Review article: liver transplantation for the pulmonary disorders of portal hypertension

Cirrhosis and non-hepatic surgery in 2023 - a precision medicine approach

INTRODUCTION

Patients with liver disease and portal hypertension frequently require surgery carrying high morbidity and mortality. Accurately estimating surgical risk remains challenging despite improved medical and surgical management.

AREAS COVERED

This review aims to outline a comprehensive approach to preoperative assessment, appraise methods used to predict surgical risk, and provide an up-to-date overview of outcomes for patients with cirrhosis undergoing non-hepatic surgery.

EXPERT OPINION

Robust preoperative, individually tailored, and precise risk assessment can reduce peri- and postoperative complications in patients with cirrhosis. Established prognostic scores aid stratification, providing an estimation of postoperative mortality, albeit with limitations. VOCAL-Penn Risk Score may provide greater precision than established liver severity scores. Amelioration of portal hypertension in advance of surgery may be considered, with prospective data demonstrating hepatic venous pressure gradient as a promising surrogate marker of postoperative outcomes. Morbidity and mortality vary between types of surgery with further studies required in patients with more advanced liver disease. Patient-specific considerations and practicing precision medicine may allow for improved postoperative outcomes.

Pulmonary hypertension due to high cardiac output

Pulmonary hypertension (PH) is usually associated with a normal or decreased cardiac output (CO). Less commonly, PH can occur in the context of a hyperdynamic circulation, characterized by high CO (>8 L/min) and/or cardiac index ≥4 L/min/m² in the setting of a decreased systemic vascular resistance. PH due to high CO can occur due to multiple conditions and in general remains understudied. In this review article we describe the pathophysiology, etiology, diagnosis, hemodynamic characteristics, and management of PH in the setting of high CO. It is important to recognize this distinct entity as PH tends to improve with treatment of the underlying etiology and PH specific therapies may worsen the hemodynamic state.

Preoperative 2D-echocardiographic assessment of pulmonary arterial pressure in subgroups of liver transplantation recipients

BACKGROUND

The clinical efficacy of preoperative 2D-echocardiographic assessment of pulmonary arterial pressure (PAP) has not been evaluated fully in liver transplantation (LT) recipients.

METHODS

From October 2010 to February 2017, a total of 344 LT recipients who underwent preoperative 2D-echocardiography and intraoperative right heart catheterization (RHC) was enrolled and stratified according to etiology, disease progression, and clinical setting. The correlation of right ventricular systolic pressure (RVSP) on preoperative 2D-echocardiography with mean and systolic PAP on intraoperative RHC was evaluated, and the predictive value of RVSP > 50 mmHg to identify mean PAP > 35 mmHg was estimated.

RESULTS

In the overall population, significant but weak correlations were observed (R = 0.27; P < 0.001 for systolic PAP, R = 0.24; P < 0.001 for mean PAP). The positive and negative predictive values of RVSP > 50 mmHg identifying mean PAP > 35 mmHg were 37.5% and 49.9%, respectively. In the subgroup analyses, correlations were not significant in recipients of deceased donor type LT (R = 0.129; P = 0.224 for systolic PAP, R = 0.163; P = 0.126 for mean PAP) or in recipients with poorly controlled ascites (R = 0.215; P = 0.072 for systolic PAP, R = 0.21; P = 0.079 for mean PAP).

CONCLUSIONS

In LT recipients, the correlation between RVSP on preoperative 2D-echocardiography and PAP on intraoperative RHC was weak; thus, preoperative 2D-echocardiography might not be the optimal tool for predicting intraoperative PAP. In LT candidates at risk of pulmonary hypertension, RHC should be considered.

Effects of sildenafil on right ventricle remodelling in Portopulmonary hypertension

Portopulmonary hypertension (PoPH) is a clinical condition associated with end-stage liver disease, described by the coexistence of pulmonary arterial hypertension (PAH) and portal hypertension. In PoPH patients, there is a right ventricle (RV) remodeling to compensate for the increased resistance in the lung circulation. There are no studies on the effects of the PAH-targeted pharmacological treatment on the RV dimension and function. The present study summarizes our experience in patients with PoPH treated with sildenafil in a period of 6 years (from 2013 to 2019). We enrolled 64 consecutive patients identified as PoPH, all treated with sildenafil (57.6% in monotherapy; in the other cases in association with macitentan; in 19.0% with initial combination therapy). A hemodynamic invasive cardiopulmonary study was performed at baseline and after 6 months of sildenafil treatment. In our population we showed a significative improvement in RV performance, with a significant increase in RV stroke volume (+33%), RV ejection fraction (+31%) and RV stroke work index (+17.5%). We registered the reduction of the RV cavity dimension over time in all patients treated with sildenafil (RV end diastolic diameter decreased by 15% after 6 months of follow-up). Regarding diastolic function, we highlighted a very significant reduction in RV end-diastolic pressure (-50% concerning baseline). Sildenafil was effective both when used as monotherapy and in combination with macitentan. In conclusion, Sildenafil had a positive impact on RV systolic and diastolic function in patients with PoPH and was able to conditionate the reverse remodeling of the RV.

