Prevalence of hepatopulmonary syndrome in patients with decompensated chronic liver disease and its impact on short-term survival

Hepatopulmonary syndrome: An update

Hepatopulmonary syndrome (HPS) is characterized by defects in oxygenation caused by intra-pulmonary vasodilation occurring because of chronic liver disease, portal hypertension, or congenital portosystemic shunts. Clinical implications of portal hypertension are very well-known, however, awareness of its effect on multiple organs such as the lungs are less known. The presence of HPS in chronic liver disease is associated with increased mortality. Medical therapies available for HPS have not been proven effective and definitive treatment for HPS is mainly liver transplantation (LT). LT improves mortality for patients with HPS drastically. This article provides a review on the definition, clinical presentation, diagnosis, and management of HPS.

Hepatopulmonary Syndrome: A Nationwide Analysis of Epidemiological Trends and Outcomes From 2012 to 2018

Background

This study was designed to determine the epidemiological trends and adverse outcomes of hepatopulmonary syndrome (HPS).

Methods

This retrospective interrupted trend study analyzed data from the Nationwide Inpatient Sample (NIS) for the years 2012, 2014, 2016 and 2018 to identify adult (≥ 18 years) hospitalizations with a diagnosis of HPS. We highlighted epidemiological trends for HPS. Inpatient mortality, mean length of stay (LOS) and mean total hospital charge (THC) were estimated using multivariate regression trend analysis.

Results

We observed an increase in the total number of HPS hospitalizations from 1,565 in 2012 to 2,495 in 2018, with mean age ranging from 55.8 to 58.1 years. There was a trend towards increasing hospitalizations (P-trend < 0.001) with increasing mean age (P-trend = 0.003) for HPS. Whites made up most of the study population. The inpatient mortality for HPS ranged from 12.4% to 12.6%, but there was no statistically significant trend for mortality (P-trend = 0.534) between 2012 and 2018. Additionally, there was no change in both mean LOS (P-trend = 0.545) and mean THC (P-trend = 0.534) for HPS for these years.

Conclusions

Hospitalizations and mean age for HPS were on the rise. Inpatient mortality ranged from 12.4% to 12.6%; however, a statistically significant trend for mortality was absent.

Approach to Emergent Neurotrauma-related Neurosurgical Procedures in Patients with Hepatic Disease

Liver diseases constitute a group of pathologies of extraordinary importance, because of the large number of patients who suffer from these as well as the consequences that they can have on these individuals if they undergo any surgical procedure. Therefore, these patients have greater risk of suffering unfavorable outcomes than a healthy person undergoing emergency neurosurgical procedures (ENP) for neurotrauma. For this reason, there is a need to classify these patients according to their surgical risk based on risk factors secondary to the concurrent hepatic derangements. Among the possible tools that allow us to stage patients with liver disease are the Child–Turcotte–Pugh (CTP) and model for end-stage liver disease (MELD) scales, which have proven utility in effectively predicting the outcomes, including morbidity and mortality in hepatic disease patients who are undergoing surgery. They also help to predict the risk of complications such as intracranial hemorrhage secondary to coagulopathy due to hepatic derangement.

Prevalence and determinants of hepatopulmonary syndrome in decompensated chronic liver disease

BACKGROUND

One of the severe complications of liver disease is hepatopulmonary syndrome (HPS). There is paucity in literature regarding the various factors associated with the development of HPS. This study was conducted to analyze the prevalence and determinants of HPS among patients with decompensated chronic liver disease (CLD).

METHODS

This study was a cross-sectional-observational study conducted in a tertiary care center. Decompensated CLD patients admitted for pre-liver transplant workup were included in the study. Demographic data, clinical findings, and biochemical and hematologic parameters were collected. Pulse oximetry, arterial blood gas analysis, bubble contrast echocardiogram, diffusion capacity of the lungs for carbon monoxide (DLCO), and spirometry were done to get the needed parameters. All data were entered into a Microsoft Excel sheet and analyzed using the statistical software SPSS for Windows, version 22.0.

RESULTS

Among 64 subjects, 58 were men (90.6%). Mean age was 54.5 years. HPS was present in 26 (40.6%) patients. Platypnea and orthodeoxia were present more often in HPS patients. DLCO was significantly impaired among patients with HPS. Portopulmonary hypertension was seen in 8 (12.5%) subjects with no difference between HPS and non-HPS patients. Subjects with HPS had more severe liver disease. A model for end-stage liver disease (MELD)-Na score > 19 was associated with HPS (sensitivity 73.08%, specificity 65.79%, PPV 59.4%, and NPV 78.1%). Multivariate analysis (binary logistic regression) revealed that a higher MELD-Na score, hepatic encephalopathy, and impaired DLCO were independently associated with HPS.

