Understanding the Pathobiology of Pulmonary Hypertension Due to Left Heart Disease

Early Alteration of Right Ventricle-Pulmonary Artery Coupling in Experimental Heart Failure With Preserved Ejection Fraction

BACKGROUND

Pulmonary hypertension and right ventricular (RV) dysfunction are major prognostic determinants in patients with heart failure with preserved ejection fraction (HFpEF). The underlying pathomechanisms remain unknown. In this context, we sought to study the pathogenesis of pulmonary hypertension and RV dysfunction in a rat model of obesity-associated HFpEF.

METHODS AND RESULTS

HFpEF was induced in obesity-prone rats fed a high-fat diet (n=13) and compared with obesity-resistant rats fed with standard chow (n=9). After 12 months, the animals underwent echocardiographic and hemodynamic evaluation followed by tissue sampling for pathobiological assessment. HFpEF rats presented mild RV pressure overload (with increased RV systolic pressure and pulmonary vascular resistance). No changes in pulmonary artery medial thickness and ex vivo vasoreactivity (to acetylcholine and endothelin-1) were observed and RNA sequencing analysis failed to identify gene clustering in HFpEF lungs. However, released nitric oxide levels were decreased in HFpEF pulmonary artery, while lung expression of preproendothelin-1 was increased. In HFpEF rats, RV structure and function were altered, with RV enlargement, decreased RV fractional area change and free wall longitudinal fractional shortening, together with altered right ventricle-pulmonary artery coupling (estimated by tricuspid annular plane systolic excursion/systolic pulmonary artery pressure). Hypertrophy and apoptosis (evaluated by transferase biotin- dUTP nick-end labeling staining) were increased in right and left ventricles of HFpEF rats. There was an inverse correlation between tricuspid annular plane systolic excursion/systolic pulmonary artery pressure and RV apoptotic rate. Plasma levels of soluble suppression of tumorigenicity-2, interleukin-1β, -6 and -17A were increased in HFpEF rats.

CONCLUSIONS

Obesity-associated HFpEF in rats spontaneously evolves to pulmonary hypertension-HFpEF associated with impaired right ventricle-pulmonary artery coupling that appears disproportionate to a slight increase in RV afterload.

A Novel Rat Model of Mild Pulmonary Hypertension Associated with Pulmonary Venous Congestion Induced by Left Pulmonary Vein Banding

Pulmonary hypertension (PH) associated with left heart disease (PH-LHD) is the most common form of PH. In PH-LHD, changes in the pulmonary vasculature are assumed to be mainly caused by pulmonary venous congestion. However, the underlying mechanisms of this form of PH are poorly understood. We aimed to establish a model of PH associated with pulmonary venous congestion. Wistar-Kyoto rats underwent partial occlusion of the left pulmonary vein to induce pulmonary venous congestion or sham surgery and were assessed at various time points post-surgery (3, 6, 9, 12 weeks). In vivo cardiopulmonary phenotyping was performed by using echocardiography along with heart catheterization. Histomorphometry methods were used to assess pulmonary vascular remodeling (e.g., wall thickness, degree of muscularization). Left pulmonary vein banding (PVB) resulted in mildly elevated right ventricular systolic pressure and moderate right ventricular hypertrophy. In PVB rats, small- and medium-sized pulmonary vessels in the left lung were characterized by increased wall thickness and muscularization. Taken together, our data demonstrate that left PVB-induced pulmonary venous congestion is associated with pulmonary vascular remodeling and mild PH.

Effect of Neutrophil-to-Lymphocyte Ratio on Post-TAVR Mortality and Periprocedural Pulmonary Hypertension

Aims

To evaluate the impact of neutrophil-to-lymphocyte ratio (NLR) on periprocedural pulmonary hypertension (PH) and 3-month all-cause mortality in patients with aortic stenosis (AS) who underwent transcatheter aortic valve replacement (TAVR) and to develop a nomogram for predicting the mortality for these patients.

