LAUSR

It is shown, that up to quarter of patients with hepatic cirrhosis may reveal pulmonary hypertension (PH) irrespective of the etiology of the liver disease. The hyperdynamic circulatory status is considered to be one of the main factors, triggering the pulmonary arterial pressure elevation. Parasite infections, especially echinococcosis can also trigger PH, developing through several mechanisms. While the hyperdynamic circulatory status can be observed in patients with echinococcosis, the pulmonary embolism with hydatid cysts may also be present, leading to severe PH in some cases. Still the descriptions of PH in patients with hydatid disease are limited to selected case reports with no data on big samples. Chronic highland exposure is another factor which may provoke the PH onset, but this type of PH remains underinvestigated. In the case–control study by Zhou et al. the authors present echocardiographic data in rather unusual groups of population, dealing simultaneously with parasite disease and highland exposure. These factors may overlap each other but both of them are regarded as possible triggering factors for PH. However, the results of the study demonstrate that the influences of the mentioned conditions should be distinguished from each other and the pathophysiological mechanisms of PH may differ. While the most case reports of echinococcosis published in the field of echocardiography research are cases of direct cardiac involvement with hydatid cysts found in the chambers of the heart or in pulmonary artery, in this study no one patient had cardiac hydatid cysts, but all patients in the main group had echinococci in the liver. The authors demonstrate that in patients with parasite disease the initial signs of biventricular systolic and diastolic dysfunction are present, which may be explained by the parasite toxic influence on the heart, however there is no data on such a conditions in the literature. For instance, Hidron et al. in the review report that arrhythmias, myocardial infarction, cardiac tamponade, pulmonary hypertension, syncope, purulent pericarditis, and sudden cardiac death are the possible clinical manifestations of cardiac echinococci. Again there is no data on cardiac clinical symptoms in patients with hepatic echinococci because most investigators focus on cardiac echinococcosis. Nevertheless, the possible toxic cardiomyopathy with significant left ventricle impairment can lead to PH in its turn, but this type of PH may have post-capillary nature. At the same time, the hyperdynamic circulatory status, which can be present in patients with highland exposure and in patients with parasite disease leads to pre-capillary PH. Also in the article, few possible explanations of the echocardiographic findings are provided. For instance, decreased systemic vascular resistance in patients with echinococci may raise the E velocity, leading to the E/e' overestimation. At the same time, the vascular remodeling, which is generally present in patients with PH may explain the smaller dimensions of pulmonary artery and its branches. Another interesting point concerning the methodology of presented study is an attempt to overcome the intra-observer variability of the measurements. This is particularly important for the studies where single imaging modality is used and no clinical correlations are assessed. In such works, the risk of bias and measurement variability interfering the results is always present. When assessing the patients suspicious for PH it may be critical to minimize the right heart measurements variability, which was successfully solved in the presented study with Bland–Altman test for inter-observer variability and paired t-test for intra-observer variability. Thus, the presented article gives the path to the future studies with the aim of distinguishing the various types of PH in patients, amenable to the multiple triggering factors. As the echocardiography still remains the initial method for PH screening and monitoring, the data on specific ultrasound markers of subclinical right and left ventricular dysfunction are valuable. Among the modern echocardiographic parameters, the right and left ventricular systolic strain may be useful, especially in revealing the toxic influence of the parasite Received: 16 July 2022 Accepted: 18 July 2022