Average Ambulatory Pressure Research Articles

Low frequency of target organ damage in Taiwanese with white coat hypertension.

The clinical importance of white coat hypertension (WCH) remains to be clarified. This study investigated the target organ damage in Taiwanese with WCH. A total of 188 consecutive Taiwanese (88 men and 100 women), aged 26 to 75 years who had an abnormal office casual blood pressure (systolic blood pressure >/= 140 mm Hg or diastolic blood pressure >/= 90 mm Hg or both) and a normal ambulatory blood pressure (ABP) average (systolic ABP average < 140 mm Hg and diastolic ABP average < 90 mm Hg) at the outpatient clinic or from a mass survey were enrolled. Office casual blood pressure measurements were obtained by standard sphygmomanometric methods. Twenty-four-hour blood pressures were recorded by a commercial ambulatory pressure recorder (Del Mar Avionics, Model 1990 Pressurometer IV System). Hypertension-related target organ complications were assessed by electrocardiogram, chest X-ray, urinalysis and eye fundus examinations. Target organ damage was found in 6.4% of subjects with WCH. Roentgenographic left ventricular hypertrophy (LVH) was found in 1.1% of subjects and electrocardiographic LVH in 2.7%. Proteinuria was found in 1.6% of subjects and retinopathy in 1.1%. The frequencies of various target organ damage were not significantly associated with age, gender and the definition of normal ABP average as 135/85 mm Hg or 140/90 mm Hg. WCH represents a low-risk stratum for target organ damage in Taiwanese. These subjects should be identified and followed up regularly. The factors responsible for the low frequency of target organ damage in Taiwanese with WCH need further study.

Reactivity as a predictor of subsequent blood pressure: racial differences in the Coronary Artery Risk Development in Young Adults (CARDIA) Study.

This study investigated the association between cardiovascular reactivity and subsequent ambulatory blood pressure in 316 black and white men and women in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Cardiovascular laboratory reactivity was examined in subjects 20 to 33 years old, and ambulatory blood pressure and heart rate were measured 3 years later. Average ambulatory pressure during a 24-hour period was regressed separately on stress reactivity and standard covariate risk factors in each race/gender subgroup. Blacks had higher blood pressure and heart rates than whites, men had higher blood pressure than women, and women had higher heart rates than men. After controlling for age, baseline systolic pressure, familial history of hypertension, smoking, alcohol consumption, body mass index, and exercise, systolic blood pressure reactivity to star tracing and cold pressor stress were significantly associated with systolic ambulatory pressure in black men and women 3 years later (partial r=0.24 to 0.37). Heart rate reactivity to video challenge and star tracing were also significantly predictive of subsequent ambulatory heart rate in blacks. Diastolic star tracing reactivity was significantly associated with subsequent ambulatory blood pressure in black women (r=0.23), and diastolic reactivity to video and star tracing were significantly predictive of ambulatory diastolic pressure in white men (r=0.39). We conclude that hyperresponsivity to stress may be a risk factor for subsequent blood pressure elevation in blacks and may be one pathway leading to the higher prevalence of hypertension in blacks than in whites.

Oscillometric ambulatory blood pressure values in healthy children.

To assess the feasibility of ambulatory blood pressure monitoring (ABPM) and establish reference values for ABPM in normal children and adolescents, 24-hour ABPM was performed in 120 normotensive, nonobese subjects, aged from 6 to 14 years (58 males, age 10.1 +/- 2.8 years; 62 females, age 9.7 +/- 3.1 years; mean +/- SD). The subjects were classified into three age groups: group A (6-8 years, n=40, 23 males, 17 females), group B (9-11 years, n=40, 21 males, 19 females), and group C (11-14 years, n=40, 18 males, 22 females). ABPM was carried out using an oscillometric device with appropriate cuff size. The monitor was programmed to measure BP every 15 min during the day (6 a.m. to 10 p.m.) and every 30 min during the night (10 p.m. to 6 a.m.). Successful rates (recording time=24 hours and > 40 recordings) were 83%, 88%, and 93% in groups A, B, and C, respectively. The recordings of 15 subjects (7 in group A, 5 in group B, 3 in group C) were not analyzed because of incomplete readings. The 24-hour mean systolic/diastolic blood pressure (SBP/DBP) for males and females were 106 +/- 7/65 +/- 5 and 105 +/- 6/64 +/- 5, 110 +/- 6/66 +/- 5 and 109 +/- 5/65 +/- 4, and 115 +/- 7/67 +/- 6 and 113 +/- 6/66 +/- 4 mmHg in groups A, B, and C, respectively. The daytime mean SBP/DBPfor males and females were 110 +/- 7/73 +/- 4 and 109 +/- 8/72 +/- 5, 117 +/- 5/75 +/- 4 and 115 +/- 8/74 +/- 6, and 122 +/- 6/76 +/- 4 and 120 +/- 7/75 +/- 6 mmHg in groups A, B, and C, respectively. The nighttime mean SBP/DBP for the corresponding sex and age groups were 97 +/- 8/58 +/- 5 and 95 +/- 7/57 +/- 6, 101 +/- 8/59 +/- 6 and 99 +/- 7/57 +/- 5, and 105 +/- 7/58 +/- 5 and 103 +/- 6/56 +/- 4 mmHg, respectively. The first fall in BP appeared after lunch (approximately 1:00 pm) and the second fall appeared during the night hours (11:00 pm to 6:00 am). There was a significant correlation between 24-hour mean ambulatory SBP and age (r=0.48, P < 0.001). In contrast, ambulatory DBP and age were not significantly correlated. A nocturnal fall of SBP/DBP was observed in all age- and sex-subgroups. This study showed that ABPM was reproducible and accurate. The normal ambulatory blood pressure (ABP) values in the pediatric age group have not been reported in Taiwan. The distribution of ABP observed in this study could serve as a preliminary reference. A multicenter study may be done to provide normal ranges of ABP in Taiwan for clinical purposes. Further studies are necessary to elucidate the role of ABPM in children.

