Pathophysiology of the right ventricle and of the pulmonary circulation in pulmonary hypertension: an update

Liver stiffness is associated with right heart dysfunction, cardiohepatic syndrome, and prognosis in pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) can lead to congestive hepatopathy, known as cardiohepatic syndrome (CHS). Hepatic congestion is associated with increased liver stiffness, which can be quantified using shear wave elastography. We aimed to investigate whether hepatic shear wave elastography detects patients at risk in the early stages of PH.

METHODS

Sixty-three prospectively enrolled patients undergoing right heart catheterization (52 diagnosed with PH and 11 with invasive exclusion of PH) and 52 healthy volunteers underwent assessments including echocardiography and hepatic shear wave elastography. CHS was defined as increased levels of ≥2 of the following: gamma-glutamyl transferase, alkaline phosphatase, and bilirubin. Liver stiffness was defined as normal (≤5.0 kPa) or high (>5.0 kPa).

RESULTS

Compared with normal liver stiffness, high liver stiffness was associated with impaired right ventricular (RV) and right atrial (RA) function (median [interquartile range] RV ejection fraction: 54 [49; 57]% vs 45 [34; 51]%, p < 0.001; RA reservoir strain: 49 [41; 54]% vs 33 [22; 41]%, p < 0.001), more severe tricuspid insufficiency (p < 0.001), and higher prevalence of hepatovenous backflow (2% vs 29%, p < 0.001) and CHS (2% vs 10%, p = 0.038). In the patient subgroup with precapillary PH (n = 48), CHS and high liver stiffness were associated with increased European Society of Cardiology/European Respiratory Society 2022 risk scores (p = 0.003).

CONCLUSIONS

Shear wave liver elastography yields important information regarding right heart function and may complement risk assessment in patients with (suspected) PH.

Prognostic role of haemodynamics at follow-up in patients with pulmonary arterial hypertension: a challenge to current European Society of Cardiology/European Respiratory Society risk tools

Background

Haemodynamic variables like right atrial pressure (RAP), cardiac index (CI), stroke volume index (SVI) and mixed venous oxygen saturation (S vO2 ) predict survival in patients with pulmonary arterial hypertension (PAH). However, there is the need to identify further prognostic haemodynamic parameters as well as to redefine their role in PAH risk stratification compared to current risk tools and non-invasive parameters.

Methods

This cohort study includes treatment-naïve patients assessed at baseline and after first-line PAH therapy with clinical, functional, exercise, laboratory and haemodynamic evaluations. Using a stepwise multivariate Cox regression analysis, independent prognostic haemodynamic parameters were identified and stratified according to cut-offs already defined in the European Society of Cardiology (ESC)/European Respiratory Society (ERS) risk table or defined based on the highest Chi-squared of the log-rank test. Their discriminatory power was tested for all-cause death and a combined end-point of death, hospitalisation and need of treatment escalation.

Results

794 patients with PAH were enrolled. At first follow-up, RAP and pulmonary artery elastance were independently associated with death. Because of high correlations between haemodynamic parameters, different multivariable analyses were done identifying six other variables (pulmonary arterial compliance, cardiac efficiency, pulmonary vascular resistance, S vO2 , CI and SVI). Haemodynamic parameters were of no added prognostic value compared to ESC/ERS risk tools for the all-cause death end-point but they showed additional value to non-invasive parameters for the combined end-point and, when taken alone, had a discriminatory capacity comparable to ESC/ERS risk tools.

Conclusion

Haemodynamics' discriminative ability for clinical worsening is comparable to current ESC/ERS risk tools and is of added value to non-invasive parameters.

Echocardiographic assessment for cardiopulmonary function in patients with congenital heart disease-related pulmonary arterial hypertension

BACKGROUND

For patients with congenital heart disease-related pulmonary arterial hypertension (CHD-PAH), cardiopulmonary exercise testing (CPET) can reflect cardiopulmonary reserve function. However, CPET may not be readily accessible for patients with high-risk conditions or limited mobility due to disability. Echocardiography, on the other hand, serves as a widely available diagnostic tool for all CHD-PAH patients. This study was aimed to identify the parameters of echocardiography that could serve as indicators of cardiopulmonary function and exercise capacity.

METHODS

A cohort of 70 patients contributed a total of 110 paired echocardiogram and CPET results to this study, with 1 year interval for repeated examinations. Echocardiography and exercise testing were conducted following standardized procedures, and the data were collected together with clinically relevant indicators for subsequent statistical analysis. Demographic comparisons were performed using t-tests and chi-square tests. Univariate and multivariate analyses were conducted to identify potential predictors of peak oxygen uptake (peak VO2) and the carbon dioxide ventilation equivalent slope (VE/VCO2 slope). Receiver operating characteristic (ROC) analysis was used to assess the performance of the parameters.

RESULTS

The ratio of tricuspid annular plane systolic excursion to pulmonary artery systolic pressure (TAPSE/PASP) was found to be the only independent indicator significantly associated with both peak VO2 and VE/VCO2 slope (both p < 0.05). Additionally, left ventricular ejection fraction (LVEF) and right ventricular fractional area change (FAC) were independently correlated with the VE/VCO2 slope (both p < 0.05). TAPSE/PASP showed the highest area under the ROC curve (AUC) for predicting both a peak VO2 ≤ 15 mL/kg/min and a VE/VCO2 slope ≥ 36 (AUC = 0.91, AUC = 0.90, respectively). The sensitivity and specificity of TAPSE/PASP at the optimal threshold exceeded 0.85 for both parameters.

CONCLUSIONS

TAPSE/PASP may be a feasible echocardiographic indicator for evaluating exercise tolerance.

Predictive Value of Smoking Index Combined with NT-proBNP for Patients with Pulmonary Hypertension Due to Chronic Lung Disease: A Retrospective Study

Purpose

Smoking is a major risk factor for the group 3 PH. NT-proBNP is a biomarker for risk stratification in PH. This study aims to investigate the effects of smoking status and smoking index (SI) on group 3 PH and to evaluate the value of SI and SI combined with NT-proBNP in early diagnosis and prediction of disease severity.

Patients and Methods

Four hundred patients with group 3 PH at the First Hospital of Shanxi Medical University between January 2020 and December 2021 were enrolled and divided into two groups: mild (30 mmHg ≤ pulmonary artery systolic pressure (PASP)≤50 mmHg) and non-mild (PASP >50 mmHg). The effect of smoking on group 3 PH was analyzed using univariate analysis, and logistic analysis was conducted to evaluate the risk of group 3 PH according to smoking status and SI. Spearman correlation coefficient was used to test the correlation between SI and the index of group 3 PH severity. The predictive value of SI was evaluated using a receiver operating characteristic (ROC) curve.

Results

Correlation and logistic analyses showed that SI was associated with PH severity. Smoking status (P=0.009) and SI (P=0.039) were independent risk factors for non-mild group 3 PH, and ROC showed that the predictive value of SI (AUC:0.596) for non-mild PH was better than that of the recognized pro-brain natriuretic peptide (NT-proBNP) (AUC:0.586). SI can be used as a single predictive marker. SI and NT-proBNP can be formulated as prediction models for screening non-mild clinical cases (AUC:0.628).

Conclusion

SI is a potentially ideal non-invasive predictive marker for group 3 PH. SI and NT-proBNP could be used to develop a prediction model for screening non-mild PH cases. This can greatly improve the predictive specificity of the established PH marker, NT-proBNP.

Right Ventricle-Pulmonary Artery Coupling in Patients Undergoing Cardiac Interventions

PURPOSE OF REVIEW

This review aims to summarize the fundamentals of RV-PA coupling, its non-invasive means of measurement, and contemporary understanding of RV-PA coupling in cardiac surgery, cardiac interventions, and congenital heart disease.

RECENT FINDINGS

The need for more accessible clinical means of evaluation of RV-PA coupling has driven researchers to investigate surrogates using cardiac MRI, echocardiography, and right-sided pressure measurements in patients undergoing cardiac surgery/interventions, as well as patients with congenital heart disease. Recent research has aimed to validate these alternative means against the gold standard, as well as establish cut-off values predictive of morbidity and/or mortality. This emerging evidence lays the groundwork for identifying appropriate RV-PA coupling surrogates and integrating them into perioperative clinical practice.

Artificial intelligence: The future for multimodality imaging of right ventricle

The crucial pathophysiological and prognostic roles of the right ventricle in various diseases have been well-established. Nonetheless, conventional cardiovascular imaging modalities are frequently associated with intrinsic limitations when evaluating right ventricular (RV) morphology and function. The integration of artificial intelligence (AI) in multimodality imaging presents a promising avenue to circumvent these obstacles, paving the way for future fully automated imaging paradigms. This review aimed to address the current challenges faced by clinicians and researchers in integrating RV imaging and AI technology, to provide a comprehensive overview of the current applications of AI in RV imaging, and to offer insights into future directions, opportunities, and potential challenges in this rapidly advancing field.

Comparison of admittance and cardiac magnetic resonance generated pressure-volume loops in a porcine model

Objective. Pressure-volume loop analysis, traditionally performed by invasive pressure and volume measurements, is the optimal method for assessing ventricular function, while cardiac magnetic resonance (CMR) imaging is the gold standard for ventricular volume estimation. The aim of this study was to investigate the agreement between the assessment of end-systolic elastance (Ees) assessed with combined CMR and simultaneous pressure catheter measurements compared with admittance catheters in a porcine model.Approach. Seven healthy pigs underwent admittance-based pressure-volume loop evaluation followed by a second assessment with CMR during simultaneous pressure measurements.Main results. Admittance overestimated end-diastolic volume for both the left ventricle (LV) and the right ventricle (RV) compared with CMR. Further, there was an underestimation of RV end-systolic volume with admittance. For the RV, however, Ees was systematically higher when assessed with CMR plus simultaneous pressure measurements compared with admittance whereas there was no systematic difference in Ees but large differences between admittance and CMR-based methods for the LV.Significance. LV and RV Ees can be obtained from both admittance and CMR based techniques. There were discrepancies in volume estimates between admittance and CMR based methods, especially for the RV. RV Ees was higher when estimated by CMR with simultaneous pressure measurements compared with admittance.

