over a mean follow-up period of ∼4 years.

All patients underwent exercise echocardiography and cardiopulmonary exercise testing at baseline and follow-up. A subgroup underwent exercise right heart catheter (RHC) investigations. The primary end-point was the echocardiographic systolic pulmonary arterial pressure at 50 W exercise (sPAP50).

We included 99 patients, of whom 58 had a complete dataset. Three out of 99 patients developed RHC-confirmed PAH (0.75 cases per 100 patient-years). sPAP50 increased (p<0.001) and peak oxygen uptake (secondary end-point) decreased significantly (p=0.001) during follow-up, but there was no significant change in resting sPAP (p=0.38). In the RHC subgroup (n=28), mean (m)PAP and pulmonary vascular resistance at 50 W increased significantly (p=0.02 and p=0.002, respectively), but resting mPAP was unchanged.

Scleroderma patients without PAH develop a mild but significant deterioration of pulmonary exercise haemodynamics and exercise capacity over a 4-year follow-up period, indicating a progression of pulmonary vascular disease. The manifestation rate of RHC-confirmed PAH was 0.75 cases per 100 patient-years.

Functional impact of exercise pulmonary hypertension in patients with borderline resting pulmonary arterial pressure

Borderline resting mean pulmonary arterial pressure (mPAP) is associated with adverse outcomes and affects the exercise pulmonary vascular response. However, the pathophysiological mechanisms underlying exertional intolerance in borderline mPAP remain incompletely characterized. In the current study, we sought to evaluate the prevalence and functional impact of exercise pulmonary hypertension (ePH) across a spectrum of resting mPAP’s in consecutive patients with contemporary resting right heart catheterization (RHC) and invasive cardiopulmonary exercise testing. Patients with resting mPAP <25 mmHg and pulmonary arterial wedge pressure ≤15 mmHg (n = 312) were stratified by mPAP < 13, 13–16, 17–20, and 21–24 mmHg. Those with ePH (n = 35) were compared with resting precapillary pulmonary hypertension (rPH; n = 16) and to those with normal hemodynamics (non-PH; n = 224). ePH prevalence was 6%, 8%, and 27% for resting mPAP 13–16, 17–20, and 21–24 mmHg, respectively. Within each of these resting mPAP epochs, ePH negatively impacted exercise capacity compared with non-PH (peak oxygen uptake 70 ± 16% versus 92 ± 19% predicted, P < 0.01; 72 ± 13% versus 86 ± 17% predicted, P < 0.05; and 64 ± 15% versus 82 ± 19% predicted, P < 0.001, respectively). Overall, ePH and rPH had similar functional limitation (peak oxygen uptake 67 ± 15% versus 68 ± 17% predicted, P > 0.05) and similar underlying mechanisms of exercise intolerance compared with non-PH (peak oxygen delivery 1868 ± 599 mL/min versus 1756 ± 720 mL/min versus 2482 ± 875 mL/min, respectively; P < 0.05), associated with chronotropic incompetence, increased right ventricular afterload and signs of right ventricular/pulmonary vascular uncoupling. In conclusion, ePH is most frequently found in borderline mPAP, reducing exercise capacity in a manner similar to rPH. When borderline mPAP is identified at RHC, evaluation of the pulmonary circulation under the stress of exercise is warranted.

Open label study of ambrisentan in patients with exercise pulmonary hypertension

A growing body of evidence suggests that exercise pulmonary hypertension (ePH) is an early form of pulmonary arterial hypertension (PAH). Identifying the disease at an early, potentially more responsive phase, and initiating treatment may improve functional status and prevent progression to severe forms of PAH. This was a single-center, open-label six-month treatment trial to evaluate the effect of ambrisentan on pulmonary hemodynamics and exercise capacity in ePH utilizing invasive cardiopulmonary exercise testing (iCPET). After six months of treatment with ambrisentan, patients repeated iCPET; exercise capacity, symptoms, and pulmonary hemodynamics were reassessed. Twenty-two of 30 patients completed the treatment phase and repeat iCPET. After six months of treatment there was a significant decline in peak exercise mPAP (−5.2 ± 5.6 mmHg, P = 0.001), TPG (−7.1 ± 8.0 mmHg, P = 0.001), PVR (−0.9 ± 0.7 Woods units, P = 0.0002), and Ca-vO₂ (−1.8 ± 2.3 mL/dL, P = 0.0002), with significant increases in peak PCWP (+2.9 ± 5.6 mmHg, P = 0.02), PVC (+0.8 ± 1.4 mL/mmHg, P = 0.03), and CO (+2.3 ± 1.4 L/min, P = 0.0001). A trend toward increased VO₂max (+4.4 ± 2.6% predicted, P = 0.07) was observed. In addition, there were improvements in 6MWD and WHO FC after 24 weeks. Our findings suggest that treatment of ePH with ambrisentan results in improved pulmonary hemodynamics and functional status over a six-month period. Treatment of ePH may prevent the progression of vascular remodeling and development of established PAH.

