Coexisting hepatopulmonary syndrome and portopulmonary hypertension: implications for liver transplantation

[Hepatopulmonary syndrome]

The hepatopulmonary syndrome (HPS) is one of the lung diseases associated with cirrhosis and portal hypertension. It should be discussed for any dyspnea in cirrhotic patients. HPS is a pulmonary vascular disease characterized by intrapulmonary vascular dilatations (IPVD). The pathogenesis is complex and seems to rely on communications between the portal and pulmonary circulations. The diagnosis is based on a triad of liver disease and portal hypertension, evidence of IPVDs, and impaired gas exchange (alveolar-arterial oxygen difference [A-aO2]≥15mmHg). HPS impairs prognosis (23% survival at 5years) and patients' quality of life. Liver transplantation (LT) allows regression of IPDVD in almost 100% of cases, normalization of gas exchange and improves survival with a 5-year post-LT survival between 76 and 87%. It is the only curative treatment, indicated in patients with severe HPS, defined by an arterial partial pressure of oxygen (PaO2) below 60mmHg. When LT is not indicated or feasible, long-term oxygen therapy may be proposed as a palliative treatment. A better understanding of the pathophysiological mechanisms is needed to improve the therapeutic possibilities in a near future.

Pulmonary Complications of Portal Hypertension

The most common pulmonary complications of chronic liver disease are hepatic hydrothorax, hepatopulmonary syndrome, and portopulmonary hypertension. Hepatic hydrothorax is a transudative pleural effusion in a patient with cirrhosis and no evidence of underlying cardiopulmonary disease. Hepatic hydrothorax develops owing to the movement of ascitic fluid into the pleural space. Hepatopulmonary syndrome and portopulmonary hypertension are pathologically linked by the presence of portal hypertension; however, their pathophysiologic mechanisms are significantly different. Hepatopulmonary syndrome is characterized by low pulmonary vascular resistance secondary to intrapulmonary vascular dilatations and hypoxemia; portopulmonary hypertension features elevated pulmonary vascular resistance and constriction/obstruction within the pulmonary vasculature.

Onset ages of hepatopulmonary syndrome and pulmonary hypertension in patients with biliary atresia

PURPOSE

Hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PoPH) are extrahepatic complications of biliary atresia (BA). Their detection is sometimes delayed, which may result in missed opportunities for liver transplantation. The aim of this study was to determine the onset ages of HPS and PoPH in BA patients.

METHODS

BA patients followed at our institution were identified. Patients visited our clinic for routine blood work, as well as regular electrocardiography, chest X-rays, and arterial blood gas tests. Lung perfusion scintigraphy and cardiac ultrasound were performed to diagnose HPS. Cardiac catheterization was conducted to diagnose PoPH.

RESULTS

The study population consisted of 88 BA patients. The median follow-up duration was 11.6 years (range 0.8-26.0 years). Six patients (6.8%) developed HPS and three patients (3.4%) developed PoPH. The median age of onset of HPS was significantly younger than that of PoPH (HPS: 4 years, PoPH: 15 years, P < 0.019). Two patients (66%) with PoPH died, while all patients with HPS survivied.

CONCLUSION

The onset of HPS was significantly earlier than that of PoPH. The mortality rate was high in patients with PoPH. Teenagers with BA should receive routine cardiac echocardiograms to detect PH in its early stages.

Evaluation of Arteriovenous Shunting in Patients With End-Stage Liver Disease: Potential Role of Early Right Heart Catheterization

BACKGROUND

In patients with end-stage liver disease (ESLD), the presence of hypoxemia suggests the presence of intrapulmonary oxygen shunting (IPS) and/or transatrial shunting. Early identification of each is imperative to avoid potentially fatal peritransplantation complications and appropriately prioritize patients for liver transplantation (LT). The aim of this work was to compare the sensitivity of transthoracic echocardiography (TTE) and right heart catheterization (RHC) with intracardiac echocardiography (ICE) for identifying the etiologies of resting hypoxemia in patients with ESLD being evaluated for LT.

METHODS

Records of 28 patients with ESLD and resting hypoxemia who underwent TTE with bubble study and RHC/ICE were reviewed. Patients with a patent foramen ovale (PFO) were compared with non-PFO patients to determine diagnostic accuracy of TTE with bubble study versus RHC/ICE.

RESULTS

TTE with bubble study diagnosed PFO, IPS, and pulmonary hypertension (PH), respectively, with sensitivities of 46%, 41%, and 25% and specificities of 46%, 45%, and 80% compared with RHC/ICE. Although IPS detected by RHC/ICE was more common in patients without a PFO (92%), 5 patients with a PFO (33%) also had IPS (P = .002). Isolated PH was detected exclusively in patients with a PFO (5/15; 33%).

