Hepatopulmonary Syndrome and Portopulmonary Hypertension: Current Status and Implications for Liver Transplantation

New updates on hepatopulmonary syndrome: A comprehensive review

Hepatopulmonary syndrome (HPS) is a serious pulmonary vascular complication that causes arterial hypoxemia in the setting of liver disease. HPS has a progressive course and is associated with a two-fold increased risk of mortality relative to cirrhotic patients without HPS. It primarily affects patients with portal hypertension. The key pathological features of HPS include intrapulmonary angiogenesis and vascular dilations (IPVDs). The prevalence of HPS varies widely due to inconsistent diagnostic criteria and a lack of standardized protocols. Despite advances in understanding its pathophysiology, no effective curative treatments for HPS exist. Liver transplantation remains the only definitive treatment, improving survival and altering the disease natural course. This review explores the pathophysiology, clinical features, and therapeutic strategies for HPS, highlighting recent advances in the literature.

Hepatopulmonary Syndrome and Liver Transplantation: Impact on Survival and Postoperative Complications

BACKGROUND Liver transplantation (LT) is the preferred treatment for patients with cirrhosis who have hepatopulmonary syndrome (HPS). However, the effect of HPS on LT remains controversial. We assessed the correlation between HPS severity and LT survival and compared the incidence of postoperative complications between patients with and without HPS undergoing LT. MATERIAL AND METHODS We retrospectively reviewed the recipients who received living-donor LT in our institute between January 2016 and July 2019. Patients with HPS (HPS group) and patients without HPS (non-HPS group) were included in our study. HPS is defined as a defect in arterial oxygenation caused by the presence of intrapulmonary vascular dilatations, which is found by transthoracic echocardiography with pre-existing liver cirrhosis. HPS severity was graded according to the value of partial pressure of arterial oxygen. The demographic characteristics and clinical outcomes between the HPS and non-HPS groups were compared. RESULTS A total of 181 patients were enrolled. Among them, 104 patients (57.5%) had HPS. The mean overall survival of HPS and non-HPS groups was 69.82±3.1 vs 63.36±3.8 months, with no significant difference (P=0.332). The overall survival between different degrees of HPS was also compared, and showed no significant difference (P=0.466). The HPS group had a higher incidence of delayed extubation (22.1% vs 10.4%, P=0.028) and chest pigtail catheter insertion (16.3% vs 10.4%, P=0.012). Nevertheless, it did not lead to a longer Intensive Care Unit/hospital stay or higher risk of short-term mortality. CONCLUSIONS Patients with HPS tend to have more post-LT pulmonary complications, but the overall survival is not adversely influenced, regardless of the severity of HPS.

A Case of Pulmonary Arteriovenous Shunt Diagnosed by Microbubble Test via a Swan-Ganz Catheter

When encountering severe hypoxemia that does not respond to oxygen supplementation, it is essential to consider underlying right-to-left shunting. Among various diagnostic approaches, the microbubble test via transthoracic echocardiography (TTE) is a simple, noninvasive method for detecting pulmonary arteriovenous shunts, particularly in hepatopulmonary syndrome (HPS). Although microbubbles are usually administered peripherally, using a Swan-Ganz (SG) catheter to inject microbubbles directly into the pulmonary artery may provide even more definitive diagnostic information. We report a case of a woman in her 60s who was admitted in cardiac arrest after several months of progressive dyspnea and one month of poor appetite. While resuscitation was successful, severe hypoxemia persisted despite intubation, mechanical ventilation, and oxygen therapy. Immediately after resuscitation, TTE revealed no intracardiac shunt but did show microbubbles in both heart chambers. The patient exhibited refractory hypoxemia, high-output status, and pulmonary hypertension. Based on a history of severe dietary irregularities, beriberi heart disease was suspected, and empirical thiamine administration improved pulmonary hypertension and high-output state; however, the hypoxemia remained unresolved. Since microbubbles had been observed in the left heart without an intracardiac shunt, a pulmonary arteriovenous shunt was suspected. Peripheral microbubble testing showed Grade 4 opacification of the left heart three to four heartbeats subsequent to the filling of the right heart. Concerns regarding hemodynamic instability and timing prompted a microbubble test via the already-placed SG catheter. Injection of microbubbles directly into the pulmonary artery again demonstrated Grade 4 opacification in the left heart alone, confirming a pulmonary arteriovenous shunt independent of intracardiac pathways. The patient later died on day six due to irreversible brain damage. The autopsy revealed cirrhosis with histopathological features of autoimmune hepatitis and pulmonary changes suggestive of a pulmonary arteriovenous shunt. Postmortem evaluations indicated low vitamin B1 levels, consistent with beriberi heart disease, and the presence of autoimmune markers suggesting Sjögren's syndrome. In beriberi heart disease, high output is associated with reduced vascular resistance and increased metabolic demand. In liver disease, excessive nitric oxide and carbon monoxide production may worsen these hemodynamic conditions, promoting pulmonary vasodilation and pulmonary arteriovenous shunt formation. Using the SG catheter for the microbubble test proved practical and effective, especially when standard peripheral methods are complicated by hemodynamic instability, difficulty visualizing the right heart, the potential presence of intracardiac shunts, or contraindications to transesophageal echocardiography (TEE). This technique, relying on commonly available cardiovascular equipment, may facilitate earlier diagnosis of shunt-related diseases in complex clinical scenarios.

