Doppler flow patterns in the evaluation of pulmonary hypertension

Pulmonary arterial hypertension is defined as a group of diseases characterised by a progressive increase in pulmonary vascular load, leading to marked increase in pulmonary artery pressure, right ventricular failure and premature death. Given the nonspecific nature of its early symptoms and signs, pulmonary arterial hypertension (PAH) is often diagnosed in its advanced stages. Although clinical assessment is essential when initially evaluating patients with suspected PAH, echocardiography is a key screening tool in the diagnostic algorithm, because, in comparison with invasive measurements, it has the advantages of being safe, portable, and repeatable. Therefore, Doppler echo is the modality most frequently used in pulmonary hypertension patients. Several echocardiographic techniques centered on the Doppler principle (both conventional Doppler parameters and tissue Doppler imaging) used in the assessment of PAH magnitude and its cardiac effects are presented in this paper. They provide important data on the severity, possible causes and consequences of pulmonary hypertension, both initially and during follow-up, therefore having the ability to estimate disease progression, prognosis, or to monitor therapeutic response. Doppler echocardiography allows to noninvasively estimate systolic pulmonary arterial pressure (SPAP), mean and end-diastolic pulmonary arterial pressure, as well as the quantification of right ventricular (RV) function and the evaluation of pulmonary vascular resistance (PVR).