Non-invasive imaging techniques for early diagnosis of bilateral cardiac dysfunction in pulmonary hypertension: current crests, future peaks

Pulmonary arterial hypertension (PAH) is a chronic and progressive disease that eventually leads to heart failure (HF) and subsequent fatality if left untreated. Right ventricular (RV) function has proven prognostic values in patients with a variety of heart diseases including PAH. PAH is predominantly a right heart disease; however, given the nature of the continuous circulatory system and the presence of shared septum and pericardial constraints, the interdependence of the right and left ventricles is a factor that requires consideration. Accurate and timely assessment of ventricular function is very important in the management of patients with PAH for disease outcomes and prognosis. Non-invasive modalities such as cardiac magnetic resonance (CMR) and echocardiography (two-dimensional and three-dimensional), and nuclear medicine, positron emission tomography (PET) play a crucial role in the assessment of ventricular function and disease prognosis. Each modality has its own strengths and limitations, hence this review article sheds light on (i) ventricular dysfunction in patients with PAH and RV-LV interdependence in such patients, (ii) the strengths and limitations of all available modalities and parameters for the early assessment of ventricular function, as well as their prognostic value, and (iii) lastly, the challenges faced and the potential future advancement in these modalities for accurate and early diagnosis of ventricular function in PAH.

Combined physical training protects the left ventricle from structural and functional damages in experimental pulmonary arterial hypertension

BACKGROUND

Under the adverse remodeling of the right ventricle and interventricular septum in pulmonary arterial hypertension (PAH) the left ventricle (LV) dynamics is impaired. Despite the benefits of combined aerobic and resistance physical trainings to individuals with PAH, its impact on the LV is not fully understood.

OBJECTIVE

To test whether moderate-intensity combined physical training performed during the development of PAH induced by MCT in rats is beneficial to the LV's structure and function.

METHODS

Male Wistar rats were divided into two groups: Sedentary Hypertensive Survival (SHS, n = 7); and Exercise Hypertensive Survival (EHS, n = 7) to test survival. To investigate the effects of combined physical training, another group of rats were divided into three groups: Sedentary Control (SC, n = 7); Sedentary Hypertensive (SH, n = 7); and Exercise Hypertensive (EH, n = 7). PAH was induced through an intraperitoneal injection of MCT (60 mg/kg). Echocardiographic evaluations were conducted on the 22nd day after MCT administration. Animals in the EHS and EH groups participated in a combined physical training program, alternating aerobic (treadmill running: 50 min, 60% maximum running speed) and resistance (ladder climbing: 15 climbs with 1 min interval, 60% maximum carrying load) exercises, one session/day, 5 days/week for approximately 4 weeks.

RESULTS

The physical training increased survival and tolerance to aerobic (i.e., maximum running speed) and resistance (i.e., maximum carrying load) exertions and prevented reductions in ejection fraction and fractional shortening. In addition, the physical training mitigated oxidative stress (i.e., CAT, SOD and MDA) and inhibited adverse LV remodeling (i.e., Collagen, extracellular matrix, and cell dimensions). Moreover, the physical training preserved the amplitude and velocity of contraction and hindered the reductions in the amplitude and velocity of the intracellular Ca2+ transient in LV single myocytes.

CONCLUSION

Moderate-intensity combined physical training performed during the development of MCT-induced PAH in rats protects their LV from damages to its structure and function and hence increases their tolerance to physical exertion and prolongs their survival.

Canagliflozin inhibits PASMCs proliferation via regulating SGLT1/AMPK signaling and attenuates artery remodeling in MCT-induced pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) was a devastating disease characterized by artery remodeling, ultimately resulting in right heart failure. The aim of this study was to investigate the effects of canagliflozin (CANA), a sodium-glucose cotransporter 2 inhibitor (SGLT2i) with mild SGLT1 inhibitory effects, on rats with PAH, as well as its direct impact on pulmonary arterial smooth muscle cells (PASMCs). PAH rats were induced by injection of monocrotaline (MCT) (40 mg/kg), followed by four weeks of treatment with CANA (30 mg/kg/day) or saline alone. Pulmonary artery and right ventricular (RV) remodeling and dysfunction in PAH were alleviated with CANA, as assessed by echocardiography. Hemodynamic parameters and structural of pulmonary arteriole, including vascular wall thickness and wall area, were reduced by CANA. RV hypertrophy index, cardiomyocyte hypertrophy, and fibrosis were decreased with CANA treatment. PASMCs proliferation was inhibited by CANA under stimulation by platelet-derived growth factor (PDGF)-BB or hypoxia. Activation of AMP kinase (AMPK) was induced by CANA treatment in cultured PASMCs in a time- and concentration-dependent manner. These effects of CANA were attenuated when treatment with compound C, an AMPK inhibitor. Abundant expression of SGLT1 was observed in PASMCs and pulmonary arteries, while SGLT2 expression was undetectable. SGLT1 increased in response to PDGF-BB or hypoxia stimulation, while PASMCs proliferation was inhibited and beneficial effects of CANA were counteracted by knockdown of SGLT1. Our research demonstrated for the first time that CANA inhibited the proliferation of PASMCs by regulating SGLT1/AMPK signaling and thus exerted an anti-proliferative effect on MCT-induced PAH.

Pulmonary hypertension survival and hospitalisations in people living with HIV: a systematic review and meta-analysis

INTRODUCTION

People living with HIV (PLHIV) have a higher risk of developing pulmonary hypertension (PH) with subsequent poorer prognosis. This review aimed to determine the (1) survival outcomes and (2) proportion of emergency department (ED) visits and hospitalisations of PLHIV and PH.

METHODS

We conducted a systematic review and meta-analysis of observational studies reporting survival outcomes for PLHIV and PH. Electronic databases (Medline, EMBASE, PubMed, Web of Science, Global Index Medicus and Cochrane Library), trial registries and conference proceedings were searched until 22 July 2023. We pooled similar measures of effect, assessed apriori subgroups and used meta-regression to determine mortality and associated variables.

RESULTS

5248 studies were identified; 28 studies were included with a total of 5459 PLHIV and PH. The mean survival (95% CI) of PLHIV and PH was 37.4 months (29.9 to 44.8). Participants alive at 1, 2 and 3 years were 85.8% (74.1% to 95.0%), 75.2% (61.9% to 86.7%) and 61.9% (51.8% to 71.6%), respectively. ED visits and hospitalisation rates were 73.3% (32.5% to 99.9%) and 71.2% (42.4% to 94.2%), respectively. More severe disease, measured by echocardiogram, was associated with poorer prognosis (β -0.01, 95% CI -0.02 to 0.00, p=0.009). Survival was higher in high-income countries compared with lower-income countries (β 0.50, 95% CI 0.28 to 0.73, p<0.001) and in Europe compared with the America (β 0.56, 95% CI 0.37 to 0.75, p<0.001).

CONCLUSION

Our study confirms poor prognosis and high healthcare utilisation for PLHIV and PH. Prognosis is associated with country income level, geographic region and PH severity. This highlights the importance of screening in this population.

PROSPERO REGISTRATION NUMBER

CRD42023395023.

The intricate physiology of veno-venous extracorporeal membrane oxygenation: an overview for clinicians

During veno-venous extracorporeal membrane oxygenation (V-V ECMO), blood is drained from the central venous circulation to be oxygenated and decarbonated by an artificial lung. It is then reinfused into the right heart and pulmonary circulation where further gas-exchange occurs. Each of these steps is characterized by a peculiar physiology that this manuscript analyses, with the aim of providing bedside tools for clinical care: we begin by describing the factors that affect the efficiency of blood drainage, such as patient and cannulae position, fluid status, cardiac output and ventilatory strategies. We then dig into the complexity of extracorporeal gas-exchange, with particular reference to the effects of extracorporeal blood-flow (ECBF), fraction of delivered oxygen (FdO2) and sweep gas-flow (SGF) on oxygenation and decarbonation. Subsequently, we focus on the reinfusion of arterialized blood into the right heart, highlighting the effects on recirculation and, more importantly, on right ventricular function. The importance and challenges of haemodynamic monitoring during V-V ECMO are also analysed. Finally, we detail the interdependence between extracorporeal circulation, native lung function and mechanical ventilation in providing adequate arterial blood gases while allowing lung rest. In the absence of evidence-based strategies to care for this particular group of patients, clinical practice is underpinned by a sound knowledge of the intricate physiology of V-V ECMO.

