24-hour ambulatory blood pressure monitoring

How to reliably diagnose arterial hypertension: lessons from 24 h blood pressure monitoring

BACKGROUND

Hypertension is a common condition in modern society. As blood pressure fluctuates with time, a single blood pressure measurement is useless to diagnose hypertension. Nevertheless, no well-defined number of measurements is often used for this purpose. Diagnosis and therapeutic control of hypertension are therefore suboptimal.

OBJECTIVE

To determine the number and timing of measurements needed to give a trustworthy approximation of an individual's average blood pressure.

METHODS

In this observational study 306 clinically indicated 24h ABPM datasets were analysed. Hypertension was defined as a daytime blood pressure mean exceeding 135/85 mm Hg. Kappa coefficients determined the best time of day for measuring blood pressure. The optimal number of measurements was estimated using canonical correlation.

RESULTS

162 (53%) patients were diagnosed with hypertension. Kappa statistics indicated that measuring during the afternoon gave the best agreement with the 24h blood pressure mean (κ = 0.78). According to canonical correlation, about 8-10 blood pressure readings give enough information for hypertension diagnosis.

CONCLUSIONS

Eight to ten blood pressure measurements between 01:00 and 05:00 p.m. are sufficient to give a clinically useful approximation of the daytime mean blood pressure and therefore for diagnosing hypertension accurately. Future research should determine the ideal dispersion of measurements and include patient characteristics which could influence the required number and timing of measurements. These results may increase the future importance of telemonitoring in diagnosing hypertension.

The differential diagnostic value of serum homocysteine for white coat hypertension

Objective

To assess the value of serum homocysteine (Hcy) in differential diagnosis of white coat hypertension (WCH).

Results

In this retrospective study, serum Hcy levels were elevated in hypertensive patients (P < 0.001) compared to WCH patients. Serum Hcy levels were positively correlated with 24-h mean systolic blood pressure, r = 0.1378, P < 0.001. The results of the receiving operating characteristic (ROC) curve showed that the AUC value of Hcy was 0.80 (95% CI, 0.77–0.83), the cut-off value was 13.8 μmol/L, the sensitivity was 68.58% and the specificity 87.21%. In the prospective study, the AUC value of Hcy was 0.73 (95% CI: 0.67–0.78), higher than N - terminal pro - brain natriuretic peptide(NT-pro-BNP) (0.64, 95% CI:0.58–0.70) and cystatin C (Cys-C) (0.62, 95% CI:0.55–0.68). Hcy, NT-proBNP and Cys-C combined, provided a better indication of a differential diagnosis of WCH, than Hcy alone.

Materials and Methods

This investigation involved both a retrospective and a prospective study. Clinical data including blood pressure, age, sex, height, weight, BMI, smoking status, past history, and behavioral electrocardiogram of patients who had undergone 24-hour ambulatory blood pressure monitoring (ABPM) with elevated clinical blood pressure (BP) were recorded. Pearson correlation analysis was used to test the correlation between Hcy and BP. The ROC curve was used to analyze the value of measuring Hcy levels in differential diagnosis of WCH.

Conclusions

Serum Hcy was decreased in WCH patients and therefore could be a biomarker for differential diagnosis of WCH.

Effects of Rubus occidentalis extract on blood pressure in patients with prehypertension: Randomized, double-blinded, placebo-controlled clinical trial

OBJECTIVE

Black raspberry (Rubus occidentalis) is known for improving vascular function. However, there has been no study evaluating its effects on 24-h systolic and diastolic blood pressure in prehypertensive patients. The aim of this study was to examine those effects.

METHODS

Patients with prehypertension (N = 45) were prospectively randomized into a moderate-dose black raspberry group (n = 15, 1500 mg/d), a high-dose black raspberry group (n = 15, 2500 mg/d), or a placebo group (n = 15) during an 8-wk follow-up period. Raspberries were consumed in the form of a dried powder extract that was fashioned into capsules. The capsules contained 187.5 and 312.5 mg of raspberry powder, which was equivalent to 1500 and 2500 mg raspberries. Ambulatory 24-h blood pressure (BP); central BP; pulse-wave velocity; abdominal visceral fat; serum renin; angiotensin-converting enzyme; and inflammatory cytokines such as interleukin-6, tumor necrosis factor-α, C-reactive protein, soluble intercellular adhesion molecule-1, soluble vascular cell adhesion molecule-1, and plasminogen activator inhibitor-1 were measured at baseline and at 8-wk follow-up.

