Changes Of Superior Vena Cava Spectra Doppler Flow Velocity In Pulmonary Hypertension By Echocardiography

Objective1. To establish a canine model with acute thrombo-embolic pulmonaryhypertension monitored by echocardiography; and to explore the relationshipbetween the pulmonary arterial pressure and the changes of spectrum of superiorvena cava blood flow in the canine model of acute pulmonary hypertension.2. To investigate the feasibility of establishing a rabbit model of chronicpulmonary hypertension using monocrotaline; to study the structure and functionof the heart, the diameter and the spectra of superior vena cava blood flow inhealthy New Zealand rabbits with two-dimensional and Dopplerechocardiography, and to establish reference value for these parameters in rabbits.3. To study the characteristics of the spectra of superior vena cana bloodflow in a rat model with chronic monocrotaline-induced pulmonary hypertensionby echocardiography; to explore the characteristics of cardiac structure andfunction in rats of pulmonary hypertension by echocardiography. MaterialMaterials and methods1. The femoral vein puncture and the right heart catheterization to monitorpulmonary arterial pressure were operated in 27 canines guided byechocardiography, while the autologous blood clot was injected to thecontralateral femoral vein. The criterion for diagnosing pulmonary hypertensionis that the pulmonary arterial systolic pressure was higher than 30mmHg. Anexamination of the spectra of superior vena cava blood flow was simultaneouslyperformed in the right supraclavicular fossa view by Doppler echocardiography.2. Eighty-four New Zealand rabbits were anesthetized using pentobarbital(30mg/kg, intraperitoneally). Monocrotaline solution (60mg/kg) was injectedintraperioneally in 60 rabbits to develop chronic pulmonary hypertension(monocrotaline group). The same dose of the mixed ethanol and saline wasinjected intraperioneally in 24 rabbits as control (control group). The pulmonaryarterial pressures and the right atrial and ventricular pressures were monitored 4weeks after injection using a pressure-guided microcatheter.The diameter and flow velocities of two superior vena cavas of 84 healthyNew Zealand rabbits were displayed respectively from the both supraclavicularregion view. The diameter and flow velocities were measured, and the respirationcurve and ECG were recorded simultaneously.Systolic left and right atrial dimensions (LAS, RAS), systolic and diastolicleft ventricular dimensions (LVS, LVD) and systolic right ventricular dimension(RVS) were measured by two-dimensional echocardiography. Transmitral andtricuspid inflow (E, A) as well as the mitral and tricuspid annular velocities (e, a)were measured by Doppler echocardiography.LV ejection fraction (EF), short-axis fractional shortening (FS), stroke volume (SV), E/A ratio, e/a ratio, andTei index were calculated. Electrocardiogram and respiration curves weresynchronously recorded.3. The chronic pulmonary hypertension model was developed bymonocrotaline solution (60mg/kg) injection into abdominal cavity in 32 SD rats,and the placebo was injected into abdominal cavity in 8 rats as control group. Anexamination of the spectra of superior vena cava blood flow had been performedby Doppler echocardiography in both supraclavicular fossa view before and28-day after the injection in pulmonary hypertension group. Then the pulmonaryarterial systolic pressure was detected by pressure-guided micro-catheter put intothe pulmonary artery in 28-day after the injection in the control and pulmonaryhypertension group.The left and right ventricular cardiac structrue and function were alsodetected by echocardiography.ResultResults1. Echocardiography accurately guided the placement of right heartcatheterization and observed the pressure testing of pulmonary artery. Of twentyseven healthy experiment dogs, twenty-four models developed acutethrombo-embolic pulmonary hypertension successfully with successful rate88.9%. Compared with the pre-embolization, blood flow to the heart reduced inthe pulmonary hypertension group. S-wave peak velocity were significantlydecreased in the moderate and severe pulmonary hypertension group(P＜0.05).AR-wave peak velocity were significantly higher in the moderate and severehypertension group than