Noninvasive Study of Endothelial Function in White Coat Hypertension

Abstract

Abstract-Several studies have demonstrated that endothelial dysfunction is present in patients with essential hypertension.However, the presence of endothelial dysfunction in patients with white coat hypertension has not been studied. We evaluated the variation in the diameter of the brachial artery produced by flow-mediated dilation after a mechanical stimulus in patients with recently diagnosed mild to moderate sustained essential hypertension compared with patients with white coat hypertension. A total of 29 patients fulfilled inclusion criteria; 15 healthy volunteers were also included. After 24-hour ambulatory blood pressure monitoring, 15 patients were classified with sustained essential hypertension; 14 patients with white coat hypertension. Vascular ultrasound scans were performed according to the method described by Celermajer et al, with modification for noninvasive determination of endothelial dysfunction. Basal brachial artery diameter did not differ significantly among the 3 groups. Changes in arterial diameter 60 seconds after cuff deflation were higher in the control group compared with both hypertensive groups, but no significant differences were found between the sustained essential hypertension group and the white coat hypertension group. Flow-mediated dilation was similar in white coat hypertensives and sustained essential hypertensives. The presence of endothelial dysfunction in subjects with white coat hypertension suggests that it should not be considered a harmless trait and that white coat hypertension has common features with sustained essential hypertension. The prevalence of WCH has been estimated by several transversal studies between 20% and 40% among the population of mild hypertensives. 3,4 Whether this group of patients has an increased cardiovascular risk similar to that of sustained essential hypertensives (SEHs), or similar to that of normotensive subjects, is an interesting and still unsolved question that could entail therapeutic implications. 5 Only a few studies have been published about the natural history of WCH; some of them have found a higher frequency of progression to SEH compared with that of normotensive subjects. 6,7 Endothelial dysfunction (ED) is considered an early event in the development of atherosclerosis, 8 and several studies have demonstrated that ED is present in patients with essential hypertension. 9 However, the presence of ED in patients with WCH has not been studied. ED was first studied by measuring the increase of the diameter of coronary arteries after intravenous infusion of acetylcholine; the absence of vasodilation in response to acetylcholine was considered a marker of ED. 10 More recent publications studied ED by measuring vasodilation in response to acetylcholine in brachial or femoral arteries with plethysmography. 11 Nowadays, noninvasive methods based on flow-mediated dilation (FMD) after the compression of the arterial wall with a pneumatic tourniquet have been validated for the study of ED, and they are used in most recent works. 12 Th...

Effect of acute sympathetic nervous system activation on flow-mediated dilation of brachial artery

“…These data collectively indicate that FMD does not appear to be impaired by an acute increase in SNA. The data are consistent with the no impairment of FMD in one study of white-coat hypertension (29), but this finding is controversial (13,22) and awaits further explanation of the link to the consistent finding of impaired endothelial function with essential hypertension (10,26,28). There are important implications from the current study.…”

“…Lind et al (24) noted that, although the magnitude of FMD with acute mental stress was not different from control, the ratio of FMD to blood flow was significantly reduced. Many of the studies (9,13,14,17,29,35) cited here either did not measure blood flow during hyperemia or did not report the data. To achieve the same peak shear stress in our mental arithmetic test as in the control, we reduced the duration of the period of occlusion.…”

Closer look at white-coat hypertension

“…In the PAMELA study, Cardillo, Weber, Mancia and Mulè reported that LVMI was increased in WCHT patients compared with NT patients (P < 0.01), whereas Pierdomenico and Hoeghelm found no difference in LVMI [5,[26][27][28][29][30][31] . Arterial compliance was lower in WCHT patients than in the NT group in studies by Karter's (P < 0.001) and Gomez [25,32] . Turfaner et al [33] analyzed 47 dipper and 43 non-dipper WCHT patients and determined, that non-dipping in WCHT patients was related to decreased arterial compliance and that the global risk load for target organ damage was higher in non-dipper WCHT subjects.…”

Ambulatory Blood Pressure Monitoring in Children and Adolescents: Recommendations for Standard Assessment

“…Although adult studies find that patients with WCH have lower LVM than those with sustained hypertension, their cardiac mass is higher than that of normal controls. 43 Furthermore, other forms of target organ damage, such as endothelial dysfunction 44 and increased c-IMT, 45 are associated with WCH and may account for the increase in adverse cardiovascular disease outcomes noted with this condition. 46 Data in children are sparse, but youth with WCH have been shown to have greater body mass index and a tendency toward elevated LVM index, strengthening the indications for ABPM follow-up of WCH.…”