CONCLUSIONS

TTE with bubble study is neither sensitive nor specific to exclude a PFO in patients with ESLD. RHC/ICE is a safe and accurate diagnostic/interventional modality in this group of patients and is useful to diagnose other comorbidities, such as IPS and PH, that may coexist and contribute to resting hypoxemia.

Portopulmonary hypertension

Portopulmonary hypertension (PoPH) refers to the condition that pulmonary arterial hypertension (PAH) occur in the stetting of portal hypertension. The development of PoPH is thought to be independent of the severity of portal hypertension or the etiology or severity of liver disease. PoPH results from excessive vasoconstriction, vascular remodeling, and proliferative and thrombotic events within the pulmonary circulation that lead to progressive right ventricular failure and ultimately to death. Untreated PoPH is associated with a poor prognosis. As PoPH is frequently asymptomatic or symptoms are generally non-specific, patients should be actively screened for the presence of PoPH. Two-dimensional transthoracic echocardiography is a useful non-invasive screening tool, but a definitive diagnosis requires invasive hemodynamic confirmation by right heart catheterization. Despite a dearth of randomized, prospective data, an ever-expanding clinical experience shows that patients with PoPH benefit from therapy with PAH-specific medications including with endothelin receptor antagonists, phosphodiesterase-5 inhibitors, and/or prostanoids. Due to high perioperative mortality, transplantation should be avoided in those patients who have severe PoPH that is refractory to medical therapy.

Pulmonary Arterial Hypertension Associated with Congenital Portosystemic Shunts Treated with Transcatheter Embolization and Pulmonary Vasodilators

Cardiopulmonary abnormalities are often present in patients with liver diseases. We herein report a case of congenital portosystemic shunts complicated by hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PoPH). A 57-year-old woman complained of dyspnea and was subsequently diagnosed with HPS and PoPH caused by congenital portosystemic shunts. Although shunt closure by transcatheter embolization was successfully performed, her dyspnea worsened and pulmonary artery pressure and pulmonary vascular resistance elevated. Conventional vasodilator therapy was started, resulting in an improvement of pulmonary hypertension (PH). In some patients with congenital portosystemic shunts, shunt closure could exacerbate PH, and vasodilator therapy may be effective.

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.

A 45-Year-Old Undiagnosed Cirrhotic Patient with Hepatopulmonary Syndrome as First Presentation: A Case Report

Patient: Male, 45

Final Diagnosis: Hepatopulmonary syndrome

Symptoms: Dyspnea • edema of feet

Medication: —

Clinical Procedure: None

Specialty: Gastroenterology and Hepatology

Hepatopulmonary syndrome and portopulmonary hypertension: recent knowledge in pathogenesis and overview of clinical assessment

Hepatopulmonary syndrome and portopulmonary hypertension are cardiopulmonary complications, which are not infrequently seen in patients with liver disease and/or portal hypertension. These entities are both clinically and pathophysiologically different: the hepatopulmonary syndrome is characterized by abnormal pulmonary vasodilation and right-to-left shunting resulting in gas exchange abnormalities, whereas portopulmonary hypertension is caused by pulmonary artery vasoconstriction leading to hemodynamic failure. As both hepatopulmonary syndrome and portopulmonary hypertension are associated with significantly increased morbidity and mortality, and as these patients are commonly asymptomatic, all liver transplantation candidates should be actively screened for the presence of these two complications. The aim of is this review is to provide an overview on the hepatopulmonary syndrome and portopulmonary hypertension with primary focus on diagnosis and recent knowledge regarding pathogenesis and therapeutic targets.

Aggravation of hepatopulmonary syndrome after sildenafil treatment in a patient with coexisting portopulmonary hypertension

Hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PPHTN) are complications of portal hypertension and cirrhosis. Their pathophysiological mechanisms clearly differ. HPS is characterized by a defect in arterial oxygenation induced by pulmonary vascular dilatation. In contrast, PPHTN is predominantly due to excessive pulmonary vasoconstriction and vascular remodeling, but is rarely associated with hypoxia. We report a case of a patient who had both HPS and PPHTN at the time of presentation. HPS was aggravated after sildenafil administration for the treatment of PPHTN. We demonstrated increased amount of intrapulmonay shunt after sildenafil challenge by using agitated saline contrast transthoracic echocardiography.

