Development of Intravascular and Intracardiac Ultrasound System Combined with Color Doppler Flow Imaging and Its Clinical Application in Cardiovascular Surgery

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The efficacy of intravascular ultrasound(IVUS) in the detection of intraluminal thrombi, vessel dissection, or for the estimation of blood flow dynamics is limited. Some of these limitations could be overcome if a new IVUS system could simultaneously provide data about flow velocity and flow volume in the vessels. The main purposes of this research were firstly to develop a new Intravascular Ultrasound System combined with Color Doppler Flow Imaging Systems, secondly to evaluate the feasibility of newly developed "IVUS system" for visualizing blood flow and quantifying flow velocity and volume, and finally to study the possibility of clinical use in Cardiovascular Surgery. In vitro experiments were performed using circulation flow model. The static flows with various velocity (0-l50cm/sec) were produced by altering rotation rate of a centrifugal pump. The transducer was placed at center of a flow tube. The new IVUS system consists of a commercially available color Doppler ultrasound un … More it, a 8F IVUS catheter which a 10MHz mechanically rotated transducer was mounted obliquely (45 degree) on the tip of catheter. It rotates at a rate of 5 to 10 cycles/sec. Two-dimensional flow images were displayed in the same way as conventional color Doppler techniques. The color Doppler images have been obtained in flows with velocity over 2 cm/sec. The color tone turned at velocity indication aliasing. The mean velocities obtained by color Doppler significantly correlate with those measured by pulsed wave Doppler (r=0.9998, p<less than or equal>0.O1) and electromagnetic flow meter (r=0.943, p<less than or equal>0.01) respectively. After the confirmation of safety and effectiveness of the new color Doppler catheter in in-vitro experiment, we studied the capability of the new system in three pigs and two patients with dissecting aneurysm. The results demonstrated the clinical feasibility especially in aortic diseases. It is our conclusion that this new system which combined IVUS with color Doppler technique is potentially useful for detection of abnormal blood flow in the vessel lumen, quantification of flow velocity and volume and estimation of flow dymanics, and should advance diagnostic capability of conventional IVUS in application of cardiovascular surg Less