Pulmonary Complications in Candidates for Liver Transplantation

The liver plays a pivotal role in maintaining the homeostasis of various organ systems. Also, end-stage liver disease and its complications are major causes of morbidity and mortality among adults. Individuals who develop a chronic liver disease are at increased risk of progression to multi-organ dysfunction, including the pulmonary system. The clinical complications of pulmonary problems related to the presence of liver disease range from mild (such as hypoxemia) to life-threatening diseases (such as portopulmonary hypertension and hepatopulmonary syndrome). Herein, the major pulmonary complications related to liver cirrhosis and considerations for performing liver transplantation are reviewed.

[Anesthesiological aspects of liver transplantation]

Liver transplantation (LTPL) is the only curative option for patients with end stage liver disease (ESLD) or with hepatocellular carcinoma (HCC). Eurotransplant in Leiden, the Netherlands, is responsible for organ allocation. The model of end stage liver disease (MELD) score, which describes the severity of the liver disease, is decisive for organ allocation. The heterogeneous patient collective and hepatic-related comorbidities and their dynamics represent challenges. The anesthesiologist is responsible for evaluating the overall prognosis, whereby cardiac, pulmonary, renal and neurological comorbidities must be taken into consideration. During LTPL surgery is divided into several stages. Besides volume management, heat preservation and coagulation management, major challenges for the anesthesiologist are hemodynamic stabilization and regulation of the acid-base balance.

Living Donor Liver Transplantation in Biliary Atresia Children with Pulmonary Hypertension

OBJECTIVE

Though living donor liver transplantation (LDLT) is commonly performed for pediatric patients with biliary atresia (BA), pulmonary hypertension (PH) is seldom encountered or reported previously. The aim of this study is mainly to identify the prevalence of PH in pediatric patients undergoing liver transplantation and assess whether PH significantly augment the operative risk and evaluate the outcomes in this series of patients.

DESIGN

Retrospectively cohort study.

SETTING

Renji hospital, Shanghai, China.

PARTICIPANTS

This study comprised 161 pediatric patients undergoing LDLT.

INTERVENTIONS

Patient diagnosed of PH in preoperative examination was compared to those without PH in intra- or post- operative complications or outcomes.

MEASUREMENTS AND MAIN RESULTS

We collected clinical records of LDLT surgery for pediatric patients during the year of 2016 in our hospital. Results suggested that pediatric patients undergoing LDLT had a substantial number of PH with a prevalence of 16.1% in this study. No significant difference was identified between two groups of patients regarding intraoperative outcomes and postoperative complications and mortality.

CONCLUSION

LDLT is a safe procedure in a selected group of BA patients with PH, however, further long-term clinical investigations and mechanical researches are needed.

Portopulmonary hypertension: Still an appropriate consideration for liver transplantation?

Liver transplantation (LT) in patients with portopulmonary hypertension (PoPH) has historically resulted in unpredictable and often poor outcomes. The United Kingdom experience for the period 1992-2012 is reported in this article. A retrospective analysis of patients, preoperatively fulfilling the PoPH European Respiratory Society Task Force on Pulmonary-Hepatic Vascular Disorders diagnostic criteria was conducted across all UK LT centers. Data collection included comorbidities, use of preoperative and postoperative pharmacotherapy, patient survival, and cause of death. To enable survival stratification, PoPH was classified as mild, moderate, or severe based on mean pulmonary pressure of <35 mm Hg, 35-49 mm Hg, and ≥50 mm Hg, respectively. Of 127 patients reported to have PoPH, just 28 fulfilled the diagnostic criteria (14 mild, 9 moderate, 5 severe). Twenty (71.4%) patients were male with median age and Model for End-Stage Liver Disease of 50 years (range, 23-62 years) and 18 (range, 6-43), respectively. Twelve (42.9%) patients died within 5 years of LT. The majority of deaths (10 of 12; 83%) occurred within the first 6 months after LT, aetiologies of which included right heart failure (n = 3), progressive PoPH (n = 2), and sepsis (n = 2). Of those receiving preoperative pharmacotherapy (n = 8), 5 are currently alive and were classified as mild to moderate PoPH. Both severe PoPH patients optimized preoperatively with pharmacotherapy died within a year of LT. Development of effective vasodilatory therapies in the setting of pulmonary arterial hypertension has led to a dramatic improvement in patient survival. The available data indicate that in this era of pharmacotherapy, PoPH in isolation no longer represents a valid consideration to transplant. Liver Transplantation 22 1637-1642 2016 AASLD.

