Ambulatory blood pressure monitoring use in hypertension research and clinical practice

Twenty-four-hour ambulatory blood pressure monitoring in infants and toddlers

During the past several years, 24-hour (24-h) ambulatory blood pressure monitoring (ABPM) has become a useful tool for the diagnosis and management of children and adolescents with elevated blood pressure (BP). Some reports have also provided blood pressure nomograms for particular devices. However, there are very few reports of the use of this method in very young children. In our study we investigated the applicability of ABPM in 97 healthy infants and toddlers, aged from 2 to 30 months. A satisfactory ABPM profile was obtained in 86.6% of the children, with an average of 75.0% satisfactory BP recordings. The mean +/- SD systolic and diastolic BP of healthy infants and toddlers was 99+/-12/62+/-12 mmHg during the daytime and 95+/-11/57+/-10 mmHg during the night, with no gender difference being observed. The 24-h mean +/- SD systolic and diastolic BP, which may be a more appropriate measure of BP in this particular age group, was found to be 97+/-12/59+/-11 mmHg. We also confirmed the increase in systolic and diastolic BP with increased height (length). There was only a slight nocturnal decrease in BP. We conclude that this method is applicable for the assessment of blood pressure in very young children.

Biofeedback-assisted Relaxation Training for Essential Hypertension

The main purpose of this study was to develop a way to predict which persons with essential hypertension would benefit most from biofeedback-assisted relaxation (BFAR) training. Second, the authors evaluated the effect of BFAR on blood pressure (BP) reduction, which was measured in the clinic and outside the clinic using an ambulatory BP monitor. Fifty-four adults with stage 1 or 2 hypertension (78% taking BP medications) received 8 weeks of relaxation training coupled with thermal, electromyographic, and respiratory sinus arrhythmia biofeedback. Blood pressure was measured in the clinic and over 24 hours using an ambulatory BP monitor pretraining and posttraining. Systolic BP dropped from 135.0 +/- 9.8 mmHg pretraining to 132.2 +/- 10.5 mmHg posttraining (F = 6.139, P = .017). Diastolic BP dropped from 80.4 +/- 8.1 mmHg pretraining to 78.5 +/- 10.0 mmHg posttraining (F = 4.441, P = .041). Data from 37 participants with baseline BP of 130/85 mmHg or greater were used to develop a prediction model. Regression showed that those who were able to lower their SBP 5 mm Hg or more were (1) not taking antihypertensive medication, (2) had lowest starting finger temperature, (3) had the smallest standard deviation in daytime mean arterial pressure, and (4) the lowest score on the Multidimensional Health Locus of Control-internal scale. Since these types of persons are most likely to benefit from BFAR, they should be offered BFAR prior to starting hypertensive medications.

Office compared with ambulatory blood pressure in assessing response to antihypertensive treatment: a meta-analysis

OBJECTIVE

To undertake a systematic review of the studies on the effect of antihypertensive treatment on ambulatory (ABP) and office blood pressure in order to obtain a differential assessment of the magnitude of the reduction in (1) office blood pressure compared with 24-h average ABP values, and (2) daytime compared with night-time average blood pressure values.

DATA SOURCES

Medline search, Cochrane Library.

REVIEW METHODS

This review is based on a meta-analysis (carried out according to the Quality of Reports of Meta-analyses of Randomized Controlled Trials Group statement, whenever applicable) of papers on the effect of antihypertensive drugs on blood pressure. Papers were selected if they provided information on drug-induced changes in one or both of: (1) both office blood pressure and 24-h ABP, and/or (2) both daytime and night-time average blood pressure. Additional inclusion criteria were administration of antihypertensive drugs for at least 1 week and good quality ABP, according to current guidelines. Comparison between the effect of treatment on blood pressure values was made by meta-regression of the data provided by the individual studies (weighted by their size) and by calculating differences between weighted average values obtained by pooling the results of individual papers.

RESULTS

We identified 984 papers on this issue by Medline search, with no additional information from the Cochrane Library. The inclusion criteria were satisfied by only 44 papers, which were included in the final analysis. The results showed that treatment-induced reduction in blood pressure is both smaller for the 24-h average than for the office systolic and diastolic blood pressure and smaller for night-time than for daytime average diastolic blood pressure, the average ratio ranging from 0.67 to 0.75. A different ratio characterized the treatment-induced changes in office blood pressure and ABP in the Heart Outcomes Prevention Evaluation (HOPE) ABP substudy.

CONCLUSIONS

The effect of antihypertensive treatment is greater on office blood pressure than on ABP, and is unevenly distributed between day and night. This suggests caution when interpreting trials on cardiovascular protection by antihypertensive treatment that are based only on office blood pressure readings, and advocates a more systematic adoption of ABP monitoring in these trials. The conflicting data provided by the main HOPE study and by the HOPE-ABP monitoring substudy on the role of blood pressure reduction in explaining the reduced event rates associated with treatment by angiotensin-converting enzyme inhibitors are a clear example of the importance of performing ABP monitoring in trials on cardiovascular protection.

Comparison of the antihypertensive effects of the fixed dose combination enalapril 10 mg/nitrendipine 20 mg vs losartan 50 mg/hydrochlorothiazide 12.5 mg, assessed by 24-h ambulatory blood pressure monitoring, in essential hypertensive patients

Fixed combinations of calcium channel blockers and angiotensin converting enzyme inhibitors represent an alternative to diuretic-based combination therapy. The aim of the present study was to compare the antihypertensive efficacy of the combination enalapril 10 mg/nitrendipine 20 mg (E/N) vs losartan 50 mg/hydrochlorothiazide 12.5 mg (L/H), assessed by 24-h ambulatory blood pressure monitoring. This multicentre, double-blind, parallel study included 97 hypertensive patients (office diastolic blood pressure (DBP) 90-109 mmHg and daytime DBP > 85 mmHg). After a 2- to 3-week period of single-blind placebo, they were randomized to receive double-blind treatment with E/N (n = 48) or L/H (n = 49) for a 4-week period. The primary outcome measure was the difference in 24-h DBP reduction between treatments from randomization to the end of the double-blind period. Secondary efficacy variables included differences in 24-h systolic (S) BP reduction, daytime, night-time and office SBP and DBP reduction, proportion of responders and controlled patients, trough-to-peak ratio and smoothness indexes. Safety was assessed by the proportion of patients with adverse events and the detection of laboratory abnormalities. No significant differences were observed in the primary outcome measure. The group receiving E/N tended to show greater reductions in most measures (24 h, daytime and office SBP and DBP) and higher BP control rates, but only the difference in the rate of office SBP control (< 140 mmHg) reached statistical significance (42.2 vs 22.4%; P = 0.048). The trough-to-peak ratios and smoothness indexes were similar in both groups. The incidence of adverse events related to the treatment was 27.1% (95% CI 14.5-39.6%) in E/N-treated patients and 14.3% (95% CI 4.5-45.8%) in the L/H group, but differences were not significant. The kind of event more frequently observed were flushing and headache in E/N, and dizziness and asthenia in L/H; all observed adverse events were mild. We conclude that E/N and L/H have a similar antihypertensive efficacy, assessed by office or ambulatory blood pressure monitoring. E/N achieved a significantly higher office SBP control rate, but this was accompanied by an apparently higher proportion of mild adverse events.

