Pulmonary hypertension: diagnosis, imaging techniques, and novel therapies

Fluid loading during the hemodynamic evaluation of pulmonary hypertension: a cross-sectional study

Background

Compensated pulmonary hypertension due to left heart disease (PH-LHD) may be difficult to identify based on resting hemodynamics. Fluid challenge is commonly used to unmask occult PH-LHD. We sought to determine the hemodynamic effect of fluid loading and its association with the clinical pretest probability of PH-LHD.

Methods

We included consecutive patients evaluated for PH who underwent right heart catheterization (RHC) with fluid challenge at Cleveland Clinic between April 2013 and January 2019. We obtained hemodynamic measurements at rest and after intravenous rapid fluid challenge (500 mL of normal saline). We calculated the pretest probability of PH-LHD based on the 6th World Symposium on PH proceedings. For statistical analyses we used t-test, analysis of variance (ANOVA), Chi-square, paired t-test, Wilcoxon signed-rank test and linear regression as indicated.

Results

We included 174 patients with mean ± standard deviation (SD) age of 63.7±13.0 years and 123 (71%) of female sex. Baseline pulmonary artery wedge pressure (PAWP) was 11±5 mmHg, with a PAWP/cardiac output (CO) ratio of 2.1±1.1 Wood units (WU). The absolute increase in PAWP and PAWP/CO was 6.9±3.6 mmHg and 1.06±0.91 WU, respectively. The change in PAWP was inversely associated with baseline PAWP (P<0.001). The PAWP with fluids was >18 mmHg in 81% of the patients with baseline PAWP 13-15 mmHg. We found no strong associations between the change in PAWP, PAWP/CO or right atrial pressure to pulmonary arterial wedge pressure ratio (RAP/PAWP) and the pretest probability of PH-LHD.

Conclusions

The absolute change in PAWP, PAWP/CO, or achieving a PAWP >18 mmHg with rapid fluid loading was not robustly associated with the pretest probability of PH-LHD. Patients with PAWP between 13-15 mmHg commonly had a positive fluid challenge, questioning the utility of this intervention in these patients.

Inhaled nitric oxide: can it serve as a savior for COVID-19 and related respiratory and cardiovascular diseases?

Nitric oxide (NO), as an important gaseous medium, plays a pivotal role in the human body, such as maintaining vascular homeostasis, regulating immune-inflammatory responses, inhibiting platelet aggregation, and inhibiting leukocyte adhesion. In recent years, the rapid prevalence of coronavirus disease 2019 (COVID-19) has greatly affected the daily lives and physical and mental health of people all over the world, and the therapeutic efficacy and resuscitation strategies for critically ill patients need to be further improved and perfected. Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator, and some studies have demonstrated its potential therapeutic use for COVID-19, severe respiratory distress syndrome, pulmonary infections, and pulmonary hypertension. In this article, we describe the biochemistry and basic characteristics of NO and discuss whether iNO can act as a "savior" for COVID-19 and related respiratory and cardiovascular disorders to exert a potent clinical protective effect.

Diagnostic value of two-dimensional echocardiographic measurements of the pulmonary artery diameter and the pulmonary artery distensibility index to detect pulmonary hypertension in horses

INTRODUCTION/OBJECTIVES

Echocardiographic diagnosis of pulmonary hypertension (PH) in horses is usually based on Doppler interrogation of tricuspid (TR) or pulmonic regurgitation (PR). This study aimed at investigating two-dimensional echocardiographic (2DE) variables, including pulmonary artery diameter (PAD) and pulmonary artery distensibility index (PADI), to diagnose PH.

ANIMALS, MATERIALS AND METHODS

41 healthy horses; 82 horses with TR or PR and normal intracardiac pressure gradients; and 35 horses with TR or PR velocities indicating PH. The 2DE variables were compared between groups, cut-offs for the diagnosis of PH were determined, and conditional inference trees served to identify the variable best predicting PH in the absence of TR or PR.

RESULTS

Horses with PH had larger end-diastolic cross-sectional (short-axis) PAD (PADed-sx) (5.8 ± 1.0 cm; mean ± SD) and smaller PADI[/PADps] (15.4 ± 7.7%) than healthy horses (5.0 ± 0.6 cm, P<0.0001; 20.5 ± 4.4%, P<0.001) and horses with TR or PR but no PH (5.3 ± 0.6 cm, P=0.003; 18.8 ± 4.2%, P=0.005). PADed-sx predicted PH with sensitivity (Se) = 36% and specificity (Sp) = 94% (cut-off 6.0 cm, AUC = 0.668, P=0.002), while PADI[/PADps] predicted PH with Se = 43% and Sp = 92% (cut-off 13.7%, AUC = 0.662, P=0.004). In the absence of TR, PADed-sx and the end-diastolic long-axis aortic diameter-to-PADed-sx ratio (AoDed-lx/PADed-sx) were most suitable to diagnose PH.

