Abstract 18165: Flow Mediated Constriction in Patients Undergoing Coronary Artery Bypass Grafting Surgery
Introduction: Non-invasive measures of vascular function have been shown to be predictive of future cardiovascular events and associated with known cardiovascular disease. Flow mediated constriction (FMC) is a novel measure of vascular function. The objective of this study was to assess the association between FMC and established measures of vascular function in patients with severe coronary artery disease.
Methods: One hundred and fifty six patients awaiting coronary artery bypass grafting surgery were recruited. All subjects underwent baseline assessment including history and physical exam. Within 7 days prior to surgery, brachial artery ultrasound (BAUS) and peripheral arterial tonometry (PAT) were used to assess vascular function. Brachial artery diameter measures were taken at baseline, an occlusive cuff was inflated distal to the artery for 5 minutes, and diameter was re-measured in the last 30 seconds prior to cuff release and following cuff release. From BAUS, FMC ((pre-cuff release diameter-baseline diameter)/baseline diameter) x 100), maximum flow-mediated dilation (FMD) and hyperemic velocity (VTI) were obtained. The correlation between each vascular function measure and FMC was assessed using Pearson’s correlation.
Results: Subjects had a mean age of 66.3 years and were largely male (118 men, 75.6%). The baseline brachial artery diameter was 4.59 (±0.67) mm. FMC was measureable on 149 subjects; 65 subjects had constriction, while 84 subjects had dilation prior to cuff release. Mean FMC was +0.75% (SD 3.8%). FMC was positively correlated with FMD (R2=0.4749, p<0.0001) (Figure), but not correlated with VTI (0.0871, p=0.2908) or PAT (0.1091, p=0.2061).
Conclusions: Unlike in populations without significant CAD, patients awaiting CABG do not consistently demonstrate constriction towards the end of occlusive cuff placement. Further, FMC and FMD are correlated in this population. The mechanisms underlying FMC need further investigation.
- © 2012 by American Heart Association, Inc.