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The right ventricle and its stress response is perhaps the most important arbiter of survival in patients with pulmonary hypertension of many causes. The physiology of the cardiopulmonary unit and definition of right heart failure proposed in the 2018 World Symposium on Pulmonary Hypertension have proven useful constructs in subsequent years. Here, we review updated knowledge of basic mechanisms that drive right ventricular function in health and disease, and which may be useful for therapeutic intervention in the future. We further contextualise new knowledge on assessment of right ventricular function with a focus on metrics readily available to clinicians and updated understanding of the roles of the right atrium and tricuspid regurgitation. Typical right ventricular phenotypes in relevant forms of pulmonary vascular disease are reviewed and recent studies of pharmacological interventions on chronic right ventricular failure are discussed. Finally, unanswered questions and future directions are proposed., Competing Interests: Conflict of interest: A.R. Hemnes reports grants from NIH/NHLBI, consultancy fees from Bayer, Gossamer Bio, Merck, Janssen, United Therapeutics and Tenax, participation on a data safety monitoring board or advisory board with NIH/NHLBI, leadership roles with Nashville Ballet and Pulmonary Vascular Research Institute, and stock (or stock options) with Tenax Therapeutics. D.S. Celermajer has no potential conflicts of interest to disclose. M. D'Alto reports consultancy fees and payment or honoraria for lectures, presentations, manuscript writing or educational events from Merck Sharp and Dhome, Dompé, AOP and Janssen, and support for attending meetings from Dompé, AOP and Janssen. F. Haddad reports grants from Johnson & Johnson, and consultancy fees from Merck. P.M. Hassoun reports grants from NIH/NHLBI (R01 R01HL114910), and participation on a data safety monitoring board or advisory board with MSD and ARIA-CV. K.W. Prins reports grants from NHLBI (R01 HL158795 and 162927) and Bayer (PHAB grant), and consultancy fees from Edwards. R. Naeije reports consultancy fees from AOP Orphan Pharma, Johnson & Johnson, United Therapeutics and Lung Biotechnology, payment or honoraria for lectures, presentations, manuscript writing or educational events from AOP Orphan Pharma, support for attending meetings from AOP Orphan Pharma, and participation on a data safety monitoring board or advisory board with Johnson & Johnson, AOP Orphan Pharma and United Therapeutics. A. Vonk Noordegraaf reports payment or honoraria for lectures, presentations, manuscript writing or educational events from Actelion and Johnson & Johnson., (Copyright ©The authors 2024.)

Aims: Recent studies have shown that lung ultrasound-assessed pulmonary congestion is worse in heart failure when pulmonary vascular resistance (PVR) is increased, suggesting a paradoxical relationship between right heart failure and increased lung water content. Accordingly, we wondered if lung ultrasound would reveal otherwise clinically silent pulmonary congestion in patients with pulmonary arterial hypertension (PAH)., Methods and Results: All patients referred for suspicion of PAH in a tertiary centre from January 2020 to December 2022 underwent a complete diagnostic work-up including echocardiography, lung ultrasound and right heart catheterization. Pulmonary congestion was identified by lung ultrasound B-lines using an 8-site scan. The study enrolled 102 patients with idiopathic PAH (mean age 53 ± 13 years; 71% female). World Health Organization functional classes I, II, and III were found in 2%, 52%, and 46% of them, respectively. N-terminal pro-brain natriuretic peptide (NT-proBNP) was 377 pg/ml (interquartile range [IQR] 218-906). B-lines were identified in 77 out of 102 patients (75%), with a median of 3 [IQR 1-5]. At univariable analysis, B-lines were positively correlated with male sex, age, NT-proBNP, systolic pulmonary artery pressure (sPAP), right atrial pressure (RAP), PVR, left ventricular end-diastolic volume and tricuspid annular plane systolic excursion (TAPSE), and negatively with cardiac output and stroke volume. At multivariable analysis, RAP (p < 0.001), TAPSE/sPAP (p = 0.001), and NT-proBNP (p = 0.04) were independent predictors of B-lines., Conclusion: Lung ultrasound commonly discloses pulmonary congestion in PAH. This finding is related to right ventricular to pulmonary artery uncoupling, and may tentatively be explained by increased central venous pressure impeding lymphatic outflow., (© 2024 European Society of Cardiology.)

Background: Exercise echocardiography is used for assessment of pulmonary circulation and right ventricular function, but limits of normal and disease-specific changes remain insufficiently established., Objectives: The objective of this study was to explore the physiological vs pathologic response of the right ventricle and pulmonary circulation to exercise., Methods: A total of 2,228 subjects were enrolled: 375 healthy controls, 40 athletes, 516 patients with cardiovascular risk factors, 17 with pulmonary arterial hypertension, 872 with connective tissue diseases without overt pulmonary hypertension, 113 with left-sided heart disease, 30 with lung disease, and 265 with chronic exposure to high altitude. All subjects underwent resting and exercise echocardiography on a semirecumbent cycle ergometer. All-cause mortality was recorded at follow-up., Results: The 5th and 95th percentile of the mean pulmonary artery pressure-cardiac output relationships were 0.2 to 3.5 mm Hg.min/L in healthy subjects without cardiovascular risk factors, and were increased in all patient categories and in high altitude residents. The 5th and 95th percentile of the tricuspid annular plane systolic excursion to systolic pulmonary artery pressure ratio at rest were 0.7 to 2.0 mm/mm Hg at rest and 0.5 to 1.5 mm/mm Hg at peak exercise, and were decreased at rest and exercise in all disease categories and in high-altitude residents. An increased all-cause mortality was predicted by a resting tricuspid annular plane systolic excursion to systolic pulmonary artery pressure <0.7 mm/mm Hg and mean pulmonary artery pressure-cardiac output >5 mm Hg.min/L., Conclusions: Exercise echocardiography of the pulmonary circulation and the right ventricle discloses prognostically relevant differences between healthy subjects, athletes, high-altitude residents, and patients with various cardio-respiratory conditions. (Right Heart International NETwork During Exercise in Different Clinical Conditions; NCT03041337)., Competing Interests: Funding Support and Author Disclosures All authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: The differential diagnosis between pulmonary arterial hypertension (PAH) and postcapillary pulmonary hypertension (PH) in heart failure with preserved ejection fraction (HFpEF) is sometimes difficult despite guidelines-derived standardized step-by-step diagnostic algorithms. We therefore explored the added value of lung ultrasound to a previously validated echocardiographic score of right heart catheterization measurements., Methods: Patients referred for PH underwent a right heart catheterization, echocardiography, and lung ultrasound before and after rapid infusion of 7 mL/kg of saline. A 7-point echocardiographic score based on cardiac chamber dimensions and estimates of filling pressures was implemented for the prediction of precapillary PH. Pulmonary congestion was identified by lung ultrasound B lines., Results: The study enrolled 70 patients with PAH and 77 patients with HFpEF. The PAH patients had a higher echocardiographic score (3.5 ± 1.8 vs 1.6 ± 1.5; P < .001). The HFpEF patients had more B lines both before (8.1 ± 4.2 vs 5.1 ± 3.0; P < .001) and after fluid challenge (14.6 ± 5.4 vs 7.6 ± 3.5; P < .001) and a more important increase (Δ) of B lines after fluid challenge (6.5 ± 2.9 vs 2.5 ± 1.6; P < .001). The sensitivity and specificity of the echocardiographic score (cutoff ≥2) alone for PAH were 0.91 and 0.49, respectively (area under the curve of 0.78). The best diagnostic improvement was observed with addition of ΔB lines + E/e' post-fluid challenge to the echocardiographic score, with a significant increase of the area under the curve (0.98) and (with a cutoff given by the presence of echo score ≥2, ΔB lines <4 and E/e' post < 11) a sensitivity of 0.90 (95% CI, 0.83; 0.97) and specificity of 0.84 (95% CI, 0.76; 0.93)., Conclusions: Lung ultrasound combined with echocardiography at baseline and after fluid challenge has an incremental value for the differential diagnosis between PAH and PH-HFpEF., (Copyright © 2023 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.)