Liver cirrhosis: current status and treatment options using western or traditional Chinese medicine

Liver cirrhosis arises from liver fibrosis and necroinflammation caused by various mechanisms of hepatic injury. It is a prevalent condition in clinical practice characterized by hepatocellular dysfunction, portal hypertension, and associated complications. Despite its common occurrence, the etiology and pathogenesis of liver cirrhosis remain incompletely understood, posing a significant health threat. Effective prevention of its onset and progression is paramount in medical research. Symptoms often include discomfort in the liver area, while complications such as sarcopenia, hepatic encephalopathy, ascites, upper gastrointestinal bleeding, and infection can arise. While the efficacy of Western medicine in treating liver cirrhosis is uncertain, Chinese medicine offers distinct advantages. This review explores advancements in liver cirrhosis treatment encompassing non-pharmacological and pharmacological modalities. Chinese medicine interventions, including Chinese medicine decoctions, Chinese patent medicines, and acupuncture, exhibit notable efficacy in cirrhosis reversal and offer improved prognoses. Nowadays, the combination of Chinese and Western medicine in the treatment of liver cirrhosis also has considerable advantages, which is worthy of further research and clinical promotion. Standardized treatment protocols based on these findings hold significant clinical implications.

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.

Pathophysiological basis of hepatopulmonary syndrome

Circulatory changes with increased blood flow and vasodilatation/vasoconstriction imbalance are an integral consequence of liver cirrhosis and portal hypertension and can affect the pulmonary circulation with the development of vascular disorders, with hepatopulmonary syndrome (HPS) being the most common. HPS is a serious pulmonary complication of progressive liver disease, resulting in a poor clinical prognosis. Vascular tone decrease, monocytic infiltration of pulmonary vessels, formation of intrapulmonary arteriovenous shunts, dysfunction of alveolar type II cells, destruction of the endothelial glycocalyx are important in the pathogenesis of HPS. Abnormalities of pulmonary capillaries lead to hypoxemia caused by a violation of the ventilation/perfusion ratio, diffusion disorders, and the development of arteriovenous anastomoses. Infiltration of the pulmonary vessels by monocytes is one of the key factors of HPS. This migration is facilitated by the intestinal microbiota translocation into the portal bloodstream with increased expression of proinflammatory cytokines (tumor necrosis factor α, interleu­kins 1, 6), leading to the activation of monocytes. Monocytes located in the pulmonary circulation promote the vasodilation through the activation of inducible nitric oxide (NO) synthase and thus NO production. This is also associated with endothelial dysfunction due to a decreased hepatic secretion of bone morphogenetic protein 9 and increased endothelin 1, endothelial overexpression of endothelin B receptors, and increased endothelial NO production. Proangiogenic factors such as vascular endothelial growth factor, platelet-derived growth factor, and placental growth factor play an important role in the proliferation of pulmonary capillaries. Circulation of tumor necrosis factor α, bile acids and monocyte infiltration in the pulmonary circulation lead to increased apoptosis of alveolar type II cells and decreased surfactant synthesis. Chronic inflammation in HPS disrupts the continuity of the endothelial glycocalyx layer. This article provides an overview of the current knowledge on the pathogenesis of HPS, summarizes many features of the disease based on the literature research in MEDLINE database on the PubMed platform.