The role of blood pressure variability in end-organ damage

The ultimate goal when treating high blood pressure is to reduce the incidence of end-organ damage and prevent cardiovascular disease, and thus reduce the incidence of premature death. Cuff blood pressure measurements have some prognostic value and have traditionally been used to predict the risk of end-organ damage. Such measurements, however, do not reflect accurately the 24-h mean blood pressure and hourly variations. For any value of cuff blood pressure, a lower 24-h mean blood pressure was associated with a lower prevalence and severity of end-organ damage. In the Pressioni Arteriose Monitorate E Loro Associazioni (PAMELA) study, data from 24-h ambulatory blood pressure monitoring (ABPM) were more strongly associated with prognosis than other blood pressure data. Longitudinal evidence of the clinical relevance of 24-h ABPM data in predicting cardiovascular risk is less extensive. However, results from the Study on Ambulatory Monitoring of Pressure and Lisinopril Evaluation (SAMPLE) trial show the superiority of mean 24-h, daytime and night-time blood pressures over clinic readings in predicting the regression of left ventricular mass index in treated hypertensive patients. Furthermore, a direct, positive relationship has been established between 24-h blood pressure variability and the severity and rate of progression of end-organ damage. In addition, ABPM data demonstrate that hypertensive patients who do not exhibit a nocturnal reduction in blood pressure have a higher incidence of end-organ damage. Future directions for research and treatment of hypertension will need to consider the circadian cycle of blood pressure, the effect of treatment on blood pressure variability, and the magnitude of blood pressure changes in daily life.

Extracorporeal Shockwave Lithotripsy for Kidney Stones Reduces Blood Pressure: Use of 24-Hour Ambulatory Monitoring for Study of Blood-Pressure Changes Induced by SWL

PURPOSE

To investigate the effects of shockwave lithotripsy (SWL) on blood pressure with the use of 24-hour ambulatory blood-pressure monitoring (ABPM).

PATIENTS AND METHODS

We studied three groups of patients. Group I consisted of 60 patients with kidney stones treated with SWL. Group II was formed by 30 patients with stones in the lower third of the ureter treated in situ with SWL, and group III consisted of 30 patients with ureteral stones treated with ureteroscopy (URS). The ABPM measurements were performed before stone treatment, immediately after, and then every 3 months through 1 year.

RESULTS

There was no new onset of hypertension in any group. The prevalences of hypertension before stone treatment were 21 (35%), 12 (40%), and 9 (30%) for groups I, II, and III, respectively. One-year post treatment, the numbers of hypertensive patients found for groups I, II, and III were 15 (25%), 11 (33.3%), and 8 (22.2%), respectively. In group I, a statistically significant decrease in blood pressure values was noted 1 year post-treatment (p<0.05). This decrease was related (p<0.05) to the power (r=0.35), as well as to the product of the number and the power (r=0.25), of the shockwaves applied.

CONCLUSION

Extracorporeal lithotripsy for kidney stone may be responsible for a drop in blood pressure possibly caused by alteration in intrarenal metabolism.

Ambulatory blood pressure monitoring: is the daytime period enough for making clinical decisions?

AIM

To assess the agreement between the clinical information provided by the ambulatory daytime average and 24 h average blood pressure value for diagnosing hypertension and assessing the effects of antihypertensive treatment.

METHODS

We analysed 261 24 h ambulatory monitoring records (SpaceLabs 90207, SpaceLabs, Redmond, Washington, USA) obtained from hypertensives over 18 years of age (mean age 55.8 years) in order to make a diagnosis of hypertension or assess its control in response to treatment. Recording was programmed to occur every 20 min during waking periods and every 30 min during sleep, daily activity also being registered. The criteria compared in the diagnosis of hypertension were: (1) the evaluation criterion: an average blood pressure for the activity period of less than 135/85 mmHg (Joint National Committee VI); (2) the gold standard: an average blood pressure over 24 h of less than 125/80 mmHg (World Health Organization-International Society of Hypertension, 1999).

RESULTS

In 90% of the records, there was agreement between both criteria. In 7.2%, the awake blood pressure average was normal and the 24 h average high. Values obtained were: sensitivity, 89% (95% confidence interval 84-89%); specificity, 92% (95% CI 88-95%); positive predictive value, 95.6% (95% CI 93-98%); negative predictive value, 81% (95% CI 75-85%); pretest probability, 66% (95% CI 60-72%); positive likelihood ratio, 11; and negative likelihood ratio, 0.3. There were no significant differences in age, gender or percentage of treated subjects between the groups with and without agreement.

CONCLUSIONS

Daytime and 24 h average blood pressure may indeed carry similar information for diagnosing hypertension and assessing the effects of antihypertensive treatment in clinical practice. Ambulatory blood pressure monitoring used only during the daytime period could be better tolerated and agreed to by patients than 24 h monitoring.

Primary care physician beliefs regarding usefulness of self-monitoring of blood pressure

BACKGROUND

Recent studies suggest that the self-monitoring of blood pressure (SMBP) may improve the identification and control of hypertension. Although endorsed by the Joint National Committee VII guidelines, home monitoring is not currently part of the standard care of hypertension.

OBJECTIVE

To assess community- and university-based primary care physicians' opinions of SMBP.

METHODS

A written, 5-point, Likert-scale questionnaire was mailed to physicians in a primary care research network.

RESULTS

We received completed surveys from 138 of 170 providers (81%). Physician ages ranged from 25 to 72 years. Half of the providers were female, and approximately half were residents. Most physicians (63%) reported having patients using SMBP. Physician opinions of SMBP were unrelated to age, gender and number of years in practice. Three key beliefs were expressed: SMBP could be useful, economical and problematic. Community-based physicians were more likely than university-based physicians to believe in the benefits of SMBP use, and to disagree that the use of SMBP could cause problems for them or their patients (P < 0.05). Compared with their peers, physicians with fewer than five patients using SMBP agreed more strongly with statements that SMBP use could cause problems for themselves and their patients in hypertension treatment.

CONCLUSIONS

Overall, the providers responded that SMBP could be useful to them in managing hypertension but seem hesitant to endorse it fully at this time, possibly anticipating potential problems that could arise with SMBP use. Physicians with more patients using self-monitoring were more likely to endorse it.

Once-daily fixed-combination irbesartan 300 mg/ hydrochlorothiazide 25 mg and circadian blood pressure profile in patients with essential hypertension

BACKGROUND

More than 60% of patients with hypertension included in morbidity and mortality trials needed >or=2 drugs to achieve a substantial, sustained reduction in blood pressure. Tolerable combinations using higher doses of antihypertensive drugs are frequently required to control blood pressure.

OBJECTIVE

The goal of this study was to assess the effect of a once-daily fixed combination of irbesartan 300 mg/hydrochlorothiazide (HCTZ) 25 mg on the circadian blood pressure profile in patients with essential hypertension that was not controlled with full-dose single therapy or low-dose combined therapy.

METHODS

Study patients were recruited consecutively from the outpatient hypertension clinics of 3 university hospitals in Spain. After a 1-week washout period, patients with a mean daytime blood pressure >135/85 mm Hg were treated with irbesartan 300 mg/HCTZ 25 mg once daily for 12 weeks. Twenty-four-hour ambulatory blood pressure monitoring was performed at the end of the washout period and during the last week of treatment.