Background: The right ventricle has a complex contraction pattern of uncertain clinical relevance. We aimed to assess the relationship between right ventricular (RV) contraction pattern and RV-pulmonary arterial (PA) coupling defined by the gold-standard pressure-volume loop-derived ratio of end-systolic/arterial elastance (Ees/Ea)., Methods: Prospectively enrolled patients with suspected or confirmed pulmonary hypertension underwent three-dimensional echocardiography, standard right heart catheterization, and RV conductance catheterization. RV-PA uncoupling was categorized as severe (Ees/Ea < 0.8), moderate (Ees/Ea 0.8-1.29), and none/mild (Ees/Ea ≥ 1.3). Clinical severity was determined from hemodynamics using a truncated version of the 2022 European Society of Cardiology/European Respiratory Society risk stratification scheme., Results: Fifty-three patients were included, 23 with no/mild, 24 with moderate, and 6 with severe uncoupling. Longitudinal shortening was decreased in patients with moderate vs no/mild uncoupling (p <0.001) and intermediate vs low hemodynamic risk (p < 0.001), discriminating low risk from intermediate/high risk with an optimal threshold of 18% (sensitivity 80%, specificity 87%). Anteroposterior shortening was impaired in patients with severe vs moderate uncoupling (p = 0.033), low vs intermediate risk (p = 0.018), and high vs intermediate risk (p = 0.010), discriminating high risk from intermediate/low risk with an optimal threshold of 15% (sensitivity 100%, specificity 83%). Left ventricular (LV) end-diastolic volume was decreased in patients with severe uncoupling (p = 0.035 vs no/mild uncoupling)., Conclusions: Early RV-PA uncoupling is associated with reduced longitudinal function, whereas advanced RV-PA uncoupling is associated with reduced anteroposterior movement and LV preload, all in a risk-related fashion., Clinicaltrials: GOV: NCT04663217., Competing Interests: Disclosure statement This study was funded by Deutsche Forschungsgesellschaft, Grant Agreement Number CRC 1213, Project B08. Dr Rako, Ms Yildiz, Mr da Rocha, Dr Kremer and Dr Vadász report nonfinancial support from the University of Giessen during the conduct of the study. Dr Yogeswaran reports nonfinancial support from the University of Giessen during the conduct of the study and personal fees from MSD outside the current study. Dr Lakatos, Dr Fábián, and Dr Kovács report personal fees from Argus Cognitive, Inc. during the conduct of the study. Dr Ghofrani reports nonfinancial support from the University of Giessen and grants from the German Research Foundation during the conduct of the study and personal fees from Bayer, Actelion, Pfizer, Merck, GSK and Takeda, grants and personal fees from Novartis, Bayer HealthCare and Encysive/Pfizer, and grants from Aires, the German Research Foundation, Excellence Cluster Cardiopulmonary Research, and the German Ministry of Education and Research outside the current study. Dr Seeger reports grants from the German Research Foundation and nonfinancial support from the University of Giessen during the conduct of the current study and personal fees from Pfizer and Bayer Pharma AG outside the submitted work. Dr Gall reports grants from the German Research Foundation and nonfinancial support from the University of Giessen during the conduct of the current study and personal fees from Actelion, AstraZeneca, Bayer, BMS, GSK, Janssen-Cilag, Lilly, MSD, Novartis, OMT, Pfizer, and United Therapeutics outside the current study. Dr Richter reports nonfinancial support from the University of Giessen during the conduct of the current study and research support from United Therapeutics and Bayer, speaker honoraria from Bayer, Actelion, Mundipharma, Roche, and OMT, and consultancy fees from Bayer outside the submitted work. Dr Bauer reports consultancy fees from Bristol Myers Squibb/Pfizer and speaker fees from Bristol Myers Squibb/Pfizer, AstraZeneca and Amgen. Dr Tedford reports no direct conflicts of interest during the conduct of the current study and consulting relationships with Abiomed (research advisory board), Medtronic, Abbott (steering committee), Aria CV Inc., Acceleron/Merck (steering committee and hemodynamic core lab work for Merck), Alleviant, CareDx, Cytokinetics, Itamar, Edwards LifeSciences (national principal investigator for the RIGHT-FLOW clinical trial), Eidos Therapeutics, Lexicon Pharmaceuticals, and Gradient outside the submitted work. Dr Naeije reports relationships including consultancies, speaker’s fees and membership of advisory boards with AOP Orphan Pharmaceuticals, Johnson & Johnson, Lung Biotechnology Corporation and United Therapeutics. Dr Tello reports nonfinancial support from the University of Giessen during the conduct of the current study and speaker honoraria from Actelion and Bayer outside the submitted work. We thank Claire Mulligan, PhD (Beacon Medical Communications Ltd, Brighton, UK) for editorial assistance, funded by the University of Giessen., (Copyright © 2023 International Society for the Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Background: Normative changes in right ventricular (RV) structure and function have not been characterized in the context of treatment-associated functional recovery (RV functional recovery [RVFnRec]). The aim of this study is to assess the clinical relevance of a proposed RVFnRec definition., Methods: We evaluated 63 incident patients with pulmonary arterial hypertension by right heart catheterization and cardiac magnetic resonance imaging at diagnosis and cardiac magnetic resonance imaging and invasive cardiopulmonary exercise testing following treatment (≈11 months). Sex, age, ethnicity matched healthy control subjects (n=62) with 1-time cardiac magnetic resonance imaging and noninvasive cardiopulmonary exercise testing were recruited from the PVDOMICS (Redefining Pulmonary Hypertension through Pulmonary Vascular Disease Phenomics) project. We examined therapeutic cardiac magnetic resonance imaging changes relative to the evidence-based peak oxygen consumption (VO 2peak )>15 mL/(kg·min) to define RVFnRec by receiver operating curve analysis. Afterload was measured as mean pulmonary artery pressure, resistance, compliance, and elastance., Results: A drop