Analysis of Doppler flow spectra of the superior vena cava in a canine model of acute thromboembolic pulmonary hypertension.

We aimed to establish a canine model of acute thromboembolic pulmonary hypertension (ATEPH) and to explore the feasibility of diagnosing pulmonary hypertension (PH) through the Doppler flow spectra of the superior vena cava (SVC). A canine model of ATEPH was developed by infusing thrombus into the right femoral vein. The pulmonary arterial pressure was simultaneously measured via a right heart catheter with the guidance of ultrasound. The maximum 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 by transthoracic echocardiography. ATEPH was successfully established in 24 dogs (88.9%) with the pulmonary arterial systolic pressure (PASP) greater than 30 mmHg. ARPV increased significantly with the increase of PASP, and was positively correlated with PASP (P<0.001). The ARPV/SPV larger than 0.8 could be better adopted to identify all the subjects with PH in this study. The Doppler flow spectra of the SVC could be employed to assess the severity of ATEPH.

Doppler flow spectra of the superior vena cava in a rat model of chronic pulmonary hypertension.

The aim of this study was to explore the changes of the Doppler flow spectra of the superior vena cava (SVC) in a rat model of chronic pulmonary hypertension (PH). Thirty-two rats were injected with monocrotaline (MCT) to establish a model of chronic PH. Eight rats from the control group had a sham operation by injecting Dulbecco's phosphate-buffered solution. Serial echocardiographic parameters of the SVC were analysed four weeks after treating with MCT or placebo, and the relationship was analysed between the Doppler flow spectra of SVC and the pulmonary arterial systolic pressure (PASP). PH models were successfully established in 29 rats. The right ventricular systolic pressure, mean pulmonary arterial pressure and PASP in the PH group were significantly higher than those in the sham group at 28 days (P < 0.001). The ratios of SVC maximum reverse peak flow velocity/maximum systolic peak flow velocity (VAr/VS) and maximum reverse peak velocity time integral/maximum systolic peak velocity time integral (VTIAr/VTIS) increased significantly (P < 0.05) after MCT injection. These results demonstrate that echocardiography can be used to monitor the haemodynamic changes in SVC in MCT-induced chronic PH rat models. The ratios of VAr/VS and VTIAr/VTIS may be sensitive indices for evaluating PH.

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.

A rabbit model with acute thrombo-embolic pulmonary hypertension created with echocardiography guidance.

A rabbit model of acute thrombo-embolic pulmonary hypertension was developed by infusing self-thrombi into the right femoral vein and simultaneously measuring the pulmonary artery pressure via a right heart catheter and echocardiography. The model was used to explore the usefulness of an ultrasound-guided protocol. In the present study, acute thrombo-embolic pulmonary hypertension was produced in 25 of 30 healthy New Zealand rabbits; the success rate was 83%. A significant and positive correlation between the right ventricle-right atrial pressure gradient, an estimate of the pulmonary artery systolic pressure derived from tricuspid regurgitation and the pulmonary artery systolic pressure measured using the right heart catheter (r=0.765, P=0.002) was noted. During the process of establishing a rabbit model of acute thrombo-embolic pulmonary hypertension, it was demonstrated that echocardiography can be used to guide the right heart catheter to obtain pulmonary artery systolic pressure measurements, to quantify the tricuspid regurgitation jet to assess the pulmonary artery systolic pressure and to observe cardiac morphologic changes so as to evaluate cardiac function. Based on the present study, it is clear that echocardiography is valuable in improving the success rate of producing the animal model of acute thrombo-embolic pulmonary hypertension. This could ultimately facilitate preclinical research and clinical research in humans.