Prevalence and Associated Factors of Portopulmonary Hypertension in Patients with Portal Hypertension: A Case-Control Study

Portopulmonary hypertension: peculiarities of diagnosis and treatment

Portopulmonary hypertension is defined as the development of pulmonary hypertension secondary to portal one. Its exact prevalence is difficult to determine due to the lack of routine screening in patients with portal hypertension. Hemodynamic changes associated with portal hypertension, including the hyperdynamic state, portosystemic shunts, and splanchnic vasodilation, cause significant disturbances in the pulmonary vasculature and play a key role in the pathogenesis of the disease. Without treatment, portopulmonary hypertension leads to progressive right ventricular failure with a poor prognosis. Although Doppler echocardiography is the best initial screening tool for symptomatic patients and candidates for liver transplant, right heart catheterization remains the gold standard for disease diagnosis. Treatment of patients with portopulmonary hypertension is aimed at improving cardiac function, reducing pulmonary vascular resistance, and optimizing functional capacity. Pulmonary hypertension-specific therapy, which includes prostacyclin and its receptor agonists, endothelin receptor antagonists, phosphodiesterase inhibitors, and guanylate cyclase stimulators, plays a key role in the treatment of patients with portopulmonary hypertension. Small uncontrolled and recent single randomized controlled trials have reported promising results of vasodilator therapy in terms of clinical and hemodynamic improvement in patients, allowing certain patients to undergo liver transplantation. This review discusses the epidemiology, approach to diagnosis and treatment of patients with portopulmonary hypertension. We used MEDLINE database on the PubMed platform and the Cochrane library to search for literature sources using the keywords: portopulmonary hypertension, portal hypertension, pulmonary hypertension, liver cirrhosis, pulmonary complications.

Is pulmonary arterial hypertension associated with schistosomiasis distinct from pulmonary arterial hypertension associated with portal hypertension?

Pulmonary arterial hypertension associated with schistosomiasis (SchPAH) and pulmonary arterial hypertension associated with portal hypertension (PoPAH) are lung diseases that develop in the presence of liver diseases. However, mechanistic pathways by which the underlying liver conditions and other drivers contribute to the development and progression of pulmonary arterial hypertension (PAH) are unclear for both etiologies. In turn, these unknowns limit certainty of strategies to prevent, diagnose, and reverse the resultant PAH. Here we consider specific mechanisms that contribute to SchPAH and PoPAH, identifying those that may be shared and those that appear to be unique to each etiology, in the hope that this exploration will both highlight known causal drivers and identify knowledge gaps appropriate for future research. Overall, the key pathophysiologic differences that we identify between SchPAH and PoPAH suggest that they are not variants of a single condition.

Portopulmonary Hypertension: An Updated Review

Portal hypertension may have major consequences on the pulmonary vasculature due to the complex pathophysiological interactions between the liver and lungs. Portopulmonary hypertension (PoPH), a subset of group 1 pulmonary hypertension (PH), is a serious pulmonary vascular disease secondary to portal hypertension, and is the fourth most common subtype of pulmonary arterial hypertension. It is most commonly observed in cirrhotic patients; however, patients with noncirrhotic portal hypertension can also develop it. On suspicion of PoPH, the initial evaluation is by a transthoracic echocardiogram in which, if elevated pulmonary pressures are shown, patients should undergo right heart catheterization to confirm the diagnosis. The prognosis is extremely poor in untreated patients; therefore, management includes pulmonary arterial hypertension therapies with the aim of improving pulmonary hemodynamics and moving patients to orthotopic liver transplantation (OLT). In this article, we review in detail the epidemiology, pathophysiology, process for diagnosis, and most current treatments including OLT and prognosis in patients with PoPH. In addition, we present a diagnostic algorithm that includes the current criteria to properly select patients with PoPH who are candidates for OLT.