RESULTS

Fifty-seven patients with essential hypertension (28 men, 29 women) were enrolled; their mean (SD) age was 60.4 (7.2) years (range, 45-78 years). After treatment, a significant reduction in both clinic and ambulatory mean (SD) blood pressure values was observed in the whole group of 57 patients (from 146.0 [11.0] mm Hg to 123.3 [13.3] mm Hg, P < 0.001 for 24-hour systolic blood pressure [SBP]; from 89.9 [8.2] mm Hg to 76.5 [9.4] mm Hg, P < 0.001 for 24-hour diastolic blood pressure [DBP]. The mean lowering of ambulatory SBP and DBP at peak was 25.2 (14.5) mm Hg and 14.7 (9.5) mm Hg, respectively, and at trough, 22.3 (18.3) mm Hg and 12.3 (10.9) mm Hg. The trough-to-peak ratio of the group was 0.92 for SBP (0.97 in responders) and 0.84 for DBP (0.89 in responders). The smoothness index, calculated as the mean of all individual values, was 1.7 (1.0) for SBP (1.8 [0.9] in responders) and 1.3 (0.8) for DBP (1.5 [0.6] in responders). Seven side effects in 6 patients were reported. No metabolic changes were observed, and no patient discontinued the study because of treatment-related adverse effects.

CONCLUSIONS

The fixed combination of irbesartan 300 mg/HCTZ 25 administered once daily produced a crude meaningful effect in reducing 24-hour blood pressure and was well tolerated. The circadian profile was preserved, as shown by trough-to-peak ratios and smoothness index values for both SBP and DBP.

Daily life blood pressure changes are steeper in hypertensive than in normotensive subjects

Target organ damage in hypertensive patients is related to their increased average blood pressure and greater 24-hour blood pressure variability. Whether the rate of blood pressure changes is also greater in hypertension, producing a greater stress on arterial walls, is not known, however. Our study aimed at addressing this issue by computer analysis of 24-hour ambulatory intra-arterial blood pressure recordings in 34 subjects (29 males), 13 normotensive subjects and 21 uncomplicated hypertensive subjects (mean age+/-SD, 40.4+/-11.8 years). The number, slope (mm Hg/s), and length (beats) of systolic blood pressure ramps of 3 or more consecutive beats characterized by a progressive increase (+) or reduction (-) in systolic blood pressure of at least 1 mm Hg per beat were computed for each hour and for the whole 24-hour period. Twenty-four-hour average systolic blood pressure was 112.9+/-2.1 and 159.4+/-5.7 mm Hg in normotensive and hypertensive subjects, respectively. Over the 24 hours, the number and length of systolic blood pressure ramps were similar in both groups, whereas the slope was markedly different (24-hour mean+/-SE slope, 4.80+/-0.30 in normotensives and 6.50+/-0.40 mm Hg/s in hypertensives, P<0.05). Ramp slope was not influenced by age or reflex pulse interval changes, but it was greater for higher ramp initial systolic blood pressure values. Thus, in daily life, hypertensive subjects are characterized by steeper blood pressure changes than normotensives, and this, regardless of the mechanisms, may have clinical implications, because it may be associated with greater traumatic effect on the vessel walls of hypertensive patients.

Doxazosin GITS trough to peak ratio and 24-hour blood pressure monitoring in the management of hypertension in renal transplant patients

We have studied 20 patients, 10 male, 10 female, mean age 52.5+/-10.9 years, who received a cadaver kidney transplant between June 1996 and January 1999. The patients presented with mild or moderate high BP and were treated on a maintained immunosuppression with an anti-calcineurin agent and steroids, associated or not to mycophenolate-mofetil. At baseline, a 24-hour ambulatory BP monitoring was performed. General biochemical parameters were determined and doxazosin GITS (Gastro-Intestinal Therapeutic System) in a single dose of 4 mg/d was started. Doxazosin GITS was titrated four weeks after up to 8 mg/d if the BP was greater than 140/90 mm Hg. At week 12, biochemical analysis were repeated as well as the 24-hour BP monitoring and the T/P ratio was calculated.

RESULTS

The patients were divided in responders, T/P index >50%, n=10 or not-responders, T/P index <50%, n=10 patients). No differences in systolic BP (SBP), diastolic BP(DBP), plasma creatinine or proteinuria were seen at base-line. DBP was lower in responders than in non-responders (P=ns). Doxazosin doses were 5.5+/-3 mg/d vs 5.8+/-3 and T/P ratio 0.70+/-0.13 vs 0.17+/-0.14, (P=.001). There were no variations in pl. t. cholesterol, triglycerides, glucose or uric acid.

CONCLUSIONS

Treatment was safe and efficient, not increasing metabolic adverse effects. Doxazosin GITS is a safe agent which can reduce cardiovascular risk. In our patients, the good T/P ratio has been associated with a best diastolic BP control. This good profile should be taken into account for 24-hour BP control in hypertensive renal transplant patients.

Ambulatory blood pressure measurement is indispensable to good clinical practice

The traditional technique of blood pressure measurement is being phased out in most countries and is being replaced by automated measurement. The era of automated blood pressure measurement brings its own problems, not least being the need to evaluate blood pressure measuring devices independently for accuracy. Towards this end, the Working Group on Blood Pressure Monitoring of the European Society of Hypertension has published an international protocol with the aim of having all devices assessed for basic accuracy before being put on the market. The main thrust of this review is that if ambulatory blood pressure measurement has become indispensable to the management of patients with hypertension, it then becomes imperative to encourage the use of ambulatory blood pressure measurement (ABPM) in general practice rather than restricting its availability to specialist hospital centres. However, if ABPM is to be widely used in general practice, there is a need to establish appropriate educational processes and to improve the methods of presenting and analysing ABPM data.

Loaned self-measurement equipment model compared with ambulatory blood pressure monitoring

OBJECTIVE

To compare the correspondence between the loaned self-measurement equipment model (LSEM), 24 h awake ambulatory blood pressure monitoring (ABPM) and clinic blood pressure (CBP).

DESIGN

A cross-sectional study was carried out involving 90 hypertensive and normotensive subjects.

METHODS

We used a variation of home measurement, the loaned self-measurement equipment model (LSEM), that consisted of lending a number of sphygmomanometers, the property of the clinic, to patients for 3-day periods. The correspondence of results from LSEM was measured against the difference between the two averages, the correlation coefficients and the average unweighted absolute differences.

RESULTS

The average difference between CBP and ABPM was 6.1/2.5 mmHg (P<0.001, r =0.54/0.63). Between CBP and LSEM, it was 6.6/1.4 mmHg (P<0.001/ 0.08, r =0.52/0.63), and between the ABPM and LSEM 0.5/-1.0 mmHg (P=0.70/0.14, r =0.71/0.75). The average unweighted absolute differences between LSEM and ABPM readings were 5.5 and 1.5 mmHg for systolic and diastolic blood pressure, respectively, whereas the average difference between CBP and ABPM means was much higher, at 6.8 mmHg for systolic and 2.7 mmHg for diastolic pressure. Agreement in the diagnosis of systolic hypertension between LSEM and ABPM was found in 78.8% of the individuals, and of diastolic hypertension in 76.7%.

