Diurnal Variation of Blood Pressure in Elderly Patients with Essential Hypertension

Biomarkers of high salt intake

High salt intake is associated with hypertension, which is a leading modifiable risk factor for cardiovascular disease (CVD) and chronic kidney disease (CKD). International Guidelines recommend a large reduction in the consumption of sodium to reduce blood pressure, organ damage, and mortality. In its early stages, the symptoms of CKD are generally not apparent. CKD proceeds in a "silent" manner, necessitating the need for urinary biomarkers to detect kidney damage at an early stage. Since traditional renal biomarkers, such as serum creatinine, are not sufficiently sensitive, difficulties are associated with detecting kidney damage induced by a high salt intake, particularly in normotensive individuals. Several new biomarkers for renal tubular damage, such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), vanin-1, liver-type fatty acid-binding protein (L-FABP), and monocyte chemotactic protein-1 (MCP-1), have recently been identified. However, few studies have investigated early biomarkers for CKD progression associated with a high salt diet. This chapter provides insights into novel biomarkers for CKD in normo- and hypertensive individuals with a high salt intake. Recent studies using spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) fed a high salt diet identified urinary vanin-1 and NGAL as early biomarkers for renal tubular damage in SHR and WKY, whereas urinary KIM-1 was a useful biomarker for salt-induced renal injury in SHR only. Clinical studies are needed to confirm these findings.

Effect of Chronotherapy of Antihypertensives in Chronic Kidney Disease: A Randomized Control Trial

Introduction:

There is a higher prevalence of non-dipping pattern in hypertensive chronic kidney disease (CKD) patients. Nocturnal hypertension has been shown to predict cardiovascular mortality and morbidity and is often superior to daytime blood pressure. We studied the effect of shifting or adding antihypertensive to night time on blood pressure profile of CKD III-IV patients.

Methods:

In this single-center, prospective, randomized controlled trial, eligible participants were adults from eastern India aged 18–65 years with CKD stages 3 and 4, with a non-dipping pattern on ambulatory blood pressure monitor (ABPM). The intervention group received all the antihypertensives in the night time whereas the standard care group continued to take the medication in the morning. Both groups were followed up for 1 year. The primary outcome was the number of patients changed from non-dippers to dippers in the standard care group and intervention group. Secondary outcomes included a change in estimated glomerular filtration rate (eGFR) and change in the cardiac structure.

Results:

39 patients in the intervention group and 36 patients in the standard care group were analyzed. 10 patients (26%) reverted to dipping pattern in the intervention group as compared to none in the standard care group. Mean changes in eGFR were −2.55 and −0.18 mL/min/1.73 m² in the standard care and intervention group at the end of the study, respectively. Between-group difference in eGFR was significant at 1 year (5.22 [95% CI, 4.3–6.1] ml/min/1.73 m²); (P = 0.03). The cardiac structure showed no significant changes in either group.

Conclusions:

Bedtime administration of antihypertensives reverted non-dippers to dippers and slowed the decline in eGFR in CKD stages 3 and 4 compared to morning administration of antihypertensives.

Inverted circadian variation of arterial pressure in a geriatric patient: an indicator of autonomic dysfunction

BACKGROUND

Orthostatic hypotension (OH) in geriatric patients frequently involves a component of autonomic failure (AF). The combination of OH with nocturnal hypertension (NHT) is indicative of AF, which is described as pure (PAF), when neurologic symptoms are absent, or as multisystem atrophy (MSA), when combined with motor disturbance (Parkinsonism or Parkinson disease).

CASE PRESENTATION

An 87-year-old man presented with long-lasting OH. He frequently fell, causing several fractures, and he developed heart failure. Blood pressure (BP) registration revealed a reversal of the day-night rhythm with NHT. An 18-FDG PET brain CT scan showed cerebellar hypometabolism, indicating MSA.

CONCLUSIONS

This case demonstrates the use of continuous BP registration in geriatric patients with OH for diagnosing NHT. It illustrates the usefulness of 18-FDG PET brain CT scan to specify the nature of the AF. The case also illustrates the difficulty of managing the combination of OH and NHT.

Nocturnal blood pressure measured by home devices: evidence and perspective for clinical application

: Studies using ambulatory blood pressure (BP) monitoring have shown that BP during night-time sleep is a stronger predictor of cardiovascular outcomes than daytime ambulatory or conventional office BP. However, night-time ambulatory BP recordings may interfere with sleep quality because of the device cuff inflation and frequency of measurements. Hence, there is an unmet need for obtaining high quality BP values during sleep. In the last two decades, technological development of home BP devices enabled automated BP measurements during night-time. Preliminary data suggest that nocturnal home BP measurements yield similar BP values and show good agreement in detecting nondippers when compared with ambulatory BP monitoring. Thus, nocturnal home BP measurements might be a reliable and practical alternative to ambulatory BP monitoring to evaluate BP during sleep. As the use of home BP devices is widespread, well accepted by users and has relatively low cost, it may prove to be more feasible and widely available for routine clinical assessment of nocturnal BP. At present, however, data on the prognostic relevance of nocturnal BP measured by home devices, the optimal measurement schedule, and other methodological issues are lacking and await further investigation. This article offers a systematic review of the current evidence on nocturnal home BP, highlights the remaining research questions, and provides preliminary recommendations for application of this novel approach in BP management.