in RV end-diastolic volume of -15 mL best defined RVFnRec (area under the curve, 0.87; P =0.0001) and neared upper 95% CI RV end-diastolic volume of controls. This cutoff was met by 22 out of 63 (35%) patients which was reinforced by freedom from clinical worsening, RVFnRec 1 out of 21 (5%) versus no RVFnRec 17 out of 42, 40% (log-rank P =0.006). A therapy-associated increase of 0.8 mL/mm Hg in compliance had the best predictive value of RVFnRec (area under the curve, 0.76; [95% CI, 0.64-0.88]; P =0.001). RVFnRec patients had greater increases in stroke volume, and cardiac output at exercise., Conclusions: RVFnRec defined by RV end-diastolic volume therapeutic decrease of -15 mL predicts exercise capacity, freedom from clinical worsening, and nears normalization. A therapeutic improvement of compliance is superior to other measures of afterload in predicting RVFnRec. RVFnRec is also associated with increased RV output reserve at exercise., Competing Interests: Disclosures Dr Rischard has consulting relationships with Bayer and receives research support from Ismed, United Therapeutics, Bayer, Acceleron, Merck, and Janssen. Dr Naeije reports relationships including consultancies, speakers fees, and membership of advisory boards with AOP Orphan Pharmaceuticals, Johnson & Johnson, Lung Biotechnology Corporation, and United Therapeutics. Dr Garcia is Chief Executive Officer and founder of Aqualung Therapeutics Corporation. Dr Frantz has consulting, steering committee, and advisory board relationships with Altavant Sciences, Bayer, Gossamer Bio, Janssen, Shouti, France Foundation, IQVIA, Tenax, UpToDate, and United Therapeutics. Dr Hassoun has served as consultant for Merck. Dr Hemnes has consulting relationships with Janssen, Merck, Gossamer, Bio, United Therapeutics, Bayer, Tenax. She owns stock in Tenax therapeutics and she has received research support from National Heart, Lung, and Blood Institute and Cardiovascular Medical Research and Education Fund. Dr Hill is the chair for an Aerovate steering committee. He is a consultant for Bellerophon and Liquidia and Merck. Dr Horn has consulting relationships with Biotronik and AADI biosciences. She serves on the DSMB for SoniVie and V-waves Ltd. She receives research support from Merck and Cereno. Dr Leopold Abbott has served as a consultant for Aria. She has research support from Astellas Pharma and United Therapeutics. Dr Rosenzweig has received consulting fees from Acceleron for a scientific advisory board meeting; and her institution receives grant support from Bayer, United Therapeutics, Janssen, and SonVie. Dr Tang served as consultant for Sequana Medical, Cardiol Therapeutics, Genomics plc, Zehna Therapeutics, Renovacor, WhiteSwell, Kiniksa, Boston Scientific, and CardiaTec Biosciences and has received honorarium from Springer Nature and American Board of Internal Medicine. The other authors report no conflicts.

Background: Right ventricular (RV) diastolic dysfunction may be prognostic in pulmonary hypertension (PH). However, its assessment is complex and relies on conductance catheterisation. We aimed to evaluate echocardiography-based parameters as surrogates of RV diastolic function, provide validation against the gold standard, end-diastolic elastance (Eed), and define the prognostic impact of echocardiography-derived RV diastolic dysfunction., Methods: Patients with suspected PH who underwent right heart catheterisation including conductance catheterisation were prospectively recruited. In this study population, an echocardiography-based RV diastolic function surrogate was derived. Survival analyses were performed in patients with precapillary PH in the Giessen PH Registry, with external validation in patients with pulmonary arterial hypertension at Sapienza University (Rome)., Results: In the derivation cohort (n=61), the early/late diastolic tricuspid inflow velocity ratio (E/A) and early tricuspid inflow velocity/early diastolic tricuspid annular velocity ratio (E/e') did not correlate with Eed (p>0.05). Receiver operating characteristic analysis revealed a large area under the curve (AUC) for the peak lateral tricuspid annulus systolic velocity/right atrial area index ratio (S'/RAAi) to detect elevated Eed (AUC 0.913, 95% confidence interval (CI) 0.839-0.986) and elevated end-diastolic pressure (AUC 0.848, 95% CI 0.699-0.998) with an optimal threshold of 0.81 m 2 ·s -1 ·cm -1 . Subgroup analyses demonstrated a large AUC in patients with preserved RV systolic function (AUC 0.963, 95% CI 0.882-1.000). Survival analyses confirmed the prognostic relevance of S'/RAAi in the Giessen PH Registry (n=225) and the external validation cohort (n=106)., Conclusions: Our study demonstrates the usefulness of echocardiography-derived S'/RAAi for noninvasive assessment of RV diastolic function and prognosis in PH., Competing Interests: Conflicts of interest: A. Yogeswaran reports non-financial support from the University of Giessen during the conduct of the study, and personal fees from MSD outside the submitted work. Conflicts of interest: Z.A. Rako and N.C. Kremer report non-financial support from the University of Giessen during the conduct of the study. Conflicts of interest: S. Yildiz has no conflict of interest or disclosures. Conflicts of interest: H.A. Ghofrani reports grants from the German Research Foundation and non-financial support from the University of Giessen during the conduct of the study, and personal fees from Bayer, Actelion, Pfizer, Merck, GSK, and Takeda, grants and personal fees from Novartis, Bayer HealthCare, and Encysive/Pfizer, and grants from Aires, the German Research Foundation, Excellence Cluster Cardio-pulmonary Research, and the German Ministry for Education and research outside the submitted work. Conflicts of interest: W. Seeger reports grants from the German Research Foundation and non-financial support from the University of Giessen during the conduct of the study, and personal fees from Pfizer and Bayer Pharma AG outside the submitted work. Conflicts of interest: B. Brito da Rocha has no conflict of interest and nothing to disclose. Conflicts of interest: H. Gall reports grants from the German Research Foundation and non-financial support from the University of Giessen during the