Differing Perspectives on White Coat Hypertension

One of the more consistent findings to emerge from studies that have compared clinic (or office) and ambulatory blood pressure values in hypertensive patients has been that the agreement between the two is not very close and that there are a substantial number of patients in whom the clinic pressure overestimates the pressure at other times. 1 This has led to the concept of white coat hypertension, which may be defined as a persistently elevated clinic pressure together with a normal ambulatory pressure. In a carefully conducted population-based study reported in this issue, Pearce et aI 2 come to quite different conclusions, namely, that clinic blood pressure is a good predictor of blood pressure at other times and that white coat hypertension is uncommon. If this is true, it has major implications for the use of ambulatory blood pressure monitoring in clinical practice. The rationale underlying the use of clinic

Clinical Applications of Ambulatory Blood Pressure Monitoring

The estimation of an individual's true blood pressure by conventional clinical measurement is subject to a number of errors, stemming partly from the inherent variability of blood pressure, and also from the white coat syndrome, which is an elevation of blood pressure limited to the clinic setting. This may occur in about 20% of patients with mild hypertension, and is hypothesized to be a learned or conditioned response. Ambulatory monitoring may help to identify such patients. Other potential clinical applications of the technique include evaluation of patients with resistant hypertension, with excessively labile blood pressure, or with autonomic insufficiency, which may be characterized not only by hypotensive episodes, but also by hypertensive episodes during the night. An unresolved question is the definition of the upper limit of normal ambulatory pressure, which is required before ambulatory monitoring finds wide clinical acceptance.

Noninvasive ambulatory blood pressure monitoring in patients with recently detected systemic hypertension

Noninvasive ambulatory blood pressure monitoring and Doppler echocardiography were used in a recent study evaluating persons aged 18 to 50 years who were initially found to have mild hypertension by casual blood pressure determination. Ambulatory blood pressure recordings were performed on a day of usual activity in 54 subjects; a subgroup of 24 patients had evaluation of left ventricular dimensions and diastolic filling patterns by Doppler echocardiography. Average ambulatory systolic pressures of 42% of subjects were ≥130 mm Hg. Only 35% had average diastolic pressures ≥85 mm Hg, and 57% had either systolic or diastolic pressures ≥130/85 mm Hg. Correlation between casual and ambulatory pressures was not significant. No subject had left ventricular hypertrophy determined by echocardiography. Abnormal left ventricular diastolic filling was noted in 38% of those patients with average ambulatory pressures ≥130/85 mm Hg, but in no patients with average pressures <130/85 mm Hg (p < 0.05). These results suggest that ambulatory blood pressure monitoring may be a specific method for detecting those patients with mild hypertension who may have early and potentially reversible cardiac abnormalities.

Effect of ambulatory blood pressure monitoring on the diagnosis and cost of treatment for mild hypertension

Detection of mild hypertension by a small number of casual blood pressures may be inaccurate for the determination of average blood pressure. Nonetheless, casual pressures remain the basis for the diagnosis and treatment of hypertensive patients. We compared casual and noninvasive ambulatory blood pressure monitoring in a consecutive series of 60 subjects evaluated for possible mild hypertension on the basis of casual pressures. Ambulatory blood pressure monitoring was performed on days of usual activity. Correlations between casual systolic and average ambulatory systolic pressures or casual diastolic and average ambulatory diastolic pressures were not significant. Nearly half of the subjects had average ambulatory systolic pressures <130 mm Hg. Sixty percent had average ambulatory diastolic pressures <85 mm Hg. Nearly 40% had both systolic and diastolic pressures less than those limits. A preliminary analysis of the effects of these results on the short-term cost of antihypertensive treatment was made, assuming that treatment could be withheld from those with average ambulatory pressures < 130 85 mm Hg . This approach suggests that ambulatory blood pressure monitoring need not increase overall cost, if the results of this evaluation are used in the decision to treat.