Intravascular ultrasound imaging of vascular responsiveness in isolated perfused canine arteries

We investigated the feasibility of using intravascular ultrasound imaging to analyze vascular physiology in various arterial beds. Canine superficial femoral, external iliac, and common carotid arteries were harvested and suspended and perfused in a bath of oxygenated, heated, physiologic salt solution. A 6-Fr, 20-MHz ultrasound imaging catheter was inserted into the lumen of the arteries and serial images were acquired after bolus injections of either serotonin or normal saline into the extravascular bathing medium. Serotonin resulted in a significant time- and dose-dependent decrease in cross-sectional area in muscular femoral arteries (P less than .001): -5.2% with 10(-8) M serotonin, -15% with 10(-7) M, and -28% with 10(-6) M. Histologically transitional iliac arteries demonstrated less marked changes, while elastic carotid arteries demonstrated no significant changes. Our results indicate that intravascular ultrasound may be used to quantify and differentiate responses to vasoconstrictive agents in different vascular beds.