conduct of the study, and personal fees from Actelion, AstraZeneca, Bayer, BMS, GSK, Janssen-Cilag, Lilly, MSD, Novartis, OMT, Pfizer, and United Therapeutics outside the submitted work. Conflicts of interest: P. Douschan, S. Papa, C.D. Vizza and D. Filomena have no conflict of interest or disclosures. Conflicts of interest: R.J. Tedford reports no direct conflicts of interest related to this manuscript; he reports general disclosures to include consulting relationships with Medtronic, Abbott, Aria CV Inc., Acceleron, Alleviant, CareDx, Cytokinetics, Itamar, Edwards LifeSciences, Eidos Therapeutics, Lexicon Pharmaceuticals, and Gradient. Conflicts of interest: R.J. Tedford is the national principal investigator for the RIGHT-FLOW clinical trial (Edwards), serves on a steering committee for Merck and Abbott as well as a research advisory board for Abiomed. He also does hemodynamic core lab work for Merck. Conflicts of interest: R. Naeije has relationships with drug companies including AOP Orphan Pharmaceuticals, Johnson & Johnson, Lung Biotechnology Corporation, and United Therapeutics. In addition to being an investigator in trials involving these companies, relationships include consultancy service, research grants, and membership of scientific advisory boards. Conflicts of interest: M.J. Richter reports grants from the German Research Foundation and non-financial support from the University of Giessen during the conduct of the study, and personal fees from Actelion, Bayer, Janssen-Cilag, MSD, OMT, Pfizer, and United Therapeutics outside the submitted work. Conflicts of interest: R. Badagliacca received grants and personal fees from Ferrer, Dompè, AOP, United Therapeutics, MSD, Janssen, and Bayer outside the submitted work. Conflicts of interest: K. Tello reports grants from the German Research Foundation and non-financial support from the University of Giessen during the conduct of the study, and personal fees from Actelion outside the submitted work., (Copyright ©The authors 2023.)

The contribution of the right ventricle (RV) to cardiac output is negligible in normal resting conditions when pressures in the pulmonary circulation are low. However, the RV becomes relevant in healthy subjects during exercise and definitely so in patients with increased pulmonary artery pressures both at rest and during exercise. The adaptation of RV function to loading rests basically on an increased contractility. This is assessed by RV end-systolic elastance (Ees) to match afterload assessed by arterial elastance (Ea). The system has reserve as the Ees/Ea ratio or its imaging surrogate ejection fraction has to decrease by more than half, before the RV undergoes an increase in dimensions with eventual increase in filling pressures and systemic congestion. RV-arterial uncoupling is accompanied by an increase in diastolic elastance. Measurements of RV systolic function but also of diastolic function predict outcome in any cause pulmonary hypertension and heart failure with or without preserved left ventricular ejection fraction. Pathobiological changes in the overloaded RV include a combination of myocardial fibre hypertrophy, fibrosis and capillary rarefaction, a titin phosphorylation-related displacement of myofibril tension-length relationships to higher pressures, a metabolic shift from mitochondrial free fatty acid oxidation to cytoplasmic glycolysis, toxic lipid accumulation, and activation of apoptotic and inflammatory signalling pathways. Treatment of RV failure rests on the relief of excessive loading., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Purpose of the Review: Tricuspid regurgitation is associated with increased mortality in proportion to right ventricular adaptation to increased volume loading and pulmonary artery pressure. We here review recent progress in the understanding of right ventricular adaptation to pre- and after-loading conditions for improved recommendations of tricuspid valve repair., Recent Findings: Trans-catheter tricuspid valve repair has made the correction of tricuspid regurgitation more easily available, triggering a need of tighter indications. Several studies have shown the feasibility and relevance to the indications of tricuspid valve repair of imaging of right ventricular ejection fraction measured by magnetic resonance imaging or 3D-echocardiography, and the 2D-echocardiography of the tricuspid annular plane systolic excursion to systolic pulmonary artery pressure ratio combined with invasively determined mean pulmonary artery pressure and pulmonary vascular resistance. Improved definitions of right ventricular failure and pulmonary hypertension may be considered in future recommendations on the treatment of tricuspid regurgitation., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Aims: Upregulated p38 MAPK signaling is implicated in the accelerated proliferation of pulmonary artery smooth muscle cells (PA-SMCs) and the pathogenesis of pulmonary artery remodeling observed in pulmonary arterial hypertension (PAH). Previously, we reported that after endothelin-1 (ET-1) pretreatment, bone morphogenetic protein 2 (BMP2) activates p38 MAPK signaling and accelerates PA-SMC proliferation. The activity of p38 MAPK signaling is tightly regulated by the inactivation of dual-specificity phosphatase 1 (DUSP1). Activated p38 MAPK induces DUSP1 expression, forming a negative feedback loop. Prostacyclin IP receptor agonists (prostacyclin and selexipag) are used to treat PAH. In this study, we aimed to verify whether IP receptor agonists affect DUSP1 expression and accelerate the proliferation of PA-SMCs., Main Methods: PA-SMCs were treated with BMP2, ET-1, prostacyclin, and MRE-269, an active metabolite of selexipag, either alone or in combination. We quantified mRNA expressions using real-time quantitative polymerase chain reaction. Pulmonary artery specimens and PA-SMCs were obtained during lung transplantation in patients with PAH., Key Findings: Both prostacyclin and MRE-269 increased DUSP1 expression. Combined treatment with BMP2 and ET-1 induced cyclin D1 and DUSP1 expression and increased PA-SMC proliferation. MRE-269 attenuated BMP2/ET-1-induced cell proliferation. ET-1 increased DUSP1 expression in PA-SMCs from control patients