Intrapulmonary vascular dilatations are common in portopulmonary hypertension and may be associated with decreased survival

Hepatopulmonary syndrome (HPS) and portopulmonary hypertension (POPH) are pulmonary vascular complications of portal hypertension with divergent clinicopathologic features and management. The presence of intrapulmonary vascular dilatations (IPVDs), detected by agitated saline contrast-enhanced transthoracic echocardiography (cTTE), is an essential feature of HPS but is not typically characteristic of POPH. Although IPVDs have been reported rarely in POPH, the prevalence and significance of this finding have not been systematically studied. We conducted a retrospective chart review of 80 consecutive patients diagnosed with POPH from January 1, 2002 to June 30, 2014 with documentation of cTTE findings, pulmonary hemodynamics, oxygenation, and survival. A total of 34 of the 80 patients (42%) underwent cTTE during initial diagnosis of POPH. IPVDs were detected in 20/34 patients (59%); intracardiac shunting was detected in 9/34 patients (26%; 4 also had IPVDs); and 9 patients (26%) had negative cTTE with no evidence of IPVD or intracardiac shunting. Patients with IPVD had decreased survival as compared to those without IPVD (P = 0.003), a trend that persisted after exclusion of liver transplant recipients (P =  0.07). The IPVD group had a trend toward higher Model for End-Stage Liver Disease score with and without incorporating sodium (MELD or MELD-Na; P = 0.05 for both). The right ventricular index of myocardial performance (RIMP) was lower in the IPVD group (median, 0.4 versus 0.6; P = 0.006). Patients with moderate or large IPVDs (n = 6) had worse oxygenation parameters (partial pressure of arterial oxygen, diffusing capacity of the lung for carbon monoxide, and alveolar-arterial oxygen gradient) as compared to the rest of the cohort. Unexpectedly, IPVDs were frequently documented in POPH and associated with decreased survival. To further understand this observation, we recommend screening for IVPD in all patients with POPH.

Hepatopulmonary Syndrome

Hepatopulmonary syndrome (HPS) is a pulmonary complication observed in patients with chronic liver disease and/or portal hypertension, attributable to an intrapulmonary vascular dilatation that may induce severe hypoxemia. Microvascular dilation and angiogenesis in the lung have been identified as pathologic features that drive gas exchange abnormalities in experimental HPS. Pulse oximetry is a useful screening test for HPS, which can guide subsequent use of arterial blood gases. Contrast-enhanced echocardiography, perfusion lung scanning, and pulmonary arteriography are three currently used diagnostic imaging modalities that identify the presence of intrapulmonary vascular abnormalities. The presence of HPS increases mortality and impairs quality of life, but is reversible with liver transplantation. No medical therapy is established as effective for HPS. At the present time, liver transplantation is the only available treatment for HPS.

"Porto-pulmonary hypertension: a comprehensive review"

Porto-pulmonary hypertension (PoPH) is a rare but threatening vasculopathy, defined by the presence of pulmonary arterial hypertension (PAH) in the setting of portal hypertension. Although most commonly observed in cirrhotic patients, those with non-cirrhotic portal hypertension are also at risk of developing it. Little is known about the mechanisms by which PAH develop in patients with portal hypertension, but genetic factors, pulmonary vascular wall shear stress, and a dysregulation of vasoactive, proliferative and inflammatory mediators might be involved. PoPH is estimated to occur in 3 to 10% of patients with end-stage liver disease, although its frequency is not related to the severity of liver dysfunction or the degree of portal hypertension. Moderate-to-severe PoPH portends an extremely poor prognosis. Presentation is highly variable, therefore a high index of suspicion is required to establish the diagnosis. PoPH should be screened by transthoracic echocardiography (TTE) in cirrhotic patients presenting with dyspnoea as well as in all patients being evaluated for liver transplantation (LT) regardless of their symptoms. If TTE shows elevated pulmonary pressures, patients should undergo right heart catheterisation, which is required for the definitive diagnosis of PoPH. Without LT, the overall 5-year mortality in PoPH patients is 70%, but it should not be considered an indication for LT. Moderate-to-severe PoPH contraindicates LT, since it is associated with a prohibitively increased intra and postoperative mortality. However, there is now evidence supporting the use of PAH-specific therapies pre-LT in order to improve pulmonary haemodynamic measurements, so the procedure can then be performed with significantly lower risks.

