| Objective To evaluate the accuracy in estimating pulmonary arterial pressure with four ultrasonic Doppler modalities(pulmonary arterial acceleration time,pulmonary arterial acceleration time/pulmonary arterial ejection time,pulmonary arterial acceleration time/heart rate and tricuspid regurgitation peak flow velocity)in rats treated with monocrotaline(MCT)for 4 weeks.Methods The total of 41 male Sprague-Dawley rats at the age of 8 weeks were subjected todimethyl sulfoxide(DMSO)(2 ml/kg)or MCT(60 mg/kg,2 ml/kg)subcutaneous injection on the neck(MCT group:n=30,control group:n=11respectively).Four weeks after treatment,comprehensive trans-thoracic echocardiography was performed on the rats under intravenous anesthesia.Two-dimensional ultrasongraphy was utilized to measure right ventricular anterior wall thickness(RVAW),left ventricular end-systolic and end-diastolic volume,thus calculating the left ventricular ejection fraction(EF).The pulmonary arterial acceleration time(PAAT),pulmonary arterial ejection time(PET),tricuspid regurgitation peak flow velocity(TR peak)and heart rate(HR)were measured with Pulse or Continuous-Wave Doppler.All of rats’invasive pulmonary arterial pressure(PAP)was measured with direct puncture of right ventricle oulflow tract and advancing the catheter into pulmonary artery.The invasive PAP which was applied as gold standard to assess the correlation with following ultrasonic parameters as PAAT,PAAT/PET,PAAT/HR and TR peak.Thereafter,the rats were given euthanasia after PAP direct measurement.The heart and lung tissue was excised completely and fixed in the formalin followed with hematoxylin-eosin staining.The changes of pulmonary vascular histopathology were observed under optical microscope.Then we measured the maximal external diameter of pulmonary arterioles(ED)and the media thickness between the internal and outer elastic lamina(MT).Finally,according to the formula:WT%=(2MT÷ED)×100%,the percentage of medial membrane thickness of pulmonary arterioles(WT%)was calculated to evaluate the proportion of medial membrane thickness of pulmonary vessels.Results The MCT-treated rats had higher PAP and RVAW after 4 weeks treatment compared with controlled rats respectively(22.2±1.78 vs 34.7±9.43 mm Hg,P<0.01;0.712±0.097 vs 0.879±0.172 mm,P<0.01).The four ultrasonic Doppler parameters of PAAT,PAAT/PET,PAAT/HR,PET were significantly different between the two groups(30.85±3.82 vs 23.44±5.32 ms,P<0.01;0.410±0.066 vs 0.286±0.075,P<0.01;0.094±0.020 vs 0.077±0.022,P<0.05;76.47±11.22 vs 82.77±7.80 ms,P<0.05).The ratio of tunica media of pulmonary arterioles in MCT-treated rats was markedly increased compared with the controlled rats(0.764±0.086 vs 0.225±0.067,P<0.01).Furthermore,the PAAT,PAAT/PET,PAAT/HR were closely negatively-correlated with the invasive mean pulmonary arterial pressure(PAP)(r~2=0.49,0.469,0.267,P<0.05).TR peak had the lowest relationship with the mean pulmonary artery pressure.ROC curve showed that PAAT/PET had the highest diagnostic value and it’s cut off value of 0.381 had 0.818 and 0.90 in sensitivity and specificity respectively on estimating pulmonary arterial hypertension(m PAP≥25mm Hg).Conclusion The ratio of PAAT to PET was more reliable to assess pulmonary artery pressure in rats with PAH than TR peak. |
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