Ambulatory blood pressure monitoring

Assessment of Nocturnal Blood Pressure: Importance of Determining the Time in Bed-A Pilot Study

Objectives: Nocturnal blood pressure (BP) monitoring is essential for evaluating cardiovascular risk and guiding treatment decisions. However, the standardized narrow-fixed nighttime period between 10 p.m. and 6 a.m. may not accurately reflect individual sleep schedules. This pilot study aimed to investigate the comparability between the standardized nighttime period and actual time in bed (TIB) regarding BP assessment. Further, our goal was to evaluate the clinical relevance of the observed BP differences. Methods: A total of 30 participants underwent 24 h ambulatory blood pressure monitoring (ABPM). Patient-specific TIB was precisely assessed through an accelerometer and a position sensor from the SOMNOtouch NIBP™ (SOMNOmedics GmbH, Randersacker, Germany). We analysed the effect of considering individual TIB as nighttime instead of the conventional narrow-fixed interval on the resulting nocturnal BP levels and dipping patterns. Results: We observed differences in both systolic and diastolic BP between the standardized nighttime period and the TIB. Furthermore, a notable percentage of patients (27%) changed their dipping pattern classification as a function of the nighttime definition adopted. We found strong correlations between the start (r = 0.75, p < 0.01), as well as the duration (r = -0.42, p = 0.02) of TIB and the changes in dipping pattern classification. Conclusions: Definition of nocturnal period based on the individual TIB leads to clinically relevant changes of nocturnal BP and dipping pattern classifications. TIB is easily detected using a body position sensor and accelerometer. This approach may thus improve the accuracy of cardiovascular risk evaluation and enhance treatment strategies.

[Chronotherapy in arterial hypertension]

The blood pressure profile in most normo- and hypertensive subjects are currently known, as well as the impact their changes induced on the cardio- and cerebrovascular risk. Ambulatory blood pressure monitoring (ABPM) has contributed greatly to the knowledge of this parameter. It to correct the schedule of drug administration (chronotherapy) with changes in any component of the BP profile that have better correlation with risk. These include the nocturnal decrease and the morning BP surge. Investigations in this direction are still scarce, and multicenter studies need to be conducted that can answer the true preventive impact of such modifications.

Morning surge in blood pressure is associated with reactivity of the sympathetic nervous system

BACKGROUND

An exaggerated morning surge in blood pressure (BP) closely relates to target organ damage and cardiovascular risk, but whether the causative mechanism involves greater reactivity of the sympathetic nervous system (SNS) is unknown. We determined whether the response of the SNS to a cold pressor test predicted the BP morning surge.

METHODS

Ambulatory BP recordings were obtained from 14 men and 19 women (age = 41±4 years), and the amplitude (day-night difference), rate of rise (RoR), rate by amplitude product (BPPower), and morning BP surge (MBPS; post-awake minus pre-awake) of morning mean arterial pressure (MAP) were determined. The reactivity of the SNS to CPT was assessed by recording of muscle sympathetic nerve activity (MSNA).

RESULTS

CPT induced a marked increase in MAP and all parameters of MSNA, including burst amplitude. Log-normalized BPPower positively correlated with the overall average CPT-induced increases in total MSNA (r = 0.38; P = 0.04) and burst amplitude (r = 0.43; P = 0.02) but was not related to the increase in MSNA frequency. Furthermore, a strong positive linear trend in the CPT-induced changes in burst amplitude across tertiles of BPPower and RoR was observed. BPPower and RoR were not related to CPT-induced hemodynamic changes. The MBPS did not correlate with any of the CPT-induced changes in vascular or MSNA variables.

CONCLUSIONS

These results suggest that the central nervous system mechanisms influencing the increase in MSNA burst amplitude during arousal may also be fundamental in determining the rate and power of BP rise during the morning period.

Nocturnal systemic hypotension increases the risk of glaucoma progression

OBJECTIVE

The objective of this prospective, longitudinal study of patients with normal-tension glaucoma (NTG) was to determine whether patients with nocturnal hypotension are at greater risk for visual field (VF) loss over 12 months than those without nocturnal hypotension.

DESIGN

Prospective, longitudinal study.

