WHAT IS THE IDEAL MOMENT FOR ULTRASOUND MEASUREMENT OF BRACHIAL ARTERY FLOW-MEDIATED DILATION?

Introduction and aims. The technical guides to measuring the brachial artery flow-mediated dilation (BFMD) recommend that it should be measured in the diastolic phase in order to prevent results from being influenced by arterial distensibility (compliance). No studies have been conducted, however, to confirm this hypothesis and this is therefore the main purpose of our research. Subjects and methods. Two groups of subjects were recruited on the basis of the following criteria: group I, healthy subjects with an ankle-brachial index (ABI) > 0.9 and below 30 years of age, and group II, composed of patients with symptomatic peripheral arterial disease that was defined by an ABI < 0.9. Brachial artery flow-mediated dilation was measured in the right arm in both the systolic (S) and diastolic (D) phases. The ABI was measured at the same time and the risk factors and treatments were collected. Flow-mediated dilation was also determined in both femoral arteries (FFMD). Results. Groups I and II consisted of 36 and 33 subjects respectively. The dilation values in the S and D phases were compared and represented as a group: S / D (value p). BFMD: I + II: 8.1 perpendicular to 4.6% / 7.6 +/- 4.9% (p = 0.3); I: 10.8 +/- 2.9% / 9.9 +/- 3.8% (p = 0.055); II: 5.2 +/- 4.3% / 5.16 +/- 4.8% (p = 0.3). FFMD: I + II: 3.13 +/- 3.6% / 2.8 +/- 3.6% (p = 0.35); I: 5.3 +/- 2.9% / 4.8 +/- 2.6% (p = 0.02); II: 0.6 +/- 2.5% / 0.6 +/- 3.4% (p = 0.9). Conclusions. If it is assumed that compliance influences arterial dilation, systolic flow-mediated dilation is seen to be higher than in the diastolic phase in healthy subjects, whereas this difference is practically inexistent in patients. Although the difference in the brachial artery of healthy subjects does not reach significance (p = 0.055), it does in the femoral artery (p = 0.02). Therefore, on appraising the data as a whole, we recommend measurement in the diastolic phase in order to avoid the occurrence of biases when comparing between healthy and sick subjects.