pre-embolization (P＜0.05). VR-wave peak velocity were significantly higher in the severe pulmonary hypertension group (P＜0.05).The ratio of AR/S increased significantly with the increase of PASP, and waspositively correlated with PASP (P＜0.01). The ratio of AR/S larger than 0.8could be better adopted to identify all the subjects with pulmonary hypertensionin this study.2. In rabbits except the right atrial diastolic pressure, all the intracardiac andpulmonary arterial pressures in the monocrotaline group did not show significantincrease when comparing with those in the control group (P＞0.05). The averagepulmonary arterial systolic pressure in the monocrotaline group was less than30mmHg though the pulmonary endothelial and smooth muscle cells wereproliferated revealed by pathology. All of the two-dimensional and Dopplerechocardiography images were successfully obtained from the both supraclavicularregion view. The diameter of right superior vena cava (0.29±0.06cm) was largerthan that of left one (0.20±0.04cm, P＜0.01) in the end of inspiration. The S-wavepeak velocity and D-wave peak velocity were higher during inspiration than thoseduring expiration (P＜0.01). There were no statistical differences in VR-wave peakvelocity and AR-wave peak velocity between inspiration and expiration (P＞0.05).The normal values of the cardiac size and function were as follows: LAS0.55±0.13 cm, LVS 0.76±0.17 cm, LVD 1.24±0.15 cm, RVS 0.34±0.06 cm andRAS 0.56±0.11 cm; EF 70.30±8.86 %, FS 36.81±7.38 % and SV 2.64±0.92 ml.E, A, E/A ratio and e of tricuspid valve, but not the a and e/a ratio, weresignificantly increased on inspiration than on expiration (P＜0.05). This was notthe case with the parameters of the mitral valve and the Tei index (P＞0.05).3. Twenty-nine rat models with chronic monocrotaline-induced pulmonaryhypertension had been successfully developed. The spectral characteristics of superior vena cana blood flow were showed that the S-wave peak velocity ofright superior vena cava decreased than before monocrotaline solution injection(P＜0.05). The AR-wave peak velocity and the ratio s of AR/S and ARVTI/SVTIincreased apparently than those before monocrotaline solution injection (P＜0.01)in both sides of superior vena cana.The length of right ventricular in end-diastolic diameter of pulmonaryhypertension group significantly increased (P＜0.05). The pulmonary systolicpressure, pulmonary arterial mean pressure and right ventricular systolic pressureincreased apparently than that before monocrotaline solution injection (P＜0.01).The E/A of mitral and tricuspid valve significantly reduced (P＜0.05). Comparedwith those before injection, there were no significant differences in the LVEF,LVFS and SV after injection (P＞0.05).ConclusioConclusion1. This canine model with acute thrombo-embolic pulmonary hypertensionguided by echocardiography is easy to operate repeatable. The detection of bloodflow spectrum of superior vena cava via right supraclavicular fossa view is highlypractical in non-invasive quantification of pulmonary hypertension rapidly. Theratio of AR/S increased significantly with the increase of PASP, and waspositively correlated with PASP. The ratio of AR/S larger than 0.8 could be betteradopted to identify all the subjects with pulmonary hypertension in this study.The superior vena cava flow spectra may provide good indexes for theassessment of pulmonary arterial pressure.2. Establishment of a model of chronic pulmonary hypertension using thecommonly used dosage of monocrotaline seems not feasible in rabbits. The superior vena cava images of two-dimensional, color and spectralDoppler can be obtained satisfactorily from the supraclavicular plane. There aredifferences in the diameter between two sides. The superior vena cava flowspectra varid with the respiratory cycle.The cardiac structure and function could be evaluated by conventionalechocardiography in rabbits. Normal reference values are set up in this study.3. It may be useful to use AR/S and ARVTI/SVTI ratio as parameters forearly diagnosis of chronic pulmonary hypertension in rats. The structural of rightventricle and the diastolic function of two ventricles altered in the rat withchronic pulmonary hypertension. The systolic function of left ventricular did notdecreased significantly in short-term.