CONCLUSIONS

HPS is associated with more severe liver disease (as per Child-Turcotte-Pugh [CTP] stage and MELD-Na score). There was no relation between HPS and causes of CLD. Higher MELD-Na score, hepatic encephalopathy, impaired DLCO, clubbing, and spider naevi were independently associated with HPS.

Liver disease is an independent predictor of poor 30-day outcomes following surgery for degenerative disease of the cervical spine

BACKGROUND AND CONTEXT

The impact of underlying liver disease on surgical outcomes has been recognized in a wide variety of surgical disciplines. However, less empiric data are available about the importance of liver disease in spinal surgery.

PURPOSE

To measure the independent impact of underlying liver disease on 30-day outcomes following surgery for the degenerative cervical spine.

STUDY DESIGN

Retrospective comparative study.

PATIENT SAMPLE

A cohort of 21,207 patients undergoing elective surgery for degenerative disease of the cervical spine from the American College of Surgeons National Surgical Quality Improvement Program.

OUTCOME MEASURES

Outcome measures included mortality, hospital length of stay, and postoperative complications within 30 days of surgery.

METHODS

The NSQIP dataset was queried for patients undergoing surgery for degenerative disease of the cervical spine from 2006 to 2015. Assessment of underlying liver disease was based on aspartate aminotransferase-to-platelet ratio index and Model of End-Stage Liver Disease-Sodium scores, computed from preoperative laboratory data. The effect of liver disease on outcomes was assessed by bivariate and multivariate analyses, in comparison with 16 other preoperative and operative factors.

RESULTS

Liver disease could be assessed in 21,207 patients based on preoperative laboratory values. Mild liver disease was identified in 2.2% of patients, and advanced liver disease was identified in 1.6% of patients. The 30-day mortality rates were 1.7% and 5.1% in mild and advanced liver diseases, respectively, compared with 0.6% in patients with healthy livers. The 30-day complication rates were 11.8% and 31.5% in these patients, respectively, compared with 8.8% in patients with healthy livers. In multivariate analysis, the presence of any liver disease (mild or advanced) was independently associated with an increased risk of mortality (OR=2.00, 95% CI=1.12-3.55, p=.019), morbidity (OR=1.35, 95% CI=1.07-1.70, p=.012), and length of hospital stay longer than 7 days (OR=1.73, 95% CI=1.40-2.13, p<.001), when compared with 18 other preoperative and operative factors. Liver disease was also independently associated with perioperative respiratory failure (OR=1.80, 95% CI=1.21-2.68, p=.004), bleeding requiring transfusion (OR=1.43, 95% CI=1.01-2.02, p=.044), wound disruption (OR=2.82, 95% CI=1.04-7.66, p=.042), and unplanned reoperation (OR=1.49, 95% CI=1.05-2.11, p=.025).

CONCLUSIONS

Liver disease independently predicts poor perioperative outcome following surgery for degenerative disease of the cervical spine. Based on these findings, careful consideration of a patient's underlying liver function before surgery may prove valuable in surgical decision-making, preoperative patient counseling, and postoperative patient care.

Clinical efficacy of transjugular intrahepatic portosystemic shunt in the treatment of hepatopulmonary syndrome

