Noninvasive Assessment of Coronary Vasodilating Capacity using Freehand 3D Echocardiography with Rotational Scanning

Youn, Ho Joong; Lim, Sang Hyun; Park, Chul Soo; Lee, Jong Min; Oh, Yong Seog; Cho, Eun Ju; Jung, Hae Ok; Jeon, Hui Kyung; Chung, Wook Sung; Kim, Jae Hyung; Choi, Kyu Bo; Hong, Soon Jo

Abstract

BACKGROUND AND OBJECTIVES
Noninvasive measurements of the coronary vasomotion are important for evaluating patients with coronary artery disease (CAD). The aim of this study was to investigate the efficacy of free-hand 3D echocardiography (3DE) with rotational geometry for assessing epicardial coronary artery vasodilation.
SUBJECTS AND METHODS
Forty-five subjects were studied: 29 subjects (age 51+/-12 years, M:F=14:15, Control group) with a normal coronary angiogram and 16 patients with multivessel CAD (age 60+/-12 years, M:F=9:7, CAD group). After obtaining the tubular color flow signals of the distal left anterior descending coronary artery (LAD) using an ultra-band transducer (5-12 MHz) with a special preset program in the low velocity range, the peak (PDV), mean diastolic velocity (MDV) and velocity time integral (VTI) were measured before and after administering sublingual nitroglycerin (NTG) (0.6 mg). In all subjects, 3DE image acquisition and reconstruction of the distal LAD flow was performed before and after sublingual nitroglycerin (NTG) using a 3DE unit with a magnetic tracking system (TomTec Imaging Systems) linked to the conventional 2D ultrasound system (Sonos 7500). Quantitative analysis of coronary vasodilation was performed on cross-sectional images.
RESULTS
The % change in the PDV, MDV and VTI after NTG administration was 41.3+/-14.0%, 37.9+/-13.8% and 40.3+/-18.2% in the control group and 23.0+/-13.9%, 19.1+/-11.5% and 26.1+/-12.4% in the CAD group (p<0.05, versus Control group, respectively) The distal LAD diameter on the coronary 3DE after NTG administration increased from 2.28+/-0.79 mm to 3.32+/-1.07 mm (52.3+/-28.5%) in the control group and from 2.36+/-0.65 mm to 2.89+/-0.81 mm (23.7+/-23.9%) in the CAD group (p<0.005 versus Control group). The magnitude of vasodilation correlated with the % change in the PDV (r=0.516, p<0.005), MDV (r=0.519, p<0.005) and % VTI (r=0.392, p=0.008).
CONCLUSION
These results suggest that level of vasodilation after NTG administration is reduced in advanced atherosclerosis and can be measured noninvasively. A 3D reconstruction of the distal LAD flow using free-hand 3DE with rotational scanning is a promising noninvasive technique for examining the coronary vasomotor function.