but not in PA-SMCs from patients with PAH., Significance: This study showed that the p38 MAPK /DUSP1 negative feedback loop is impaired in PAH, contributing to unregulated p38 MAPK activation and PA-SMC hyperplasia. IP receptor agonist MRE-269 increases DUSP1 expression and inhibit p38 MAPK -mediated PA-SMC proliferation. Future elucidation of the detailed mechanism underlying reduced DUSP1 expression would be informative for PAH treatment., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Rationale: Donor brain death-induced lung injury may compromise graft function after transplantation. Establishing strategies to attenuate lung damage remains a challenge because the underlying mechanisms remain uncertain. Objectives: The effects of tacrolimus pretreatment were evaluated in an experimental model of brain death-induced lung injury. Methods: Brain death was induced by slow intracranial infusion of blood in anesthetized pigs after randomization to tacrolimus (orally administered at 0.25 mg ⋅ kg -1 twice daily the day before the experiment and intravenously at 0.05 mg ⋅ kg -1 1 h before the experiment; n  = 8) or placebo ( n  = 9) pretreatment. Hemodynamic measurements were performed 1, 3, 5, and 7 hours after brain death. After euthanasia of the animals, lung tissue was sampled for pathobiological and histological analysis, including lung injury score (LIS). Measurements and Main Results: Tacrolimus pretreatment prevented increases in pulmonary arterial pressure, pulmonary vascular resistance, and pulmonary capillary pressure and decreases in systemic arterial pressure and thermodilution cardiac output associated with brain death. After brain death, the ratio of Pa O 2 to Fi O 2 decreased, which was prevented by tacrolimus. Tacrolimus pretreatment prevented increases in the ratio of IL-6 to IL-10, VCAM1 (vascular cell adhesion molecule 1), circulating concentrations of IL-1β, and glycocalyx-derived molecules. Tacrolimus partially decreased apoptosis ( Bax [ Bcl2 -associated X apoptosis regulator]-to- Bcl2 [B-cell lymphoma-2] ratio [ P  = 0.07] and number of apoptotic cells in the lungs [ P  < 0.05]) but failed to improve LIS. Conclusions: Immunomodulation through tacrolimus pretreatment prevented pulmonary capillary hypertension as well as the activation of inflammatory and apoptotic processes in the lungs after brain death; however, LIS did not improve.

Background: Obesity-related exercise intolerance may be associated with pulmonary vascular and right ventricular dysfunction. This study tested the hypothesis that decreased pulmonary vascular reserve and right ventricular (RV)-pulmonary arterial (PA) uncoupling contributes to exercise limitation in subjects with obesity., Methods: Seventeen subjects with obesity were matched to normo-weighted healthy controls. All subjects underwent; exercise echocardiography, lung diffusing capacity (DL) for nitric oxide (NO) and carbon monoxide (CO) and an incremental cardiopulmonary exercise test. Cardiac output (Q), PA pressure (PAP) and tricuspid annular plane systolic excursion (TAPSE) were recorded at increasing exercise intensities. Pulmonary vascular reserve was assessed by multipoint mean PAP (mPAP)/Q relationships with more reserve defined by lesser increase in mPAP at increased Q, and RV-PA coupling was assessed by the TAPSE/systolic PAP (sPAP) ratio., Results: At rest, subjects with obesity displayed lower TAPSE/sPAP ratios (1.00 ± 0.26 vs. 1.19 ± 0.22 ml/mmHg, P < 0.05), DL CO and pulmonary capillary blood volume (52 ± 11 vs. 64 ± 13 ml, P < 0.01) compared to controls. Exercise was associated with steeper mPAP-Q slopes, decreased TAPSE/sPAP and lower peak O 2 uptake (VO 2 peak). The changes in TAPSE/sPAP at exercise were correlated to the body fat mass ( R = 0.39, P = 0.01) and VO 2 peak ( R = 0.44, P < 0.01)., Conclusion: Obesity is associated with a decreased pulmonary vascular and RV-PA coupling reserve which may impair exercise capacity., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Na, Kevin, Yoshiki, Corentin, Malgorzata, Robert and Vitalie.)

Background: According to current guidelines, the diagnosis of pulmonary hypertension (PH) relies on echocardiographic probability followed by right heart catheterisation (RHC). How echocardiography predicts PH recently redefined by mean pulmonary arterial pressure (mPAP) >20 mmHg instead of ≥25 mmHg and pulmonary vascular disease defined by pulmonary vascular resistance (PVR) ≥3 or >2 WU has not been established., Methods: A total of 278 patients referred for PH underwent comprehensive echocardiography followed by RHC. 15 patients (5.4%) were excluded because of insufficient quality echocardiography., Results: With PH defined by mPAP >20 mmHg, 23 patients had no PH, 146 had pre-capillary PH and 94 had post-capillary PH. At univariate analysis, maximum tricuspid regurgitation velocity (TRV) 2.9-3.4 m·s -1 , left ventricle (LV) eccentricity index >1.1, right ventricle outflow tract acceleration time (RVOT-AT) <105 ms or notching, RV/LV basal diameter >1 and pulmonary artery diameter predicted PH, whereas inferior vena cava diameter and right atrial area did not. At multivariable analysis, only TRV ≥2.9 m·s -1 independently predicted PH. Additional independent prediction of PVR ≥3 WU was offered by LV eccentricity index >1.1, and RVOT-AT <105 ms and/or notching, but with no improvement of optimal combination of specificity and sensitivity or positive prediction., Conclusions: Echocardiography as recommended in current guidelines can be used to assess the probability of redefined PH in a referral centre. However, the added value of indirect signs is modest and sufficient quality echocardiographic signals may not be recovered in some patients., Competing Interests: Conflict of interest: M. D'Alto reports participation on a monitoring board for Actelion-Janssen, MSD, Dompè and Ferrer, outside the submitted work. R. Naeije reports lecture honoraria from AOP Pharmaceuticals; participation on a monitoring board for Johnson & Johnson, Actelion, Lung Biotechnology Corp and United Therapeutics, outside the submitted work. All other authors have nothing to disclose., (Copyright ©The authors 2022. For reproduction rights and permissions contact permissions@ersnet.org.)