Methods and Results

124 patients undergoing TAVR were categorized into three groups according to systolic pulmonary artery pressure (sPAP): Group I (no PH, n = 61) consisted of patients with no pre- and post-TAVR PH; Group II (improved PH, n = 35) consisted of patients with post-TAVR systolic pulmonary artery pressure (sPAP) decreased by more than 10 mmHg compared to pre-TAVR levels; and Group III (persistent PH, n = 28) consisted of patients with post-TAVR sPAP no decrease or less than 10 mmHg, or new-onset PH after the TAVR procedure. The risk of all-cause mortality within 3 months tended to be higher in Group II (11.4%) and Group III (14.3%) compared to Group I (3.3%) (P=0.057). The multinomial logistic regression analysis demonstrated a positive correlation between NLR and both improved PH (OR: 1.182, 95% CI: 1.036-1.350, P=0.013) and persistent PH (OR: 1.181, 95% CI: 1.032-1.352, P=0.016). Kaplan-Meier analysis revealed a significant association between higher NLR and increased 3-month all-cause mortality (16.1% vs. 3.1% in lower NLR group, P=0.021). The multivariable Cox regression analysis confirmed that NLR was an independent predictor for all-cause mortality within 3 months, even after adjusting for clinical confounders. A nomogram incorporating five factors (BNP, heart rate, serum total bilirubin, NLR, and comorbidity with coronary heart disease) was developed. ROC analysis was performed to discriminate the ability of the nomogram, and the AUC was 0.926 (95% CI: 0.850-1.000, P < 0.001).

Conclusions

Patients with higher baseline NLR were found to be at an increased risk of periprocedural PH and all-cause mortality within 3 months after TAVR.

Clinical-imaging-pathological correlation in pulmonary hypertension associated with left heart disease

Pulmonary hypertension (PH) is highly prevalent in patients with left heart disease (LHD) and negatively impacts prognosis. The most common causes of PH associated with LHD (PH-LHD) are left heart failure and valvular heart disease. In LHD, passive backward transmission of increased left-sided filling pressures leads to isolated post-capillary PH. Additional pulmonary vasoconstriction and remodelling lead to a higher vascular load and combined pre- and post-capillary PH. The increased afterload leads to right ventricular dysfunction and failure. Multimodality imaging of the heart plays a central role in the diagnostic work-up and follow-up of patients with PH-LHD. Echocardiography provides information about the estimated pulmonary artery pressure, morphology and function of the left and right side of the heart, and valvular abnormalities. Cardiac magnetic resonance imaging is the gold standard for volumetric measurements and provides myocardial tissue characterisation. Computed tomography of the thorax may show general features of PH and/or LHD and is helpful in excluding other PH causes. Histopathology reveals a spectrum of pre- and post-capillary vasculopathy, including intimal fibrosis, media smooth muscle cell hyperplasia, adventitial fibrosis and capillary congestion. In this paper, we provide an overview of clinical, imaging and histopathological findings in PH-LHD based on three clinical cases.

A novel clinical prediction scoring system of high-altitude pulmonary hypertension

Background

High-altitude pulmonary hypertension (HAPH) is a common disease in regions of high altitude where performing right heart catheterization (RHC) is challenging. The development of a diagnostic scoring system is crucial for effective disease screening.

Methods

A total of 148 individuals were included in a retrospective analysis, and an additional 42 residents were prospectively enrolled. We conducted a multivariable analysis to identify independent predictors of HAPH. Subsequently, we devised a prediction score based on the retrospective training set to anticipate the occurrence and severity of HAPH. This scoring system was further subjected to validation in the prospective cohort, in which all participants underwent RHC.

Results

This scoring system, referred to as the GENTH score model (Glycated hemoglobin [OR = 4.5], Echocardiography sign [OR = 9.1], New York Heart Association-functional class [OR = 12.5], Total bilirubin [OR = 3.3], and Hematocrit [OR = 3.6]), incorporated five independent risk factors and demonstrated strong predictive accuracy. In the training set, the area under the curve (AUC) values for predicting the occurrence and severity of HAPH were 0.851 and 0.832, respectively, while in the validation set, they were 0.841 and 0.893. In the validation set, GENTH score model cutoff values of ≤18 or >18 points were established for excluding or confirming HAPH, and a threshold of >30 points indicated severe HAPH.

Conclusions

The GENTH score model, combining laboratory and echocardiography indicators, represents an effective tool for distinguishing potential HAPH patients and identifying those with severe HAPH. This scoring system improves the clinical screening of HAPH diseases and offers valuable insights into disease diagnosis and management.

Importance of heart failure duration for development of pulmonary hypertension in advanced heart failure

BACKGROUND AND OBJECTIVES

Pulmonary vascular resistance (PVR) is critical when evaluating candidacy for advanced heart failure (HF) therapies, but risk factors for elevated PVR are not well studied. We hypothesized that HF duration would be associated with elevated PVR.

METHODS

Danish single-center registry of consecutive in- and outpatients undergoing right heart catheterization as part of advanced HF work up. The relation between HF duration and PVR was estimated by regression analysis. Finally, the relation between PVR and long-term mortality was assessed by Cox proportional hazards regression and Kaplan-Meier analyses.