The Xanthine Derivative KMUP-1 Inhibits Hypoxia-Induced TRPC1 Expression and Store-Operated Ca2+ Entry in Pulmonary Arterial Smooth Muscle Cells

Exposure to hypoxia results in the development of pulmonary arterial hypertension (PAH). An increase in the intracellular Ca2+ concentration ([Ca2+]i) in pulmonary artery smooth muscle cells (PASMCs) is a major trigger for pulmonary vasoconstriction and proliferation. This study investigated the mechanism by which KMUP-1, a xanthine derivative with phosphodiesterase inhibitory activity, inhibits hypoxia-induced canonical transient receptor potential channel 1 (TRPC1) protein overexpression and regulates [Ca2+]i through store-operated calcium channels (SOCs). Ex vivo PASMCs were cultured from Sprague-Dawley rats in a modular incubator chamber under 1% O2/5% CO2 for 24 h to elucidate TRPC1 overexpression and observe the Ca2+ release and entry. KMUP-1 (1 μM) inhibited hypoxia-induced TRPC family protein encoded for SOC overexpression, particularly TRPC1. KMUP-1 inhibition of TRPC1 protein was restored by the protein kinase G (PKG) inhibitor KT5823 (1 μM) and the protein kinase A (PKA) inhibitor KT5720 (1 μM). KMUP-1 attenuated protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA, 1 μM)-upregulated TRPC1. We suggest that the effects of KMUP-1 on TRPC1 might involve activating the cyclic guanosine monophosphate (cGMP)/PKG and cyclic adenosine monophosphate (cAMP)/PKA pathways and inhibiting the PKC pathway. We also used Fura 2-acetoxymethyl ester (Fura 2-AM, 5 μM) to measure the stored calcium release from the sarcoplasmic reticulum (SR) and calcium entry through SOCs in hypoxic PASMCs under treatment with thapsigargin (1 μM) and nifedipine (5 μM). In hypoxic conditions, store-operated calcium entry (SOCE) activity was enhanced in PASMCs, and KMUP-1 diminished this activity. In conclusion, KMUP-1 inhibited the expression of TRPC1 protein and the activity of SOC-mediated Ca2+ entry upon SR Ca2+ depletion in hypoxic PASMCs.

Sendaway capillary NT-proBNP in pulmonary hypertension

BACKGROUND

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a biomarker of cardiac ventricular wall stress that is incorporated into pulmonary hypertension (PH) risk stratification models. Sendaway sampling may enable patients to perform NT-proBNP tests remotely. This UK-wide study aimed to assess the agreement of sendaway NT-proBNP with standard venous NT-proBNP and to assess the effect of delayed processing.

METHODS

Reference venous NT-proBNP was collected from PH patients. Samples for capillary and venous sendaway tests were collected contemporaneously, mailed to a reference laboratory and processed at 3 and 7 days using a Roche Cobas e411 device. Differences in paired measurements were analysed with Passing-Bablok regression, percentage difference plots and the % difference in risk strata.

RESULTS

113 patients were included in the study. 13% of day 3 capillary samples were insufficient. Day 3 capillary samples were not equivalent to reference samples (Passing Bablok analysis slope of 0.91 (95% CI 0.88 to 0.93) and intercept of 6.0 (95% CI 0.2 to 15.9)). The relative median difference was -7% and there were acceptable limits of agreement. Day 3 capillary NT-proBNP accurately risk stratified patients in 93.5% of cases. By comparison, day 3 venous results accurately risk stratified patients in 90.1% of cases and were equivalent by Passing-Bablok regression. Delayed sampling of sendaway tests led to an unacceptable level of agreement and systematically underestimated NT-proBNP.

CONCLUSIONS

Sendaway NT-proBNP sampling may provide an objective measure of right ventricular strain for virtual PH clinics. Results must be interpreted with caution in cases of delayed sampling.

Effects of 5-Week Oral Acetazolamide on Incremental Cycling Exercise in Pulmonary Arterial and Chronic Thromboembolic Pulmonary Hypertension: A Randomized Placebo-Controlled, Double-Blinded, Crossover Trial

INTRODUCTION

Acetazolamide (AZA) improves nocturnal and daytime blood oxygenation in patients with pulmonary vascular disease (PVD), defined as pulmonary arterial and distal chronic thromboembolic pulmonary hypertension (CTEPH), and may improve exercise performance.

METHODS

We investigated the effect of 5 weeks of AZA (250 mg bid) versus placebo on maximal load during incremental cycling ramp exercise in patients with PVD studied in a randomized controlled, double-blind, crossover design, separated by > 2 weeks of washout.

RESULTS

Twenty-five patients (12 pulmonary arterial hypertension, 13 CTEPH, 40% women, age 62 ± 15 years) completed the trial according to the protocol. Maximum load was similar after 5 weeks of AZA versus placebo (113 ± 9 vs. 117 ± 9 watts [W]), mean difference -4 W (95% CI: -9 to 1, p = 0.138). With AZA, maximum (max)-exercise partial pressure of O2 (PaO2) was significantly higher by 1.1 kPa (95% CI: 0.5-1.8, p = 0.003), while arterial pH and partial pressure of CO2 were significantly lower. Gas exchange threshold was reached at a higher load with AZA (108 ± 8 W vs. 97 ± 8 W) and was therefore delayed by 11 W (95% CI: 3-19, p = 0.013), while the ventilatory equivalent for O2 and CO2 were significantly higher at both the max-exercise and gas exchange threshold with AZA versus placebo.

CONCLUSION

AZA for 5 weeks did not significantly change maximum exercise capacity in patients with PVD despite a significant increase in PaO2. The beneficial effects of increased blood oxygenation may have been diminished by increased ventilation due to AZA-induced metabolic acidosis and increased dyspnea.

Reversal of Pulmonary Hypertension in a Human-Like Model: Therapeutic Targeting of Endothelial DHFR

BACKGROUND

Pulmonary hypertension (PH) is a progressive disorder characterized by remodeling of the pulmonary vasculature and elevated mean pulmonary arterial pressure, resulting in right heart failure.

METHODS

Here, we show that direct targeting of the endothelium to uncouple eNOS (endothelial nitric oxide synthase) with DAHP (2,4-diamino 6-hydroxypyrimidine; an inhibitor of GTP cyclohydrolase 1, the rate-limiting synthetic enzyme for the critical eNOS cofactor tetrahydrobiopterin) induces human-like, time-dependent progression of PH phenotypes in mice.

RESULTS

Critical phenotypic features include progressive elevation in mean pulmonary arterial pressure, right ventricular systolic blood pressure, and right ventricle (RV)/left ventricle plus septum (LV+S) weight ratio; extensive vascular remodeling of pulmonary arterioles with increased medial thickness/perivascular collagen deposition and increased expression of PCNA (proliferative cell nuclear antigen) and alpha-actin; markedly increased total and mitochondrial superoxide production, substantially reduced tetrahydrobiopterin and nitric oxide bioavailabilities; and formation of an array of human-like vascular lesions. Intriguingly, novel in-house generated endothelial-specific dihydrofolate reductase (DHFR) transgenic mice (tg-EC-DHFR) were completely protected from the pathophysiological and molecular features of PH upon DAHP treatment or hypoxia exposure. Furthermore, DHFR overexpression with a pCMV-DHFR plasmid transfection in mice after initiation of DAHP treatment completely reversed PH phenotypes. DHFR knockout mice spontaneously developed PH at baseline and had no additional deterioration in response to hypoxia, indicating an intrinsic role of DHFR deficiency in causing PH. RNA-sequencing experiments indicated great similarity in gene regulation profiles between the DAHP model and human patients with PH.

CONCLUSIONS

Taken together, these results establish a novel human-like murine model of PH that has long been lacking in the field, which can be broadly used for future mechanistic and translational studies. These data also indicate that targeting endothelial DHFR deficiency represents a novel and robust therapeutic strategy for the treatment of PH.

Monitoring of the right ventricular responses to pressure overload: prognostic value and usefulness of echocardiography for clinical decision-making

Regardless of whether pulmonary hypertension (PH) results from increased pulmonary venous pressure in left-sided heart diseases or from vascular remodeling and/or obstructions in pre-capillary pulmonary vessels, overload-induced right ventricular (RV) dysfunction and its final transition into right-sided heart failure is a major cause of death in PH patients. Being particularly suited for non-invasive monitoring of the right-sided heart, echocardiography has become a useful tool for optimizing the therapeutic decision-making and evaluation of therapy results in PH. The review provides an updated overview on the pathophysiological insights of heart-lung interactions in PH of different etiology, as well as on the diagnostic and prognostic value of echocardiography for monitoring RV responses to pressure overload. The article focuses particularly on the usefulness of echocardiography for predicting life-threatening aggravation of RV dysfunction in transplant candidates with precapillary PH, as well as for preoperative prediction of post-operative RV failure in patients with primary end-stage left ventricular (LV) failure necessitating heart transplantation or a LV assist device implantation. In transplant candidates with refractory pulmonary arterial hypertension, a timely prediction of impending RV decompensation can contribute to reduce both the mortality risk on the transplant list and the early post-transplant complications caused by severe RV dysfunction, and also to avoid combined heart-lung transplantation. The review also focuses on the usefulness of echocardiography for monitoring the right-sided heart in patients with acute respiratory distress syndrome, particularly in those with refractory respiratory failure requiring extracorporeal membrane oxygenation support. Given the pathophysiologic particularity of severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection to be associated with a high incidence of thrombotic microangiopathy-induced increase in the pulmonary resistance, echocardiography can improve the selection of temporary mechanical cardio-respiratory support strategies and can therefore contribute to the reduction of mortality rates. On the whole, the review aims to provide a theoretical and practical basis for those who are or intend in the future to be engaged in this highly demanding field.

Acute changes in cardiac dimensions, function, and longitudinal mechanics in healthy individuals with and without high-altitude induced pulmonary hypertension at 4559 m

BACKGROUND

High-altitude pulmonary hypertension (HAPH) has a prevalence of approximately 10%. Changes in cardiac morphology and function at high altitude, compared to a population that does not develop HAPH are scarce.