Pulmonary arterial hypertension (PAH) is a rare dyspnoea-fatigue syndrome caused by a progressive increase in pulmonary vascular resistance and eventual right ventricular (RV) failure. In spite of extensive pulmonary vascular remodelling, lung function in PAH is generally well preserved, with hyperventilation and increased physiological dead space, but minimal changes in lung mechanics and only mild to moderate hypoxaemia and hypocapnia. Hypoxaemia is mainly caused by a low mixed venous oxygen tension from a decreased cardiac output. Hypocapnia is mainly caused by an increased chemosensitivity. Exercise limitation in PAH is cardiovascular rather than ventilatory or muscular. The extent of pulmonary vascular disease in PAH is defined by multipoint pulmonary vascular pressure-flow relationships with a correction for haematocrit. Pulsatile pulmonary vascular pressure-flow relationships in PAH allow for the assessment of RV hydraulic load. This analysis is possible either in the frequency domain or in the time domain. The RV in PAH adapts to increased afterload by an increased contractility to preserve its coupling to the pulmonary circulation. When this homeometric mechanism is exhausted, the RV dilates to preserve flow output by an additional heterometric mechanism. Right heart failure is then diagnosed by imaging of increased right heart dimensions and clinical systemic congestion signs and symptoms. The coupling of the RV to the pulmonary circulation is assessed by the ratio of end-systolic to arterial elastances, but these measurements are difficult. Simplified estimates of RV-pulmonary artery coupling can be obtained by magnetic resonance or echocardiographic imaging of ejection fraction., Competing Interests: Conflicts of interest: R. Naeije reports relationships including consultancies, speaker fees and membership of advisory boards with AOP Orphan Pharmaceuticals, Johnson & Johnson, Lung Biotechnology Corporation and United Therapeutics. Conflicts of interest: M.J. Richter has received funding from the German Research Foundation (DFG, 413584448) and from the Collaborative Research Center (SFB) 1213 – Pulmonary Hypertension and Cor Pulmonale (grant number SFB1213/1, project B08; German Research Foundation, Bonn, Germany). Conflicts of interest: L.J. Rubin reports consultancies with Actelion, SoniVie, Gossamer Bio and Bellerophon., (Copyright ©The authors 2022.)

Introduction: Careful, stepwise assessment is required in all patients with atrial septal defect (ASD) to exclude pulmonary vascular or left ventricular (LV) disease. Fluid challenge and balloon occlusion may unmask LV disease and post-capillary pulmonary hypertension, but their role in the evaluation of patients with 'operable' ASDs is not well established., Methods: We conducted a prospective study in three Italian specialist centres between 2018 and 2020. Patients selected for percutaneous ASD closure underwent assessment at baseline and after fluid challenge, balloon occlusion and both., Results: Fifty patients (46 (38.2, 57.8) years, 72% female) were included. All had a shunt fraction >1.5, pulmonary vascular resistance (PVR) <5 Wood Units (WU) and pulmonary arterial wedge pressure (PAWP) <15 mm Hg. Individuals with a PVR ≥2 WU at baseline (higher PVR group) were older, more symptomatic, with a higher baseline systemic vascular resistance (SVR) than the lower PVR group (all p<0.0001). Individuals with a higher PVR experienced smaller increases in pulmonary blood flow following fluid challenge (0.3 (0.1, 0.5) vs 2.0 (1.5, 2.8) L/min, p<0.0001). Balloon occlusion led to a more marked fall in SVR (p<0.0001) and a larger increase in systemic blood flow (p=0.024) in the higher PVR group. No difference was observed in PAWP following fluid challenge and/or balloon occlusion between groups; four (8%) patients reached a PAWP ≥18 mm Hg following the addition of fluid challenge to balloon occlusion testing., Conclusions: In adults with ASD without overt LV disease, even small rises in PVR may have significant implications on cardiovascular haemodynamics. Fluid challenge may provide additional information to balloon occlusion in this setting., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Despite numerous therapeutic advances in pulmonary arterial hypertension, patients continue to suffer high morbidity and mortality, particularly considering a median age of 50 years. This article explores whether early, robust reduction of right ventricular afterload would facilitate substantial improvement in right ventricular function and thus whether afterload reduction should be a treatment goal for pulmonary arterial hypertension. The earliest clinical studies of prostanoid treatment in pulmonary arterial hypertension demonstrated an important link between lowering mean pulmonary arterial pressure (or pulmonary vascular resistance) and improved survival. Subsequent studies of oral monotherapy or sequential combination therapy demonstrated smaller reductions in mean pulmonary arterial pressure and pulmonary vascular resistance. More recently, retrospective reports of initial aggressive prostanoid treatment or initial combination oral and parenteral therapy have shown marked afterload reduction along with significant improvements in right ventricular function. Some data suggest that reaching threshold levels for pressure or resistance (components of right ventricular afterload) may be key to interrupting the self-perpetuating injury of pulmonary vascular disease in pulmonary arterial hypertension and could translate into improved long-term clinical outcomes. Based on these clues, the authors postulate that improved clinical outcomes might be achieved by targeting significant afterload reduction with initial oral combination therapy and early parenteral prostanoids.

