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

Abstract

We read with interest the recently published article by Fussner et al. (1) in Liver Transplantation. The authors showed that intrapulmonary vascular dilatations (IPVDs), detected by agitated saline contrast-enhanced transthoracic echocardiography (cTTE), were common in patients with portopulmonary hypertension (POPH)-59% of patients. Moreover, this finding was associated with decreased survival, and the authors suggest the possibility of a pathophysiological overlap between POPH and hepatopulmonary syndrome in patients with end-stage liver disease. (1) Interestingly, this feature was previously described in patients with schistosomiasis. (2,3) Early reports of the disease identified a unique pattern of pulmonary involvement in patients with schistosomiasis: pulmonary hypertension with central cyanosis in the absence of intracardiac shunt. (2) In 1 study, IPVD was found in 20% of patients with schistosomiasis cor pulmonale. (3) According to necroscopic studies, cyanosis was associated with arteriovenous fistulae, possibly due to bypass of Schistosoma eggs in pulmonary circulation. Furthermore, other investigators confirm this finding and hypothesized that it could be related to repeated worm infestation, common in endemic areas. The pathophysiology of schistosomiasis-associated pulmonary arterial hypertension (Sch-PAH) is not completely understood, but it probably shares some similarities with POPH, in a model without liver cirrhosis.Sch-PAH is potentially the most common cause of pulmonary hypertension worldwide and is associated with higher survival rates compared to IPAH. (4) Our group recently published an article contrasting physiological responses to incremental exercise in cardiopulmonary exercise tests (CPETs) between naive patients with Sch-PAH (n 5 8) and with idiopathic pulmonary arterial hypertension (IPAH) (n 5 9) with similar resting hemodynamics. Interestingly, Sch-PAH showed less impaired physiological responses to incremental exercise than IPAH patients, suggesting a more preserved cardiopulmonary response to exercise in Sch-PAH, which could be related to its better clinical course compared to IPAH. (5) However, at that time, the mechanisms involved were not identified. Even though none of the patients with Sch-PAH had cyanosis or hypoxemia (only 3 had SpO 2 90% at the end of the incremental CPET), cTTE was performed after the publication, and IPVD was detected in 6/8 (75%) Sch-PAH patients (data not published). It is noteworthy that despite the high prevalence of IVPD in this study, only 2 patients died to date (1 of them was without IPVD), which contrasts with the poor prognosis of the presence of IPVD in patients with cirrhosis described by Fussner et al. (1) The clinical relevance of the presence of IPVD in patients with Sch-PAH is not clear, but it is possible to hypothesize that IPVD could attenuate right ventricular stress during exercise. Further studies are needed in order to obtain a better understanding of the natural history of IPVD associated with schistosomiasis as well as to assess...

Portopulmonar hypertension: Is there something new?

“…POPH is identified by an increase in pulmonary arterial pressure and a bloodstream flow impediment secondary to progressive obstruction of the arterial vascular bed 7 , leading to a step-by-step dysfunction of the right-sided heart. POPH criteria were described in 2004 by the Task Force on pulmonary-hepatic disorders and were maintained in the International Liver Transplant Society practice guidelines for the hepatopulmonary syndrome and POPH [8][9][10] (Table 1).…”

“…Intrapulmonary vascular dilations (IPVDs) have been reported in up to 59% of patients, suggesting an overlap between POPH and the hepatopulmonary syndrome. Their presence can compromise treatment (induce hypoxemia) as well as outcome/survival, especially in the LT setting 7 .…”