Superior Vena Cava Doppler Flow Changes in Rabbits With Acute Thromboembolic Pulmonary Hypertension

OBJECTIVE: The purpose of this study was to explore the superior vena cava (SVC) Doppler flow changes in rabbits with acute thromboembolic pulmonary hypertension (ATEPAH) and its value in evaluating pulmonary pressure. METHODS: The systolic peak flow velocity (SPV), ventricular reverse peak flow velocity (VrPV), diastolic peak flow velocity (DPV), and atrial reverse peak flow velocity (ArPV) of the SVC were measured on end expiration with pulsed wave Doppler echocardiography in 30 rabbits with different degrees of ATEPAH. Linear regression and the Bland-Altman method were used to analyze the correlation of Doppler flow velocities of the SVC to the catheter-measured pulmonary arterial systolic pressure (PASP). RESULTS: The SPV values of all groups were significantly lower after pulmonary embolism (PE) than before PE (P < .05). The VrPV values of the mild and the moderate groups but not the severe group were significantly higher after PE than before PE. The DPV values of the severe ATEPAH group were significantly lower after PE than before PE, but they were not lower in the other 2 groups. The SPV had a significantly negative relationship with the PASP (r = -0.692; P < .0001). The VrPV/SPV ratios of all groups showed a significant positive correlation with the PASP (r = 0.698; P < .0001). The end-diastolic diameter of the SVC gradually enlarged with the rapidly increased PASP and showed a significantly positive relationship in all groups (r = 0.594; P = .002). CONCLUSIONS: Analysis of the Doppler flow SPV and VrPV, the VrPV/SPV ratio, and the diameter of the SVC might provide an alternative method for catheterization in estimating pulmonary pressure.