2.4. Assessment of flow‐mediated dilation

Endothelium‐dependent FMD was evaluated as described previously, using a multifrequency (12 MHz) linear array transducer.25, 26 Patients were placed in supine position, in a quiet, air‐conditioned room (22‐25°C), 15 minutes prior to the examination. High‐resolution B‐mode images of the brachial artery were obtained in the longitudinal plane, 3‐5 cm proximal to the elbow of the right arm. Care was taken to maintain probe position during the investigation. Reactive hyperemia was induced by inflating a blood pressure cuff around the forearm for 4‐5 minutes at 50 mm Hg above systolic blood pressure, followed by prompt deflation. Brachial artery diameter was assessed by measuring the distance between the two lumen‐intima interfaces at end‐diastole. Three measurements were performed at baseline and post‐occlusion. Baseline and post‐occlusive measurements were subsequently averaged. FMD was defined as the relative increase in brachial artery diameter ((diameter post‐occlusion − basal diameter)/basal diameter) × 100)).

Echocardiography, assessment of intima‐media thickness, and assessment of flow‐mediated dilation were performed by consensus of two experienced cardiac ultrasonographers (AD and AE), who were blinded to clinical data (eg, cause of hypertension).