CONCLUSION

Blood pressure readings taken using LSEM have a better correspondence than CBP in predicting the awake ABPM value, although the disagreement in terms of diagnosing hypertension should be noted.

Combination of lisinopril and nifedipine GITS increases blood pressure control compared with single drugs in essential hypertensive patients

The present study was designed to evaluate the effect of combination therapy using the angiotensin-converting enzyme-inhibitor lisinopril and the dihydropyridine calcium antagonist nifedipine GITS on the degree and homogeneity of 24-hour blood pressure reduction in essential hypertensive patients. After a 4-week placebo run-in period, 51 patients (mean age, 54.4 +/- 9.4 years) with essential hypertension and clinic diastolic blood pressure between 105 and 115 mm Hg were randomized to 4-week treatment with lisinopril (20 mg), nifedipine GITS (30 mg), or their combination according to a multicenter, randomized, double-blind, crossover study. Trough clinic blood pressure and 24-hour ambulatory blood pressure were measured at the end of the run-in period and after 4 weeks of treatment. In addition to clinic and 24-hour average blood pressure reduction, the trough-to-peak ratio and the smoothness index, a new measure for the homogeneity of blood pressure reduction, were also calculated. Although both lisinopril and nifedipine GITS produced a significant reduction in clinic and 24-hour average blood pressure values, the reduction obtained with the combination was significantly (P < 0.001) greater. Moreover, the combination therapy increased (P < 0.01) the smoothness index as compared with each single drug for both systolic (lisinopril, 1.02; nifedipine GITS, 1.1; combination, 1.76) and diastolic (lisinopril, 0.98; nifedipine GITS, 0.87; combination, 1.54) blood pressure values, whereas trough-to-peak ratio values (expressed as median) for systolic (lisinopril, 0.41; nifedipine GITS, 0.52; combination, 0.55) and diastolic (lisinopril, 0.35; nifedipine GITS, 0.40; combination, 0.49) blood pressure values were not significantly increased by the combination therapy. Thus, antihypertensive treatment with the combination of lisinopril and nifedipine GITS is more effective and balanced over the 24 hours than the combination components administered alone, confirming that the smoothness index is superior to the trough-to-peak ratio in assessing homogeneity of pharmacologic blood pressure reduction.

Smooth blood pressure control obtained with extended-release felodipine in elderly patients with hypertension: evaluation by 24-hour ambulatory blood pressure monitoring

OBJECTIVE

To assess, by smoothness index (SI), distribution of the antihypertensive effect of extended-release (ER) felodipine over 24 hours in elderly patients with hypertension.

METHODS

After a 4-week washout phase, 35 elderly patients (mean age 69 +/- 4 years) with mild-to-moderate hypertension received 2 weeks' treatment with ER felodipine 5mg once daily. The dosage of ER felodipine was doubled to 10 mg/day and given for a further 2 weeks in non-responders (sitting clinic blood pressure > 140/90mm Hg). The study had an open-label design with no placebo control. After each period, clinic and ambulatory blood pressures were measured. Trough-to-peak (T/P) ratio was computed by dividing the blood pressure (BP) change at trough (22 to 24 hours after drug intake) by the change at peak (2 adjacent hours with a maximal BP reduction between the second and eighth hour after drug intake). SI was calculated as the ratio between the average of the 24, hourly, treatment-induced BP changes and its standard deviation.

RESULTS

After the initial 2-week treatment period, clinic and 24-hour ambulatory BP values were higher in non-responders (145 +/- 11/87 +/- 8 and 135 +/- 17/80 +/- 6mm Hg, respectively) than in responders (133 +/- 6/81 +/- 3 and 130 +/- 9/77 +/- 7mm Hg). In non-responders, clinic and 24-hour BP values were lowered after a further 2 weeks of treatment with ER felodipine 10 mg/day (128 +/- 11/78 +/- 6 and 128 +/- 12/75 +/- 5mm Hg). SI was high in responders (0.8 +/- 0.8/0.7 +/- 0.7 for systolic/diastolic BP) and low in non-responders (0.5 +/- 0.6/0.3 +/- 0.6) during the first 2-week treatment period. It increased in non-responders after an additional 2 weeks of treatment with ER felodipine 10 mg/day (1.0 +/- 0.8/0.7 +/- 0.6). Median T/P ratios were 0.73 and 0.61 (systolic BP and diastolic BP) in responders and 0.41 and 0.61 in non-responders after 2 weeks of treatment. At variance with SI, T/P ratios did not increase in non-responders after doubling the dosage of ER felodipine (0.34 and 0.18). ER felodipine did not increase 24-hour heart rate. A total of nine adverse events were recorded in six patients (17%), but no patients withdrew from the study.

CONCLUSION

ER felodipine 5 to 10 mg/day smoothly and safely reduces 24-hour ambulatory BP in elderly patients with hypertension.

Trough-to-peak ratio, smoothness index, and circadian blood pressure profile after treatment with once-daily fixed combination of losartan 100 and hydrochlorothiazide 25 in essential hypertension

The once-daily fixed combination of losartan 100 mg/hydrochlorothiazide 25 mg was evaluated for safety and efficacy in a multicenter open study by using 24-h ambulatory blood pressure monitoring in untreated patients with moderate-to-severe essential hypertension or patients with uncontrolled hypertension despite treatment with monotherapy or low-dose combination. After a 2-week washout period, 41 patients (22 men, 19 women) aged 34-74 years, showing a mean daytime blood pressure > 135/85 mm Hg, were treated with losartan 100 mg/hydrochlorothiazide 25 for 8 weeks. Ambulatory blood pressure was monitored at the end of the washout period and during the last week of treatment. A significant reduction in the average values of clinic blood pressure (from 169.9 +/- 13.5 mm Hg to 139.5 +/- 15.6 mm Hg, p < 0.001 for systolic blood pressure [SBP]; and from 102.2 +/- 7.1 mm Hg to 85.1 +/- 9.5 mm Hg, p < 0.001 for diastolic blood pressure [DBP]) was observed after treatment in the whole group of 41 patients. Likewise, average values of both 24-h SBP and 24-h DBP were significantly reduced (from 145.7 +/- 13.1 mm Hg to 128.3 +/- 14.6 mm Hg, p < 0.001 for 24-h SBP; and from 90.3 +/- 7.3 mm Hg to 79.2 +/- 8.6 mm Hg, p < 0.001 for 24-h DBP). The average lowering at peak was 20.2 +/- 11.8 mm Hg for 24-h SBP and 12.1 +/- 7.4 mm Hg for 24-h DBP, whereas the lowering at trough was 17.8 +/- 12.0 mm Hg and 10.4 +/- 8.1 mm Hg, respectively. The trough-to-peak ratio (T/P) was 0.88 for SBP and 0.86 for DBP, and the smoothness index was 7.36 for SBP and 6.37 for DBP. The response rate was 87.8% (blood pressure lowering > 5 mm Hg of either 24-h SBP or 24-h DBP average values). Among responders, T/P ratio was 0.89 for SBP and 0.87 for DBP, and the smoothness index was 8.09 for SBP and 7.15 for DBP. No side effects or changes in metabolic parameters were observed. The fixed combination of losartan 100 mg/hydrochlorothiazide 25 was very effective and well tolerated.