METHODS

Four hundred twenty-one subjects were screened in a hypoxic chamber inspiring a FiO2  = 12% for 2 h. In 33 subjects an exaggerated increase in systolic pulmonary artery pressure (sPAP) could be confirmed in two independent measurements. Twenty nine of these, and further 24 matched subjects without sPAP increase were examined at 4559 m by Doppler echocardiography including global longitudinal strain (GLS).

RESULTS

SPAP increase was higher in HAPH subjects (∆ = 10.2 vs. ∆ = 32.0 mm Hg, p < .001). LV eccentricity index (∆ = .15 vs. ∆ = .31, p = .009) increased more in HAPH. D-shaped LV (0 [0%] vs. 30 [93.8%], p = .00001) could be observed only in the HAPH group, and only in those with a sPAP ≥50 mm Hg. LV-EF (∆ = 4.5 vs. ∆ = 6.7%, p = .24) increased in both groups. LV-GLS (∆ = 1.2 vs. ∆ = 1.1 -%, p = .60) increased slightly. RV end-diastolic (∆ = 2.20 vs. ∆ = 2.7 cm2 , p = .36) and end-systolic area (∆ = 2.1 vs. ∆ = 2.7 cm2 , p = .39), as well as RA end-systolic area index (∆ = -.9 vs. ∆ = .3 cm2 /m2 , p = .01) increased, RV-FAC (∆ = -2.9 vs. ∆ = -4.7%, p = .43) decreased, this was more pronounced in HAPH, RV-GLS (∆ = 1.6 vs. ∆ = -.7 -%, p = .17) showed marginal changes.

CONCLUSIONS

LV and LA dimensions decrease and left ventricular function increases at high-altitude in subjects with and without HAPH. RV and RA dimensions increase, and RV longitudinal strain increases or remains unchanged in subjects with HAPH. Changes are negligible in those without HAPH.

High and intermediate risk pulmonary embolism in the ICU

Pulmonary embolism (PE) is a common and important medical emergency, encountered by clinicians across all acute care specialties. PE is a relatively uncommon cause of direct admission to the intensive care unit (ICU), but these patients are at high risk of death. More commonly, patients admitted to ICU develop PE as a complication of an unrelated acute illness. This paper reviews the epidemiology, diagnosis, risk stratification, and particularly the management of PE from a critical care perspective. Issues around prevention, anticoagulation, fibrinolysis, catheter-based techniques, surgical embolectomy, and extracorporeal support are discussed.

The ALPHA phase 1 study: pulmonary ArteriaL hypertension treated with CardiosPHere-Derived allogeneic stem cells

BACKGROUND

Pulmonary Arterial Hypertension (PAH) is a progressive condition with no cure. Even with pharmacologic advances, survival remains poor. Lung pathology on PAH therapies still shows impressive occlusive arteriolar remodelling and plexiform lesions. Cardiosphere-derived cells (CDCs) are heart-derived progenitor cells exhibiting anti-inflammatory and immunomodulatory effects, are anti -fibrotic, anti-oxidative and anti-apoptotic to potentially impact several aspects of PAH pathobiology. In preclinical trials CDCs reduced right ventricular (RV) systolic pressure, RV hypertrophy, pulmonary arteriolar wall thickness and inflammation.

METHODS

The ALPHA study was a Phase 1a/b study in which CDCs were infused into patients with Idiopathic (I)PAH, Heritable (H) HPAH, PAH-connective tissue disease (CTD) and PAH-human immunodeficiency virus (HIV). The study was IRB approved and DSMB monitored. Phase 1a, was an open label study (n = 6). Phase 1b was a double-blind placebo-controlled study (n = 20) in which half received 100 million CDCs (the maximum feasible dose from manufacturing perspective) and half placebo (PLAC) infusions. Right heart catheterization (RHC) and cardiac MR imaging (cMR) were performed at baseline and at 4 months post infusion. Patients were followed over a year.

FINDINGS

No short-term clinical safety adverse events (AE) were related to the IP, the primary outcome measure. There were no adverse hemodynamic, gas exchange, rhythm or other clinical events following infusion and in the 1st 23 h monitored in hospital. There were no long-term AEs over 12 months noted, including unrelated limited hospitalizations. No immunologic short or long-term AEs were noted. We examined exploratory outcomes across multiple domains to determine encouraging signals to motivate future advanced phase testing. Phase 1a data showed encouraging observations for both 50 and 100 million CDC doses. Several encouraging findings favouring CDCs (n = 16) compared to placebo (n = 10) were noted. On cMR, the RV end diastolic volume (RVEDV) and index (RVEDVI) decreased with CDCs with a rise in the PLAC group. The 6-min walk distance was increased 2 months post infusion in the CDC group compared with PLAC. With PLAC, diffusing capacity (DLCO) decreased at 4 months but was unchanged with CDCs. Serum creatinine decreased with CDCs at 4 months. Encouraging observations favouring CDCs were also noted for RV fractional area change on echo and RV ejection fraction (RVEF) on cMR at 4 months. No differences were observed for mean pulmonary artery pressures or pulmonary vascular resistance. Review of long-term data to 12 months showed continued decline in DLCO for the PLAC cohort at 6 months with no change through 12 months. By contrast, CDC subjects showed an unchanged DLCO over 12-months. For parameters exhibiting early encouraging exploratory findings in CDC subjects, no further improvement was noted in long-term follow up through 12 months.

INTERPRETATION

Intravenous CDCs were safe in both the short and long term in PAH subjects and thus may be safe in larger cohorts, in line with our extensive track record of safety in clinical trials for other conditions. Further, CDCs exhibited encouraging exploratory findings across several domains. Repeat dosing (quarterly, over one year) of intravenous CDCs has been reported to yield highly significant sustained disease-modifying bioactivity in subjects with advanced Duchenne muscular dystrophy. Because only single CDC doses were used here, the findings represent a lower limit estimate of CDC's potential in PAH. Upcoming phase 2 studies would logically use a repeat dosing paradigm.

FUNDING

California Institute for Regenerative Medicine (CIRM). Project Number: CLIN2-09444.

The SGLT2i Dapagliflozin Reduces RV Mass Independent of Changes in RV Pressure Induced by Pulmonary Artery Banding

BACKGROUND

Sodium glucose linked transporter 2 (SGLT2) inhibition not only reduces morbidity and mortality in patients with diagnosed heart failure but also prevents the development of heart failure hospitalization in those at risk. While studies to date have focused on the role of SGLT2 inhibition in left ventricular failure, whether this drug class is efficacious in the treatment and prevention of right heart failure has not been explored.

HYPOTHESIS

We hypothesized that SGLT2 inhibition would reduce the structural, functional, and molecular responses to pressure overload of the right ventricle.

METHODS

Thirteen-week-old Fischer F344 rats underwent pulmonary artery banding (PAB) or sham surgery prior to being randomized to receive either the SGLT2 inhibitor: dapagliflozin (0.5 mg/kg/day) or vehicle by oral gavage. After 6 weeks of treatment, animals underwent transthoracic echocardiography and invasive hemodynamic studies. Animals were then terminated, and their hearts harvested for structural and molecular analyses.

RESULTS

PAB induced features consistent with a compensatory response to increased right ventricular (RV) afterload with elevated mass, end systolic pressure, collagen content, and alteration in calcium handling protein expression (all p < 0.05 when compared to sham + vehicle). Dapagliflozin reduced RV mass, including both wet and dry weight as well as normalizing the protein expression of SERCA 2A, phospho-AMPK and LC3I/II ratio expression (all p < 0.05).

SIGNIFICANCE

Dapagliflozin reduces the structural, functional, and molecular manifestations of right ventricular pressure overload. Whether amelioration of these early changes in the RV may ultimately lead to a reduction in RV failure remains to be determined.

The nitric oxide-soluble guanylate cyclase-cGMP pathway in pulmonary hypertension: from PDE5 to soluble guanylate cyclase

The nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway plays a key role in the pathogenesis of pulmonary hypertension (PH). Targeted treatments include phosphodiesterase type 5 inhibitors (PDE5i) and sGC stimulators. The sGC stimulator riociguat is approved for the treatment of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). sGC stimulators have a dual mechanism of action, enhancing the sGC response to endogenous NO and directly stimulating sGC, independent of NO. This increase in cGMP production via a dual mechanism differs from PDE5i, which protects cGMP from degradation by PDE5, rather than increasing its production. sGC stimulators may therefore have the potential to increase cGMP levels under conditions of NO depletion that could limit the effectiveness of PDE5i. Such differences in mode of action between sGC stimulators and PDE5i could lead to differences in treatment efficacy between the classes. In addition to vascular effects, sGC stimulators have the potential to reduce inflammation, angiogenesis, fibrosis and right ventricular hypertrophy and remodelling. In this review we describe the evolution of treatments targeting the NO-sGC-cGMP pathway, with a focus on PH.

The value of right ventricular to pulmonary arterial coupling in the critically ill: a National Echocardiography Database of Australia (NEDA) substudy

BACKGROUND

Right ventricular (RV) function is tightly coupled to afterload, yet echocardiographic indices of RV function are frequently assessed in isolation. Normalizing RV function for afterload (RV-PA coupling) using a simplified ratio of tricuspid annular plane systolic excursion (TAPSE)/ tricuspid regurgitant velocity (TRV) could help to identify RV decompensation and improve risk stratification in critically ill patients. This is the first study to explore the distribution of TAPSE/TRV ratio and its prognostic relevance in a large general critical care cohort.

