Objectives: Atherosclerotic changes in the rabbit have been evaluated by various methods. Although most previous studies have analyzed atherosclerotic plaque in the femoral, carotid and iliac arteries of rabbits by intravascular ultrasound (IVUS) because of easier access, we established a method for the precise measurement of plaque volume as well as plaque area in the thoracic descending aorta in the Watanabe heritable hyperlipidemic (WHHL) rabbit, which has severe atherosclerosis.
Methods: WHHL and Japanese White (JW)rabbits were used. An IVUS catheter was inserted into the right femoral artery and advanced to the left subclavian artery, which was used as an anatomical landmark. After IVUS image acquisition, the catheter was removed. Vessel volume, lumen volume and plaque volume were analyzed.
Results: Atheroma of the aorta was easily detected in WHHL rabbits by IVUS examination, whereas atherosclerosis was not observed in JW rabbits. The atheroma showed a low-echoic lesion compared to the adventitia, with morphological characteristics similar to human lipid-rich, soft atheromatous plaques. In 15-month-old WHHL rabbits, the vessel volume, lumen volume and plaque volume in the thoracic descending aorta were 815 +/- 109, 559 +/- 107 and 256 +/- 10 mm3/ 3 cm, respectively.
Conclusions: We established a method for the precise quantitation of plaque volume by IVUS technology in WHHL rabbits aorta for the first time. This method is useful for evaluating several locally or generally delivered therapeutic agents in a hyperlipidemic animal model.