Transjugular intrahepatic portosystemic shunt (TIPS) reduces the portal venous pressure of patients with hepatopulmonary syndrome (HPS).To describe the patients who underwent TIPS for the treatment of HPS.A retrospective study was performed on 81 patients with HPS and gastrointestinal hemorrhage treated with TIPS. Thirty patients underwent TIPS through the main portal vein (group A), 24 through the left branch of the portal vein (group B), and 27 through the right branch of the portal vein (group C). The partial pressure of arterial oxygen (PaO2), alveolar-to-arterial oxygen partial pressure gradient (A-aPO2), oxygen saturation (SO2), and complications were recorded and compared. The survival rate for each group was calculated.The technical success rate was 100% in the 3 groups. Preoperative portal vein pressure showed no significant differences between the 3 groups, which was decreased post-TIPS operation. In group A, PaO2 and SO2 were higher in 15 days and 3 months postoperative than preoperative (P < .05), whereas A-aPO2 was lower (P < .05). No difference occurred between 12 months post- and preoperative group. In group C, PaO2 and SO2 did not alter significantly at each time point after operation (P > .05), whereas A-aPO2 decreased at 3 months (P = .041) than preoperative. In group B, all indicators at each follow-up time point after TIPS were improved significantly as compared with the preoperative group (P < .05), which showed an excellent effect on hypoxemia treatment. Although the 1-year survival rate of 3 groups of patients was 92.85%, 90.90%, and 91.67%, respectively, the rate of hepatic encephalopathy and hepatic myelopathy was 33.33% (10/30), 16.67% (4/24), and 33.33% (9/27) after TIPS.TIPS reduced the pressure of the portal vein effectively and alleviated hypoxemia in most HPS patients successfully. Thus, the left branch of the portal vein is optimal for TIPS owing to fewer complications and efficacy in improving PaO2 as compared with the main portal vein and right branch.

Schistosomiasis and hepatopulmonary syndrome: the role of concomitant liver cirrhosis

BACKGROUND

Hepatopulmonary syndrome (HPS) is defined as an oxygenation defect induced by intrapulmonary vasodilation in patients with liver disease or portal hypertension. It is investigated in patients with liver cirrhosis and less frequently in those with portal hypertension without liver cirrhosis, as may occur in hepatosplenic schistosomiasis (HSS).

OBJECTIVES

To investigate the prevalence of HPS in patients with HSS, and to determine whether the occurrence of HPS is influenced by concomitant cirrhosis.

METHODS

We evaluated patients with HSS with or without concomitant liver cirrhosis. All patients underwent laboratory testing, ultrasound, endoscopy, contrast echocardiography, and arterial blood gas analysis.

FINDINGS

Of the 121 patients with HSS, 64 were also diagnosed with liver cirrhosis. HPS was diagnosed in 42 patients (35%) and was more frequent among patients with concomitant liver cirrhosis than in those without cirrhosis (42% vs. 26%), but the difference was not significant (p = 0.069). HPS was more common in those with spider naevi, Child-Pugh classes B or C and high model for end stage liver disease (MELD) scores (p < 0.05 each).

MAIN CONCLUSIONS

The prevalence of HPS was 35% in this study. The occurrence of liver cirrhosis concomitantly with HSS may have influenced the frequency of patients presenting with HPS.

MIR196A2 rs11614913 C > T polymorphism correlates with an increased risk of hepatopulmonary syndrome in liver cirrhosis: a case-control study in China

OBJECTIVE

This case-control study is designed to explore the relationship between microRNA-196a2 (MIR196A2) rs11614913 C > T polymorphism and the risk of hepatopulmonary syndrome (HPS) in liver cirrhosis.

METHODS

From January 2013 to January 2015, 163 liver cirrhosis patients with HPS (case group), 264 liver cirrhosis patients without HPS (control group), and 195 healthy people (normal group) were selected. A DNA extraction kit was used to extract plasma DNA from peripheral blood. Polymerase chain reaction-restriction fragment length polymorphism was used to detect the allele and genotype frequencies of MIR196A2 C > T polymorphism. Real-time quantitative polymerase chain reaction was adopted to detect the relative expression of MIR196A.

RESULTS

The frequencies of C allele in the case group were higher than those in the control and normal groups (all P < 0.05), whereas no significant difference was found between the control and normal groups, which indicated that MIR196A2 C > T polymorphism was closely associated with an increased risk of HPS in patients with liver cirrhosis. Compared with the normal group, the relative expression of MIR196A in the case group was significantly increased (P < 0.05), but there was no significant difference in the control group (P > 0.05). In the case group, compared with patients carrying the TT genotype, the relative expression of MIR196A of patients carrying the C allele (CT + CC) evidently increased (P < 0.05).

CONCLUSIONS

The MIR196A2 rs11614913 C > T polymorphism may contribute to an increased risk of HPS in liver cirrhosis patients.

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.

Role of angiogenic factors/cell adhesion markers in serum of cirrhotic patients with hepatopulmonary syndrome

BACKGROUND & AIMS

Hepatopulmonary syndrome is a complication of chronic liver disease resulting in increased morbidity and mortality. It is caused by intrapulmonary vascular dilations and arteriovenous connections with devastating influence on gas exchange. The pathogenesis is not completely understood but evidence mounts for angiogenesis. Aims of this study were to identify angiogenic factors in serum of patients with hepatopulmonary syndrome and to study the possibility to predict its presence by these factors.