METHODS

We undertook retrospective analysis of echocardiographic, clinical, and mortality data of intensive care unit (ICU) patients between January 2012 and May 2017. A total of 1077 patients were included and stratified into tertile groups based on TAPSE/TRV ratio: low (< 5.9 mm.(m/s)-1), middle (≥ 5.9-8.02 mm.(m/s)-1), and high (≥ 8.03 mm.(m/s)-1). The distribution of the TAPSE/TRV ratio across ventricular function subtypes of normal, isolated left ventricular (LV), isolated RV, and biventricular dysfunction was explored. The overall prognostic relevance of the TAPSE/TRV ratio was tested, including distribution across septic, cardiovascular, respiratory, and neurological subgroups.

RESULTS

Higher proportions of ventricular dysfunctions were seen in low TAPSE/TRV tertiles. TAPSE/TRV ratio is impacted by LV systolic function but to a lesser extent than RV dysfunction or biventricular dysfunction. There was a strong inverse relationship between TAPSE/TRV ratio and survival. After multivariate analysis, higher TAPSE/TRV ratios (indicating better RV-PA coupling) were independently associated with lower risk of death in ICU (HR 0.927 [0.872-0.985], p < 0.05). Kaplan-Meier analysis demonstrated higher overall survival in middle and high tertiles compared to low tertiles (log rank p < 0.0001). The prognostic relevance of TAPSE/TRV ratio was strongest in respiratory and sepsis subgroups. Patients with TAPSE/TRV < 5.9 mm (m/s)-1 had a significantly worse prognosis than those with higher TAPSE/TRV ratios.

CONCLUSION

The TAPSE/TRV ratio has prognostic relevance in critically ill patients. The prognostic power may be stronger in respiratory and septic subgroups. Larger prospective studies are needed to investigate the role of TAPSE/TRV in pre-specified subgroups including its role in clinical decision-making.

In Vitro Experimental Approach for Studying Human Pulmonary Artery Smooth Muscle Cells and Endothelial Cells Proliferation and Migration

Pulmonary arterial hypertension (PAH) is a severe vascular disease characterized by persistent precapillary pulmonary hypertension, leading to right heart failure and death. Despite intense research in the last decades, PAH remains an incurable disease with high morbidity and mortality. New directions and therapies to improve understanding and treatment of PAH are desperately needed. The pathological mechanisms leading to this fatal disorder remain mostly undetermined, although structural remodeling of the pulmonary vessels is known to be an early feature of PAH. Pulmonary vascular remodeling includes proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells (PAECs). The use of in vitro approaches is useful to delineate the mechanisms involved in the pathogenesis of PAH and to identify new therapeutic strategies for PAH. In this chapter, we describe protocols for culturing and assessing proliferation and migration of human PASMCs and PAECs.

Echocardiography assessment of right ventricular-pulmonary artery coupling: Validation of surrogates and clinical utilities

Right ventricular-pulmonary artery (RV-PA) coupling indicates efficiency of energy transfer from the right ventricle to the pulmonary circulation. The gold standard measurement, end-systolic elastance/arterial elastance ratio (Ees/Ea), is derived from invasive pressure-volume loop, which is technically demanding, expensive and limited in clinical practice. Recent studies have proposed various non-invasive surrogates of Ees/Ea based on echocardiography assessment, of which TAPSE/PASP ratio is an easily-obtained and validated parameter in severe pulmonary hypertension and rapidly applicated in the diagnosis and risk evaluation of various diseases and cardiac intervention. In this review, we summarized principles and validations of echocardiographic surrogates, and their clinical utilities and also limitations. The goal is to systematically review the research advances of echocardiography assessment of RV-PA coupling and help to guide clinical practice.

Toward the Implementation of Optimal Cardiac Magnetic Resonance Risk Stratification in Pulmonary Arterial Hypertension

BACKGROUND

The 2022 European Society of Cardiology/European Respiratory Society pulmonary hypertension (PH) guidelines incorporate cardiac magnetic resonance (CMR) imaging metrics in the risk stratification of patients with pulmonary arterial hypertension (PAH). Thresholds to identify patients at estimated 1-year mortality risks of < 5%, 5% to 20%, and > 20% are introduced. However, these cutoff values are mostly single center-based and require external validation.

RESEARCH QUESTION

What are the discriminative prognostic properties of the current CMR risk thresholds stratifying patients with PAH?

STUDY DESIGN AND METHODS

We analyzed data from incident, treatment-naïve patients with PAH from the Amsterdam University Medical Centres, Vrije Universiteit, The Netherlands. The discriminative properties of the proposed CMR three risk strata were tested at baseline and first reassessment, using the following PH guideline variables: right ventricular ejection fraction, indexed right ventricular end-systolic volume, and indexed left ventricular stroke volume.

RESULTS

A total of 258 patients with PAH diagnosed between 2001 and 2022 fulfilled the study criteria and were included in this study. Of these, 172 had follow-up CMR imaging after 3 months to 1.5 years. According to the CMR three risk strata, most patients were classified at intermediate risk (n = 115 [45%]) upon diagnosis. Only 29 (11%) of patients with PAH were classified at low risk, and 114 (44%) were classified at high risk. Poor survival discrimination was seen between risk groups. Appropriate survival discrimination was seen at first reassessment.

INTERPRETATION

Risk stratifying patients with PAH with the recent proposed CMR cutoffs from the European Society of Cardiology/European Respiratory Society 2022 PH guidelines requires adjustment because post-processing consensus is lacking and general applicability is limited. Risk assessment at follow-up yielded better survival discrimination, emphasizing the importance of the individual treatment response.

Surgery and Anesthesia in Patients with Pulmonary Hypertension

Pulmonary hypertension is characterized by right ventricular impairment and a reduced ability to compensate for hemodynamic insults. Consequently, surgery can be challenging but is increasingly considered in view of available specific therapies and improved longer term survival. Optimal management requires a multidisciplinary patient-centered approach involving surgeons, anesthetists, pulmonary hypertension clinicians, and intensivists. The optimal pathway involves risk:benefit assessment for the proposed operation, optimization of pulmonary hypertension and any comorbidities, the appropriate anesthetic approach for the specific procedure and patient, and careful monitoring and management in the postoperative period. Where patients are carefully selected and meticulously managed, good outcomes can be achieved.

Perioperative Management in Pulmonary Endarterectomy

Pulmonary endarterectomy (PEA) is the treatment of choice for patients with chronic thromboembolic pulmonary hypertension (PH), provided lesions are proximal enough in the pulmonary vasculature to be surgically accessible and the patient is well enough to benefit from the operation in the longer term. It is a major cardiothoracic operation, requiring specialized techniques and instruments developed over several decades to access and dissect out the intra-arterial fibrotic material. While in-hospital operative mortality is low (<5%), particularly in high-volume centers, careful perioperative management in the operating theater and intensive care is mandatory to balance ventricular performance, fluid balance, ventilation, and coagulation to avoid or treat complications. Reperfusion pulmonary edema, airway hemorrhage, and right ventricular failure are the most problematic complications, often requiring the use of extracorporeal membrane oxygenation to bridge to recovery. Successful PEA has been shown to improve both morbidity and mortality in large registries, with survival >70% at 10 years. For patients not suitable for PEA or with residual PH after PEA, balloon pulmonary angioplasty and/or PH medical therapy may prove beneficial. Here, we describe the indications for PEA, specific surgical and perioperative strategies, postoperative monitoring and management, and approaches for managing residual PH in the long term.

Cardiac magnetic resonance imaging-derived septum swing index detects pulmonary hypertension: A diagnostic study

Background and Objectives

Because of pressure differences between the pulmonary artery and aorta, the ventricular septum moves in a swinging motion that is commonly observed on cardiac MR (CMR) cine sequences in patients with pulmonary hypertension (PH). We aimed to assess the use of septum swing index (SSI) derived by CMR for detecting PH.

Methods

We retrospectively identified consecutive patients with suspected PH who underwent right heart catheterization (RHC) and CMR at a PH referral center between July 2019 and December 2020. The diagnostic accuracy of SSI for identifying PH (mean pulmonary artery pressure [mPAP] ≥ 25 mmHg) was assessed by receiver operating characteristic curves, sensitivity, specificity, and positive and negative predictive values.

Results

A total of 105 patients (mean age: 47.8 ± 15.0 years; 68 females) were included in the final analysis. SSI and mPAP were negatively correlated in the total study population and patients with PH, but not in patients without PH. SSI was an independent predictor of PH (adjusted odds ratio: 12.9, 95% confidence interval: 3.6 to 45.5, P = 0.003). The area under the curve for SSI was 0.91, with a cut-off value of 0.9673 yielding the best balance of sensitivity (86.4%), specificity (88.2%), positive predictive value (97.4%), negative predictive value (55.6%), and accuracy (86.7%) for detecting PH.

Conclusions

Septum swing index was lower in patients with PH and is a simple, reliable method for detecting PH.

Pressure-Volume Loops for Reviewing Right Ventricular Physiology and Failure in the Context of Left Ventricular Assist Device Implantation

Right ventricular (RV) function is complex as a number of determinants beyond preload, inotropy and afterload play a fundamental role. In particular, arterial elastance (Ea), ventriculo-arterial coupling (VAC), and (systolic) ventricular interdependence play a vital role for the right ventricle. Understanding and actively visualizing these interactions in the failing RV as well as in the altered hemodynamic and morphological situation of left ventricular assist device (LVAD) implantation may aid clinicians in their understanding of RV dysfunction and failure. While, admittedly, hard data is scarce and invasive pressure-volume loop measurements will not become routine in cardiac surgery, we hope that clinicians will benefit from the comprehensive, simulation-based review of RV pathology. In particular, the aim of this article is to first, address and clarify the pathophysiologic hemodynamic factors that lead to RV dysfunction and then, second, expand upon this basis examining the changes occurring by LVAD implantation. This is illustrated using Harvi software which shows elastance, ventricular arterial coupling, and ventricular interdependence by simultaneously showing pressure volume loops of the right and left ventricle.