Effects of the calcium channel antagonist amlodipine in cats with surgically induced hypertensive renal insufficiency

OBJECTIVE

To determine whether amlodipine besylate decreases systemic arterial blood pressure (BP) and reduces the prevalence of complications in cats with induced hypertensive renal insufficiency.

ANIMALS

20 cats with partial nephrectomy.

PROCEDURE

Following reduction in renal mass, 10 cats were administered 0.25 mg of amlodipine/kg, PO, q 24 h (group A). Ten cats served as a control group (group C). Systolic BP (SBP), diastolic BP (DBP), and mean BP (MBP), physical activity, and pulse rate were measured continuously for 36 days by use of radiotelemetric devices.

RESULTS

Compared with values for clinically normal cats, SBP, DBP, and MBP were significantly increased in cats of group C. Cats in group A had significant reductions in SBP, DBP, and MBP, compared with values for cats in group C. Albuminuria but not urine protein-to-creatinine ratio was significantly correlated (R2 = 0.317) with SBP in hypertensive cats. Prevalence of ocular lesions attributable to systemic hypertension in group C (7 cats) was greater than that observed in group A (2). Two cats in group C were euthanatized on day 16 because of nuerologic complications attributed to systemic hypertension. One normotensive cat in group A was euthanatized because of purulent enteritis of unknown cause on day 27.

CONCLUSIONS AND CLINICAL RELEVANCE

Amlodipine had an antihypertensive effect in cats with coexistent systemic hypertension and renal insufficiency. Its use may improve the prognosis for cats with systemic hypertension by decreasing the risk of ocular injury or neurologic complications induced by high BP.

Myocardial ischemia and autonomic activity in dippers and non-dippers with coronary artery disease: assessment of normotensive and hypertensive patients

OBJECTIVES

The aim of this study was to assess the relations between the circadian variations of blood pressure (BP) and the pattern of ischemia and autonomic activity in normotensive and hypertensive patients with coronary artery disease (CAD).

PATIENTS AND METHODS

On the basis of the results of ambulatory BP monitoring, 115 patients with stable CAD were divided into Group 1 (with arterial hypertension) and Group 2 (normotensives). Groups were subdivided into dippers and non-dippers. Holter monitoring was performed to assess the occurrence and circadian pattern of ischemic episodes. Time domain and frequency domain HRV analyses were performed to evaluate the autonomic activity.

RESULTS

The total number of ischemic episodes was similar in dippers and non-dippers. Non-dippers had a greater number of silent episodes and a different circadian pattern of ischemia with more night episodes. Among the time-domain HRV parameters, only SDNN was similar in dippers and non-dippers. Non-dippers had lower pNN50 and rMSSD-the parameters expressing parasympathetic activity. Differences between diurnal and nocturnal results of spectral HRV analysis were observed in dipper patients only. They presented an elevation of HF power and a decline of LF power at night. All differences between dippers and non-dippers were of similar significance in both hypertensives and normotensives.

CONCLUSIONS

A lack of a nocturnal fall in BP is present in normotensive and hypertensive patients with CAD. Non-dippers with CAD had silent and nighttime ischemia more often. They also had an abnormal pattern of autonomic activity with higher sympathetic and lower parasympathetic modulation.

Twenty-four hour ambulatory blood pressure in the International Nifedipine GITS Study Intervention as a Goal in Hypertension Treatment (INSIGHT)

OBJECTIVES

The International Nifedipine GITS Study Intervention as a Goal in Hypertension Treatment (INSIGHT) showed, by means of office blood pressure measurements, that long-term treatment with nifedipine GITS is as effective as diuretics in preventing cardiovascular and cerebrovascular complications. However, since office blood pressure measurements reflect to a limited extent blood pressure outside the office, a side-arm INSIGHT study in which patients underwent both office measurement and 24 h ambulatory blood pressure monitoring was also performed.

DESIGN AND METHODS

The study had a randomized, double-blind, parallel group design. After 4 weeks of placebo, mild-to-moderate essential hypertensive patients were randomized to nifedipine GITS 30 mg or amiloride 2.5 + hydrochlorothiazide 5 mg for 3.1 years. Dose titration was performed by dose doubling and addition of atenolol 25-50 mg or enalapril 5-10 mg, or other drugs when needed. Analysis was carried out by intention-to-treat and included computation of 24 h, day and night ambulatory blood pressure and heart rate values. Additional analyses included computation of the trough-to-peak ratio and the smoothness index (the ratio between the average of the 24-hourly blood pressure reductions after treatment and its standard deviation).

RESULTS

A total of 151 patients were recruited and 149 were valid for analysis: 78 patients had 24 h ambulatory recordings both at baseline and during treatment and 134 during treatment. Office, 24 h and day and night blood pressures were all significantly and similarly reduced by both treatments. Office and ambulatory heart rate was left unchanged by diuretics, while it was slightly reduced by nifedipine. Median trough-to-peak ratios were always > 0.5 and superimposable between the two treatment groups. Similarly, smoothness indices of systolic and diastolic blood pressures were comparably high for nifedipine and diuretics, thus demonstrating a similar well-balanced antihypertensive response to both drugs. No significant differences were observed between the two treatment groups in the number of cardiovascular events (17 in the nifedipine-based and 26 in the diuretics-based treatment group).

CONCLUSIONS

In the INSIGHT study, the long-term antihypertensive effect on 24 h blood pressure and the cardiovascular protection of nifedipine was similar to that of diuretics.

Relationship between home blood pressure and longitudinal changes in target organ damage in treated hypertensive patients

Cross-sectional studies have shown that home blood pressure (BP) correlates with hypertensive target organ damage better than clinic BP. However, there have been few longitudinal studies regarding the predictive value of home BP on the changes in organ damage in treated hypertensive patients. Clinic and home BP over a 12-month period, antihypertensive medication use, echocardiographic and electrocardiographic results, and serum creatinine and urinary protein levels were examined in 209 treated hypertensive patients in 1993. These patients were prospectively followed for 5 years. The patients were divided into 4 subgroups according to hypertension control as follows: good control (<140/90 mmHg for clinic BP, <135/85 mmHg for home BP), improved, worsened, and poor control. The average clinic BP was 147.0+/-14.9/87.0+/-7.6 mmHg (mean+/-SD) in 1993 and 146.0+/-13.7/84.1+/-7.5 mmHg in 1998. The average home BP was 136.8+/-10.4/84.3+/-7.6 mmHg in 1993 and 136.1+/-9.7/81.2+/-7.7 mmHg in 1998. The left ventricular mass index (LVMI) positively correlated with both home systolic BP and clinic systolic BP in 1998 but not in 1993. The correlation tended to be closer for home BP than for clinic BP. LVMI did not change in patients with good or improved home systolic BP, while it increased in those with poor or worsened home systolic BP. The relationship between changes in LVMI and clinic BP was not significant. In conclusion, Home BP was more effective than clinic BP as a predictor of changes in left ventricular hypertrophy in treated hypertensive patients. Home BP should be controlled to below 135/85 mmHg to prevent cardiac hypertrophy.