PARTICIPANTS

Consecutive patients with NTG with at least 5 prior VF tests were screened for eligibility.

METHODS

The baseline evaluation assessed demographic and clinical characteristics, covering systemic comorbid conditions, including systemic hypertension. All oral and ophthalmologic medications were recorded. A complete ophthalmological examination was performed at baseline and follow-up. Patients had their blood pressure (BP) monitored every 30 minutes for 48 hours with an ambulatory recording device at baseline and 6 and 12 months.

MAIN OUTCOME MEASURES

The primary outcome was based on the global rates of VF progression by linear regression of the mean VF threshold sensitivity over time (decibels/year).

RESULTS

Eighty-five patients with NTG (166 eyes; mean age, 65 years; 67% were women) were included. Of the 85 patients, 29% had progressed in the 5 VFs collected before study enrollment. The nocturnal mean arterial pressure (MAP) was compared with the daytime MAP. Multivariate analysis showed that the total time that sleep MAP was 10 mmHg below the daytime MAP was a significant predictor of subsequent VF progression (P<0.02).

CONCLUSIONS

Cumulative nocturnal hypotension predicted VF loss in this cohort. Our data suggest that the duration and magnitude of decrease in nocturnal blood pressure below the daytime MAP, especially pressures that are 10 mmHg lower than daytime MAP, predict progression of NTG. Low nocturnal blood pressure, whether occurring spontaneously or as a result of medications, may lead to worsening of VF defects.

Ambulatory blood pressure monitoring and structural changes in carotid arteries in normotensive workers occupationally exposed to lead

Occupational exposure to lead may cause an increase in blood pressure. The aim of the study was to estimate the effect of occupational exposure to lead on selected parameters of ambulatory blood pressure monitoring (ABPM) and structural changes in carotid arteries. The study included 33 normotensive men occupationally exposed to lead and 39 unexposed men employed in administration of the foundry. All of the men underwent 24-hour ambulatory blood pressure monitoring and high-resolution B-mode ultrasonography to determine intima-media thickness (IMT). The group of men occupationally exposed to lead manifested significantly higher mean systolic blood pressure (MSBP), mean diastolic blood pressure (MDBP), mean blood pressure (MBP), pulse pressure (PP), variability of diastolic blood pressure (VDBP), and IMT than the unexposed group. The studied groups did not differ in mean values of variability of systolic blood pressure (VSBP). As compared to the unexposed group, in men exposed to lead, atherosclerotic plaques were significantly more common. In the group of persons exposed to lead the Pearson’s correlation coefficient analysis revealed significant linear positive correlations between MSBP and IMT, between lead level and the number of atherosclerotic plaques, and between lead level and PP. Multivariate stepwise regression analysis demonstrated that higher lead level in blood and higher triglyceride concentration in blood represent independent risk factors of an increased pulse pressure in the group of individuals occupationally exposed to lead. Occupational exposure to lead can be associated with increased blood pressure and accelerated progression of atherosclerosis.

Home blood pressure telemonitoring improves hypertension control in general practice. The TeleBPCare study

BACKGROUND

Self blood pressure monitoring at home may improve blood pressure control and patients' compliance with treatment, but its implementation in daily practice faces difficulties. Teletransmission facilities may offer a more efficient approach to long-term home blood pressure monitoring.

METHODS

Twelve general practitioners screened 391 consecutive uncontrolled mild-moderate hypertensive patients (80% treated), 329 of whom (58 +/- 11 years, 54% men) were randomized to either usual care on the basis of office blood pressure (group A, n = 113) or to integrated care on the basis of teletransmitted home blood pressure (group B, n = 216). Twenty-four-hour ambulatory blood pressure monitoring was performed at baseline and after 6 months, during which treatment was optimized according to either office (group A) or home (group B) blood pressure values. We compared differences between groups in the rate of daytime ambulatory blood pressure normalization (<130/80 mmHg), need of treatment changes during follow-up, quality of life scores, and healthcare costs.