Current clinical understanding and effectiveness of portopulmonary hypertension treatment

Portopulmonary hypertension (PoPH) is a rare subtype of Group 1 pulmonary arterial hypertension (PAH) with a poor prognosis. According to the most up-to-date definition, PoPH is characterized by a mean pulmonary arterial pressure (PAP) of >20 mmHg at rest, a pulmonary artery wedge pressure of ≤15 mmHg, and a pulmonary vascular resistance (PVR) of >2 Wood units with portal hypertension. Like PAH, PoPH is underpinned by an imbalance in vasoactive substances. Therefore, current guidelines recommend PAH-specific therapies for PoPH treatment; however, descriptions of the actual treatment approaches are inconsistent. Given the small patient population, PoPH is often studied in combination with idiopathic PAH; however, recent evidence suggests important differences between PoPH and idiopathic PAH in terms of hemodynamic parameters, treatment approaches, survival, socioeconomic status, and healthcare utilization. Therefore, large, multi-center registry studies are needed to examine PoPH in isolation while obtaining statistically meaningful results. PoPH has conventionally been excluded from clinical drug trials because of concerns over hepatotoxicity. Nevertheless, newer-generation endothelin receptor antagonists have shown great promise in the treatment of PoPH, reducing PVR, PAP, and World Health Organization functional class without causing hepatotoxicity. The role of liver transplantation as a treatment option for PoPH has also been controversial; however, recent evidence shows that this procedure may be beneficial in this patient population. In the future, given the shortage of liver donors, predictors of a favorable response to liver transplantation should be determined to select the most eligible patients. Collectively, advances in these three areas could help to standardize PoPH treatment in the clinic.

Risk factors for portopulmonary hypertension in patients with cirrhosis: a prospective, multicenter study

BACKGROUND

Tricuspid regurgitation pressure gradient (TRPG) measurement by echocardiography is recommended as the most objective examination to detect portopulmonary hypertension (PoPH). This study aimed to identify factors associated with a high TRPG in patients with cirrhosis and develop a scoring model for identifying patients who are most likely to benefit from echocardiography investigations.

RESULTS

A total of 486 patients who underwent echocardiography were randomly allocated to the derivation and validation sets at a ratio of 2:1. Of the patients, 51 (10.5%) had TRPG ≥ 35 mmHg. The median brain natriuretic peptide (BNP) was 39.5 pg/mL. Shortness of breath (SOB) was reported by 91 (18.7%) patients. In the derivation set, multivariate analysis identified female gender, shortness of breath, and BNP ≥ 48.9 pg/mL as independent factors for TRPG ≥ 35 mmHg. The risk score for predicting TRPG ≥ 35 mmHg was calculated as follows: - 3.596 + 1.250 × gender (female: 1, male: 0) + 1.093 × SOB (presence: 1, absence: 0) + 0.953 × BNP (≥ 48.9 pg/mL: 1, < 48.9 pg/mL: 0). The risk score yielded sensitivity of 66.7%, specificity of 75.3%, positive predictive value of 25.5%, negative predict value of 94.3%, and predictive accuracy of 74.4% for predicting TRPG ≥ 35 mmHg. These results were almost similar in the validation set, indicating the reproducibility and validity of the risk score.

CONCLUSIONS

This study clarified the characteristics of patients with suspected PoPH and developed a scoring model for identifying patients at high risk of PoPH, which may be used in selecting patients that may benefit from echocardiography.

Clinical Management and Outcomes of Patients With Portopulmonary Hypertension Enrolled in the Japanese Multicenter Registry

