New experimental animal model of intracardiac thrombus created with epicardial echocardiographic guidance.

Background: 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 echo-cardiography, 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.