RESULTS

Baseline office blood pressures were 149 +/- 12/89 +/- 9 and 148 +/- 13/89 +/- 7 mmHg in groups A (n = 111) and B (n = 187) respectively, the corresponding daytime values being 140 +/- 11/84 +/- 8 and 139 +/- 11/84 +/- 8 mmHg. The percentage of daytime blood pressure normalization was higher in group B (62%) than in group A (50%) (P < 0.05). There were less frequent treatment changes in group B than in group A (9 vs. 14%, P < 0.05). Quality of life tended to be higher and costs lower in group B.

CONCLUSION

Patients' management based on home blood pressure teletransmission led to a better control of ambulatory blood pressure than with usual care, with a more regular treatment regimen.

Ambulatory blood pressure variability is increased in diabetic hypertensives

The purpose of this study was to examine the possible difference in the 24-hr BP profile--including short-term BP variability, assessed as the standard deviation--between diabetic and non-diabetic hypertensives. We measured 24-hr ambulatory BP in 11 diabetic hypertensives (diabetic HT) and 10 non-diabetic hypertensives (non-diabetic HT) who were hospitalized for the educational program in our hospital and were under stable salt intake. Renal function and sleep apnea were also estimated. There were no significant differences in 24-hr systolic BP (141 mmHg vs. 135 mmHg, ns), daytime systolic BP (143 mmHg vs. 138 mmHg, ns), and nighttime systolic BP (135 mmHg vs. 130 mmHg, ns) between diabetic HT and non-diabetic HT. The values of 24-hr HR (69.7 beats/min vs. 65.2 beats/min, ns) and 24-hr HR variability (9.9 beats/min vs. 10.1 beats/min, ns) were also similar between the groups. Interestingly, diabetic HT had a significantly greater 24-hr systolic and diastolic BP variability than non-diabetic HT (18.2 mmHg vs. 14.5 mmHg, p < 0.05; 11.5 mmHg vs. 9.6 mmHg, p < 0.05, respectively). The values for creatinine clearance, urinary protein excretion, and apnea-hypopnea index were similar between the groups. Bivariate linear regression analysis demonstrated that fasting blood glucose was the primary determinant of 24-hr diastolic BP variability (r = 0.661, p < 0.01). Multiple stepwise regression analysis revealed that fasting blood glucose was a significant and independent contributor to 24-hr systolic BP variability (r = 0.501, p < 0.05). Taken together, these results demonstrate that BP variability is increased in diabetic hypertensives. Furthermore, it is possible that an elevation of fasting blood glucose may contribute to the enhanced BP variability in hypertensives.

Relationship of Office, Home, and Ambulatory Blood Pressure to Blood Glucose and Lipid Variables in the PAMELA Population

Alterations in blood glucose and cholesterol are more frequently detectable in hypertensive than in normotensive conditions. However, no information exists as to whether this phenomenon involves only office or also home and 24-hour ambulatory blood pressure (ie, when values are representative of daily life). In 2045 subjects enrolled in the Pressioni Arteriose Monitorate E Loro Associazioni (PAMELA) study, we measured home, 24-hour, and office blood pressure. Measurements also included fasting blood glucose and serum total and HDL cholesterol values. Prevalence of diabetes (> or =126 mg/dL or use of antidiabetic drugs), impaired fasting blood glucose (> or =110 to <126 mg/dL), and hypercholesterolemia (serum total cholesterol > or =240 mg/dL or 200 mg/dL) increased progressively from "optimal" to "normal," "high-normal," and "elevated" office systolic or diastolic blood pressure. Fasting blood glucose and total serum cholesterol also increased progressively from the first to the fourth group, with HDL cholesterol values showing a concomitant progressive decrease. This was also the case for quartiles of office, home, and 24-hour blood pressure. In the whole population, there was a positive correlation between serum cholesterol or blood glucose and all blood pressure values (P always <0.0001), with a much smaller and less consistent relationship with heart rate. In a multivariate analysis that included gender, body mass index, age, and antihypertensive treatment, all blood pressure values remained highly significantly related to values of either metabolic variables. Thus, in the PAMELA population, glucose and lipid values are independently related to blood pressure. This is also the case when daily life blood pressure values are considered.

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.