Blood pressure measurement in research

OBJECTIVE

The aim of this paper is to summarize the issues raised during a consensus conference on the role of different blood pressure (BP) monitoring techniques in research, including pathophysiological studies, clinical outcome trials and clinical pharmacology trials.

METHODS

This review includes the contribution of the participants in a task force at the Eighth Consensus Conference on Ambulatory BP Monitoring (October 28-31, 2001, Sendai, Japan) and the results of a discussion open to all conference participants. Individual contributions have been summarized together with the points raised during the subsequent discussion, and the main statements are also presented in a table format.

POINTS OF CONSENSUS

(1) BP monitoring in pathophysiological studies. The essential role played by continuous BP monitoring in this field had been acknowledged, and further development of non-invasive beat-by-beat monitoring techniques has been advocated. (2) BP monitoring in clinical trials. In clinical trials automated ambulatory BP monitoring (ABPM) and self BP measurements (SBPM) at home share similar advantages, with specific features that make these approaches not alternative solutions but rather approaches able to complement each other. A few examples of application of ABPM and SBPM in clinical trials include the Treatment of Hypertension according to Home or Office Blood Pressure (THOP) trial and the Trial of Preventing Hypertension (TROPHY). (3) Use of ABPM in clinical pharmacology studies. Use of ABPM is now an established routine, aimed at describing the 24-h effect of new antihypertensive drugs. An example of these applications that was discussed in the conference is the use of ABPM in the evaluation of a new long-acting calcium channel blocker (Barnidipine) (J-MUBA study). (4) Specific models for the analysis of BP fluctuations. The features characterizing the chronobiological approach to description of 24-h BP profiles and its limitations (mainly consisting of the high risk of data over-modelling) are discussed. Also the possible occurrence of a circaseptan (approximately with a 7-day period) rhythm in BP has been addressed, although repeated performance of 24-h ABPM over a week obviously faces a number of practical problems. (5) Progress in technology: BP monitoring and telemedicine. The possibility to implement an interactive telemonitoring system of home SBPM values and the perspectives for a clinical application of this technology in the Hypertension Objective treatment based on Measurement by Electrical Devices of Blood Pressure (HOMED-BP) trial is discussed.

Relationship between left ventricular mass and blood pressure in treated hypertension

This study evaluated prospectively whether there is still a relationship between left ventricular mass and blood pressure once hypertension is treated and determined the relative importance of daytime vs night-time blood pressure, systolic vs diastolic blood pressure and office vs ambulatory blood pressure. A total of 649 patients (305 or 47% female) with essential hypertension, treated with antihypertensive drugs for at least 3 months, underwent office blood pressure measurement and both daytime and night-time ambulatory blood pressure measurement, electrocardiography and echocardiography. Correlations were made between blood pressure values and parameters of left ventricular mass. Electrocardiographic voltage criteria and even more so echocardiographic parameters correlate significantly albeit weakly (r < or = 0.28) with blood pressure in treated hypertension. Correlations are consistently higher when systolic blood pressure is considered. Overall, the best correlations are found between 24-h ambulatory systolic or night-time blood pressure and the Sokolow-Lyon voltage as well as the echocardiographic age and body mass index adjusted left ventricular mass. In conclusion, once hypertension is treated, the relationship between blood pressure and left ventricular mass is low. Nevertheless, in this the largest single centre study of its kind, echocardiographic parameters of left ventricular mass in treated hypertensive subjects correlate better with blood pressure than electrocardiographic parameters. Parameters of hypertrophy are more closely related to systolic blood pressure than to diastolic blood pressure. In accordance with the finding that dippers have a better prognosis than non-dippers, night-time blood pressure consistently correlates better with left ventricular mass than daytime blood pressure.

A multicenter, randomized, double-blind comparison of the efficacy and safety of irbesartan and enalapril in adults with mild to moderate essential hypertension, as assessed by ambulatory blood pressure monitoring: the MAPAVEL Study (Monitorización Ambulatoria Presión Arterial APROVEL)

BACKGROUND

When blood pressure (BP)-lowering efficacy is assessed by measurements taken in a clinic setting, angiotensin II-receptor antagonists show similar efficacy to angiotensin-converting enzyme inhibitors and better tolerability. A search of MEDLINE to date, however, reveals no randomized, double-blind studies using ambulatory BP monitoring (ABPM) to compare the BP-lowering efficacy of irbesartan and enalapril in a large number of patients ( > 200) with essential hypertension.

OBJECTIVE

This study compared 24-hour BP reduction and BP control, as assessed by ABPM, in patients with mild to moderate essential hypertension treated with irbesartan or enalapril. The relative tolerability of the 2 treatments was also evaluated.

METHODS

This was a multicenter, randomized, double-blind study in patients with mild to moderate essential hypertension (office diastolic BP [DBP] 90-109 mm Hg or systolic BP [SBP] 140-179 mm Hg). After a 3-week, single-blind placebo washout phase, patients with a mean daytime DBP > or = 85 mm Hg, as measured by ABPM between 10 AM and 8 PM, were randomized to 12 weeks of active treatment with irbesartan or enalapril. Starting doses were 150 and 10 mg/d, respectively, with titration to 300 or 20 mg/d if clinic DBP was > or = 90 mm Hg at week 4 or 8. Based on clinic measurements, BP control was defined as a BP reading < 140/90 mm Hg after 12 weeks of treatment; patients achieving a reduction in DBP of > or = 10 mm Hg at 12 weeks were considered responders. The ABPM criterion for BP control, independent of clinic values, was achievement of a daytime BP < 130/85 mm Hg after 12 weeks of treatment; patients achieving a reduction in 24-hour DBP > or = 5 mm Hg at 12 weeks were considered responders, in dependent of clinic values.

RESULTS

A total of 238 patients were randomized to treatment, 115 to irbesartan and 123 to enalapril. The study population was approximately 52.0% female and 48.0% male, with a mean ( +/- SD) age of 52.7 +/- 10.6 years. The study was completed by 111 patients in the irbesartan group (dose titrated to 300 mg/d in 72.0% of patients) and 115 patients in the enalapril group (dose titrated to 20 mg/d in 76.5% of patients). BP reductions were similar in the 2 groups, both as measured in the clinic (DBP, 12.7 +/- 8.8 mm Hg irbesartan vs 12.4 +/- 7.4 mm Hg enalapril; SBP, 19.0 +/- 14.1 mm Hg vs 17.5 +/- 14.0 mm Hg) and by 24-hour ABPM (DBP, 9.4 +/- 8.5 mm Hg vs 8.8 +/- 8.5 mm Hg: SBP, 14.7 +/- 14.7 mm Hg vs 12.6 +/- 13.1 mm Hg). As assessed by ABPM, rates of BP control were 40.5% (45/111) for irbesartan and 33.9% (39/115) for enalapril, and the response rates were a respective 71.2% (79/111) and 71.3% (82/115). The overall incidence of adverse events (40.0% irbesartan, 51.2% enalapril) was not statistically different between groups, although the incidence of adverse events considered probably related to antihypertensive treatment was significantly higher with enalapril than with irbesartan (24.6% vs 9.2%, respectively; P = 0.026), essentially because of the higher incidence of cough (8.1% vs 0.9%).