Invasive Hemodynamic Assessment of Patients with Heart Failure and Pulmonary Hypertension

OPINION STATEMENT

Right heart catheterization (RHC) with a pulmonary artery (PA) catheter is a minimally invasive method of obtaining hemodynamic data (e.g., right atrial and pulmonary pressures, cardiac output, pulmonary vascular resistance), which are used to diagnose and manage patients with advanced heart failure (HF), HF with preserved ejection fraction, and pulmonary hypertension (PH). Invasive hemodynamic data obtained from RHC can aid in the prognostication of HF and PH patients and are important in guiding decisions of implanting mechanical circulatory support devices and listing patients for heart and/or lung transplantation. The basis of RHC has also paved the way for implantable hemodynamic devices to monitor pulmonary artery pressures in the outpatient setting, which can reduce rates of HF-related hospitalizations. We will discuss the utility of PA catheters in the diagnosis and management of the aforementioned disease states, the role of implantable hemodynamic monitors, and the complications associated with RHC procedures.

Pulmonary hypertension due to left heart disease

Pulmonary hypertension due to left heart disease, also known as group 2 pulmonary hypertension according to the European Society of Cardiology/European Respiratory Society classification, is the most common cause of pulmonary hypertension. In patients with left heart disease, the development of pulmonary hypertension favours right heart dysfunction, which has a major impact on disease severity and outcome. Over the past few years, this condition has been considered more frequently. However, epidemiological studies of group 2 pulmonary hypertension are less exhaustive than studies of other causes of pulmonary hypertension. In group 2 patients, pulmonary hypertension may be caused by an isolated increase in left-sided filling pressures or by a combination of this condition with increased pulmonary vascular resistance, with an abnormally high pressure gradient between arteries and pulmonary veins. A better understanding of the conditions underlying pulmonary hypertension is of key importance to establish a comprehensive diagnosis, leading to an adapted treatment to reduce heart failure morbidity and mortality. In this review, epidemiology, mechanisms and diagnostic approaches are reviewed; then, treatment options and future approaches are considered.

Pulmonary and Systemic Vascular Resistances After Cardiopulmonary Bypass: Role of Hemolysis

OBJECTIVES

Prolonged cardiopulmonary bypass (CPB) is associated with hemolysis, resulting in increased plasma oxyhemoglobin and vascular nitric oxide depletion. The authors hypothesized that hemolysis associated with CPB would reduce nitric oxide bioavailability, resulting in high pulmonary and systemic vascular resistances that after CPB would normalize gradually over time, due to clearance of plasma oxyhemoglobin. The authors also investigated whether prolonged CPB (≥140 min) produced increased levels of hemolysis and greater pulmonary and systemic vasoconstriction.

DESIGN

Prospective cohort study.

SETTING

Single-center university hospital.

PATIENTS

The study comprised 50 patients undergoing elective cardiac surgery requiring CPB.

INTERVENTIONS

Plasma hemoglobin and plasma nitric oxide consumption were measured before surgery and after CPB. Pulmonary and systemic hemodynamics were measured after CPB. The effects of short (<140 min) and prolonged (≥140 min) CPB on these parameters were considered.

MEASUREMENTS AND MAIN RESULTS

Pulmonary and systemic vascular resistances and plasma hemoglobin and nitric oxide consumption were highest at 15 minutes after CPB and then decreased over time. Pulmonary and systemic vascular resistances and plasma hemoglobin and plasma nitric oxide consumption were higher in patients requiring prolonged CPB. The reduction in plasma nitric oxide consumption from 15 minutes to 4 hours after CPB was correlated independently with the reductions in pulmonary and systemic vascular resistances.

