Elevated pulmonary pressure and right ventricular (RV) dysfunction are the hallmarks of pulmonary vascular disease in animal models and human patients with pulmonary arterial hypertension (PAH). Monocrotaline models of PAH are widely used to study the pathophysiology of PAH. The purpose of this study was to evaluate the severity of PAH rat model by tissue Doppler imaging (TDI).

PAH was induced in Sprague-Dawley rats by monocrotaline (M) group. The peak systolic (s'), early diastolic (e'), and late diastolic myocardial velocities (a') were measured using TDI at basal segments. Tricuspid annular plane systolic excursion (TAPSE) was measured in the 4-chamber view. Velocity of a tricuspid regurgitation (TR) jet was measured to estimate the pulmonary artery pressure to assess the severity of PAH.

Decrease in the RV shortening fraction and ejection fraction were observed in the M group compared with the control (C) group. RV e' velocity and s' velocity were significantly lower in the M group compared with the C group. The TAPSE was significantly lower in the M group compared with the C group (1.26±0.22 mm vs. 2.83±0.34 mm). The TR velocity was significantly higher in the M group compared with the C group (4.48±0.34 m/sec vs. 1.23±0.02 m/sec).

TAPSE is an easily obtainable, widely recognized and clinically useful echocardiographic parameter of global RV function in the PAH rat model. We recommend that TDI would be a helpful diagnostic tool to evaluate the RV function in PAH rat model.