Noninvasive Assessment of Coronary Vasodilating Capacity Using Freehand 3-Dimensional Echocardiography with Rotational Scanning

Background Noninvasive measurement of coronary vasomotion is important for the evaluation of patients with coronary artery disease (CAD). We tested the possibility of the assessment of epicardial coronary artery vasodilating capacity using freehand 3-dimensional (3D) echocardiography. Methods In 45 individuals (29 control subjects [age 51 ± 12 years, male:female = 14:15; control group] with normal coronary angiogram and 16 patients with multivessel CAD ([age 60 ± 12 years, male:female = 9:7; CAD group]), using a 3D echocardiography unit with magnetic tracking system linked to the conventional 2-dimensional ultrasound system, 3D echocardiography image acquisition and reconstruction of the distal left anterior descending coronary artery (LAD) flow were performed before and after sublingual nitroglycerin administration (0.6 mg). Quantitative analysis of coronary vasodilation was performed on cross-sectional 3D images and was compared with the mean diameter of the distal LAD by quantitative coronary angiography. Results The distal LAD diameter on coronary 3D increased from 2.28 ± 0.79 to 3.32 ± 1.07 mm (52.3 ± 28.5%) in control group and from 2.36 ± 0.65 to 2.89 ± 0.81 mm (23.7 ± 23.9%) in CAD group after nitroglycerin administration ( P < .005 vs control group). The cut surface diameter of the 3D LAD flow was 2.17 ± 0.34 mm and the mean diameter using quantitative coronary angiography was 1.99 ± 0.28 mm. There was a good correlation between baseline diameter of 3D image and mean quantitative coronary angiography data ( R = 0.673, P < .005). Conclusion The vasodilation after nitroglycerin administration is reduced in advanced atherosclerosis and can be noninvasively measured. The 3D reconstruction of the distal LAD flow is a promising noninvasive technique to study coronary vasomotor function.