METHODS

Multiplex assays were used to measure the concentration of angiogenic factors in patients with (n = 30) and without hepatopulmonary syndrome (n = 30). Diagnosis was based on the presence of gas exchange abnormality and intrapulmonary vasodilations according to published guidelines.

RESULTS

Patients with and without hepatopulmonary syndrome had similar MELD scores (median: 11.2 vs. 11.6; P = 0.7), Child-Pugh score (P = 0.7) and PaCO2 values (median: 35 vs. 37; P = 0.06). PaO2 and P(A-a) O2 gradient were significantly different (respectively median of 80 vs. 86, P = 0.02; and 24 vs. 16, P = 0.004). Based on area under the curve (AUC) data and P-values, the best predictors were vascular cell adhesion molecule 1 (VCAM1) (AUC = 0.932; P < 0.001) and intercellular adhesion molecule 3 (ICAM3) (AUC = 0.741; P = 0.003). Combining these factors results in an AUC of 0.99 (after cross-validation still 0.99).

CONCLUSIONS

VCAM1 and ICAM3 might be promising biomarkers for predicting hepatopulmonary syndrome. Combining these factors results in an AUC of 0.99 and a negative predictive value of 100%. Determining the concentration of these biomarkers might be a screening method to detect hepatopulmonary syndrome. The use of these biomarkers should be validated in larger groups of patients.

Clinical characteristics, predictors, and survival among patients with hepatopulmonary syndrome

BACKGROUND

Hepatopulmonary syndrome (HPS) is a complication of advanced liver disease. The impact of HPS on survival is not clearly understood.

MATERIAL AND METHODS

A prospective study was carried out at Department of Medicine, King Edward Medical University Lahore from June 2011 to May 2012. Patients with cirrhosis of liver were evaluated for presence of HPS with arterial blood gas analysis and saline bubble echocardiography. All patients were followed for 6 months for complications and mortality. Cox regression analysis was done to evaluate role of HPS on patient survival.

RESULTS

110 patients were included in the study. Twenty-nine patients (26%) had HPS. MELD score was significantly higher (p < 0.01) in patients with HPS (18.93 ± 3.51) as compared to that in patients without HPS (13.52 ± 3.3). Twenty two (75.9%) patients of Child class C, 5 (17.2%) patients of Child class B and 2 (6.9%) patients of Child class A had HPS (P 0.03). The clinical variables associated with presence of HPS were spider nevi, digital clubbing, dyspnea, and platypnea. HPS significantly increased mortality during six month follow up period (HR: 2.47, 95% CI: 1.10- 5.55). Child-Pugh and MELD scores were also associated with increased mortality. HPS was no longer associated with mortality when adjustment was done for age, gender, Child-Pugh, and MELD scores (HR: 0.44, 95% CI: 0.14-1.41). Both the Child-Pugh and MELD scores remained significantly associated with mortality in the multivariate survival analysis.

CONCLUSIONS

HPS indicates advanced liver disease. HPS does not affect mortality when adjusted for severity of cirrhosis.

Schistosomiasis-associated pulmonary hypertension

Schistosomiasis, a parasite-borne disease, is highly prevalent in Africa and Asia; it is estimated that close to 20 million people worldwide have a severe form of the disease. The chronic form can affect the gastrointestinal system and lead to hepatosplenic disease, and it may cause cardiopulmonary complications, including pulmonary hypertension. The exact pathogenesis of schistosomiasis-associated pulmonary hypertension (Sch-PH) remains unclear, although several mechanisms, including parasitic arterial embolization, pulmonary arteriopathy, and portopulmonary hypertension-like pathophysiology, have been suggested. The immunopathology of the disease is also unclear, although there are similarities with the immunology of idiopathic pulmonary arterial hypertension (PAH). Finally, the treatment of Sch-PH has not been well studied. There is some evidence on treating the underlying infection, with unclear effect on Sch-PH, and advanced PAH therapies are now being suggested, but more studies are needed to confirm their efficacy.

