Abstract

Objective: To study whether vascular function assessment using flow-mediated constriction (L-FMC), a novel non-invasive method, complements the information obtained with “traditional” flow-mediated dilation (FMD).

Design and patients: In protocol 1, 12 healthy young volunteers underwent FMD and L-FMC measurements at rest and immediately after isometric exercise of the same hand. In protocol 2, 24 patients with coronary artery disease, 24 with congestive heart failure, 24 hypertensives and 64 healthy volunteers were enrolled to undergo L-FMC and FMD measurements.

Results: in protocol 1, exercise was associated with increases in radial artery blood flow, diameter and L-FMC (from -5.1±1.5% to -7.8±3.4%, P<0.05), while FMD was significantly blunted (from 6.0±2.4% to 3.0±3.2%, P<0.05). In protocol 2, both FMD and L-FMC were blunted in patient groups. Receiver-operating curve analysis showed that, as compared to FMD alone, the combination of L-FMC and FMD significantly improves the sensitivity and specificity in detecting patients diagnosed with cardiovascular disease (P<0.05).

Conclusion: In the first protocol, we show that FMD and L-FMC are reciprocally regulated. We propose that a blunted FMD might be expression of increased resting vascular activation and not only of impaired endothelial function. In the second protocol, a statistical approach shows that implementation of L-FMC provides a better characterization of vascular function in cardiovascular disease. Vascular (endothelial) function is a complex phenomenon which requires a multifaceted approach; we propose that combination of L-FMC and FMD will provide additive and complementary information to “traditional” FMD measurements.