Echocardiographic evaluation of monocrotaline induced pulmonary arterial hypertension in rats

Objective To analyze the correlation between the direct measurement of pulmonary artery pressure and the related echocardiographic parameters in rats with pulmonary arterial hypertension (PAH), and establish a predictable equation for pulmonary artery pressure using non-invasive ultrasonic parameters. Methods Fifteen male Wistar rats were randomly divided into normal control (NC) group with five rats and PAH model group with 10 rats.PAH model was established by intraperitoneal injection of 1% MCT solution in the dose of 60 mg/kg. All the rats were examined by ultrasonic apparatus to record cardiac parameters including right ventricle anterior wall thickness (RVAWT), pulmonary artery diameter (PAD), aorta diameter (AOD), pulmonary artery acceleration time (PAAT), pulmonary artery ejection time (PAET), right ventricle end-diastolic diameter (RVEDD), right ventricle end-diastolic length (RVEDL), tricuspid annular plane systolic excursion (TAPSE) and left ventricular ejection fraction(LVEF) before experiments as well as 2 and 4 weeks after modeling. At the fifth week of modeling, all the rats were administrated with thoracotomy and right ventricular catheter to obtain pulmonary artery systolic, diastolic and mean pressures (PASP, PADP and PAMP). Results As time went on, measures of RVAWT, PAD, PAD/AOD, RVEDD, RVEDL, RVEDD/RVEDL increased, while measurements of PAAT, PAAT/PAET, TAPSE decreased in the model group.The changes of RVAWT, PAD, PAAT/PAET, RVEDD in the model group appeared early in the second week in contrast to data before molding (P<0.05). When comparing model group with NC group, there were statistic differences of RVAWT, PAAT/PAET as early as 2 weeks after modeling measuring (all P<0.05) and the dramatic variance in the parameters of PAD/AOD, PAAT, RVEDD, RVEDD/RVEDL, TAPSE appeared in 4-week observation. Correlation analysis suggested there were high-degree correlations between PAAT, PAAT/PAET and PASP, PAMP (for PASP: r=-0.829, -0.865, P<0.05; for PAMP: r=-0.831, -0.842, P<0.05), and moderate-degree correlations between RVAWT, PAD/AOD, RVEDD, RVEDD/RVEDL, TAPSE and PASP, PAMP (for PASP: |r|=0.615-0.786, P<0.05; for PAMP: r=0.683-0.799, P<0.05). The linear dependent equations were established as PASP=-169.392PAAT/PAET+ 105.092 (r2=0.748, P=0.000), PASP=49.576RVAWT+ 67.314RVEDD/RVEDL-45.198 (r2=0.731, P=0.003), PAMP=-150.664PAAT/PAET+ 88.156 (r2=0.709, P=0.001), PAMP=37.988RVAWT+ 82.072RVEDD/RVEDL-50.517 (r2=0.794, P=0.001) to represent the relationships between PASP or PAMP and PAAT/PAET or RVAWTcombined RVEDD/RVEDL. Conclusions Echocardiography can monitor changes in heart structure and hemodynamics.Ultrasonic parameters especially PAAT/PAET or RVAWT, RVEDD/RVEDL could be used to estimate PASP or PAMP measured by catheterization. Key words: Echocardiography; Hypertension, pulmonary; Monocrotaline; Rat