Intrapulmonary vascular dilatation evaluated by 99mTc-MAA scintigraphy and its association with portal hypertension in schistosomiasis

Background

Portal hypertension is responsible for various complications in patients with schistosomiasis, among them intrapulmonary vascular dilations (IPVD). In cirrhotic patients the presence of IPVD is a sign of poor prognosis, but in patients with hepatosplenic schistosomiasis (HSS) there are no studies assessing the significance of this change. The aim of this study was to evaluate the occurrence of IPVD through ^99mTc-MAA scintigraphy in patients with HSS and its relationship with clinical, laboratory, endoscopic and ultrasound parameters.

Methods

Cross-sectional study evaluating 51 patients with HSS. Patients were diagnosed with IPVD when the brain uptake of ^99mTc-MAA was higher than 6%. Subsequently, they were divided according to presence (G1) or absence (G2) of IPVD and variables were compared between groups.

Results

Overall, 51 patients with mean age of 56±12 years were assessed. IPVD was observed in 31 patients (60%). There was no statistically significant differences between groups when clinical, laboratory and endoscopic parameters were compared. Regarding ultrasound parameters, the splenic vein diameter was smaller in G1 (0.9±0.3 cm) compared to G2 (1.2±0.4 cm), p = 0.029.

Conclusion

In patients with HSS, the occurrence of IPVD by ^99mTc-MAA scintigraphy was high and was associated with lower splenic vein diameter, which can be a mechanism of vascular protection against portal hypertension. However, more studies are needed to determine the clinical significance of the early diagnosis and natural evolution of IPVD in this population.

Intrapulmonary vascular dilatation (IPVD) is the key event in development of hepatopulmonary syndrome, an arterial oxygenation defect in patients with portal hypertension. IPVD diagnosis can be made by EchoDopplercardiography or ^99mTc-macroaggregated albumin scintigraphy (^99mTc-MAA), and ethiopatogeny is still unknown. In Northeastern Brazil, hepatosplenic schistossomiasis (HSS) is the main cause of portal hypertension. In cirrhotics, the presence of IPVD influences survival and candidacy for liver transplantation, however, in HSS patients, IPVD has been poorly studied, specially using lung perfusion scan with ^99mTc-MAA. Some authors believe that IPVD is common in HSS and in the existence of differences in indirect portal hypertension parameters between patients with and without IPVD. All patients were distributed into two groups according to presence or not of IPVD, and laboratorial, endoscopy and ultrasound tests were perfomed. Occurrence of IPVD was high and was associated with lower splenic vein diameter, which can be a vascular protection mechanism against portal hypertension status.

Left ventricle enlargement and increased systolic velocity in the mitral valve are indirect markers of the hepatopulmonary syndrome

BACKGROUND AND AIMS

Hepatopulmonary syndrome (HPS) has been associated with left atrial enlargement, but the presence of other markers of left and right diastolic and/or systolic cardiac dysfunction has not been clarified. We prospectively evaluated the possible associations between echocardiographical-Doppler findings and HPS.

METHODS

Seventy-nine cirrhotic patients without endogenous heart or pulmonary disease were included. HPS was diagnosed by the presence of increased arterial-alveolar-difference and intrapulmonary right-to-left shunt at contrast-enhanced transthoracic echocardiography. Echocardiographical systolic and diastolic indices, tissue Doppler imaging (TDI) of mitral and tricuspid annular motion and M-mode echocardiography measurements were recorded.

RESULTS

Hepatopulmonary syndrome was diagnosed in 12 (15.2%) patients. Patients with compared with those without HPS had significantly younger age, albumin levels and saturation of oxygen (SaO(2)) in an erect position, but higher left ventricular end diastolic diameter (LVEDD), ejection fraction, E-wave peak velocity of tricuspid valve, left atrial volume, TDI E wave (early diastolic period) at the right free wall/tricuspid annulus (cm/s) and TDI S wave (systolic) at the left lateral wall/mitral annulus (TDI Smv). In multivariate analysis, the presence of HPS was found to be independently associated with younger age (P=0.027), lower SaO(2) in an erect position (P=0.023), higher LVEDD (P=0.019) and higher TDI Smv (P=0.026). LVEDD and TDI Smv offered good diagnostic accuracy for HPS diagnosis (AUROC/c-statistic: 0.724 and 0.736 respectively).

CONCLUSIONS

We confirmed that in patients with cirrhosis, the development of HPS is associated with higher cardiac output and hyperdynamic circulation. Left ventricle enlargement and higher systolic velocity in the mitral valve represent satisfactory indirect markers of HPS.