RESULTS

High-dose black raspberry significantly reduced 24-h systolic blood pressure (SBP; 3.3 ± 10 mm Hg versus -6.7 ± 11.8 mm Hg; P < 0.05) and nighttime SBP (5.4 ± 10.6 mm Hg versus -4.5 ± 11.3 mm Hg; P < 0.05) compared with controls during the 8-wk follow-up. Black raspberry powder did not produce any significant changes in most of the parameters other than BP.

CONCLUSION

The use of black raspberry significantly lowered 24-h BP in prehypertensive patients during the 8-wk follow-up. Black raspberry used as a dietary supplement could be beneficial in reducing SBP in prehypertensive patients.

Ambulatory blood pressure monitoring and blood pressure load in obese children

BACKGROUND AND OBJECTIVES

This study was aimed at evaluating the significance of blood pressure (BP) load in ambulatory blood pressure monitoring (ABPM) in obese children and adolescents.

SUBJECTS AND METHODS

ABPM was conducted for 60 selected patients who had visited Sunlin Hospital between January 2008 and August 2008. Patients were classified into 3 groups; an obese group whose body mass index (BMI) was > the 95th percentile, an overweight group whose BMI was > the 85th percentile but less than the 95th percentile, and a normal group whose BMI was below the 85th percentile. Overall mean BP, day and night BP and BP load were measured by ABPM.

RESULTS

Of the 60 patients, twenty-seven children belonged to the obese group, 9 and 24 to the overweight and the normal group, respectively. Among the three groups, the overall average systolic and diastolic BP, daytime diastolic BP, and systolic BP loads in daytime and nighttime were statistically different. Comparing the obese group with the normal group, systolic BP loads in daytime and nighttime in the obese group were significantly higher than those in the normal group. Also, the obese group had more patients whose BP loads were over 25% greater than the normal group while the difference in the number of patients with overall hypertension was not significantly different.

CONCLUSION

Assessment of children's BP through assessment of BP load is a more detailed and precise tool than assessment through mean BP using ABPM and BP can be better controlled using measurement of BP load.

Effect of a weight-loss program on mental stress–induced cardiovascular responses and recovery

OBJECTIVE

We assessed the effect of weight loss on blood pressure (BP) and pulse rate during rest, psychological stress, and recovery after stress.

METHODS

Two groups of men completed two mental stress tests 12 wk apart. The control group continued their usual diet, whereas the weight-loss group underwent a dietary weight-loss program in which they were randomized to a high-fruit/vegetable and low-fat dairy diet or a low-fat diet.

RESULTS

Fifty-five men with a baseline BP of 125.9 +/- 6.9/83.6 +/- 7.1 mmHg (mean +/- SD) completed the study (weight-loss group, n = 28; control group, n = 27). The weight-loss group lost weight (mean +/- SEM, -4.3 +/- 0.3 versus +0.4 +/- 0.4 kg, P = 0.001) compared with controls and had a significant decrease in resting systolic BP (SBP; -2.0 +/- 1.1% versus +2.0 +/- 1.1%, P < 0.05). There was a greater decrease in SBP (P < 0.05) and pulse rate (P < 0.05) at all time points during the stress test in the weight loss compared with the control group. At week 12, SBP in 23 (82%) subjects in the weight-loss group and 24 (89%) in the control group returned to resting levels, with recovering levels in the weight-loss group returning to resting levels 6.1 +/- 2.6 min earlier than in the control group (P < 0.05). There was an overall greater decrease in diastolic BP (DBP; P < 0.05) and DBP during recovery up to 27 min after stress (P < 0.05) in the high-fruit/vegetable and low-fat dairy diet group (n = 14) compared with the low-fat diet group (n = 14).

CONCLUSION

A 5% loss of weight decreased BP during rest and returned SBP to resting levels faster, thus decreasing the period of increased BP as a result of mental stress, which is likely to lower the risk of cardiovascular disease in the long term.