Introduction
Pulmonary hypertension (PHTN) is a disease of small pulmonary arteries characterized by a progressive increase in pulmonary vascular resistance leading to right ventricular failure. The World Health Organization (WHO) defined a classification for pulmonary hypertension diagnosis , based on the cause of the disease. PHTN is defined as a mean pulmonary artery pressure (mPAP) of 25 mm Hg at rest in Right Heart cath (RHC). PHTN results in right ventricular (RV) pressure overload, which ultimately leads to right-heart failure and death(1,2). The gold standard for the diagnosis of PHTN is right heart catheterization (1). Due to its invasive character and lack of access to the required equipment, RHC cannot be used as a routine screening method. (2, 3).
Echocardiography is an affordable technique and is widely used in diagnosis of cardiac abnormalities in PHTN patients. It has been shown that echocardiography has an acceptable accuracy in detecting mPAP and thus can be used as a screening tool for PHTN in suspicious cases (4). The current advancements in Doppler echocardiography has made it more suitable for the assessment of mPAP (4). The PAP can be determined based on various echocardiographic parameters including pulmonic valvular regurgitation, acceleration time of Pulsed-wave Doppler interrogation of the RV outflow tract and systolic TR jet(which is used to estimate systolic pulmonary artery pressure ,SPAP), too. SPAP is achieved only based on TR jet. TR jet might result in inaccurate SPAP due to trivial regurgitant jet, suboptimal continuous-wave, unclear jet envelope and severe TR, where the peak velocity may not reflect the true RV–right atrial pressure (RAP)gradient because of early equalization of RV pressure and RAP. So, echocardiography was shown to underestimate or overestimate SPAP compared to invasive methods (5). Based on the limitations in the methods for assessing the modalities for detecting PAP, other modalities should be tested to identify PAP with an acceptable accuracy.
It was previously reported that flow velocity, waveform morphology of middle hepatic vein (MHV) and inferior vena cava (IVC) were significantly related to RA pressure (6). The hepatic vein has a smaller angle compared to the IVC (6). Therefore, echocardiographic parameters pertaining to hepatic vein may serve as easy measures for assessing right atrial (RA) pressure (3, 7). It was previously shown that chronic pulmonary hypertension increases the sensitivity of HV systolic filling fraction in detecting cardiac chamber dysfunction (8, 9). The aim of this study was to identify the proper hepatic vein Doppler echocardiographic parameters in predicting PHTN.