ASSESSMENT OF LEFT-VENTRICULAR AREA AT RISK BY MYOCARDIAL CONTRAST 2-DIMENSIONAL ECHOCARDIOGRAPHY - AN EVALUATION OF A NEW ANIMAL-MODEL

Background: New echocardiographic contrast agents are commonly tested in the dog model. However, this species has a number of drawbacks, inc luding difficulties in experimentation, cost, and ethical consideratio ns. The rabbit has a number of advantages due to its relative simple c oronary circulation. The present study was designed to evaluate the ra bbit model for determination of areas of risk (ARs) by contrast echoca rdiography. Methods: Eight rabbits were intubated and mechanically ven tilated after occlusion of the left coronary artery with a ligature. T he transducer (operating at 7.5 MHz) was positioned on the right ventr icle through a right thoracotomy. The images were obtained after intra -aortic injection of 1 ml of Albunex, followed by 3 mi of dye (Blue Un iperse) for histological analysis postmortem. The ARs were obtained af ter circumscription of the various echocardiographic and histological images. Results: Excellent echocardiographic images were obtained, lar gely due to the hemodynamic stability of the rabbit to ischemia. Echoc ardiographic ventricular areas, absolute AR, and relative AR correlate d closely with postmortem data (r = 0.86, 0.94, and 0.94, respectively ). The measurements were highly reproducible with low variability Conc lusions: The rabbit model shows promise for study by contrast echocard iography of myocardium subjected to ischemia. This method for determin ation of ARs was validated against postmortem findings. The method als o should be of value in the evaluation of reperfusion.