The Preliminary Study Of Diagnostic Ultrasound Combined With Left-heart Acoustic Contrast Agent In Vitro Thrombolysis And The Construction Of A New Animal Model Of Intracardiac Thrombosis

Objective:To investigate the dissolution of thrombus in vitro by diagnostic ultrasound combined with ultrasound contrast agent.Method:Forty-nine thrombus models were made from New Zealand white rabbit blood and were randomly divided into seven groups,each contains seven thrombus.(1)Simple saline group(V1);(2)Simple urokinase group(V2);(3)Simple contrast agent group(V3);(4)Saline+ultrasound irradiation group(V4);(5)Urokinase+ultrasound irradiation group(V5);(6)Contrast agent+ultrasound irradiation group(V6);(7)Contrast agent+urokinase+ultrasound irradiation group(V7).The diagnostic ultrasound instrument was Vivid E9 color Doppler ultrasound diagnostic instrument and the irradiation time was 30 minutes.The probes include linear array probe L9 and sector probe M5Sc.The frequency of ultrasound irradiation were 2 MHz,2.5 MHz and 3 MHz.The weight of each thrombus before experiment(Wo)and after experiment(W1)were weighed and the thrombolysis rate was calculated,the thrombolysis rate=[(W0-W1)/W0]X100%.After 180 minutes,the thrombus was stained pathologically.Results:Thrombolysis results showed that:Ultrasound irradiation frequency were 2 MHz,2.5 MHz and 3 MHz,the thrombolytic rates in V4 group were 34.23±4.49%,33.34±2.82%and 35.77±3.44%respectively.The thrombolytic rates in V6 group were 37.56+4.97%、37.50±3.92%and 34.54±3.09%respectively.Compared of V4 group and V6 group,P>0.05,the thrombolytic rate had no statistical significance.Compared of Vi and V2 group,V4 and V5 group,V4 and V7 group,V5 and V6 group,V6 and V7 group,P<0.05;compared of V0 and V3 group,V1 and V4 group,V2 and V5 group,V3 and V6 group,V5 and V7 group,P>0.05;compared of V2,V5 and V7 group,P>0.05.Conclusions:1.Ultrasound combined with ultrasound contrast agent had no obvious effect on thrombolysis under diagnostic ultrasound conditions in this experiment.2.The thrombolytic effect of the simple urokinase group(V2 group),the urokinase+ultrasound group(V5 group)and the contrast agent+ultrasound+urokinase group(V7 group)was clear and consistent.In terms of both economic and safety factors,the cost-effectiveness ratio of the urokinase+ultrasound group(V5 group)was superior to the other two groups(V2 and V7 groups).Objective:Models of intracardiac thrombus are very difficult to establish and have rarely been reported.We designed and established a new,inexpensive,practical animal model for intracardiac thrombus created with epicardial echocardiographic guidance.Methods:Male New Zealand white rabbits weighing 2 to 3.9 kg(3.10+0.58 kg)were used in this study.Cylindrical thrombi were created in plastic tubing and then aspirated with saline into a syringe.The thrombus in saline suspension was then slowly injected into a heart chamber and confirmed with echocardiography,including two-dimensional and contrast-enhanced ultrasound.Results:Intracardiac thrombi were created successfully in the left ventricle,right ventricle,and left and right atrial appendages.The average preparation time was about 3 hours.There were no significant differences among the four heart chambers in the success rate of thrombus model creation.Thrombi embolized to the pulmonary artery after failure of the right heart model.After failure of the left heart model,emboli were found in the carotid artery,renal artery,and truncus coeliacus.In two cases thrombi extended from the left ventricular apex into the aorta and in one case the thrombus extended from the left atrial appendage to the left atrium;there was no such extension from the other chambers.The rabbits’ vital signs remained stable after establishment of the model,with no significant changes in heart structure or function.Conclusions:This new method of creating an intracardiac thrombus model in rabbits showed initial success.