CONCLUSIONS

As assessed by ABPM, irbesartan 150 to 300 mg/d was as effective in lowering BP and achieving BP control as enalapril 10 to 20 mg/d. Based on the number of treatment-related adverse events, irbesartan was better tolerated than enalapril.

Relationship between muscle sympathetic nerve activity and diurnal blood pressure profile

The physiological mechanisms mediating the variability and diurnal rhythm of blood pressure are unclear. We tested the hypothesis that resting sympathetic activity is linked to the variability characteristics and 24-hour profile of ambulatory blood pressure measurements. We evaluated the relationship between muscle sympathetic nerve activity (MSNA) and the level, variability, and nocturnal fall of ambulatory blood pressure in 69 normal men. Subjects were subdivided according to the tertiles of MSNA distributions. Mean 24-hour blood pressure was not significantly different across the 3 groups. Compared with subjects in the first tertile (lowest MSNA, <18 bursts/min), subjects in the third tertile (highest MSNA, >25 bursts/min) had significantly greater daytime blood pressure variability, whether expressed as absolute values (10.2+/-0.5 versus 8.1+/-0.4 mm Hg for systolic blood pressure and 9.4+/-0.4 versus 7.2+/-0.4 mm Hg for diastolic blood pressure; P<0.01 for both comparisons) or as variation coefficients (8.1+/-0.4% versus 6.6+/-0.3% for systolic blood pressure and 12.7+/-0.7% versus 10.1+/-0.6% for diastolic blood pressure; P<0.01 for both comparisons). Subjects in the third tertile also had a more striking absolute and percentage fall in systolic blood pressure from daytime to nighttime than subjects in the first tertile (17+/-2 versus 10+/-2 mm Hg, P=0.02, or 13+/-1% versus 8.2+/-1.4%, P=0.02). In conclusion, higher resting measurements of sympathetic traffic are associated with greater daytime blood pressure variability and a more marked nocturnal decline in blood pressure in normal subjects. These findings suggest that sympathetic neural mechanisms may contribute importantly to the regulation of blood pressure over the 24-hour period.

Reliability of ambulatory blood pressure monitoring

OBJECTIVE

To focus on the reliability of ambulatory blood pressure monitoring and on its limitations in clinical practice, and to construct adequate strategies to improve ambulatory monitoring performance.

METHODS

The literature was reviewed, and personal data were used.

DISCUSSION

Since the beginning of non-invasive ambulatory blood pressure monitoring, it appeared that some subjects had a high proportion of outlying readings that were unlikely to be accurate. Although ambulatory blood pressure is more reproducible than clinic blood pressure, large day-to-day differences have also been reported in reproducibility studies for average 24 h blood pressure. It has been shown that, for day-to-day 24 h blood pressure differences greater than 4/3 mmHg, ambulatory blood pressure is poorly predictive of the degree of target organ damage. The variability of average 24 h blood pressure may arise from several causes, including true biological variability, a lack of standardization of activities and measurement errors. Artefactual readings can easily occur if patients are not properly instructed. Although editing procedures can eliminate outliers, it is often impossible to identify inaccurate readings included within the patient's trend. To optimize ambulatory blood pressure monitoring, health-care providers should be instructed adequately on how to perform this technique. Appropriate patient selection, a proper application of instrumentation and the checking of its performance, careful instructions to patients, the immediate evaluation of the patient's diary and 24 h tracing after completion of the recording should improve the results of ambulatory monitoring.

CONCLUSIONS

A checklist of criteria that should be used for optimizing ambulatory monitoring in clinical practice should be proposed by the Consensus Conference on ambulatory blood pressure monitoring. To improve doctors' proficiency, strategies including educational protocols and training programmes should be implemented.

Blood pressure variability as a risk factor

Blood pressure variability is clinically relevant because of the evidence that the degree of blood pressure fluctuation may independently contribute to organ damage and to the cardiovascular risk of hypertensive patients. This review will focus on the evidence available to support this concept. As such, data obtained from cross-sectional studies, longitudinal studies in humans and experimental studies in animals will be discussed. The possibility of antagonizing an excessive degree of blood pressure variability by administering drugs to provide a long-lasting and smooth antihypertensive action will also be discussed, as will the usefulness of mathematical indices aimed at quantifying the homogeneity of the blood pressure reduction by treatment.

Relation between blood pressure variability and carotid artery damage in hypertension: baseline data from the European Lacidipine Study on Atherosclerosis (ELSA)

BACKGROUND

Baseline data from the European Lacidipine Study on Atherosclerosis (ELSA) have shown that carotid intima-media thickness (IMT) is not related to diastolic blood pressure (BP), but that it is related to clinic systolic (S) or pulse pressure (PP) and more so to their 24 h average values. The aim of the present study was to determine whether IMT independently relates to additional information obtained through ambulatory BP, in particular to SBP or PP variability.

METHODS AND RESULTS

In 1663 hypertensive patients, after a wash-out period from antihypertensive treatment (mean age 56.2 +/- 7.65 years), IMT was assessed from 12 different carotid sites. Ambulatory BP measurements were performed every 15 min (day) and every 20 min (night). IMT values were positively related to 24 h, day and night average SBP and PP. There was some relationship of IMT with day-night or clinic-day SBP and PP differences. The most important finding, however, was that IMT values were related with 24 h SBP or PP standard deviation (P < 0.001), a measure of overall SBP or PP variability. The relationship was seen also by multiple regression analysis, the standard deviation for SBP or PP only following age and 24 h average SBP or PP in accounting for IMT values.

CONCLUSIONS

This is the first demonstration from a large database that not only average 24 h PP and SBP values, but also 24 h BP fluctuations, are associated with, and possibly determinants of, the alterations of large artery structure in hypertension.

Marked improvement in cardiovascular function after successful transsphenoidal surgery in acromegalic patients

OBJECTIVE

Transsphenoidal surgery results in biochemical remission of acromegaly in 45-80% of patients; however, few studies have addressed the impact of transsphenoidal surgery on cardiovascular function in acromegalic patients. The aim of this prospective study was to investigate the effects of postoperative GH/IGF-I normalization on echocardiographic parameters and blood pressure (BP) in a series of patients with active acromegaly.

DESIGN

An open prospective study.

PATIENTS

Thirty newly diagnosed acromegalic patients undergoing transsphenoidal surgery.

MEASUREMENTS

Doppler echocardiography and 24-h ambulatory blood pressure monitoring were performed before and 6 months after transsphenoidal surgery.

RESULTS

Fifteen patients were considered to be well controlled postoperatively (group A), as defined by normal age-corrected IGF-I levels and glucose-suppressed GH levels less than 2 mU/l, the remaining 15 patients being considered as poorly controlled (group B). In group A, a postoperative decrease of left ventricular mass index was observed (104.4 +/- 6.6 vs. 127.1 +/- 7.7 g/m2; P < 0.001), associated with an improvement of some indices of diastolic function, such as an increase of the early/late transmitral peak flow velocity (P < 0.05) and a decrease of isovolumic relaxation time (P < 0.01). No significant change was observed in group B. A significant decrease of 24-h systolic BP was also observed in group A (P < 0.05) and five of six patients normalized their BP circadian rythm. In contrast, a nonsignificant increase in BP values, with a persistent blunted BP profile where present, was observed in group B.

