Experimental Study On The Diagnostic Value Of Echocardiography In Acute Pulmonary Embolism On Rabbits

Experimental Study on the Diagnostic Value of Echocardiography in Acute Pulmonary Embolism on RabbitsPrefaceAcute pulmonary embolism(APE) is a pathology and physiology integrative signs of clinic acute pulmonary circulatory disturbance caused by all kinds of endogenous and external embolus obstructing pulmonary artery.According to the study on epidemiology in the world,the incidence of APE is next only to coronary heart disease and high blood pressure.In the West country,APE is the third underlying cause of death.Although it was always considered that there is very low incidence of APE in china in the past,APE increases to some extent as a result of the changed living habits, the use of acyeterion for controlling the population,developing intervention technology and so on.Due to its high incidence rate,high death rate and misdiagnosis rate,APE has become a noteworthy problem in the medical treatment and health care.At present, many approaches can be used to diagnose and clinically observe APE accurately,such as pulmonary artery CT,pulmonary vascular image,MRI and nuclide imaging.But these inspection methods are all expensive,and they are very difficult to be a routine in the most of national hospital for limited condition.It is well known that ultrasound has been becoming an irreplaceable clinical diagnosis method.It posses many advantages such as its simple,fast,noninvasive,repeatable,movable operation.As indicated in "Guide to Diagnosis and Therapy on Acute Pulmonary Embolism",echocardiography is the best choice for the suspected and diagnosed APE patient.The standard of echocardiography for diagnosing APE by transthoracic echocardiography:a) accurately diagnosed PE:direct signs + acute corpulmonale + pulmonary hypertension;b) Possible PE:acute corpulmonale + pulmonary hypertension;c) Suspected PE:acute corpulmonary.The direct 2D signs for echocardiography of APE is a obvious echo of embolus in right atrium,right ventricle,pulmonary artery and its branches.However, there is a very low detection rate in echocardiography through direct signs,and it was reported as merely 10%-15%.Therefore,it is very important to detect the indirect signs of PE for diagnosing PE.The ultrasonic scholars both at home and abroad contribute to the research of this area deeply,but they rarely focused on how to improve the specificity and sensibility of echocardiography for PE diagnosis.In order to offer a diagnostic standard and reference for quantitive APE diagnosis by echocardiography, this project is aimed to investigate the diagnostic significance of echocardiography on APE through the model experiment of echocardiography on detecting APE of rabbit.Materials and methods1.Bilateral Pulmonary Arterial Flow Discordance after Acute Pulmonary Embolism on Rabbits(1) Twenty-five healthy Japanese white rabbits were anesthetized using an intraperitoneal injection of 2%pentobarbital sodium physiological saline solution 115ml/kg(30mg/kg).Routine surface electro cardio was monitored.A micro-catheter was inserted into pulmonary artery via left femoral vein to monitor pulmonary artery systolic pressure of pro-embolism and post-embolism.Arterial blood of pro-embolism and post-embolism were drew by left femoral arterial cannula for blood gas analysis.The rabbit models of acute pulmonary embolism were created by femoral vena catheter using gelatin sponge.Four gelatin sponge emboli, 2mm×2mm×10mm each,were injected separately to right atrium via the right external jugular vein following with 5ml physiologic saline,which could make these emboli embolize pulmonary artery following blood stream.(2) The blood velocity and velocity-time integral,flow(V_m,V_l,V_r,VTI_m,VTI_l, VTI_r,Flow_m,F1ow_l,FIow_r)△VTI/mean,△Flow/mean etc of pro-embolism and post-embolism was obtained by echocardiography.(3) Subsequently,these model rabbits were anatomized.The appearances of lung were observed to find the areas of infarction.Later,pulmonary arteries were opened with shears along direction of pulmonary artery.Emboli were searched and tagged. Pathologic sliced were done at the same time.