Pulmonary hypertension

Pulmonary hypertension is a disease caused by elevation of pressure in pulmonary arteries. The syndrome has multiple pathways that end in high artery pressure. 

 In many patients, the diagnosis of PH is made clinically using a constellation of clinical findings and noninvasive testing. For example, a clinical diagnosis is commonly made in patients with PH that is explained by significant left heart disease (LHD) or by chronic lung disease (CLD). In contrast, other patients require a hemodynamic diagnosis using right heart catheterization (RHC; eg, patients with suspected idiopathic pulmonary arterial [PA] hypertension [PAH]). Hemodynamically, a mean PA pressure (mPAP; supine and at rest) of >20 mmHg is now considered diagnostic of PH based upon data measuring mPAP in healthy individuals, which confirmed that an mPAP of 8 to 20 mmHg at rest is normal. While in the past, PH was hemodynamically defined by an mPAP of ≥25 mmHg [41], this cutoff was somewhat arbitrary and targeted at avoiding the overdetection of PH. [1]

Once PH is suspected, the initial test of choice is transthoracic echocardiography (TTE), which then determines the sequence of subsequent testing. Importantly, patients with evidence of severe PH and/or patients with significant symptoms should be referred to a PH center for rapid evaluation. TTE evaluates the following: [1]

• The probability of PH using the tricuspid regurgitant jet velocity (TRV). TRV can also be used to estimate the pulmonary artery (PA) systolic pressure (ePASP).
• The assessment of RV size, wall thickness, and function.
• The potential contribution of left-sided heart disease to PH (if PH is identified on TTE)

In general, experts use a combination of the TRV and ePASP together with echocardiographic findings suggestive of RV hypertrophy/strain when evaluating the probability of PH. PH is suggested echocardiographically when the TRV is ≥2.8 m.s-1; the ePASP exceeds 35 mmHg in younger adults or 40 mmHg in older adults; and/or when RV size, wall thickness, and function are abnormal, understanding that PH may still be present even in the absence of these findings. Although estimation of the ePASP is practical and still used by many experts, ePASP may poorly correlate with values obtained by right heart catheterization (RHC), which may, in part, be due to variability in the measurement of right atrial pressure (RAP), which is necessary for calculating ePASP. Thus, we and others support guidelines issued by the European Society of Cardiology (ESC) and the European Respiratory Society (ERS) and endorsed by the 6th World Symposium on Pulmonary Hypertension (WSPH) that propose use of the peak TRV together with echocardiographic findings of PH rather than ePASP to report the echocardiographic probability of PH. Regardless of whether the TRV or ePASP is used, these values should always be interpreted together with clinical suspicion and signs of RV dysfunction to facilitate the decision about proceeding with additional testing for PH. [1]

TRV might be the best measure to predict PH. In general, experts use a combination of the TRV and ePASP together with echocardiographic findings suggestive of RV hypertrophy/strain when evaluating the probability of PH. PH is suggested echocardiographically when the TRV is ≥2.8 m.s-1; the ePASP exceeds 35 mmHg in younger adults or 40 mmHg in older adults; and/or when RV size, wall thickness, and function are abnormal, understanding that PH may still be present even in the absence of these findings. [1]