[Pulmonary complications in liver diseases]

Pulmonary-hepatic vascular disorders are frequent complications in patients with portal hypertension and cirrhosis. Hepatopulmonary syndrome (HPS), portopulmonary hypertension (POPH), and hepatic hydrothorax are relevant disease entities in these patients. HPS occurs in up to 30 % of patients with cirrhosis and is associated with a more than 2-fold increased mortality. The diagnosis of HPS should be established early by arterial blood gas analysis and contrast-enhanced echocardiography, whereas POPH is diagnosed by the presence of pulmonary arterial hypertension evaluated via right heart catheterization and the presence of portal hypertension. Therapeutic options include initiation of long-term oxygen therapy and liver transplantation in patients with severe HPS. Patients with POPH should receive targeted medical therapies with endothelin receptor antagonists, phosphodiesterase-5 inhibitors and/or prostanoids. In contrast, β-blockers should be avoided. This review summarizes current knowledge regarding pulmonary-hepatic vascular disorders, with a focus on HPS.

Pulse oximeter oxygen saturation in prediction of arterial oxygen saturation in liver transplant candidates

BACKGROUND

Liver transplant is the only definitive treatment for many patients with end stage liver disease. Presence and severity of preoperative pulmonary disease directly affect the rate of postoperative complications of the liver transplantation. Arterial blood gas (ABG) measurement, performed in many transplant centers, is considered as a traditional method to diagnose hypoxemia. Because ABG measurement is invasive and painful, pulse oximetry, a bedside, noninvasive and inexpensive technique, has been recommended as an alternative source for the ABG measurement.

OBJECTIVES

The aim of this study was to evaluate the efficacy of pulse oximetry as a screening tool in hypoxemia detection in liver transplant candidates and to compare the results with ABGs.

PATIENTS AND METHODS

Three hundred and ninety transplant candidates (237 males and 153 females) participated in this study. Arterial blood gas oxyhemoglobin saturation (SaO2) was recorded and compared with pulse oximetry oxyhemoglobin saturation (SpO2) results for each participants. The area under the curve (AUC) of receiver operating characteristic (ROC) curves was calculated by means of nonparametric methods to evaluate the efficacy of pulse oximetry to detect hypoxemia.

RESULTS

Roc-derived SpO2 threshold of ≤ 94% can predict hypoxemia (PaO2 < 60 mmHg) with a sensitivity of 100% and a specificity of 95%. Furthermore, there are associations between the ROC-derived SpO2 threshold of ≤ 97% and detection of hypoxemia (PaO2 < 70 mmHg) with a sensitivity of 100% and a specificity of 46%. The accuracy of pulse oximetry was not affected by the severity of liver disease in detection of hypoxemia.

CONCLUSIONS

Provided that SpO2 is equal to or greater than 94%, attained from pulse oximetry can be used as a reliable and accurate substitute for the ABG measurements to evaluate hypoxemia in patients with end stage liver disease.

Transition from hepatopulmonary syndrome to portopulmonary hypertension: a case series of 3 patients

Hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PPHTN) are the two major pulmonary vascular complications of liver disease. While HPS is characterized by low pulmonary vascular resistance, PPHTN is defined by the presence of elevated pulmonary vascular resistance. Given these seemingly opposing pathophysiologic mechanisms, these conditions were traditionally felt to be mutually exclusive. In this series, we present three patients with severe hepatopulmonary syndrome who had spontaneous resolution of their HPS with the subsequent development of PPHTN. To our knowledge, this is the largest case series presented of this phenomenon in nontransplanted patients. One proposed mechanism for the occurrence of this phenomenon involves dysregulation of the same vascular signaling pathway, which may lead to both pulmonary vascular dilatations and pulmonary arterial remodeling in the same patient. Another theory involves the possible differential binding of endothelin-1, a vasoactive signaling peptide that induces vasoconstriction when bound to receptor A and vasodilation when bound to receptor B. Although the mechanisms for this phenomenon remain unclear, it is important to be vigilant of this phenomenon as it may change the patient's overall treatment plan, especially in regard to appropriateness and timing of liver transplant.

Hepatopulmonary syndrome: update on recent advances in pathophysiology, investigation, and treatment

Hepatopulmonary syndrome (HPS) is an important cause of dyspnea and hypoxia in the setting of liver disease, occurring in 10-30% of patients with cirrhosis. It is due to vasodilation and angiogenesis in the pulmonary vascular bed, which leads to ventilation-perfusion mismatching, diffusion limitation to oxygen exchange, and arteriovenous shunting. There is evidence, primarily from animal studies, that vasodilation is mediated by a number of endogenous vasoactive molecules, including endothelin-1 and nitric oxide (NO). In experimental HPS, liver injury stimulates release of endothelin-1 and results in increased expression of ET(B) receptors on pulmonary endothelial cells, leading to upregulation of endothelial NO synthase (eNOS) and subsequent increased production of NO, which causes vasodilation. In addition, increased phagocytosis of bacterial endotoxin in the lung not only promotes stimulation of inducible NO synthase, which increases NO production, but also contributes to intrapulmonary accumulation of monocytes, which may stimulate angiogenesis via vascular endothelial growth factor pathway. Despite these insights into the pathogenesis of experimental HPS, there is no established medical therapy, and liver transplantation remains the main treatment for symptomatic HPS, although selected patients may benefit from other surgical or radiological interventions. In this review, we focus on recent advances in our understanding of the pathophysiology of HPS, and discuss current approaches to the investigation and treatment of this condition.