The association of lipopolysaccharide and inflammatory factors with hepatopulmonary syndrome and their changes after orthotopic liver transplantation

BACKGROUND

The level of lipopolysaccharides (LPS) and inflammatory factors were higher in end stage liver disease patient than in normal person for the damage of intestinal mucosal barrier function. Hepatopulmonary syndrome (HPS) was a common pulmonary complication in end stage liver disease. But the association of LPS and inflammatory factors such as toll like receptor 2 (TLR2), TNF-α and ET-1 with the development of HPS was undefined.

METHODS

Thirty-one HPS patients were researched (26 patients were performed liver transplantation, five were not). Ten healthy volunteers were recruited as negative control. Blood was collected from the 26 HPS patients before and 3, 7, 14, 21 and 28 days after orthotopic liver transplantation (OLT), and from five HPS patients without OLT and ten healthy volunteers once to detect TLR2 mRNA and iNOS mRNA in peripheral blood monocytes and plasma LPS, TNF-α and ET-1 level. Their levels before and after OLT were compared.

RESULTS

TLR2 mRNA, iNOS mRNA, LPS, TNF-α and ET-1 before OLT in HPS patients were 336,594.1±366,901.1, 63,982.2±74,127.5 copies/ugRNA, 4.3±3.3, 90.1±76.0 and 319.9±124.4 ng/L, respectively. They were 10,338.3±3,814.6, 19,168.5±2,417.4 copies/ugRNA, 0.94±0.69, 2.7±0.1 and 84.2±10.6 ng/L in normal control group. They were significantly higher in HPS patients than those in control group (P<0.05). After OLT, liver function improved to normal. Also TLR2 mRNA, TNF-α and ET-1 decreased in HPS patients after OLT compared with those before OLT. And PaO2 and PaO2/FiO2 improved greatly with intrapulmonary shunt decreased to normal after OLT.

CONCLUSIONS

Lipopolysaccharides at the end stage of liver disease with the release of series of inflammatory factors may be associated with the development of HPS.

Living-donor liver transplantation for congenital biliary atresia with porto-pulmonary hypertension and moderate or severe pulmonary arterial hypertension: Kyoto University experience

Porto-pulmonary hypertension with moderate or severe pulmonary arterial hypertension (PAH) is viewed as a contraindication to liver transplantation (LT) because of associated poor outcomes; however, patients with biliary atresia (BA) are generally good candidates for LT. Ten patients with moderate/severe PAH underwent living-donor liver transplantation (LDLT) at our institution; eight of these patients had BA and were the focus of this study. Preoperative therapies, including prostaglandin (PG)I2 , were introduced. When mean pulmonary arterial pressure (mPAP) after treatment was <40 mmHg or initial mPAP without therapy was <35 mmHg, we performed an acute volume challenge test to evaluate right ventricular function. LDLT was performed when mPAP after anesthetic induction was confirmed at ≤35 mmHg. Six patients had favorable responses to preoperative treatment and catheter testing, but two patients showed poor responses. The two patients with poor responses had poor clinical courses with unstable mPAP after LDLT. The other six patients had successful courses with well-controlled mPAP, and PGI2 was withdrawn or weaned following LDLT. Survival did not significantly differ between the eight BA recipients with moderate/severe PAH and 77 age-matched BA recipients without PAH from the same time period. LDLT has major benefits for BA patients with well-controlled PAH.

Liver in cardiopulmonary disease

Hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PoPH) are two fascinating and incompletely understood pulmonary vascular conditions seen in the setting of cirrhotic patients. Of the two HPS is more common and is primarily caused by pulmonary vasodilatation resulting in hypoxaemia and hyperdynamic circulation. PoPH is less common and conversely, pulmonary vasoconstriction and vascular remodelling occurs resulting in increased pulmonary vascular resistance. However, both conditions can co-exist and it is usually PoPH which develops in a patient with pre-existing HPS. Although these two pulmonary conditions are not common complications of chronic liver diseases, the treatment options are mainly limited to liver transplantation. Cirrhotic cardiomyopathy is closely related to haemodynamic changes in portal hypertension. The key features are normal cardiac pressures at rest, with reduced ability to compensate for physiological or iatrogenic stresses such as drug therapy or TIPSS. There is no effective therapy and outcomes after liver transplantation are variable.