RESULTS

A total of 549 patients (77% men, median age 54 (43-61) years, median HF duration 1.6 years (0.1-7.1)) were included. Univariate linear regression displayed an association between longer HF duration and increasing PVR (p = 0.014). PVR > 3 WU was present in 92 patients (17%) who were older (median p < 0.001) and had longer HF duration (p = 0.03). HF duration (per 1 year increase) did not predict PVR > 3 WU after adjustment for covariables (OR 1.00; p = 0.99). During a mean follow-up time of 4.5 years, there were 240 (44%) deaths. Increasing PVR was associated with elevated all-cause mortality risk (adjusted HR 1.24; p < 0.001). PVR > 3 WU was associated with higher mortality (adjusted HR 1.49; p = 0.027).

CONCLUSION

Longer duration of HF was associated with higher PVR in patients with advanced HF, but this association disappeared in multivariate analyses. Longer HF duration per se likely does not cause elevated PVR and should not discourage evaluation for heart transplantation.

Epigenetic regulation of programmed cell death in hypoxia-induced pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a severe progressive disease that may cause early right ventricular failure and eventual cardiac failure. The pathogenesis of PAH involves endothelial dysfunction, aberrant proliferation of pulmonary artery smooth muscle cells (PASMCs), and vascular fibrosis. Hypoxia has been shown to induce elevated secretion of vascular endothelial growth factor (VEGF), leading to the development of hypoxic PAH. However, the molecular mechanisms underlying hypoxic PAH remain incompletely understood. Programmed cell death (PCD) is a natural cell death and regulated by certain genes. Emerging evidence suggests that apoptotic resistance contributes to the development of PAH. Moreover, several novel types of PCD, such as autophagy, pyroptosis, and ferroptosis, have been reported to be involved in the development of PAH. Additionally, multiple diverse epigenetic mechanisms including RNA methylation, DNA methylation, histone modification, and the non-coding RNA molecule-mediated processes have been strongly linked to the development of PAH. These epigenetic modifications affect the expression of genes, which produce important changes in cellular biological processes, including PCD. Consequently, a better understanding of the PCD processes and epigenetic modification involved in PAH will provide novel, specific therapeutic strategies for diagnosis and treatment. In this review, we aim to discuss recent advances in epigenetic mechanisms and elucidate the role of epigenetic modifications in regulating PCD in hypoxia-induced PAH.

Group 2 pulmonary hypertension: from diagnosis to treatment

PURPOSE OF REVIEW

Pulmonary hypertension associated with left heart disease (PHLHD) is common and associated with adverse prognosis. Proper diagnosis is critical to avoid inappropriate treatment. Practical approaches to noninvasive diagnosis are available, though invasive hemodynamics including volume loading or exercise are often necessary for definitive diagnosis. Treatment strategies and research in the field is rapidly evolving.

RECENT FINDINGS

Combined pre and post capillary pulmonary hypertension is associated with remodeling of the pulmonary vasculature that is proportional to the severity of the pulmonary hypertension. Even quite mild elevation of pulmonary vascular resistance (PVR), (greater than 2.0 Wood units (WU)) is associated with adverse outcome. Guideline-directed medical therapy (GDMT) for left heart failure has rapidly evolved, including approval of SGLT2 inhibitors for treatment of heart failure with preserved ejection fraction (HFpEF). However, full implementation of GDMT is lagging. Utilization of implanted pulmonary artery pressure monitoring can facilitate patient management in selected patient phenotypes and has been utilized to demonstrate improvement in pulmonary pressures with emerging therapies in HFpEF including SGLT2 inhibitors and sacubitril/valsartan. A variety of shunt devices to create a left-to-right shunt in order to decompress the left heart are available or undergoing clinical trials. There is concern that there could be adverse response to such devices in patients who have even mild elevation of pulmonary vascular resistance. Sleep disordered breathing is common in PHLHD and should be aggressively sought out and treated.

SUMMARY

Even mild elevation in pulmonary vascular resistance is associated with adverse outcome. A systematic approach to diagnosis of PHLHD is essential. Guideline-directed medical therapy for PHLHD prioritizes optimal management of the left heart disease. Pulmonary artery pressure sensors are useful in selected patients.

Machine learning for clustering and postclosure outcome of adult CHD-PAH patients with borderline hemodynamics

BACKGROUND

Patients with uncorrected isolated simple shunts associated pulmonary arterial hypertension (PAH) had increased mortality. Treatment strategies for borderline hemodynamics remain controversial. This study aims to investigate preclosure characteristics and its association with postclosure outcome in this group of patients.