CONCLUSION

Pulmonary artery crosssectional (short-axis) diameter at end-diastole measured in a right-parasternal long axis view of the left ventricular outflow tract and Pulmonary artery distensibility index were moderately specific but not very sensitive to diagnosing PH. Nonetheless, they may be used as complementary indices suggesting PH in the absence of TR or PR.

New Drugs and Therapies in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension is a chronic, progressive disorder of the pulmonary vasculature with associated pulmonary and cardiac remodeling. PAH was a uniformly fatal disease until the late 1970s, but with the advent of targeted therapies, the life expectancy of patients with PAH has now considerably improved. Despite these advances, PAH inevitably remains a progressive disease with significant morbidity and mortality. Thus, there is still an unmet need for the development of new drugs and other interventional therapies for the treatment of PAH. One shortcoming of currently approved vasodilator therapies is that they do not target or reverse the underlying pathogenesis of the disease process itself. A large body of evidence has evolved in the past two decades clarifying the role of genetics, dysregulation of growth factors, inflammatory pathways, mitochondrial dysfunction, DNA damage, sex hormones, neurohormonal pathways, and iron deficiency in the pathogenesis of PAH. This review focuses on newer targets and drugs that modify these pathways as well as novel interventional therapies in PAH.

Molecular Pathways in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension is a multifactorial, chronic disease process that leads to pulmonary arterial endothelial dysfunction and smooth muscular hypertrophy, resulting in impaired pliability and hemodynamics of the pulmonary vascular system, and consequent right ventricular dysfunction. Existing treatments target limited pathways with only modest improvement in disease morbidity, and little or no improvement in mortality. Ongoing research has focused on the molecular basis of pulmonary arterial hypertension and is going to be important in the discovery of new treatments and genetic pathways involved. This review focuses on the molecular pathogenesis of pulmonary arterial hypertension.

Bronchoscopic Lung Volume Reduction for Emphysema: Review and Update

In carefully selected patients with severe chronic obstructive pulmonary disease, characterized by emphysema and hyperinflation, lung volume reduction is an option to reduce lung hyperinflation, improve lung function, quality of life, and exercise capacity. Currently, there are several bronchoscopic and surgical treatment options to achieve lung volume reduction. It is important to carefully phenotype these patients, to select the optimal treatment option, with consideration of possible adverse events or contraindications, and it is highly recommended to discuss these treatment strategies in a multidisciplinary team. The treatment with one-way endobronchial valves has been investigated most extensively and more data are available regarding the treatment of more "marginal cases," or subsequent lung volume reduction surgery. Other bronchoscopic lung volume reduction options include treatment with coils, thermal vapor ablation, and sclerosant agents. In this review, we aim to summarize the current clinical evidence on the bronchoscopic lung volume reduction therapies and important aspects regarding optimal patient selection.

The outcome of lung transplantation for end-stage pulmonary diseases with pulmonary hypertension: a single-center experience

BACKGROUND

Lung transplantation is a treatment for end-stage lung disease. The optimal transplant strategy for patients with end-stage lung disease complicated by pulmonary hypertension (PH) is controversial. The aim of this study is to review this experience and analyze the outcomes of lung transplantation for PH.

METHODS

This retrospective study collected data on patients with PH undergoing lung transplantation between March 2016 and December 2019 at a single center in China. The perioperative features and short- and medium-term outcomes between single-lung transplantation (SLT) and double-lung transplantation (DLT) were compared. Kaplan-Meier methods were used to analyze overall survival across a variety of transplantation procedures, age, mean pulmonary artery pressure (mPAP), body mass index (BMI), and indications of transplantation.

RESULTS

A total of 63 patients with PH were finally included in the analysis. The mean age, mean BMI, and mPAP were 56.37 years, 19.56 kg/m², and 35.4 mmHg respectively. The overall 1-, 2-, and 3-year survival was 70%, 63%, and 60%, respectively. Five (7.94%) patients died within 30 days after surgery and nine patients (14.3%) died from infection during the followed-up period. There were no significant differences in the short- and medium-term survival outcomes of SLT and DLT, but postoperative pulmonary function was better in DLT. Patients older than 60 years of age had worse survival (P=0.01).

CONCLUSIONS

The short- and medium-term survival outcomes between SLT and DLT are similar in selected patients with PH. DLT provides better pulmonary function. Patients older than 60 years are associated with worse survival.