The Right Ventricle in Pulmonary Hypertension

The right ventricle plays a pivotal role in patients with pulmonary hypertension (PH). Its adaptation to pressure overload determines a patient's functional status as well as survival. In a healthy situation, the right ventricle is part of a low pressure, high compliance system. It is built to accommodate changes in preload, but not very well suited for dealing with pressure overload. In PH, right ventricular (RV) contractility must increase to maintain cardiac output. In other words, the balance between the degree of RV contractility and afterload determines stroke volume. Hypertrophy is one of the major hallmarks of RV adaptation, but it may cause stiffening of the ventricle in addition to intrinsic changes to the RV myocardium. Ventricular filling becomes more difficult for which the right atrium tries to compensate through increased stroke work. Interaction of RV diastolic stiffness and right atrial (RA) function determines RV filling, but also causes vena cava backflow. Assessment of RV and RA function is critical in the evaluation of patient status. In recent guidelines, this is acknowledged by incorporating additional RV parameters in the risk stratification in PH. Several conventional parameters of RV and RA function have been part of risk stratification for many years. Understanding the pathophysiology of RV failure and the interactions with the pulmonary circulation and right atrium requires consideration of the unique RV anatomy. This review will therefore describe normal RV structure and function and changes that occur during adaptation to increased afterload. Consequences of a failing right ventricle and its implications for RA function will be discussed. Subsequently, we will describe RV and RA assessment in clinical practice.

Management of Acutely Decompensated Pulmonary Hypertension

Pulmonary arterial hypertension is a severe life-threatening condition associated with increased pulmonary vascular resistance and resulting right heart dysfunction. Admission to intensive care unit with acutely decompensated right heart failure is a significant negative prognostic event with a high risk of multisystem organ dysfunction and death. Presentations are heterogenous and may combine signs of both diastolic and systolic dysfunction complicating management. Renal dysfunction is often present, but other organ systems can be involved resulting in findings such as acute hepatic dysfunction or bowel wall congestion and ischemia. The goals of therapy are to rapidly reverse ventriculo-arterial decoupling and reduce right ventricular afterload to prevent progression to refractory or irreversible right heart failure. Triggering events must be investigated for and addressed urgently if identified. Volume status management is critical and both noninvasive and invasive testing can aid in prognostication and guide management, including the use of inotropes and vasopressors. In cases of refractory right heart dysfunction, consideration of urgent lung transplantation and mechanical circulatory support is necessary. These patients should be managed at expert centers in an intensive care setting with a multidisciplinary team of practitioners experienced in the management of right heart dysfunction given the high short- and long-term mortality resulting from acute decompensated right heart failure.

Medical Emergencies in Pulmonary Hypertension

The management of acute medical emergencies in patients with pulmonary hypertension (PH) can be challenging. Patients with preexisting PH can rapidly deteriorate due to right ventricular decompensation when faced with acute physiological challenges that would usually be considered low-risk scenarios. This review considers the assessment and management of acute medical emergencies in patients with PH, encompassing both pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH), acknowledging these comprise the more severe groups of PH. Management protocols are described in a systems-based approach. Respiratory emergencies include pulmonary embolism, airways disease, and pneumonia; cardiac emergencies including arrhythmia and chest pain with acute myocardial infarction are discussed, alongside PH-specific emergencies such as pulmonary artery dissection and extrinsic coronary artery compression by a dilated proximal pulmonary artery. Other emergencies including sepsis, severe gastroenteritis with dehydration, syncope, and liver failure are also considered. We propose management recommendations for medical emergencies based on available evidence, international guidelines, and expert consensus. We aim to provide advice to the specialist alongside the generalist, and emergency doctors, nurses, and acute physicians in nonspecialist centers. A multidisciplinary team approach is essential in the management of patients with PH, and communication with local and specialist PH centers is paramount. Close hemodynamic monitoring during medical emergencies in patients with preexisting PH is vital, with early referral to critical care recommended given the frequent deterioration and high mortality in this setting.

The Early Detection of Pulmonary Hypertension

BACKGROUND

Up to 1% of the world population and 10% of all persons over age 65 suffer from pulmonary hypertension (PH). The latency from the first symptom to the diagnosis is more than one year on average, and more than three years in 20% of patients. 40% seek help from more than four different physicians until their condition is finally diagnosed.

METHODS

This review is based on publications retrieved by a selective literature search on pulmonary hypertension.

RESULTS

The most common causes of pulmonary hypertension are left heart diseases and lung diseases. Its cardinal symptom is exertional dyspnea that worsens as the disease progresses. Additional symptoms of right heart failure are seen in advanced stages. Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are rare, difficult to diagnose, and of particular clinical relevance because specific treatments are available. For this reason, strategies for the early detection of PAH and CTEPH have been developed. The clinical suspicion of PH arises in a patient who has nonspecific symptoms, electrocardiographic changes, and an abnormal (NT-pro-)BNP concentration. Once the suspicion of PH has been confirmed by echocardiography and, if necessary, differential-diagnostic evaluation with a cardiopulmonary stress test, and after the exclusion of a primary left heart disease or lung disease, the patient should be referred to a PH center for further diagnostic assessment, classification, and treatment.

CONCLUSION

If both the (NT-pro-)BNP and the ECG are normal, PH is unlikely. Knowledge of the characteristic clinical manifestations and test results of PH is needed so that patients can be properly selected for referral to specialists and experts in PH.

Pulmonary Hypertension Associated with Left Heart Disease

Pulmonary hypertension (PH) is a common complication of diseases affecting the left heart, mostly found in patients suffering from heart failure, with or without preserved left ventricular ejection fraction. Initially driven by a passive increase in left atrial pressure (postcapillary PH), several mechanisms may lead in a subset of patient to significant structural changes of the pulmonary vessels or a precapillary component. In addition, the right ventricle may be independently affected, which results in right ventricular to pulmonary artery uncoupling and right ventricular failure, all being associated with a worse outcome. The differential diagnosis of PH associated with left heart disease versus pulmonary arterial hypertension (PAH) is especially challenging in patients with cardiovascular comorbidities and/or heart failure with preserved ejection fraction (HFpEF). A stepwise approach to diagnosis is proposed, starting with a proper clinical multidimensional phenotyping to identify patients in whom hemodynamic confirmation is deemed necessary. Provocative testing (exercise testing, fluid loading, or simple leg raising) is useful in the cath laboratory to identify patients with abnormal response who are more likely to suffer from HFpEF. In contrast with group 1 PH, management of PH associated with left heart disease must focus on the treatment of the underlying condition. Some PAH-approved targets have been unsuccessfully tried in clinical studies in a heterogeneous group of patients, some even leading to an increase in adverse events. There is currently no approved therapy for PH associated with left heart disease.

Severity of precapillary pulmonary hypertension: Predictive factor

BACKGROUND AND OBJECTIVES

Patients with pulmonary arterial hypertension (PAH) require risk assessments for prognosis and appropriate therapy. These assessments need to be improved by incorporating clinical and laboratory data such as the analysis of the right ventricle. We aim to establish echocardiographic morphometric data of the right ventricle and its relationship with the left ventricle, to estimate the hemodynamic severity of precapillary pulmonary hypertension (PHprecapillary).

METHODS

This cohort, prospective, observational, and cross-sectional study included 41 consecutive patients with PHprecapillary using echocardiographic study and cardiac catheterization.

RESULTS

Patients' mean age was 44.0±16.4 years, and 37 were women (90.2%). Idiopathic PAH was diagnosed in 18 patients (43.9%). The World Health Organization/New York Association functional class was III or IV in 31 patients (75.6%). The ratio of the right to left ventricles (RV/LV) echocardiographic diastolic diameters was associated with pulmonary arterial pressures in cardiac catheterization, with the best cutoff per receiver operating characteristic curve being 0.8 for systolic pressure (sensitivity 90.0%, specificity 78.3%, area under the curve [AUC] 0.882) and mean pressure (sensitivity 60.0%, specificity 95.7%, AUC 0.823). Spearman's correlation (R) of RV/LV echocardiographic ratio and the hemodynamic variables was significant for systolic pressure (R = 0.7015, p < 0.0001), mean pressure (R = 0.6332, p < 0.0001), transpulmonary pressure gradient (R = 0.6524, p < 0.0001), pulmonary vascular resistance (R = 0.6076, p = 0.0021), and pulmonary vascular resistance index (R = 0.6229, p = 0.0014).

CONCLUSION

The ratio of RV/LV echocardiographic diastolic diameters contribute to the estimates the hemodynamic severity of precapillary pulmonary hypertension. The best cutoff for this assessment was RV/LV of 0.8.

The Echocardiographic Evaluation of the Right Heart: Current and Future Advances

PURPOSE OF REVIEW

To discuss physiologic and methodologic advances in the echocardiographic assessment of right heart (RH) function, including the emergence of artificial intelligence (AI) and point-of-care ultrasound.