Aims: We sought to assess the feasibility of constructing right ventricular (RV) pressure-volume (PV) loops solely by echocardiography., Methods and Results: We performed RV conductance and pressure wire (PW) catheterization with simultaneous echocardiography in 35 patients with pulmonary hypertension. To generate echocardiographic PV loops, a reference RV pressure curve was constructed using pooled PW data from the first 20 patients (initial cohort). Individual pressure curves were then generated by adjusting the reference curve according to RV isovolumic and ejection phase duration and estimated RV systolic pressure. The pressure curves were synchronized with echocardiographic volume curves. We validated the reference curve in the remaining 15 patients (validation cohort). Methods were compared with correlation and Bland-Altman analysis. In the initial cohort, echocardiographic and conductance-derived PV loop parameters were significantly correlated {rho = 0.8053 [end-systolic elastance (Ees)], 0.8261 [Ees/arterial elastance (Ea)], and 0.697 (stroke work); all P < 0.001}, with low bias [-0.016 mmHg/mL (Ees), 0.1225 (Ees/Ea), and -39.0 mmHg mL (stroke work)] and acceptable limits of agreement. Echocardiographic and PW-derived Ees were also tightly correlated, with low bias (-0.009 mmHg/mL) and small limits of agreement. Echocardiographic and conductance-derived Ees, Ees/Ea, and stroke work were also tightly correlated in the validation cohort (rho = 0.9014, 0.9812, and 0.9491, respectively; all P < 0.001), with low bias (0.0173 mmHg/mL, 0.0153, and 255.1 mmHg mL, respectively) and acceptable limits., Conclusion: The novel echocardiographic method is an acceptable alternative to invasively measured PV loops to assess contractility, RV-arterial coupling, and RV myocardial work. Further validation is warranted., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Background: Patients with pulmonary hypertension (PH) frequently show preserved right ventricular (RV) function at rest. However, volume challenge may uncover pending RV dysfunction. We aimed to assess the physiological and prognostic impact of RV-pulmonary arterial (RV-PA) uncoupling during volume challenge in patients with precapillary PH., Methods: We prospectively assessed 32 patients with PH (pulmonary arterial hypertension, n = 27; inoperable chronic thromboembolic disease, n = 5) and 4 controls using invasive pressure-volume (PV) catheterization. PV loops were recorded during preload reduction (balloon occlusion of inferior vena cava; baseline) and acute volume loading (200 ml saline in 20 s). Contractility (multi-beat end-systolic elastance [Ees]), arterial elastance (Ea), and RV-PA coupling (Ees/Ea) were obtained at baseline and at maximum volume loading (MVL)., Results: Median [interquartile range] time to MVL was 19 [18-22] s. Ees/Ea significantly declined from baseline (0.89 [0.69-1.23]) to MVL (0.16 [0.12-0.34]; p < 0.001) in patients with PH but remained stable in controls (baseline: 1.08 [0.94-1.80]; MVL: 1.01 [0.80-2.49]; p = 0.715). The same pattern was observed for Ees, while Ea remained unchanged. The percent decline of RV-PA coupling (ΔEes/Ea) during fluid challenge was significantly associated with pulmonary resting hemodynamics, RV ejection fraction (RVEF), and RV end-diastolic volume. Kaplan-Meier analysis revealed that patients with PH who had a smaller ΔEes/Ea (<-65%) had a significantly better prognosis (log-rank p = 0.0389). In multivariate Cox regression analysis, clinical worsening was predicted by ΔEes/Ea (hazard ratio: 0.96 [95% confidence interval: 0.93-1.00]) and RVEF (hazard ratio: 0.95 [95% confidence interval: 0.92-0.98])., Conclusions: Assessment of PV loops during fluid challenge uncovers exhausted RV coupling reserve with severely reduced contractility in PH. RV-PA uncoupling during volume challenge can be predicted by pulmonary resting hemodynamics and RVEF. RV-PA uncoupling during fluid challenge and RVEF (as a noninvasive correlate) are predictors of clinical worsening., Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03403868 (January 19, 2018)., (Copyright © 2021 International Society for Heart and Lung Transplantation. All rights reserved.)

Background: The relevance of cor pulmonale in COPD and pulmonary hypertension due to COPD (PH-COPD) is incompletely understood. We aimed to investigate the relationship of right ventricular-pulmonary arterial (RV-PA) uncoupling with disease severity in COPD, and the relationship of RV-PA uncoupling and use of targeted PH therapies with mortality in PH-COPD., Methods: We retrospectively analyzed 231 patients with COPD without PH and 274 patients with PH-COPD. COPD was classified according to GOLD stages and the modified Medical Research Council dyspnoea scale. PH was categorized as mild-to-moderate or severe. RV-PA uncoupling was assessed as the echocardiographic tricuspid annular plane systolic excursion/pulmonary artery systolic pressure (TAPSE/PASP) ratio., Results: Of the cohort with COPD without PH, 21, 58, 54 and 92 were classified as GOLD I, II, III and IV, respectively. Patients in advanced GOLD stages and those with severe dyspnoea showed significantly decreased TAPSE/PASP.Of the PH-COPD cohort, 144 had mild-to-moderate PH and 130 had severe PH. During follow-up, 126 patients died. In univariate Cox regression, TAPSE/PASP and 6-min walk distance (6MWD; 10 m increments) predicted survival [hazard ratios (95% CI): 0.12 (0.03-0.57) and 0.95 (0.93-0.97), respectively]; notably, PH severity and simplified European Society of Cardiology/European Respiratory Society risk stratification did not. Among patients in the lowest or intermediate tertiles of TAPSE/PASP and 6MWD, those with targeted PH therapy had higher survival than those without (53 vs. 17% at 3 years)., Conclusion: Cor pulmonale (decreased TAPSE/PASP and 6MWD) is associated with disease severity in COPD and predicts outcome in PH-COPD., Competing Interests: AY reports non-financial support from the University of Giessen during the conduct of the study. SK reports personal fees from Chiesi, Berlin Chemie MENARINI and Insmed, and personal fees and non-financial support from GSK, Novartis and AstraZeneca outside the submitted work. HG reports grants from the German Research Foundation and non-financial support from the University of Giessen during the conduct of the study, and personal fees from Actelion, AstraZeneca, Bayer, BMS, GSK, Janssen-Cilag, Lilly, MSD, Novartis, OMT, Pfizer and United Therapeutics outside the submitted work. MF reports non-financial support from the University of Giessen during the conduct of the study. HG reports grants from the German Research Foundation and nonfinancial support from the University of Giessen during the conduct of the study, and personal fees from Bayer, Actelion, Pfizer, Merck, GSK and Takeda, grants and personal fees from Novartis, Bayer HealthCare and Encysive/Pfizer, and grants from Aires, the German Research Foundation, Excellence Cluster Cardiopulmonary Research and the German Ministry for Education and Research outside the submitted work. RN reports relationships including consultancies, speaker's fees and membership of advisory boards with AOP Orphan Pharmaceuticals, Johnson & Johnson, Lung Biotechnology Corporation and United Therapeutics. WS reports grants from the German Research Foundation and nonfinancial support from the University of Giessen during the conduct of the study, and personal fees from Pfizer and Bayer Pharma AG outside the submitted work. MR reports grants from the German Research Foundation and non-financial support from the University of Giessen during the conduct of the study, and grants from United Therapeutics, grants and personal fees from Bayer, and personal fees from Actelion, Mundipharma, Roche and OMT outside the submitted work. KT reports grants from the German Research Foundation and non-financial support from the University of Giessen during the conduct of the study, and personal fees from Actelion and Bayer outside the submitted work. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Yogeswaran, Kuhnert, Gall, Faber, Krauss, Rako, Keranov, Grimminger, Ghofrani, Naeije, Seeger, Richter and Tello.)