Bioactivities and mechanisms of natural medicines in the management of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive and rare disease without obvious clinical symptoms that shares characteristics with pulmonary vascular remodeling. Right heart failure in the terminal phase of PAH seriously threatens the lives of patients. This review attempts to comprehensively outline the current state of knowledge on PAH its pathology, pathogenesis, natural medicines therapy, mechanisms and clinical studies to provide potential treatment strategies. Although PAH and pulmonary hypertension have similar pathological features, PAH exhibits significantly elevated pulmonary vascular resistance caused by vascular stenosis and occlusion. Currently, the pathogenesis of PAH is thought to involve multiple factors, primarily including genetic/epigenetic factors, vascular cellular dysregulation, metabolic dysfunction, even inflammation and immunization. Yet many issues regarding PAH need to be clarified, such as the "oestrogen paradox". About 25 kinds monomers derived from natural medicine have been verified to protect against to PAH via modulating BMPR2/Smad, HIF-1α, PI3K/Akt/mTOR and eNOS/NO/cGMP signalling pathways. Yet limited and single PAH animal models may not corroborate the efficacy of natural medicines, and those natural compounds how to regulate crucial genes, proteins and even microRNA and lncRNA still need to put great attention. Additionally, pharmacokinetic studies and safety evaluation of natural medicines for the treatment of PAH should be undertaken in future studies. Meanwhile, methods for validating the efficacy of natural drugs in multiple PAH animal models and precise clinical design are also urgently needed to promote advances in PAH.

Expression of the microRNA-30 family in pulmonary arterial hypertension and the role of microRNA-30d-5p in the regulation of pulmonary arterial smooth muscle cell toxicity and apoptosis

The biological processes of pulmonary artery vascular smooth muscle cells (PA-SMCs) and pulmonary artery endothelial cells in pulmonary arterial hypertension (PAH) are generally abnormal, with increased levels of proliferation and reduced levels of apoptosis. Although microRNAs (miRNAs/miRs) participate in a number of biological processes in a variety of diseases, such as tumors and infections, studies on the association between miRNAs and PAH are limited. In the present study, blood samples were collected from 6 patients with patent ductus arteriosus. The experimental group included 3 patients with severe PAH, while the control group included 3 patients without PAH. Microarray technology was used to detect the presence of any associated miRNAs. Moreover, a rat PAH model was established via left lung resection followed by monocrotaline injection, involving a total of 8 rats in the PAH group and 8 untreated rat in the control group. Reverse transcription-quantitative PCR was performed to verify the expression levels of the miR-30 family in the animal model. miR-30d-5p mimics and anti-miR-30d-5p were transfected into primary cultured PA-SMCs. Levels of cytotoxicity and cell apoptosis were examined, and Notch-3 expression levels were studied using western blotting. The results of the present study demonstrated that miR-30d-5p expression was downregulated in both patient blood and animal models of the PAH group compared with control groups. In primary cultured PA-SMCs, overexpression of miR-30d-5p attenuated the platelet-derived growth factor-induced toxicity of PA-SMCs, while knockdown of miR-30d-5p resulted in the increased toxicity of PA-SMCs compared with control group. The apoptosis rate of PA-SMCs increased with the overexpression of miR-30d-5p compared with control group. Moreover, the expression levels of Notch-3 in the miR-30d-5p group were significantly reduced compared with the anti-miR-30d-5p and miR-NC groups. In total, 10 circulating miRNAs that may be associated with PAH were discovered in the present study. Moreover, the expression of the miR-30 family was verified in animal models in vivo, and seven miRNAs in this family were discovered that may be associated with PAH. Additionally, miR-30d-5p was downregulated in both patients with PAH and animal models compared with control groups. Thus, the results of the present study demonstrated that the regulatory mechanism underlying PA-SMCs may be via the Notch-3 signaling pathway.

Treatment of pulmonary arterial hypertension in children

Pulmonary arterial hypertension (PAH) is a devastating illness causing already significant morbidity in childhood. Currently approved treatment options for children comprise the endothelin receptor antagonist bosentan, as well as the phosphodiesterase-5 inhibitor sildenafil. But PAH treatment has advanced significantly over the past decade, and new classes of targeted drug therapies, such as stimulators of the soluble guanylate cyclase (riociguat) or prostacyclin receptor agonists (selexipag), are currently evaluated regarding their efficacy and safety in children, in order to limit off-label use. Due to the different etiologies in children, such as PAH-CHD, there is no evidence that initial combination therapy in children is superior to a mono-therapy with respect to survival. Special attention should also be paid to the pharmacology of PAH drugs in children, which might be impacted by ontogeny or drug-drug-interactions. Therapeutic drug monitoring may be useful in pediatric patients. There is a clear need for more controlled studies of PAH medications, alone or in combination therapy in the pediatric age group. Data from clinical trials as well as from patient registries should be pooled to optimize drug development and evaluation, trial design, and evidence-based pharmacotherapy in pediatric patients with PAH. In this review, the current treatment options of pediatric PAH are summarized, and an overview of new treatment concepts, which are already evaluated in adults, is presented.