Occurrence of hepatopulmonary syndrome in patients with cirrhosis who are candidates for liver transplantation

OBJECTIVE

To determine the occurrence of hepatopulmonary syndrome (HPS) in patients with cirrhosis who are candidates for liver transplantation; to compare demographic, clinical, laboratory, and spirometric characteristics, as well as echocardiography results, arterial blood gas analysis, and severity of liver disease between the groups of patients with and without HPS; and to describe the occurrence of HPS in the subgroup of patients with cirrhosis and schistosomiasis mansoni (mixed liver disease).

METHODS

Between January and November of 2007, we evaluated 44 patients under treatment at the Liver Transplant Outpatient Clinic of the Federal University of Pernambuco Hospital das Clínicas, in the city of Recife, Brazil. The diagnostic criteria for HPS were intrapulmonary vascular dilatation, identified by transthoracic echocardiography, and an alveolar-arterial oxygen tension difference >or= 15 mmHg or a PaO2 < 80 mmHg.

RESULTS

The mean age of the patients was 52 years, and 31 patients (70%) were male. The most common cause of cirrhosis was alcohol use. Schistosomiasis was present in 28 patients (64%). Of the 44 patients, 20 (45.5%) were diagnosed with HPS. No significant differences were found between those patients and the patients without HPS in terms of any of the characteristics studied. Of the 28 patients with cirrhosis and schistosomiasis, 10 (35.7%) were diagnosed with HPS.

CONCLUSIONS

In the population studied, HPS was highly prevalent and did not correlate with any of the variables analyzed.

Clinical study on pulmonary diffusion function in patients with chronic liver disease

OBJECTIVE

To investigate the influence of chronic liver disease (CLD) on pulmonary diffusion function.

METHODS

Arterial blood gas analysis, pulmonary function test, contrast-enhanced transthoracic echocardiography and technetium macro-aggregated albumin scanning were performed in 50 cirrhotic patients who underwent surgery on portal hypertension and liver transplantation. The severity of chronic liver disease (CLD) was evaluated by Child-Pugh-Turcotte (CPT) categorization and model for end stage liver disease (MELD) score from October 2008 to July 2009 in our surgical department and organ transplantation center.

RESULTS

A-aDO(2) was increased with the aggravation of liver dysfunction. The pulmonary diffusion capacity for carbon monoxide (DLCO) differed significantly among the three groups, which was (90.8 ± 7.3)% in CPT A group, (82.8 ± 10.8)% in CPT B group, and (73.5 ± 8.3)% in CPT C group. A-aDO(2) correlated positively with CPT (r= 0.581, P= 0.000) as well as the MELD score (r= 0.696, P= 0.000), whereas DLCO was negatively correlated with CPT (r=-0.630, P= 0.000) and the MELD score (r=-0.708, P= 0.000).

CONCLUSION

DLCO can be useful in the detection of pulmonary vascular abnormality of CLD. The MELD score may be a better criterion than the CPT score in assessing intrapulmonary vascular damage of CLD patients.

Schistosomiasis-associated pulmonary hypertension: pulmonary vascular disease: the global perspective

Inflammation is likely a critical underlying etiology in many forms of severe pulmonary hypertension (PH), and schistosomiasis-associated PH, one of the most common causes of PH worldwide, is likely driven by the host response to parasite antigens. More than 200 million people are infected with schistosomiasis, the third most common parasitic disease, and approximately 1% of those chronically infected develop PH. Acute cutaneous infection causes inflammation at the site of parasite penetration followed by a subacute immune complex-mediated hypersensitivity response as the parasite migrates through the lungs. Chronic schistosomiasis infection induces a granulomatous inflammation around ova deposited in the tissue. In particular, Schistosoma mansoni migrates to the portal venous system and causes preportal fibrosis in a subset of individuals and appears to be a prerequisite for PH. Portal hypertension facilitates shunting of ova from the portal system to the pulmonary arterial tree, resulting in localized periovular pulmonary granulomas. The pulmonary vascular remodeling is likely a direct consequence of the host inflammatory response, and portopulmonary hypertension may be a significant contributor. New specific therapies available for PH have not been widely tested in patients with schistosomiasis and often are unavailable for those infected in resource-poor areas of the world where schistosomiasis is endemic. Furthermore, the current PH therapies in general target vasodilation rather than vascular remodeling and inflammation. Further research is needed into the pathogenic mechanism by which this parasitic infection results in pulmonary vascular remodeling and PH, which also may be informative regarding the etiology of other types of PH.