Background: Portopulmonary hypertension (PoPH) is one of the major underlying causes of pulmonary arterial hypertension (PAH). However, PoPH, especially treatment strategies, has been poorly studied. Therefore, this study evaluated current treatments for PoPH, their efficacy, and clinical outcomes of patients with PoPH. Methods and Results: Clinical data were collected for patients with PoPH who were enrolled in the Japan Pulmonary Hypertension Registry between 2008 and 2021. Hemodynamic changes, functional class, and clinical outcomes were compared between patients with PoPH treated with monotherapy and those treated with combination therapies. Clinical data were analyzed for 62 patients with PoPH, including 25 treatment-naïve patients, from 21 centers in Japan. In more than half the patients, PAH-specific therapy improved the New York Heart Association functional class by at least one class. The 3- and 5-year survival rates of these patients were 88.5% (95% confidence interval [CI] 76.0-94.7) and 80.2% (95% CI 64.8-89.3), respectively. Forty-one (66.1%) patients received combination therapy. Compared with patients who had received monotherapy, the mean pulmonary arterial pressure, pulmonary vascular resistance, and cardiac index were significantly improved in patients who had undergone combination therapies. Conclusions: Combination therapy was commonly used in patients with PoPH with a favorable prognosis. Combination therapies resulted in significant hemodynamic improvement without an increased risk of side effects.

Simple algorithm to narrow down the candidates to receive echocardiography in patients with chronic liver disease for suspected pulmonary hypertension

Aims

Portopulmonary hypertension (PoPH) is a subtype of pulmonary arterial hypertension related to portal hypertension. The definitive diagnosis of PoPH is made by invasive right heart catheterization. Alternatively, pulmonary arterial hypertension may be recognized noninvasively from the tricuspid regurgitant pressure gradient (TRPG), measured by echocardiography. In this study, we aimed to establish a simple algorithm to identify chronic liver disease patients with a high TRPG value in order to narrow down the candidates to receive echocardiography.

Methods and Results

TRPG was measured by echocardiography in 152 patients with chronic liver disease. Factors predictive of TRPG >30 mmHg were investigated. There were 28 (18%) cases with TRPG >30 mmHg. Independent factors associated with a high TRPG were the presence of shortness of breath, high serum brain natriuretic peptide (BNP), and low serum albumin. Child–Pugh class or the presence of ascites, varices, or encephalopathy was not associated with TRPG. There was a correlation between the serum BNP and TRPG, and the optimal cutoff value of BNP by the Youden index was 122 pg/mL, and by 100% sensitivity was 50 pg/mL. A combination of these factors identified patients with a high probability of TRPG >30 mmHg (n = 12, positive predictive value [PPV] of 83%), no probability (n = 80, PPV 0%), and intermediate probability (n = 60, PPV 25–34%). This algorithm has reduced the number of patients needing echocardiography by 53%.

Conclusions

A simple algorithm using the presence of shortness of breath, serum BNP, and albumin levels can narrow down the candidates to receive echocardiography.

Prevalence and Clinical Features of Portopulmonary Hypertension in Patients With Hepatic Cirrhosis: An Echocardiographic Study

Objective

The present study was conducted to delineate the prevalence and clinical features of portopulmonary hypertension in patients with hepatic cirrhosis. Possible associations between echocardiographic variables and portopulmonary hypertension were also explored.

Methods

A prospective, observational study was conducted between September 2017 and August 2018. Differences in demographics, clinical presentation, laboratory findings, and echocardiographic findings in cirrhosis patients with and without portopulmonary hypertension were compared.

Results

The prevalence of portopulmonary hypertension in patients with hepatic cirrhosis was found to be 9.3%. Hemoglobin was significantly lower among patients with portopulmonary hypertension compared to those without portopulmonary hypertension (5.50±0.68 g/dl vs. 7.26±1.43 g/dl, p=0.001). All patients with portopulmonary hypertension displayed right atrial (major: p=0.0001 and minor: p=0.001) and right ventricular (basal, p=0.0001; longitudinal, p=0.0001) dilation. Several variables such as right ventricular systolic pressure (p=0.0001), pulmonary artery diameter (major: p=0.0001; right: p=0.0001; and left: p=0.007), pulmonary vascular resistance (p=0.0001), tricuspid regurgitation (p=0.0001), pulmonary regurgitation peak pressure gradient (p=0.0001), pulmonary regurgitation end diastolic gradient (p=0.0001), left atrial dimension (major axis: p=0.002), left atrial volume (p=0.04), left ventricular outflow tract (p=0.001), inferior vena cava diameter (p=0.001), and inferior vena cava collapsibility (p=0.001) were higher in patients with portopulmonary hypertension compared to patients without portopulmonary hypertension.