METHODS

Adults with uncorrected isolated simple shunts associated PAH were included. Peak tricuspid regurgitation velocity<2.8 m/sec with normalized cardiac structures was defined as the favorable study outcome. We applied unsupervised and supervised machine learning for clustering analysis and model constructions.

RESULTS

Finally, 246 patients were included. During a median follow-up of 414days, 58.49% (62/106) of patients with pretricuspid shunts achieved favorable outcome while 32.22% (46/127) of patients with post-tricuspid shunts. In unsupervised learning, two clusters were identified in both types of shunts. Generally, the oxygen saturation, pulmonary blood flow, cardiac index, dimensions of the right and left atrium, were the major features that characterized the identified clusters. Specifically, mean right atrial pressure, right ventricular dimension, and right ventricular outflow tract helped differentiate clusters in pretricuspid shunts while age, aorta dimension, and systemic vascular resistance helped differentiate clusters for post-tricuspid shunts. Notably, cluster 1 had better postclosure outcome than cluster 2 (70.83% vs 32.55%, p < .001 for pretricuspid and 48.10% vs 16.67%, p < .001 for post-tricuspid). However, models constructed from supervised learning methods did not achieve good accuracy for predicting the postclosure outcome.

CONCLUSIONS

There were two main clusters in patients with borderline hemodynamics, in which one cluster had better postclosure outcome than the other.

The Microenvironment of the Pathogenesis of Cardiac Hypertrophy

Pathological cardiac hypertrophy is a key risk factor for the development of heart failure and predisposes individuals to cardiac arrhythmia and sudden death. While physiological cardiac hypertrophy is adaptive, hypertrophy resulting from conditions comprising hypertension, aortic stenosis, or genetic mutations, such as hypertrophic cardiomyopathy, is maladaptive. Here, we highlight the essential role and reciprocal interactions involving both cardiomyocytes and non-myocardial cells in response to pathological conditions. Prolonged cardiovascular stress causes cardiomyocytes and non-myocardial cells to enter an activated state releasing numerous pro-hypertrophic, pro-fibrotic, and pro-inflammatory mediators such as vasoactive hormones, growth factors, and cytokines, i.e., commencing signaling events that collectively cause cardiac hypertrophy. Fibrotic remodeling is mediated by cardiac fibroblasts as the central players, but also endothelial cells and resident and infiltrating immune cells enhance these processes. Many of these hypertrophic mediators are now being integrated into computational models that provide system-level insights and will help to translate our knowledge into new pharmacological targets. This perspective article summarizes the last decades' advances in cardiac hypertrophy research and discusses the herein-involved complex myocardial microenvironment and signaling components.

Pulmonary Hypertension in Left Heart Diseases: Pathophysiology, Hemodynamic Assessment and Therapeutic Management

Pulmonary hypertension (PH) associated with left heart diseases (PH-LHD), also termed group 2 PH, represents the most common form of PH. It develops through the passive backward transmission of elevated left heart pressures in the setting of heart failure, either with preserved (HFpEF) or reduced (HFrEF) ejection fraction, which increases the pulsatile afterload of the right ventricle (RV) by reducing pulmonary artery (PA) compliance. In a subset of patients, progressive remodeling of the pulmonary circulation resulted in a pre-capillary phenotype of PH, with elevated pulmonary vascular resistance (PVR) further increasing the RV afterload, eventually leading to RV-PA uncoupling and RV failure. The primary therapeutic objective in PH-LHD is to reduce left-sided pressures through the appropriate use of diuretics and guideline-directed medical therapies for heart failure. When pulmonary vascular remodeling is established, targeted therapies aiming to reduce PVR are theoretically appealing. So far, such targeted therapies have mostly failed to show significant positive effects in patients with PH-LHD, in contrast to their proven efficacy in other forms of pre-capillary PH. Whether such therapies may benefit some specific subgroups of patients (HFrEF, HFpEF) with specific hemodynamic phenotypes (post- or pre-capillary PH) and various degrees of RV dysfunction still needs to be addressed.

Pulmonary Hypertension Association's 2022 International Conference Scientific Sessions Overview

The considerable progress made in recent years in the diagnosis, risk stratification, and treatment of pulmonary hypertension was highlighted during the most recent edition of the Pulmonary Hypertension Association Scientific Sessions, which was held in Atlanta, Georgia from June 9 to 11, 2022, with the theme: Vision for the PHuture: The Evolving Science and Management of PH. Content presented over the 3-day conference focused on scientific and management updates since the last sessions were held in 2018 and included didactic talks, debates, and roundtable discussions across a broad spectrum of topics related to pulmonary hypertension. This article aims to summarize the key messages from each of the session talks.