Reduction (TELMAR) as assessed by magnetic resonance imaging in patients with mild-to-moderate hypertension--a prospective, randomised, double-blind comparison of telmisartan with metoprolol over a period of six months rationale and study design

The Telmisartan Effectiveness on Left ventricular MAss Reduction (TELMAR) trial will assess the effect of the angiotensin II (Ang II) receptor blocker, telmisartan, on left ventricular hypertrophy (LVH) compared with the b-blocker, metoprolol, at similar antihypertensive doses. The rationale is that antihypertensives reduce LVH, a cardiac adaptation to pressure overload, principally by pressure-related effects. Ang II plays a key role in pressure-independent mechanisms causing LVH, and angiotensin-converting enzyme (ACE) inhibitors induce more pronounced LVH regression than some other antihypertensives. Blocking Ang II Type 1 receptors may be more effective than ACE inhibition in reducing LVH. TELMAR is a prospective, randomised, double-blind, double-dummy, parallel-group trial. A total of 140 patients (age 18 80 years) with uncontrolled essential hypertension (mean daytime systolic blood pressure [SBP] >140 mmHg or diastolic blood pressure [DBP] >90 mmHg and/or night-time SBP >120 mmHg or DBP >70 mmHg, measured by ambulatory blood pressure monitoring [ABPM]) and left ventricular mass index related to height (LVMI) >0.8 g/cm for females, >1.1 g/cm for males (defined by magnetic resonance imaging [MRI]) will be randomised to once-daily telmisartan or metoprolol. The telmisartan dose will be 40 mg for the first two weeks, 80 mg for 5.5 months and 40 mg for the last two weeks. Metoprolol will be given at a dose of 47.5 mg for two weeks, 95 mg for 5.5 months and 47.5 mg for two weeks. Concomitant add-on medication with hydrochlorothiazide and amlodipine will be allowed. The primary endpoint is the percentage change in LVMI at treatment end versus baseline, using MRI. Secondary variables include blood pressure changes and response rates assessed by ABPM and manual cuff sphygmomanometry, and end-systolic wall stress, systolic left ventricular function (LVF) and diastolic LVF determined by MRI. A separate study was performed prior to the main trial to define the normal range of MRI data in an age-matched population.

Relevance of blood pressure variation in the circadian onset of cardiovascular events

Ambulatory blood pressure monitoring (ABPM) is a highly useful diagnostic tool as it can detect non-dipping and can distinguish masked hypertension, white-coat hypertension and sustained hypertension. Furthermore, measurement of blood pressure using ABPM has greater prognostic strength than single clinic blood pressure measurements. The Systolic Hypertension in Europe study, for example, found that elevation of ambulatory systolic blood pressure, but not conventional single cuff systolic blood pressure, by 10 mmHg was associated with adverse cardiovascular outcomes. Blood pressure follows a circadian rhythm, with peak levels during the morning hours. The morning period has also been associated with a greater risk for cardiovascular events compared with the rest of the 24 h. The morning surge in blood pressure, along with haemostatic changes that promote thrombosis, is believed to contribute to this heightened risk. Long-acting antihypertensive agents that provide blood pressure control throughout the 24-h dosing interval, including the morning hours, are the most appropriate therapeutic approach to hypertension. Direct comparative studies with telmisartan and other angiotensin-II receptor blockers and with amlodipine have shown that telmisartan has a long duration of action and controls blood pressure over the 24-h dosing period.

An ambulatory blood pressure monitoring study of the comparative antihypertensive efficacy of two angiotensin II receptor antagonists, irbesartan and valsartan

BACKGROUND

The primary objective of this study was to compare the change from baseline in mean diastolic ambulatory blood pressure (ABP) at 24 h post dose (trough measurement) after 8 weeks of treatment with irbesartan or valsartan in subjects with mild-to-moderate hypertension. Secondary objectives included comparing the mean changes from baseline in systolic ABP at trough; 24-h ABP; morning and night-time ABP; self-measured systolic blood pressure (SBP) and diastolic blood pressure (DBP); and office-measured SBP and DBP at trough.

DESIGN

After a 3-week, single blind, placebo lead-in period, 426 subjects were randomized to receive either irbesartan 150 mg or valsartan 80 mg for 8 weeks.