Utility of transesophageal echocardiography during orthotopic liver transplantation: A narrative review

Orthotopic liver transplantation (OLT) is the standard of care for patients suffering from end stage liver disease (ESLD). This is a high-risk procedure with the potential for hemorrhage, large shifts in preload and afterload, and release of vasoactive mediators that can have profound effects on hemodynamic equilibrium. In addition, patients with ESLD can have preexisting coronary artery disease, cirrhotic cardiomyopathy, porto-pulomary hypertension and imbalanced coagulation. As cardiovascular involvement is invariable and patient are at an appreciable risk of intraoperative cardiac arrest, Trans esophageal echocardiography (TEE) is increasingly becoming a routinely utilized monitor during OLT in patients without contraindications to its use. A comprehensive TEE assessment performed by trained operators provides a wealth of information on baseline cardiac function, while a focused study specific for the ESLD patients can help in prompt diagnosis and treatment of critical events. Future studies utilizing TEE will eventually optimize examination safety, quality, permit patient risk stratification, provide intraoperative guidance, and allow for evaluation of graft vasculature.

Pulmonary Assessment of the Liver Transplant Recipient

Respiratory symptoms and hypoxemia can complicate chronic liver disease and portal hypertension. Various pulmonary disorders affecting the pleura, lung parenchyma, and pulmonary vasculature are seen in end-stage liver disease, complicating liver transplantation (LT). Approximately 8% of cirrhotic patients in an intensive care unit develop severe pulmonary problems. These disorders affect waiting list mortality and posttransplant outcomes. A thorough history, physical examination, and appropriate laboratory tests help diagnose and assess the severity to risk stratify pulmonary diseases before LT. Hepatopulmonary syndrome (HPS), portopulmonary hypertension (POPH), and hepatic hydrothorax (HH) are respiratory consequences specific to cirrhosis and portal hypertension. HPS is seen in 5-30% of cirrhosis cases and is characterized by impaired oxygenation due to intrapulmonary vascular dilatations and arteriovenous shunts. Severe HPS is an indication of LT. The majority of patients with HPS resolve their hypoxemia after LT. When pulmonary arterial hypertension occurs in patients with portal hypertension, it is called POPH. All other causes of pulmonary arterial hypertension should be ruled out before labeling as POPH. Since severe POPH (mean pulmonary artery pressure [mPAP] >50 mm Hg) is a relative contraindication for LT, it is crucial to screen for POPH before LT. Those with moderate POPH (mPAP >35 mm Hg), who improve with medical therapy, will benefit from LT. A transudative pleural effusion called hepatic hydrothorax (HH) is seen in 5-10% of people with cirrhosis. Refractory cases of HH benefit from LT. In recent years, increasing clinical expertise and advances in the medical field have resulted in better outcomes in patients with moderate to severe pulmonary disorders, who undergo LT.

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.

Bioinformatics Analysis of Common Genetic and Molecular Traits and Association of Portal Hypertension with Pulmonary Hypertension

Portal hypertension (PH) is an important cause of pulmonary arterial hypertension(PAH), but its mechanism is still unclear. We used genetic data analysis to explore the shared genes and molecular mechanisms of PH and PAH. We downloaded the PH and PAH data from the GEO database, and used the weighted gene coexpression network analysis method (WGCNA) to analyze the coexpression modules of idiopathic noncirrhotic portal hypertension (INCPH) and cirrhotic portal hypertension (CPH) and pulmonary hypertension, respectively. Enrichment analysis was performed on the common genes, and differential gene expressions (DEGs) were used for verification. The target genes of INCPH and PAH were obtained by string and cytoscape software, and the miRNAs of target genes were predicted by miRwalk, miRDB, and TargetScan and their biological functions were analyzed; finally, we used PanglaoDB to predict the expression of target genes in cells. In WGCNA, gene modules significantly related to PAH, CPH, and INCPH were identified, and enrichment function analysis showed that the common pathway of PAH and CPH were “P53 signaling pathway,” “synthesis of neutral lipids”; PAH and INCPH are “terminal,” “Maintenance Regulation of Granules,” and “Toxin Transport.” DEGs confirmed the results of WGCNA; the common miRNA functions of PAH and cirrhosis were enriched for “P53 signaling pathway,” “TGF-β signaling pathway,” “TNF signaling pathway,” and “fatty acid metabolism,” and the miRNAs-mRNAs network suggested that hsa-miR-22a-3p regulates MDM2 and hsa-miR-34a-5p regulates PRDX4; the target genes of PAH and INCPH are EIF5B, HSPA4, GNL3, RARS, UTP20, HNRNPA2B1, HSP90B1, METAP2, NARS, SACM1L, and their target miRNA function enrichment showed EIF5B, HNRNPA2B1, HSP90B1, METAP2, NARS, SACM1L, and HSPA4 are associated with telomeres and inflammation, panglaoDB showed that target genes are located in endothelial cells, smooth muscle cells, etc. In conclusion, the mechanism of pulmonary hypertension induced by portal hypertension may be related to telomere dysfunction and P53 overactivation, and lipid metabolism and intestinal inflammation are also involved in this process.