(4) The patterns of PE were sorted according to the outcome of anatomy and Pathology,which were the right dominant type,the left dominant type and the bilateral type,respectively.A comprehensive statistics analyses was done among these outcomes of pro- pulmonary embolism and post-pulmonary embolism.2.The Variation of Tissue Doppler Parameters after Acute Pulmonary Embolism with Pulmonary Hypertension on Rabbits(1) Twenty-five healthy Japanese white rabbits were anesthetized using an intraperitoneal injection of 2%pentobarbital sodium physiological saline solution 115ml/kg(30mg/kg).Routine surface electro cardio was monitored.A micro-catheter was inserted into pulmonary artery via left femoral vein to monitor pulmonary artery systolic pressure of pro-embolism and post-embolism.Arterial blood of pro-embolism and post-embolism were drew by left femoral arterial cannula for blood gas analysis.The rabbit models of acute pulmonary embolism were created by right external jugular vena catheter using gelatin sponge.Gelatin sponge emboli, 2mm×2mm×10mm each,saline were injected separately to right atrium via the right external jugular vein following with 5ml physiologic,which could make these emboli embolize pulmonary artery following blood stream.Stop injecting gelatin sponge emboli,when pulmonary Artery systolic pressure exceeded 30mmHg,(2) Routine echocardiography and tissue Doppler imaging were performed.Peak early and late diastolic mitral inflow velocity were obtained by routine echocardiography.Systolic velocity,early diastolic velocity,late diastolic velocity, isovolumic contraction and relaxation time of right ventricular lateral tricuspid annulus and left ventricular lateral mitral annulus,the right and the left ventricular myocardial performance indexes(MPI) were obtained by Doppler tissue echocardiography.The E-index was measured and defined as the peak early diastolic mitral inflow velocity divided by the RV MPI.The M-index was measured and defined as the RV MPI divided by the LV MPI.(3) Subsequently,these model rabbits were executed to go on anatomy and Pathological test.(4) A statistics analyze was done among these outcomes of pro-pulmonary embolism and post-pulmonary embolism.Results1.Twenty-three rabbit models with acute pulmonary embolism were successfully established.Compared with pro-embolism by echocardiography,The PASP was increased significantly with the main pulmonary artery,the left pulmonary artery and the right pulmonary artery expanding passively.The appearance of chambers heart changed prominently during post-embolism.The right ventricle increased and left ventricle decreased oppositely(P<0.01),interventricular septum expanded toward left ventricle.Compared with pro-embolism by Doppler echocardiography.The blood velocity and velocity-time integral,flow of the main pulmonary artery,the left pulmonary artery and the right pulmonary artery(V_m,V_l,V_r,VTI_m,VTI_l,VTI_r, F1ow_m,F1ow_l,FIow_r) of post-embolism were decreased(P<0.001) and△VTI/mean,△Flow/mean of post-embolism were increased(P<0.0001),especially for the right or left dominant type.2.Twenty-three acute pulmonary embolism rabbit models with signs of pulmonary hypertension were successfully established,however,three of them with atrial fibrillation were excluded from our study.Compared with pro-embolism,Peak early diastolic mitral inflow velocity was decreased,the difference was significant (P<0.0001).However,Peak late diastolic mitral in flow velocity of post-embolism had no variance(P>0.05).The RV lateral tricuspid annulus systolic velocity and early diastolic velocity were decreased,late diastolic velocity was increased reversely, isovolumic contraction and relaxation times were prolonged significantly,and RVMPI was increased significantly(P <0.01),Compared with pro-embolism,the LV lateral tricuspid annulus of post-embolism of early diastolic velocity was decreased, isovolumic contraction and relaxation time were prolonged and LVMPI was increased (P<0.05),Systolic velocity and late diastolic velocity had no variance(P > 0.05), Compared with pro-embolism.E-index of post-embolism was decreased and M-index of post-embolism was increased(both P <0.0001).Conclusion1.Compared with pro-embolism,because of the fact that the distribution of bilateral pulmonary arterial blood flow of post-embolism changed significantly,△VTI/mean and△Flow/mean were increased evidently.2.Compared with pro-embolism,because Peak early diastolic mitral inflow velocity of post-embolism with PH was decreased,E-index of post-embolism with PH, which was defined as peak early diastolic mitral inflow velocity divided by the RV MPI,decreased significantly;Due to the fact that RVMPI of post-embolism with PH was more significantly increased than LVMPI,M-index of post-embolism with PH, which was defined as RVMPI divided by the LVMPI,increased clearly.3.△VTI/mean,△Flow/mean,E-index,M-index may be have significant value in diagnosing and quantitively assessing acute pulmonary embolism.