Hepatopulmonary syndrome: update on pathogenesis and clinical features

Hepatopulmonary syndrome (HPS) is a serious vascular complication of liver disease that occurs in 5-32% of patients with cirrhosis. The presence of HPS markedly increases mortality. No effective medical therapies are currently available and liver transplantation is the only established treatment option for HPS. The definition and diagnosis of HPS are established by the presence of a triad of liver disease with intrapulmonary vascular dilation that causes abnormal arterial gas exchange. Experimental biliary cirrhosis induced by common bile duct ligation in the rat reproduces the pulmonary vascular and gas exchange abnormalities of human HPS and serves as a pertinent animal model. Pulmonary microvascular dilation and angiogenesis are two central pathogenic features that drive abnormal pulmonary gas exchange in experimental HPS, and thus might underlie HPS in humans. Defining the mechanisms involved in the microvascular alterations of HPS has the potential to lead to effective medical therapies. This Review focuses on the current understanding of the pathogenesis, clinical features and management of HPS.

A rare cause of hypoxia in a patient with liver cirrhosis

Pulmonary syndromes in the setting of hepatic disease with portal hypertension include portopulmonary hypertension (POPH), hepatopulmonary syndrome (HPS) and hepatic hydrothorax. POPH is defined as pulmonary arterial hypertension with portal hypertension in the absence of other causes of pulmonary arterial hypertension. HPS is a defect in arterial oxygenation as a result of pulmonary micro vascular dilatation in the setting of liver disease. We discuss a case of 63-year-old female with liver cirrhosis, exertional dyspnea and hypoxia associated with coexistence of POPH and HPS. The coexistence of POPH and HPS is rare entity which can generate a renewal of interest in further understanding the intricate pathologies behind these diseases.

Portopulmonary hypertension: an update

Portopulmonary hypertension (POPH) is a serious complication of cirrhosis that is associated with mortality beyond that predicted by the Model for End-Stage Liver Disease (MELD) score. Increased pulmonary vascular resistance (PVR) may be initiated by pulmonary vasoconstriction, altered levels of circulating mediators, or shear stress, and can eventually lead to the classic vascular remodeling (plexiform lesion) that characterizes POPH. Portal hypertension is a prerequisite for the diagnosis of POPH, although the severity of pulmonary hypertension is unrelated to the severity of portal hypertension or the nature or severity of liver disease. POPH precludes liver transplantation (LT) unless the mean pulmonary artery pressure (MPAP) can be reduced to a safe level. The concept of an acceptable pressure has changed: we now consider both MPAP and PVR in the diagnosis, and we include the transpulmonary pressure gradient so that we can factor in fluid overload and left ventricular failure. Pulmonary vasodilator therapy includes oral, inhaled, and parenteral agents, and one or more of these agents may significantly lower pulmonary artery pressures to the point that LT becomes possible. The United Network for Organ Sharing recommends MELD exception points for patients with medically controlled POPH, but this varies by region. Patients who undergo LT need specialized intraoperative and postoperative management, which includes the availability of intraoperative transesophageal echocardiography for assessing right ventricular function, and rapidly acting vasodilators (eg, inhaled nitric oxide and/or epoprostenol). Published case series suggest excellent outcomes after LT for patients who respond to medical therapy.

Portopulmonary hypertension: from diagnosis to treatment

Portopulmonary hypertension is a form of pulmonary arterial hypertension that has gained interest in recent years with the development of liver transplantation techniques and new pulmonary vasodilator therapies. Portopulmonary hypertension is defined as pulmonary artery hypertension associated with portal hypertension with or without advanced hepatic disease. Echocardiography plays a major role in screening for portopulmonary hypertension but right heart catheterization remains the gold standard for diagnosis. The treatment of patients with portopulmonary hypertension consists of general measures that apply to all patients that carry the diagnosis of pulmonary hypertension and specific vasodilator therapies. These new therapies showed encouraging results in patients who would otherwise have a contraindication for liver transplantation. The review presents a summary of the current knowledge on the epidemiology, diagnosis, treatment and prognosis of patients with portopulmonary hypertension.