Background: Sepsis is a common condition known to impair blood flow regulation and microcirculation, which can ultimately lead to organ dysfunction but such contribution of the coronary circulation remains to be clarified. We investigated coronary blood flow regulatory mechanisms, including autoregulation, metabolic regulation, and endothelial vasodilatory response, in an experimental porcine model of early hyperdynamic sepsis. Methods: Fourteen pigs were randomized to sham ( n = 7) or fecal peritonitis-induced sepsis ( n = 7) procedures. At baseline, 6 and 12 h after peritonitis induction, the animals underwent general and coronary hemodynamic evaluation, including determination of autoregulatory breakpoint pressure and adenosine-induced maximal coronary vasodilation for coronary flow reserve and hyperemic microvascular resistance calculation. Endothelial-derived vasodilatory response was assessed both in vivo and ex vivo using bradykinin. Coronary arteries were sampled for pathobiological evaluation. Results: Sepsis resulted in a right shift of the autoregulatory breakpoint pressure, decreased coronary blood flow reserve and increased hyperemic microvascular resistance from the 6th h after peritonitis induction. In vivo and ex vivo endothelial vasomotor function was preserved. Sepsis increased coronary arteries expressions of nitric oxide synthases, prostaglandin I 2 receptor, and prostaglandin F 2α receptor. Conclusion: Autoregulation and metabolic blood flow regulation were both impaired in the coronary circulation during experimental hyperdynamic sepsis, although endothelial vasodilatory response was preserved., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Boudart, Su, Pitisci, Dhoine, Duranteau, Jespers, Herpain, Vanderpool, Brimioulle, Creteur, Naeije, Van Obbergh and Dewachter.)

Exercise Doppler echocardiography (EDE) is a well-validated tool in ischemic and valvular heart diseases. However, its use in the assessment of the right heart and pulmonary circulation unit (RH-PCU) is limited. The aim of this study is to assess the semi-recumbent bicycle EDE feasibility for the evaluation of RH-PCU in a large multi-center population, from healthy individuals and elite athletes to patients with overt or at risk of developing pulmonary hypertension (PH). From January 2019 to July 2019, 954 subjects [mean age 54.2 ± 16.4 years, range 16-96, 430 women] underwent standardized semi-recumbent bicycle EDE with an incremental workload of 25 watts every 2 min, were prospectively enrolled among 7 centers participating to the RIGHT Heart International NETwork (RIGHT-NET). EDE parameters of right heart structure, function and pressures were obtained according to current recommendations. Right ventricular (RV) function at peak exercise was feasible in 903/940 (96%) by tricuspid annular plane systolic excursion (TAPSE), 667/751 (89%) by tissue Doppler-derived tricuspid lateral annular systolic velocity (S') and 445/672 (66.2%) by right ventricular fractional area change (RVFAC). RV-right atrial pressure gradient [RV-RA gradient = 4 × tricuspid regurgitation velocity 2 (TRV)] was feasible in 894/954 patients (93.7%) at rest and in 816/954 (85.5%) at peak exercise. The feasibility rate in estimating pulmonary artery pressure improved to more than 95%, if both TRV and/or right ventricular outflow tract acceleration time (RVOT AcT) were considered. In high specialized echocardiography laboratories semi-recumbent bicycle EDE is a feasible tool for the assessment of the RH-PCU pressure and function., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

Right ventricular (RV) functional adaptation to afterload determines outcome in pulmonary hypertension (PH). RV afterload is determined by the dynamic interaction between pulmonary vascular resistance (PVR), characteristic impedance ( Z c ), and wave reflection. Pulmonary vascular impedance (PVZ) represents the most comprehensive measure of RV afterload; however, there is an unmet need for an easier bedside measurement of this complex variable. Although a recent study showed that Z c and wave reflection can be estimated from RV pressure waveform analysis and cardiac output, this has not been validated. Estimations of Z c and wave reflection coefficient (λ) were validated relative to conventional spectral analysis in an animal model. Z c , λ, and the single-beat ratio of end-systolic to arterial elastance ( E es / E a ) to estimate RV-pulmonary arterial (PA) coupling were determined from right heart catheterization (RHC) data. The study included 30 pulmonary artery hypertension (PAH) and 40 heart failure with preserved ejection fraction (HFpEF) patients [20 combined pre- and postcapillary PH (Cpc-PH) and 20 isolated postcapillary PH, (Ipc-PH)]. Also included were 10 age- and sex-matched controls. There was good agreement with minimal bias between estimated and spectral analysis-derived Z c and λ. Z c in PAH and Cpc-PH groups exceeded that in the Ipc-PH group and controls. λ was increased in Ipc-PH (0.84 ± 0.02), Cpc-PH (0.87 ± 0.05), and PAH groups (0.85 ± 0.04) compared with controls (0.79 ± 0.03); all P values were <0.05. λ was the only afterload parameter associated with RV-PA coupling in PAH. In the PH-HFpEF group, RV-PA uncoupling was independent of RV afterload. Our findings indicate that Z c and λ derived from an RV pressure curve can be used to improve estimation of RV afterload. λ is the only afterload measure associated with RV-PA uncoupling in PAH, whereas RV-PA uncoupling in PH-HFpEF appears to be independent of afterload consistent with an inherent abnormality of the RV myocardium. NEW & NOTEWORTHY Pulmonary vascular impedance (PVZ) represents the most comprehensive measure of right ventricle (RV) afterload; however, measurement of this variable is complex. We demonstrate that characteristic impedance ( Z c ) and a wave reflection coefficient, λ, can be derived from RV pressure waveform analysis. In addition, RV dysfunction in left heart disease is independent of its afterload. The current study provides a platform for future studies to examine the pharmacotherapeutic effects and prognosis of different measures of RV afterload.