METHODS

Ambulatory blood pressure measurements were obtained at baseline and at week 8. Self-measured morning and evening DBP and SBP readings were obtained at home over a 7-day period at baseline and at week 8. Office-measured seated DBP and SBP measurements were obtained at trough, at baseline, and at week 8.

RESULTS

Irbesartan demonstrated significantly greater reductions than valsartan for mean change from baseline in diastolic ABP at trough (-6.73 versus -4.84 mmHg, respectively; P = 0.035). Irbesartan produced significantly greater reductions than valsartan for mean systolic ABP at trough (-11.62 versus -7.5 mmHg, respectively; P < 0.01) and for mean 24-h diastolic ABP (-6.38 versus -4.82 mmHg, respectively; P = 0.023) and systolic ABP (-10.24 versus -7.76 mmHg; P < 0.01). Irbesartan also produced significantly greater reductions than valsartan for office-measured seated DBP (-10.46 versus 7.28 mmHg, respectively; P < 0.01) and SBP (-16.23 versus -9.96 mmHg, respectively; P < 0.01) and for self-measured morning DBP (-6.28 versus -3.75 mmHg, respectively; P < 0.01) and SBP (-10.21 versus -6.97 mmHg, respectively; P < 0.01). Both drugs were well tolerated.

CONCLUSION

Irbesartan was more effective than valsartan in reducing DBP and SBP at trough and in providing greater overall 24-h blood pressure-lowering efficacy.

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.

Cardiovascular risk and therapeutic intervention for the early morning surge in blood pressure and heart rate

The incidence of most adverse cardiovascular events appears to follow a circadian pattern, reaching a peak in the morning shortly after wakening and arising. The activities of many physiologic parameters, including hemodynamic, hematologic and humoral factors, also fluctuate in a cyclical manner over the 24h. It has been suggested that, during the post-awakening hours, the phases of these cycles synchronize to create an environment that predisposes to atherosclerotic plaque rupture and thrombosis in susceptible individuals, thereby accounting for the heightened cardiovascular risk at this time of day. Blood pressure and heart rate are part of this physiologic process, following a clear circadian rhythm characterized by a fall during sleep and a sharp rise upon awakening. This so-called 'morning surge' in blood pressure may act as a trigger for cardiovascular events, including myocardial infarction and stroke. The clinical implication of these observations is that antihypertensive therapy should provide blood pressure control over the entire interval between doses. For agents taken once daily in the morning, the time of trough plasma drug level (and lowest pharmacodynamic effect) will often coincide with the early morning surge in blood pressure and heart rate. For these reasons, chronotherapeutic formulations of drugs and intrinsically long-acting antihypertensive agents provide the most logical approach to the treatment of hypertensive patients since they provide 24 h blood pressure control from a single daily dose as well as attenuating the early morning rise in blood pressure (and in some instances heart rate).

Comparison of angiotensin II receptor blockers: impact of missed doses of candesartan cilexetil and losartan in systemic hypertension

Blood pressure remains poorly controlled in the hypertensive population due in large part to low or unsatisfactory patient compliance. Clinical studies that incorporate an intentionally missed dose have been designed to evaluate the impact of poor patient compliance on the effectiveness of antihypertensive medications. In these studies, ambulatory blood pressure monitoring is continued throughout the dosing interval and beyond in order to determine when systolic and diastolic blood pressure increase into the hypertensive range. In an 8-week, randomized, double-blind, placebo-controlled trial in patients with mild-to-moderate hypertension, the antihypertensive effects of candesartan cilexetil 16 mg were maintained after a missed dose, whereas systolic and diastolic blood pressure increased toward baseline levels after a missed dose of losartan 100 mg. Candesartan cilexetil provided a significantly greater reduction in sitting systolic (p = 0.004) and diastolic blood pressure (p = 0.008) than losartan when measured 48 hours after the last dose. Moreover, the homogeneity of antihypertensive effects was greater after candesartan cilexetil than losartan based on calculation of the smoothness index from ambulatory systolic and diastolic measurements during the first 24-hour period after dosing and during the 12-hour period after the missed dose. These results demonstrate that missing or delaying a dose of candesartan cilexetil has less impact on antihypertensive efficacy than missing or delaying a dose of losartan.