Possible protective effect of TNF-α inhibition and triad NO/cGMP/VEGF activation on gastric ulcer in rats

Peptic ulcers are one of the world's major gastrointestinal disorders, embracing both gastric and duodenal ulcers, and affecting 10% of the world population. The current study aimed to investigate the possible protective effect of tadalafil and pentoxifylline (PTX) on indomethacin-induced peptic ulcers. Male albino rats were divided into five groups: control group; ulcerated group; Indomethacin + Tadalafil, in which animals were pretreated with tadalafil orally before indomethacin; Indomethacin+ PTX, in which animals were pretreated with PTX orally before indomethacin; and Indomethacin + Tadafil + PTX. Indomethacin treatment revealed histopathological changes and ulcer scoring and ulcer index were markedly increased. Serum levels of prostaglandin and heme oxygenase-1 were significantly decreased. The ulcerogenic also induced marked oxidative stress as evident from the increased malondialdehyde, decreased in gastric glutathione content and superoxide dismutase activity, while the gastric myeloperoxidase was increased. Gastric nitric oxide content was decreased and the expression of vascular endothelial growth factor was downregulated while the tumor necrosis factor α (TNF-α) level was dramatically increased. Pretreatment of the ulcerative group by either tadalafil or PTX or their combination improved all these pathological changes. Tadalafil or PTX may have a role in protecting gastric mucosa damage caused by indomethacin which may be useful in the future for the treatment of gastric ulceration.

Unrecognized pulmonary arterial hypertension in hospitalized patients

Pulmonary hypertension (PH) is an underdiagnosed and potentially fatal condition. The utility of screening for PH in hospitalized patients undergoing echocardiography is unknown. The goal of this study was to determine the prevalence of undiagnosed pulmonary hypertension (PH) and probable pulmonary arterial hypertension (PAH) in hospitalized patients undergoing echocardiography for any indication. All hospitalized patients undergoing echocardiography were identified and echocardiographs reviewed prospectively for the presence of a tricuspid regurgitant (TR) jet. Electronic medical records (EMR) of patients with a TR jet ≥ 3 m/s were reviewed for identifiable causes of pulmonary hypertension. Patients with no identifiable cause were classified as presumptive World Health Organization (WHO) Group 1 PH (also known as PAH). These PAH patients were compared to other PH patients for baseline demographic characteristics and comorbidities as well as 30-day readmission and mortality. The admitting physicians of patients classified as PH were advised to consider further evaluation including right heart catheterization. We reviewed 4417 consecutive echocardiograms and identified 448 with a TR jet ≥ 3 m/s. Of these 448 patients with PH, 47 were identified as "presumptive PAH" and the other 401 as having PH belonging to WHO Groups 2-5. Presumptive PAH represented 1% of screened echocardiograms and 10.5% of those identified to have an elevated TR jet. Of the patients identified as presumptive PAH, 8 underwent further evaluation including a right heart catheterization, where 5 were confirmed to have PAH. Kaplan-Meier analysis revealed 30-day readmission was higher among those classified as PAH. Our data shows that pulmonary hypertension, as defined by TR jet ≥ 3 m/s, is frequently encountered in hospitalized patients undergoing echocardiography for any reason. A careful review of echocardiogram findings and clinical history suggested 10.5% of those with PH (and 1% of all screened patients) may meet the criteria for PAH. Considering PH is a fatal condition which is frequently missed, a hospital screening program seems feasible.

Emerging role of cardiovascular magnetic resonance imaging in the management of pulmonary hypertension

Pulmonary hypertension (PH) is a clinical condition characterised by elevation of pulmonary arterial pressure (PAP) above normal range due to various aetiologies. While cardiac right-heart catheterisation (RHC) remains the gold standard and mandatory for establishing the diagnosis of PH, noninvasive imaging of the heart plays a central role in the diagnosis and management of all forms of PH. Although Doppler echocardiography (ECHO) can measure a range of haemodynamic and anatomical variables, it has limited utility for visualisation of the pulmonary artery and, oftentimes, the right ventricle. Cardiovascular magnetic resonance (CMR) provides comprehensive information about the anatomical and functional aspects of the pulmonary artery and right ventricle that are of prognostic significance for assessment of long-term outcomes in disease progression. CMR is suited for serial follow-up of patients with PH due to its noninvasive nature, high sensitivity to changes in anatomical and functional parameters, and high reproducibility. In recent years, there has been growing interest in the use of CMR derived parameters as surrogate endpoints for early-phase PH clinical trials. This review will discuss the role of CMR in the diagnosis and management of PH, including current applications and future developments, in comparison to other existing major imaging modalities.

