Influence of the hospital environment and presence of the physician on the white-coat effect :

Changes in blood pressure in 10 or 15 min periods during which a doctor repeatedly measured blood pressure by the cuff method were monitored by a continuous intra-arterial recorder. In almost all the 48 normotensive and hypertensive subjects tested the doctor's arrival at the bedside induced immediate rises in systolic and diastolic blood pressures peaking within 1 to 4 min (mean 26.7 +/- 2.3 mm Hg and 14.9 +/- 1.6 mm Hg above pre-visit values). There were large differences between individuals in the peak response (range, 4--75 mm Hg systolic and 1--36 mm Hg diastolic) unrelated to age, sex, baseline blood pressure, or blood-pressure variability. There was concomitant tachycardia (average peak response 15.9 +/- 1.5 beats/min, range 4--45 beats/min) which was only slightly correlated with the blood-pressure rise. After the peak response blood pressure declined and at the end of the visit was only slightly above the pre-visit level. A second visit by the same doctor did not change the average size of the early pressor response or the slope of its subsequent decline.

During renal sympathetic denervation (RDN), no mapping of renal nerves is performed and there is no clear end point of RDN. We hypothesized high-frequency renal nerve stimulation (RNS) may increase blood pressure (BP), and this increase is significantly blunted after RDN. The aim of this study was to determine the feasibility of RNS in patients undergoing RDN. Eight patients with resistant hypertension undergoing RDN were included. A quadripolar catheter was positioned at four different sites in either renal artery. RNS was performed during 1 min with a pacing frequency of 20 Hz. After all patients successfully underwent RDN, RNS was repeated at the site of maximum BP response before RDN in either renal artery. Mean age was 66 years. During RNS, BP increased significantly from 108/55 to 132/68 mm Hg (P 10 mm Hg was observed after RDN. In conclusion, RNS resulted in an acute temporary BP increase. This response was significantly blunted after RDN. RNS may potentially serve as an end point for RDN.

The purpose of the present study was to evaluate whether the difference between blood pressure measured in the clinic or physician's office and the average daytime blood pressure accurately reflects the blood pressure response of the patient to the physician ("white coat effect" or "white coat hypertension"). We studied 28 hypertensive outpatients (mean age, 41.8+/-11.2 years; age range, 21 to 64 years) of 35 consecutive patients attending our hypertension clinic, in whom (1) continuous noninvasive finger blood pressure was recorded before and during the visit, (2) blood pressure was measured according to the Riva-Rocci-Korotkoff method (mercury sphygmomanometer) with the patient in the supine position, and (3) daytime ambulatory blood pressure was monitored with a SpaceLabs 90207 device. The peak blood pressure increase recorded directly during the visit was compared with the difference between clinic and daytime average ambulatory blood pressures. Compared with previsit values, peak increases in finger systolic and diastolic blood pressures during the visit to the clinic were 38.2+/-3.1 and 20.7+/-1.6 mm Hg, respectively (mean+/-SEM, P<.01 for both). Daytime average systolic and diastolic blood pressures were 135.5+/-2.5 and 89.2+/-1.9 mm Hg, with both lower than the corresponding clinic blood pressure values (146.6+/-3.6 and 94.9+/-2.2 mm Hg, P<.01). These differences, however, were <30% of the peak finger blood pressure increases during the physician's visit, to which these increases showed no relation. Although the visit to the physician's office was associated with tachycardia (9.0+/-1.6 bpm, P<.01), there was no difference between clinic and daytime average heart rates. These data indicate that the clinic-daytime average blood pressure difference does not reflect the alerting reaction and the pressure response elicited by the physician's visit and thus is not a reliable measure of the white coat effect.