No abstract

Measurements of excessive exercise ventilation which consider all data points maximize the usefulness of incremental cardiopulmonary exercise testing in the prognosis evaluation of PAH.

It has been reported that schistosomiasis-associated PAH (Sch-PAH) has a more benign clinical course compared with idiopathic PAH (IPAH). We therefore hypothesized that Sch-PAH subjects would present with less impaired cardiopulmonary and metabolic responses to exercise than IPAH patients, even with similar resting pulmonary hemodynamic abnormalities. The aim of this study was to contrast physiologic responses to incremental exercise on cycle ergometer between subjects with Sch-PAH and IPAH. We performed incremental cardiopulmonary exercise tests (CPET) in subjects newly diagnosed with IPAH (n = 9) and Sch-PAH (n = 8), within 1 month of the hemodynamic study and before the initiation of specific therapy for PAH. There were no significant between-group differences in cardiac index, pulmonary vascular resistance or mean pulmonary artery pressure. However, mean peak oxygen uptake (VO2) was greater in Sch-PAH than IPAH patients (75.5±21.4 vs 54.1±16.1% predicted, p = 0.016), as well as the ratio of increase in VO2 to work rate (8.2±1.0 vs 6.8±1.8 mL/min/W, p = 0.03). Additionally, the slope of the ventilatory response as a function of CO2 output was lower in Sch-PAH (40.3±3.9 vs 55.6±19.8; p = 0.04), and the heart rate response for a given change in VO2 was also diminished in Sch-PAH compared to IPAH (80.1±20.6 vs 123.0±39.2 beats/L/min; p = 0.02). In conclusion, Sch-PAH patients had less impaired physiological responses to exercise than IPAH subjects with similar resting hemodynamic dysfunction. Our data suggest a more preserved cardiopulmonary response to exercise in Sch-PAH which might be related to its better clinical course compared to IPAH.

Compared to patients with IPAH, patients with CTEPH present more impaired gas exchange during exercise, and PetCO abnormalities may be used to identify more clinically and hemodynamically severe cases.

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...