RECENT FINDINGS

Recent studies have highlighted the prognostic value of right ventricular (RV) longitudinal strain, RV end-systolic dimensions, and right atrial (RA) size and function in pulmonary hypertension and heart failure. While RA pressure is a central marker of right heart diastolic function, the recent emphasis on venous excess imaging (VExUS) has provided granularity to the systemic consequences of RH failure. Several methodological advances are also changing the landscape of RH imaging including post-processing 3D software to delineate the non-longitudinal (radial, anteroposterior, and circumferential) components of RV function, as well as AI segmentation- and non-segmentation-based quantification. Together with recent guidelines and advances in AI technology, the field is shifting from specific RV functional metrics to integrated RH disease-specific phenotypes. A modern echocardiographic evaluation of RH function should focus on the entire cardiopulmonary venous unit-from the venous to the pulmonary arterial system. Together, a multi-parametric approach, guided by physiology and AI algorithms, will help define novel integrated RH profiles for improved disease detection and monitoring.

Restoration of right ventricular function in the treatment of pulmonary arterial hypertension

OBJECTIVE

A 45% threshold of right ventricular ejection fraction (RVEF) is proposed clinically relevant in patients with pulmonary arterial hypertension (PAH). We aim to determine treatment response, long-term right ventricular (RV) functional stability and prognosis of patients with PAH reaching or maintaining the RVEF 45% threshold.

METHODS

Incident, treatment-naive, adult PAH patients with cardiac magnetic resonance imaging at baseline and first follow-up were included (total N=127) and followed until date of censoring or death/lung transplantation. Patients were categorised into two groups based on 45% RVEF. Baseline predictors, treatment response and prognosis were assessed with logistic regression analyses, two-way analysis of variance and log-rank tests.

RESULTS

Patients were 50±17 years old, 73% female, of which N=75 reached or maintained the 45% RVEF threshold at follow-up (RVEF≥45%@FU), while N=52 patients did not (RVEF<45%@FU). RV end-diastolic volume and N-terminal pro-B-type natriuretic peptide at baseline were multivariable predictors of an RVEF ≥45% at follow-up. A 40% pulmonary vascular resistance (PVR) reduction resulted in greater improvement in RV function (ΔRVEF 17±11 vs. 5±8; pinteraction<0.001) compared to a PVR reduction <40%, but did not guarantee an RVEF ≥45%. Finally, the 45% RVEF threshold was associated with stable RV function during long-term follow-up and better survival (HR: 1.91 (95% CI: 1.11 to 3.27)). Patients failing to reach or maintain the 45% RVEF threshold at first follow-up mostly stayed below this threshold over the next consecutive visits.

CONCLUSION

After treatment initiation, 60% of patients with PAH reach or maintain the 45% RVEF threshold, which is associated with a long-term stable RV function and favourable prognosis.

Sleep-Related Hypoxia, Right Ventricular Dysfunction, and Survival in Patients With Group 1 Pulmonary Arterial Hypertension

BACKGROUND

Group 1 pulmonary arterial hypertension (PAH) is a progressive fatal condition characterized by right ventricular (RV) failure with worse outcomes in connective tissue disease (CTD). Obstructive sleep apnea and sleep-related hypoxia may contribute to RV dysfunction, though the relationship remains unclear.

OBJECTIVES

The aim of this study was to prospectively evaluate the association of the apnea-hypopnea index (AHI) and sleep-related hypoxia with RV function and survival.

METHODS

Pulmonary Vascular Disease Phenomics (National Heart, Lung, and Blood Institute) cohort participants (patients with group 1 PAH, comparators, and healthy control participants) with sleep studies were included. Multimodal RV functional measures were examined in association with AHI and percentage of recording time with oxygen saturation <90% (T90) per 10-unit increment. Linear models, adjusted for demographics, oxygen, diffusing capacity of the lungs for carbon monoxide, pulmonary hypertension medications, assessed AHI and T90, and RV measures. Log-rank test/Cox proportional hazards models adjusted for demographics, oxygen, and positive airway pressure were constructed for transplantation-free survival analyses.

RESULTS

Analysis included 186 participants with group 1 PAH with a mean age of 52.6 ± 14.1 years; 71.5% were women, 80.8% were Caucasian, and there were 43 events (transplantation or death). AHI and T90 were associated with decreased RV ejection fraction (on magnetic resonance imaging), by 2.18% (-2.18; 95% CI: -4.00 to -0.36; P = 0.019) and 0.93% (-0.93; 95% CI: -1.47 to -0.40; P < 0.001), respectively. T90 was associated with increased RV systolic pressure (on echocardiography), by 2.52 mm Hg (2.52; 95% CI: 1.61 to 3.43; P < 0.001); increased mean pulmonary artery pressure (on right heart catheterization), by 0.27 mm Hg (0.27; 95% CI: 0.05 to 0.49; P = 0.019); and RV hypertrophy (on electrocardiography), 1.24 mm (1.24; 95% CI: 1.10 to 1.40; P < 0.001). T90, but not AHI, was associated with a 17% increased 5-year risk for transplantation or death (HR: 1.17; 95% CI: 1.07 to 1.28). In non-CTD-associated PAH, T90 was associated with a 21% increased risk for transplantation or death (HR: 1.21; 95% CI: 1.08 to 1.34). In CTD-associated PAH, T90 was associated with RV dysfunction, but not death or transplantation.

CONCLUSIONS

Sleep-related hypoxia was more strongly associated than AHI with measures of RV dysfunction, death, or transplantation overall and in group 1 non-CTD-associated PAH but only with RV dysfunction in CTD-associated PAH. (Pulmonary Vascular Disease Phenomics Program [PVDOMICS]; NCT02980887).

Clinical and functional relevance of right ventricular contraction patterns in pulmonary hypertension

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.

Inhaled iloprost as an add-on therapy for advanced pulmonary arterial hypertension: An Indian perspective

Background Pulmonary arterial hypertension (PAH) is a progressive disease with high morbidity and mortality. Risk stratification and initiation of dual or triple combination therapy has a better clinical response, especially in high-risk patients. Unfortunately, prostacyclin analogues are not marketed in India; hence, the use of these medications is limited. We report the benefits and difficulties of using iloprost inhalation in patients with advanced PAH in India. Methods In this prospective observational study, we included patients with group 1 PAH. Inhaled iloprost was initiated as an add-on therapy for patients who had clinical, echocardiographic or laboratory deterioration on dual oral medications. Patients with clinical instability were excluded. All patients underwent thorough clinical evaluation, detailed echocardiogram and laboratory investigations. Patients were started on inhaled iloprost 2.5 μg six times daily and closely followed up. The dose was escalated if necessary. On follow-up, clinical echocardiographic and laboratory evaluation was done on all patients. Results Fourteen patients (11 women) with a median age of 32 years (2-66 years) with group 1 PAH were started on inhaled iloprost as an add-on therapy. Improvement in clinical parameters, WHO functional class, echocardiographic-derived right ventricular function, and N-terminal pro-brain natriuretic peptide (NT-pro-BNP) levels were observed in 10 of 14 patients. A median increase of 31% (4.2, 106%) in the distance travelled during 6-minute walk test, a median increase of 45% (-20, 120%) in right ventricular fractional area change, a median increase of 27% (-16.7, 60%) in tricuspid annular peak systolic excursion and a median decrease of 36.7% (-69.6, 17.2%) in NT-pro-BNP levels were observed after initiation of medication. Three patients had progression of symptoms and were then referred for lung/heart-lung transplant. One patient developed progression of symptoms after an excellent initial response and transitioned to subcutaneous treprostinil. Improvement in clinical, echocardiographic and laboratory features allowed us to successfully perform surgical Potts shunt in 2 patients. The medications were well tolerated with minimal and transient side-effects. There were no deaths. Conclusion Inhaled iloprost can be used with acceptable benefits and minimal side-effects in patients with PAH.

OP2113, a new drug for chronic hypoxia-induced pulmonary hypertension treatment in rat

BACKGROUND AND PURPOSE

Pulmonary hypertension (PH) is a cardiovascular disease characterised by an increase in pulmonary arterial (PA) resistance leading to right ventricular (RV) failure. Reactive oxygen species (ROS) play a major role in PH. OP2113 is a drug with beneficial effects on cardiac injuries that targets mitochondrial ROS. The aim of the study was to address the in vivo therapeutic effect of OP2113 in PH.

EXPERIMENTAL APPROACH

PH was induced by 3 weeks of chronic hypoxia (CH-PH) in rats treated with OP2113 or its vehicle via subcutaneous osmotic mini-pumps. Haemodynamic parameters and both PA and heart remodelling were assessed. Reactivity was quantified in PA rings and in RV or left ventricular (LV) cardiomyocytes. Oxidative stress was detected by electron paramagnetic resonance and western blotting. Mitochondrial mass and respiration were measured by western blotting and oxygraphy, respectively.

KEY RESULTS

In CH-PH rats, OP2113 reduced the mean PA pressure, PA remodelling, PA hyperreactivity in response to 5-HT, the contraction slowdown in RV and LV and increased the mitochondrial mass in RV. Interestingly, OP2113 had no effect on haemodynamic parameters, both PA and RV wall thickness and PA reactivity, in control rats. Whereas oxidative stress was evidenced by an increase in protein carbonylation in CH-PH, this was not affected by OP2113.

CONCLUSION AND IMPLICATIONS

Our study provides evidence for a selective protective effect of OP2113 in vivo on alterations in both PA and RV from CH-PH rats without side effects in control rats.

Clinical relevance and prognostic value of renal Doppler in acute decompensated precapillary pulmonary hypertension

AIMS

We aim to evaluate the clinical relevance and the prognostic value of arterial and venous renal Doppler in acute decompensated precapillary pulmonary hypertension (PH).