Conclusions

The present study revealed a 9.3% prevalence of portopulmonary hypertension among patients with hepatic cirrhosis. Patients with portopulmonary hypertension displayed significantly lower haemoglobin levels, right and left ventricular dilation, and higher values of several echocardiographic variables as compared to those without portopulmonary hypertension.

Screening for portopulmonary hypertension using computed tomography-based measurements of the main pulmonary artery and ascending aorta diameters in patients with portal hypertension

AIM

This study aimed to demonstrate the feasibility of identifying candidates of portopulmonary hypertension (PoPH) from general portal hypertension patients based on chest computed tomography (CT) results.

METHODS

One hundred and thirty patients with portal hypertension who had undergone interventional radiology therapies at our hospital between August 2011 and July 2021 were included, and preoperative clinical data were collected. Suspicious PoPH was defined as main pulmonary artery diameter (mPA-D) ≥ 29 mm or the ratio of mPA-D to ascending aorta diameter (mPA-D/aAo-D) ≥ 1.0, and probable PoPH as mPA-D ≥ 33 mm based on the chest CT. Prevalence of suspicious and probable PoPH was evaluated, and the differences in clinical characteristics of each population were compared.

RESULTS

Overall, 29 (22.3%) and 5 (3.8%) patients were categorized as suspicious and probable PoPH, respectively. Univariate analyses revealed that female sex, higher shortest diameter of inferior vena cava, presence of portosystemic shunts ≥ 5 mm, and lower blood urea nitrogen levels were significantly associated with suspicious PoPH (p < 0.05). Multivariate analyses identified all four factors as significantly independent determinants of suspicious PoPH (p < 0.05). In addition, among the population of suspicious PoPH, there were significant differences in seven parameters, including total bilirubin levels and spleen volume between patients with and without probable PoPH (p < 0.05). However, no significant independent indicators of probable PoPH were found.

CONCLUSIONS

CT-based measurements of mPA-D and mPA-D/aAo-D have the potential to screen patients with suspicious PoPH in clinical practice focused on portal hypertension.

Association between the albumin-bilirubin (ALBI) score and severity of portopulmonary hypertension (PoPH): A data-mining analysis

INTRODUCTION

Portopulmonary hypertension (PoPH) is a severe complication of chronic liver disease. We aimed to investigate the etiology of chronic liver disease and the factors associated with the severity of PoPH.

SUBJECTS AND METHODS

Echocardiography was undergone in 833 patients with chronic liver disease during 2005-2019 and 13 patients (1.6%) were diagnosed with PoPH in this observational study. At the diagnosis of PoPH, liver function was evaluated by albumin-bilirubin (ALBI) score. Severe PoPH was defined as (1) mean pulmonary arterial pressure (mPAP) ≥50 mmHg or (2) mPAP: 35-49 mmHg and pulmonary vascular resistance ≥400 dyne/s/cm⁵ . Factors associated with severe PoPH were evaluated by decision-tree analysis.

RESULTS

In patients with PoPH, the leading etiology of chronic liver disease was hepatitis C virus (HCV) (46.2% [sustained virological response (SVR): 23.1% and non-SVR: 15.4%]). Severe PoPH was observed in 53.8% of patients and the 5-year survival rate was 48.1%. There was a significant correlation of mPAP with ALBI score (r = 0.6456, p = 0.0171). In the decision-tree and random forest analyses, the most impacted classifier for severe PoPH was the ALBI score. In patients with ALBI score ≥-1.45, all patients showed severe PoPH, while the prevalence of severe PoPH was 25.0% in patients with ALBI score <-1.45.

CONCLUSIONS

We found that HCV including SVR was the major etiology of chronic liver disease in patients with PoPH. Moreover, we revealed that the ALBI score was the most impacted factor associated with severe PoPH. Thus, ALBI score may be useful for the estimation of pulmonary vascular resistance.