Laser Doppler assessment of dermal circulatory changes in people with coronary artery disease

Dermal microcirculation provides an easily accessible vasculature bed which can be used to assess endothelial mediated vasodilatation. We studied and compared microcirculatory changes in response to acetylcholine iontophoresis (ACh), local heating of the skin and reactive hyperaemia in patients with coronary artery disease (CAD).

Forty eight patients with CAD were studied and compared with 25 age and sex matched control subjects. Vasodilatory changes in the dermal microcirculation were assessed in response to ACh iontophoresis, local heating of the skin and reactive hyperaemia using a laser Doppler flowmeter (LDF).

Body mass index (BMI) and systolic BP were higher in people with CAD, (p=0.001, 0.043). The perfusion change (measured as absolute in agreement with our previous publish results) in response to ACh iontophoresis, local heating of the skin and reactive hyperaemia, in healthy controls was 234 (190-286), 90 (69-118), 139(106-172) arbitrary perfusion units (APU) compared to 161 (121-214), 50 (39-63), 116(77-143) APU in patients with CAD; p<0.03. The time to peak perfusion in response to reactive hyperaemia was significantly higher in patients with CAD, 14.1±4.0 vs 10.9±1.7s; p=0.001. There was a small but significant positive correlation between the perfusion change in response to ACh iontophoresis and local heating (r=0.31, p=0.035). On ROC curve analysis, perfusion changes with heating had higher sensitivity and specificity in discriminating patients with CAD from the healthy controls with an area under the curve (AUC) of 0.86, with a specificity of 92% and sensitivity of 77% compared to a perfusion changes by reactive hyperaemia, AUC of 0.68 (41% sensitivity and 91% specificity) and ACh iontophoresis, AUC of 0.76 (88% sensitivity and 60% specificity).

Vasodilatation in the dermal microcirculation measured by the three techniques is attenuated in patients with coronary artery disease. Local heating of the skin is a better discriminator of patients with CAD than ACh iontophoresis and reactive hyperaemia.