Hydroxysafflor yellow A actives BKCa channels and inhibits L-type Ca channels to induce vascular relaxation

Hydroxy-safflor yellow A (HSYA) can exert a variety of effects upon the vascular system. However, the underlying mechanisms are not clear. The present study is to investigate its vasodilating effect and the mechanisms. Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) were enrolled for studying effects of HSYA on blood pressure, vasodilation, intracellular Ca²⁺ transient and membrane ion channels. Vasodilation and intracellular Ca²⁺ transient were measured by using vasomotor assay and fluorescence imaging system, respectively. The effect of HSYA on the large conductance Ca²⁺ activated and voltage-gated potassium channel (BK_Ca channel) currents in rat mesentery artery and on L-type calcium channel (Ca-L) currents in HEK293cells expressed with Ca-L were investigated using patch clamp techniques. Blood pressure of SHR and WKY rats were concentration dependently reduced by HSYA with a larger effect of HSYA in SHR than that in WKY rats. The tension of mesenteric arteries induced by 3 μM phenylephrine was attenuated by HSYA (IC₅₀ = 90.8 μΜ). Patch clamp study showed that HSYA could activate BK_Ca channels and suppress Ca-L channels in a concentration dependent manner. The results of calcium signaling assays indicated that HSYA could reduce the intracellular free Ca²⁺ level. These findings demonstrate that HSYA could activate BK_Ca channels and inhibit Ca-L channels and reduce intracellular free Ca²⁺ level, which are probably important for its vasodilatory effect.

Imaging of pulmonary hypertension: an update

Pulmonary hypertension (PH) is characterized by elevated pulmonary arterial pressure caused by a broad spectrum of congenital and acquired disease processes, which are currently divided into five groups based on the 2013 WHO classification. Imaging plays an important role in the evaluation and management of PH, including diagnosis, establishing etiology, quantification, prognostication and assessment of response to therapy. Multiple imaging modalities are available, including radiographs, computed tomography (CT), magnetic resonance imaging (MRI), nuclear medicine, echocardiography and invasive catheter angiography (ICA), each with their own advantages and disadvantages. In this article, we review the comprehensive role of imaging in the evaluation of PH.

Dual-energy CT (DECT) lung perfusion in pulmonary hypertension: concordance rate with V/Q scintigraphy in diagnosing chronic thromboembolic pulmonary hypertension (CTEPH)

OBJECTIVES

To evaluate the concordance between DECT perfusion and ventilation/perfusion (V/Q) scintigraphy in diagnosing chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

Eighty patients underwent V/Q scintigraphy and DECT perfusion on a 2nd- and 3rd-generation dual-source CT system. The imaging criteria for diagnosing CTEPH relied on at least one segmental triangular perfusion defect on DECT perfusion studies and V/Q mismatch on scintigraphy examinations.

RESULTS

Based on multidisciplinary expert decisions that did not include DECT perfusion, 36 patients were diagnosed with CTEPH and 44 patients with other aetiologies of PH. On DECT perfusion studies, there were 35 true positives, 6 false positives and 1 false negative (sensitivity 0.97, specificity 0.86, PPV 0.85, NPV 0.97). On V/Q scans, there were 35 true positives and 1 false negative (sensitivity 0.97, specificity 1, PPV 1, NPV 0.98). There was excellent agreement between CT perfusion and scintigraphy in diagnosing CTEPH (kappa value 0.80). Combined information from DECT perfusion and CT angiographic images enabled correct reclassification of the 6 false positives and the unique false negative case of DECT perfusion.

CONCLUSION

There is excellent agreement between DECT perfusion and V/Q scintigraphy in diagnosing CTEPH. The diagnostic accuracy of DECT perfusion is reinforced by the morpho-functional analysis of data sets.

KEY POINTS

• Chronic thromboembolic pulmonary hypertension (CTEPH) is potentially curable by surgery. • The triage of patients with pulmonary hypertension currently relies on scintigraphy. • Dual-energy CT (DECT) can provide standard diagnostic information and lung perfusion from a single acquisition. • There is excellent agreement between DECT perfusion and scintigraphy in separating CTEPH and non-CTEPH patients.