CONCLUSIONS

Prolonged CPB was associated with increased plasma hemoglobin and plasma nitric oxide consumption and pulmonary and systemic vascular resistances. The reduction in plasma nitric oxide consumption at 4 hours after CPB was an independent predictor of the concomitant reductions in pulmonary and systemic vascular resistances.

Readdressing the entity of exercise pulmonary arterial hypertension

Exercise pulmonary hypertension (EPH) indicates an abnormally elevated pulmonary artery pressure (PAP) during exercise. The physiological range of PAP during exercise remains poorly defined and, therefore, a universally accepted definition of EPH remains elusive. Nevertheless, previous data concerning the distribution of PAP in normal populations and more recent retrospective clinical data enhanced our ability to define EPH. EPH can impair exercise capacity and cause dyspnea. The underlying pathophysiology of the arterial form of EPH (EPAH) appears to be similar to that seen in resting pulmonary arterial hypertension (PAH), and EPAH individuals are at risk of developing resting PAH. Patients with collagen vascular disease, especially scleroderma, are at risk for EPAH and its presence indicates a relatively poor prognosis. The prevalence of EPAH in scleroderma may be as high as 50%. The utility of pulmonary vasodilator therapy for EPAH is not well defined; however, a sizable subgroup of EPAH patients will achieve an improvement in symptoms.

Pulmonary hypertension associated with left-sided heart disease

Pulmonary hypertension associated with left-sided heart disease (PH-LHD) is the most common type of pulmonary hypertension. In patients with left-sided heart disease, the presence of pulmonary hypertension is typically a marker of more advanced disease, more severe symptoms, and worse prognosis. In contrast to pulmonary arterial hypertension, PH-LHD is characterised by an elevated pulmonary artery wedge pressure (postcapillary pulmonary hypertension) without or with an additional precapillary component (isolated postcapillary vs combined postcapillary and precapillary pulmonary hypertension). Transthoracic echocardiography is the primary noninvasive imaging tool to estimate the probability of pulmonary hypertension and to establish a working diagnosis on the mechanism of pulmonary hypertension. However, right heart catheterisation is always required if significant pulmonary hypertension is suspected and exact knowledge of the haemodynamic constellation is necessary. The haemodynamic constellation (mean pulmonary artery pressure, mean pulmonary artery wedge pressure, left ventricular end-diastolic pressure) in combination with clinical information and imaging findings (mainly echocardiography, coronary angiography and cardiac magnetic resonance imaging) will usually allow the exact mechanism underlying PH-LHD to be defined, which is a prerequisite for appropriate treatment. The general principle for the management of PH-LHD is to treat the underlying left-sided heart disease in an optimal manner using drugs and/or interventional or surgical therapy. There is currently no established indication for pulmonary arterial hypertension-specific therapies in PH-LHD, and specific therapies may even cause harm in patients with PH-LHD.

Use of thermodilution cardiac output overestimates diagnoses of exercise-induced pulmonary hypertension

Two new definitions of exercise-induced pulmonary hypertension (EIPH) have emerged. Both rely on measuring cardiac output (CO), yet this remains unstandardized. In our cohort of patients undergoing invasive cardiopulmonary exercise testing, we found that using thermodilution CO rather than direct Fick CO led to a significant excess of EIPH diagnoses.

Kinetics of Cardiac Output at the Onset of Exercise in Precapillary Pulmonary Hypertension

Purpose. Cardiac output (CO) is a cornerstone parameter in precapillary pulmonary hypertension (PH). The Modelflow (MF) method offers a reliable noninvasive determination of its beat-by-beat changes. So MF allows exploration of CO adjustment with the best temporal resolution. Methods. Fifteen subjects (5 PH patients, 10 healthy controls) performed a submaximal supine exercise on a cycle ergometer after 5 min of rest. CO was continuously determined by MF (CO_MF). Kinetics of heart rate (HR), stroke volume (SV), and CO were determined with 3 monoexponential models. Results. In PH patients, we observed a sudden and transitory drop of SV upon exercise onset. This implied a transitory drop of CO whose adjustment to a new steady state depended on HR increase. The kinetics of HR and CO for PH patients was slower than that of controls for all models and for SV in model 1. SV kinetics was faster for PH patients in models 2 and 3. Conclusion. This is the first description of beat-by-beat cardiovascular adjustments upon exercise onset in PH. The kinetics of HR and CO appeared slower than those of healthy controls and there was a transitory drop of CO upon exercise onset in PH due to a sudden drop of SV.