CONCLUSIONS

We conclude that successful transsphenoidal surgery is able to induce a significant improvement in some cardiac parameters and a slight reduction in systolic blood pressure in acromegalic patients.

Mechanisms and clinical implications of blood pressure variability

Several studies have unequivocally shown that the target-organ damage associated with the hypertensive condition is more closely related to 24 h average blood pressure values than to clinic blood pressure. Blood pressure, however, is highly variable over the daytime and night-time period, and of major interest is whether average 24 h blood pressure values, as well as 24 h blood pressure variability, correlate with, and are possibly responsible for, the hypertension-related alterations of the target-organ structure and function. This paper will address this issue by discussing the main features of blood pressure variability in hypertension. It will also examine the mechanisms involved in this phenomenon, with particular emphasis on the pathogenetic role of sympathetic neural factors. The clinical relevance of blood pressure variability in promoting target-organ damage, as well as its therapeutic implications, will finally be highlighted.

Comparative study of home and office blood pressure in hypertensive patients treated with enalapril/HCTZ 20/6 mg: the ESPADA study

The introduction and generalization of 24-h ambulatory blood pressure (BP) monitoring has shown the clinical relevance of home BP. The aim of this study was to assess the validity of home-measured BP for monitoring and controlling patients with arterial hypertension while on a homogeneous treatment. An additional objective was to establish the degree of office BP control obtained. This was a prospective, longitudinal, observational and multicenter study in a cohort of 156 patients of both sexes, aged over 18 years and with essential hypertension. All of them received the fixed combination enalapril/HCTZ 20/6 mg as the only hypertensive agent for at least 4 weeks previously. Office BP was the average of three measurements. For home BP, a semi-automated device (OMRON HEM 705 CP) was used. The patients measured their BP twice a day for 2 consecutive days. The average differences between the two measuring methods were low, but significant: 3.99 mmHg for systolic BP (SBP; p < 0.05), 2.02 mmHg for diastolic BP (DBP; p < 0.05). Pearson's regression coefficient between the office and home values was highly significant (p < 0.0001) for SBP, DBP and heart rate. Home BP measurement was highly reproducible as shown by the high within-class correlation coefficient for individual measurements on the first day compared with the second: 0.88 (95% confidence interval, CI 0.82-0.92; p < 0.00001) for SBP and 0.89 for DBP (95% CI 0.83-0.93; p < 0.00001). The percentage of patients with strict office DBP and SBP control (< 140/90 mmHg) was 61.3% and with DBP control (<90 mmHg) 92%. In conclusion, in the ESPADA study, the application of home BP measurement is valid, reproducible and shows a high correlation with office BP.

Blood pressure reduction at night: sleep and beyond

Blood pressure fall at night is commonly used to classify subjects as 'dippers' or 'non-dippers'. Such a classification is poorly reproducible, however, due to interference by a number of confounders. These include methodological problems with ambulatory blood pressure monitoring at night due to a variable hydrostatic difference between the arm cuff and the heart. Even correcting for this variable, however, does not significantly improve the reproducibility of the nocturnal blood pressure fall, which probably depends to a large extent on other factors, such as the level of daytime activity and differences in sleep patterns.

Ambulatory blood pressure monitoring and organ damage

Several papers have suggested that 24-hour average blood pressure (BP) is superior to office BP in relation to hypertension target organ damage. This review article will specifically address the evidence provided in this regard by either cross-sectional or longitudinal studies. It will also critically discuss the available data supporting the concept that not only 24-hour average BP values, but also specific BP patterns occurring within the 24 hours may have clinical relevance. This is the case for daytime versus nighttime BP, the day/night BP difference, the morning BP rise, and overall BP variability.

Reproducibility of ambulatory blood pressure monitoring in hemodialysis patients

Ambulatory blood pressure monitoring (ABPM) has been increasingly used in hemodialysis (HD) practice and research; however, no study has evaluated the reproducibility of ABPM in this population. To address this question, we performed 48-hour interdialytic ABPM on 21 HD patients (mean age, 53 +/- 16 years; 7 women) on two different occasions 68 +/- 34 days (range, 30 to 154 days) apart. To qualify for the protocol, patients had to be at the same dry weight and on the same vasoactive drug regimen at both monitoring periods. BP was analyzed according to three different methods: isolated pre-HD and post-HD values, average pre-HD and post-HD values for the five HD sessions surrounding each monitoring period, and 48-hour interdialytic ABPM. Reproducibility was determined by analysis of the SD of the differences (SDD) between the two monitoring periods and the coefficient of variation of each method of BP determination. Our results show better reproducibility of ABPM (SDD, 10.6/6.6 mm Hg; coefficient of variation, 7.5%/8.1%) compared with isolated pre-HD BP (SDD, 24.4/11.3 mm Hg; coefficient of variation, 16.7%/14.1%) or post-HD BP (SDD, 16.8/14.5 mm Hg; coefficient of variation, 11.7%/17.8%), and averaged pre-HD BP (SDD, 14.7/7.2 mm Hg; coefficient of variation, 10.1%/9.1%) or post-HD BP (SDD, 12.4/8.7 mm Hg; coefficient of variation, 8.9%/11.1%). The reproducibility of the decrease in BP during sleep was poor, with up to 43% of the subjects changing dipping category within or between interdialytic periods. We conclude that ABPM is the most accurate method to study BP in HD patients over time. However, variability is significant, and there is poor reproducibility of the nocturnal decline in BP.

Isolated office hypertension: are there any markers of future blood pressure status?

BACKGROUND

The introduction of ambulatory blood pressure monitoring into clinical practice has defined a clinical condition called 'isolated office hypertension'.

OBJECTIVE

The aim of this study was to evaluate the long-term systolic and diastolic blood pressure changes in patients with isolated office hypertension and to identify the presence of markers capable of identifying which patients will develop sustained hypertension.

METHODS

All the 407 patients enrolled had a random office systolic or/and diastolic blood pressure of over 140/90mmHg and a mean daytime ambulatory blood pressure of 130/84mmHg or less. At enrollment, each patient underwent a 'baseline examination' made up of a physical evaluation, a 24h ambulatory blood pressure monitoring, and a mental arithmetic test performed at the end of the 24h ambulatory monitoring.

RESULTS

Of the 173 patients finally studied, 102 (58.9%) developed sustained hypertension with an increase in both ambulatory systolic and diastolic blood pressure. At the time of the baseline examination, the patients were divided into two groups. Group A included patients with mean ambulatory systolic and diastolic blood pressures in the first hour of 130/84mmHg or less; group B included patients with mean ambulatory systolic and diastolic pressures in the first hour of greater than 130/84mmHg. During the mental arithmetic test, the systolic and heart rate values increased significantly only in group B patients. Of the 102 patients who had become hypertensive by the time of the follow-up examination, 84 (82%) belonged to group B.

CONCLUSION

These data suggest that isolated office hypertension may indeed be a transitional state towards the development of sustained hypertension. Moreover, the mean ambulatory blood pressure value during the first hour can be considered to be a marker of a higher risk of developing sustained hypertension.