Combined Tricuspid Valve Repair and Orthotopic Liver Transplantation in a Patient With Severe Tricuspid Regurgitation and Pulmonary Hypertension

Severe pulmonary hypertension and severe tricuspid regurgitation are often considered strict contraindications for orthotopic liver transplantation. A combined approach of tricuspid repair and subsequent liver transplantation could provide a novel approach for patients with severe pulmonary hypertension and tricuspid regurgitation to undergo orthotopic liver transplantation. A 62-year-old male with a history of end-stage renal disease on hemodialysis, cirrhosis, and third-degree atrioventricular heart block status post single lead pacemaker insertion presented for an orthotopic liver transplant. However, after placement of a Swan-Ganz catheter by the anesthesia team, the patient's central venous pressure was found to be high, and his mean pulmonary artery pressure was 40 mmHg. His case was canceled due to concern for poor postoperative outcomes after a subsequent transesophageal echocardiogram revealed a severely dilated right heart and 4+ tricuspid regurgitation with flow reversal into the hepatic veins. After discussion among the hospital's transplant committee, the patient was planned to have a tricuspid valve repair, liver transplant, and kidney transplant surgery several months later. The patient successfully underwent tricuspid valve repair and orthotopic liver transplant and then kidney transplant the following day.

Unmasking Hypoxia in Cirrhosis Patients: Six-Minute Walk Test as a Screening Tool for Hepatopulmonary Syndrome

Background

Hepatopulmonary syndrome (HPS) is one of the complications of advanced cirrhosis which has a serious impact on prognosis of patient. Finding arterial deoxygenation early and initiating higher-level treatment is one of the most critical strategies in the therapy of HPS. In this study, we aimed to assess the utility of six-minute walk test (6MWT) in the diagnosis of HPS.

Materials and Methods

We have enrolled 100 consecutive cirrhosis patients referred to the Liver Clinic of a tertiary care centre of India for >1 year. The Child-Pugh score and the MELD score were used to determine the severity of cirrhosis. All the patients underwent transthoracic contrast echocardiography, arterial blood gas measurements on room air, 6MWT, and chest imaging.

Results

A total of 100 patients were included in the study after fulfilling the inclusion criteria. HPS was present in 21 out of 100 patients (21%). Median (twenty fifth to seventy fifth percentile) MELD score in patients with HPS was 29 (26-33), which was significantly higher as compared to patients without HPS 22 (14.5-26); P <.0001. The 6MWT was positive in 20 (95.23%) HPS patients, while only 1 patient (4.77%) of HPS had negative 6MWT. If 6MWT is positive, then there was 76.92% probability of HPS and if 6MWT is negative, then 98.65% chances of no HPS.

Conclusion

The 6MWT is a simple and effective screening test for HPS, it helps in identifying the patients early who have a potential to deteriorate. This simple intervention would help in prioritizing patients for liver transplantation as liver transplant is the only effective treatment for HPS.

Cardiac autonomic modulation in children with severe liver disease, before and after liver transplantation

BACKGROUND

The cardiovascular system is directly influenced by the autonomic nervous system (ANS); its changes affect heart rate variability (HRV) and are sensitive indicators of physiological changes. Autonomic dysfunction (AD) is manifested in up to 60% of patients with cirrhosis. Therefore, we aim to analyze the indexes of HRV pre- and post-surgery of children submitted for liver transplantation (LT).

METHODS

HRV, in children of both genders from 6 months of age to 10 years, that attended at the pediatric surgery clinic in the queue for LT at the Children's Institute were analyzed. To access HRV we analyzed indexes such as standard deviation of the RR intervals (SDNN), root-mean-square of the successive normal sinus RR interval difference (RMSSD), low frequency (LF), high frequency (HF), and LF/HF.

RESULTS

The analysis of the behavior of cardiac autonomic modulation, in the period prior to LT and after surgery, showed an increase in HRV linear parameters SDNN, TINN (triangular interpolation of NN interval histogram), HFms². In the time domain, there was also an increase in the HFms² index.

CONCLUSIONS

The analysis of the period preceding LT and two months after surgery showed an increase in the HRV linear parameters representing a global HRV improvement. In the time domain, there was also an increase in the HFms² index, parasympathetic tone of the HRV.