METHODS AND RESULTS

The renal resistance index (RRI) and the Doppler-derived renal venous stasis index (RVSI) were monitored at admission and on Day 3 in a prospective cohort of precapillary PH patients managed in intensive care unit for acute right heart failure (RHF). The primary composite endpoint included death, circulatory assistance, urgent transplantation, or rehospitalization for acute RHF within 90 days following inclusion. Ninety-one patients were enrolled (58% female, age 58 ± 16 years). The primary endpoint event occurred in 32 patients (33%). In univariate logistic regression analysis, variables associated with RRI higher than the median value were non-variable parameters (age and history of hypertension), congestion (right atrial pressure and renal pulse pressure), cardiac function [tricuspid annular plane systolic excursion (TAPSE) and left ventricular outflow tract- velocity time integral], systemic pressures and NT-proBNP. Variables associated with RVSI higher than the median value were congestion (high central venous pressure, right atrial pressure, and renal pulse pressure), right cardiac function (TAPSE), severe tricuspid regurgitation, and systemic pressures. Inotropic support was more frequently required in patients with high RRI (P = 0.01) or high RVSI (P = 0.003) at the time of admission. At Day 3, a RRI value <0.9 was associated with a better prognosis after adjusting to the estimated glomerular filtration rate.

CONCLUSION

Renal Doppler provides additional information to assess the severity of patients admitted to the intensive care unit for acute decompensated precapillary PH.

iCPET Calculator: A Web-Based Application to Standardize the Calculation of Alpha Distensibility in Patients With Pulmonary Arterial Hypertension

Background Pulmonary vascular distensibility associates with right ventricular function and clinical outcomes in patients with unexplained dyspnea and pulmonary hypertension. Alpha distensibility coefficient is determined from a nonlinear fit to multipoint pressure-flow plots. Study aims were to (1) create and test a user-friendly tool to standardize analysis of exercise hemodynamics including distensibility, and (2) investigate changes in distensibility following treatment in patients with pulmonary arterial hypertension. Methods and Results Participants with an exercise right heart catherization were retrospectively identified from the University of Arizona Pulmonary Hypertension (UA PH) registry and split into a pulmonary arterial hypertension group, a comparator group, and a control group. Right ventricular function was quantified using the coupling ratio and diastolic stiffness. Prototypes of the invasive cardiopulmonary exercise testing (iCPET) calculator were developed using Matlab, Python, and RShiny to analyze exercise hemodynamics and alpha distensibility coefficient, α (%/mm Hg) from multipoint pressure flow plots. Interclass correlation coefficients were calculated for interplatform and interobserver variability in alpha. No significant bias in the intraplatform (Matlab versus RShiny; intraclass correlation coefficient: 0.996) or interobserver (intraclass correlation coefficient: 0.982) comparison of alpha values. Afterload significantly decreased (P<0.05) with no change in alpha distensibility in the pulmonary arterial hypertension group at follow-up. The comparator group had no change in pressure, resistance or alpha distensibility. There were no significant changes in RV diastolic stiffness at follow-up. Conclusions The interactive user interface in the iCPET calculator allows exploration of alpha distensibility using standardized methods. No significant change in alpha distensibility at follow-up suggests that alpha may be less modifiable in patients with long-standing pulmonary arterial hypertension.

Prognostic Role of Right Ventricular-Pulmonary Artery Coupling Assessed by TAPSE/PASP Ratio in Patients With Acute Heart Failure

BACKGROUND

Right ventricular (RV) dysfunction is a significant risk of major adverse cardiac events in patients with acute heart failure (AHF). In this study, we evaluated RV-pulmonary artery (PA) coupling, assessed by tricuspid annular plane systolic excursion (TAPSE)/pulmonary artery systolic pressure (PASP) and assessed its prognostic significance, in AHF patients.

METHODS

We measured the TAPSE/PASP ratio and analyzed its correlations with other echocardiographic parameters. Additionally, we assessed its prognostic role in AHF patients.

RESULTS

A total of 1147 patients were included in the analysis (575 men, aged 70.81 ± 13.56 years). TAPSE/PASP ratio exhibited significant correlations with left ventricular (LV) ejection fraction(r = 0.243, p < 0.001), left atrial (LA) diameter(r = -0.320, p < 0.001), left atrial global longitudinal strain (LAGLS, r = 0.496, p < 0.001), mitral E/E' ratio(r = -0.337, p < 0.001), and right ventricular fractional area change (RVFAC, r = 0.496, p < 0.001). During the median follow-up duration of 29.0 months, a total of 387 patients (33.7%) died. In the univariate analysis, PASP, TAPSE, and TAPSE/PASP ratio were significant predictors of mortality. After the multivariate analysis, TAPSE/PASP ratio remained a statistically significant parameter for all-cause mortality (hazard ratio [HR], 0.453; p = 0.037) after adjusting for other parameters. In the receiver operating curve analysis, the optimal cut-off level of TAPSE/PASP ratio for predicting mortality was 0.33 (area under the curve = 0.576, p < 0.001), with a sensitivity of 65% and a specificity of 47%. TAPSE/PASP ratio < 0.33 was associated with an increased risk of mortality after adjusting for other variables (HR, 1.306; p = 0.025).

CONCLUSIONS

In AHF patients, TAPSE/PASP ratio demonstrated significant associations with RVFAC, LA diameter and LAGLS. Moreover, a decreased TAPSE/PASP ratio < 0.33 was identified as a poor prognostic factor for mortality.

Unrecognized Pulmonary Hypertension in Non-Cardiac Surgical Patients: At-Risk Populations, Preoperative Evaluation, Intraoperative Management and Postoperative Complications

Pulmonary hypertension is a well-established independent risk factor for perioperative complications after elective non-cardiac surgery. Patients undergoing cardiac surgery are routinely evaluated for the presence of pulmonary hypertension in the preoperative period. Better monitoring in the postoperative critical care setting leads to more efficient management of potential complications. Data among patients with pulmonary hypertension undergoing elective non-cardiac surgery are scant. Moreover, the condition may be unidentified at the time of surgery. Also, monitoring after non-cardiac surgery can be very limited in the PACU setting, as opposed to the critical care setting. All these factors can result in a higher postoperative complication rate and poor outcomes.

Computational modeling of ventricular-ventricular interactions suggest a role in clinical conditions involving heart failure

Introduction: The left (LV) and right (RV) ventricles are linked biologically, hemodynamically, and mechanically, a phenomenon known as ventricular interdependence. While LV function has long been known to impact RV function, the reverse is increasingly being realized to have clinical importance. Investigating ventricular interdependence clinically is challenging given the invasive measurements required, including biventricular catheterization, and confounding factors such as comorbidities, volume status, and other aspects of subject variability. Methods: Computational modeling allows investigation of mechanical and hemodynamic interactions in the absence of these confounding factors. Here, we use a threesegment biventricular heart model and simple circulatory system to investigate ventricular interdependence under conditions of systolic and diastolic dysfunction of the LV and RV in the presence of compensatory volume loading. We use the end-diastolic pressure-volume relationship, end-systolic pressure-volume relationship, Frank Starling curves, and cardiac power output as metrics. Results: The results demonstrate that LV systolic and diastolic dysfunction lead to RV compensation as indicated by increases in RV power. Additionally, RV systolic and diastolic dysfunction lead to impaired LV filling, interpretable as LV stiffening especially with volume loading to maintain systemic pressure. Discussion: These results suggest that a subset of patients with intact LV systolic function and diagnosed to have impaired LV diastolic function, categorized as heart failure with preserved ejection fraction (HFpEF), may in fact have primary RV failure. Application of this computational approach to clinical data sets, especially for HFpEF, may lead to improved diagnosis and treatment strategies and consequently improved outcomes.

Right Heart Adaptation to Exercise in Pulmonary Hypertension: An Invasive Hemodynamic Study

BACKGROUND

Right heart failure (RHF) is associated with a dismal prognosis in patients with pulmonary hypertension (PH). Exercise right heart catheterization may unmask right heart maladaptation as a sign of RHF. We sought to (1) define the normal limits of right atrial pressure (RAP) increase during exercise; (2) describe the right heart adaptation to exercise in PH owing to heart failure with preserved ejection fraction (PH-HFpEF) and in pulmonary arterial hypertension (PAH); and (3) identify the factors associated with right heart maladaptation during exercise.

METHODS AND RESULTS

We analyzed rest and exercise right heart catheterization from patients with PH-HFpEF and PAH. Right heart adaptation was described by absolute or cardiac output (CO)-normalized changes of RAP during exercise. Individuals with noncardiac dyspnea (NCD) served to define abnormal RAP responses (>97.5th percentile). Thirty patients with PH-HFpEF, 30 patients with PAH, and 21 patients with NCD were included. PH-HFpEF were older than PAH, with more cardiovascular comorbidities, and a higher prevalence of severe tricuspid regurgitation (P < .05). The upper limit of normal for peak RAP and RAP/CO slope in NCD were >12 mm Hg and ≥1.30 mm Hg/L/min, respectively. PH-HFpEF had higher peak RAP and RAP/CO slope than PAH (20 mm Hg [16-24 mm Hg] vs 12 mm Hg [9-19 mm Hg] and 3.47 mm Hg/L/min [2.02-6.19 mm Hg/L/min] vs 1.90 mm Hg/L/min [1.01-4.29 mm Hg/L/min], P < .05). A higher proportion of PH-HFpEF had RAP/CO slope and peak RAP above normal (P < .001). Estimated stressed blood volume at peak exercise was higher in PH-HFpEF than PAH (P < .05). In the whole PH cohort, the RAP/CO slope was associated with age, the rate of increase in estimated stressed blood volume during exercise, severe tricuspid regurgitation, and right atrial dilation.

CONCLUSIONS

Patients with PH-HFpEF display a steeper increase of RAP during exercise than those with PAH. Preload-mediated mechanisms may play a role in the development of exercise-induced RHF.