Diurnal rhythm of blood pressure in patients with polycythemia vera

AIMS

Polycythemia vera increases the risk of hypertension, but there is limited information about the effect on daily blood pressure fluctuations. This study aimed to demonstrate how diurnal blood pressure rhythm is affected in polycythemia vera patients.

METHODS

Fifty (50) patients (33 men; mean age 48 ± 15 years) with a diagnosis of polycythemia vera and 51 age and sex-matched healthy subjects for the control group were prospectively evaluated. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were evaluated by ambulatory blood pressure monitoring (ABPM) as average 24-hour, daytime and nighttime measures.

RESULTS

Average 24-hour SBP and DBP, daytime SBP and DBP were similar in both groups. However, nighttime SBP and DBP were significantly higher in the polycythemia vera group compared with the control group (125.3 ± 17.2 and 73.7 ± 12.2 vs. 118.9 ± 12.2 and 69.5 ± 8.5; P = 0.034 and P = 0.044). Both nocturnal SBP fall and nocturnal DBP fall were blunted in the polycythemia vera group compared with the control group (-6.9 ± 8.9 and -11.3 ± 12.2 vs. -11.6 ± 7.7 and -16.3 ± 12.0, respectively). Both hemoglobin and hematocrit levels were positively correlated with nocturnal SBP fall (r = 0.306, P = 0.002 and r = 0.355, P < 0.001; respectively) in all patients.

CONCLUSION

We found that the polycythemia vera group had significantly decreased nocturnal dipping compared with healthy controls. The SBP fall was also positively correlated with hemoglobin and hematocrit levels.

Diurnal blood pressure changes

The definition of diurnal blood pressure changes varies widely, which can be confusing. Short-term blood pressure variability during a 24-h period and the dipping status of diurnal blood pressure can be captured by ambulatory blood pressure monitoring, and these metrics are reported to have prognostic significance for cardiovascular complications. Morning blood pressure surge also indicates this risk, but its effect may be limited to populations with specific conditions. Meanwhile, the combined use of conventional office blood pressure and out-of-office blood pressure allows us to identify people with white-coat and masked hypertension. Current home devices can measure nocturnal blood pressure during sleep more conveniently than ambulatory monitoring; however, we should pay attention to blood pressure measurement conditions regardless of whether they are in a home, ambulatory, or office setting. The relatively poor reproducibility of diurnal blood pressure changes, including the nocturnal fall of blood pressure, is another underestimated issue to be addressed. Although information on diurnal blood pressure changes is expected to be used more effectively in the future, we should also keep in mind that blood pressure levels have remained central to the primary and secondary prevention of blood pressure-related cardiovascular diseases in clinical practice.

The Relationship Between β-Receptor Sensitivity and Nocturnal Blood Pressure and Heart Rate Recovery in Normotensive People

This study examined the relationship between nocturnal blood pressure (BP) dipping and chronotropic dose25 (CD25) as an indicator of β-adrenergic receptor functioning in normotensive people. In addition, the authors evaluated the influence of β-receptor functioning on heart rate recovery after exercise. The sample consisted of 41 participants (18 men, 23 women). Ambulatory BP monitoring took place in each patient's home. On a separate occasion, β-adrenergic receptor sensitivity was determined by response to isoproterenol infusion. Heart rate (HR) recovery was defined as the change from peak HR to that measured after 1 and 2 minutes of recovery. Relationships between dipping and CD25 were found such that participants with higher CD25 values had less nocturnal decline in systolic BP, diastolic BP, and mean arterial pressure ( r =–0.445, –0.533, –0.510, respectively; p<0.004, 0.001, 0.001, respectively). Heart rate recovery at 1 and 2 minutes after exercise was 28.8 ±5 and 49.9 ±6 beats/minute, respectively. Participants with higher CD25 values had more heart rate decline during the first 2 minutes of recovery ( r =0.407, p<0.008). In addition, heart rate recovery was inversely related to systolic, diastolic, and mean nocturnal blood pressure dipping ( r =–0.348, –0.432, –0.408, respectively, p<0.028, 0.005, 0.009, respectively). Normotensive people with an abnormal circadian pattern of blood pressure may have desensitized β-adrenergic receptors. This desensitization may contribute to blunted nocturnal blood pressure and increased heart rate recovery as measured at 2 minutes following exercise testing.

Non-dipper hypertension is associated with slow coronary flow among hypertensives with normal coronary angiogram

AIM

A person with a drop of more than 10% in nocturnal arterial blood pressure during the circadian rhythm is referred to as a dipper and one with a smaller decrease is referred to as a non-dipper. In our study, we aimed to compare the thrombolysis in myocardial infarction (TIMI) frame count in non-dipper and dipper hypertensive patient groups who had normal coronary artery angiography.

METHODS

Patients with normal coronary arteries and with ambulatory blood pressure monitoring follow ups were retrospectively investigated and 60 patients (35%, female) were included in our study. The patients were grouped as dipper (n = 30) and non-dipper (n = 30) hypertensives.

RESULTS

The TIMI frame counts in all three coronary arteries and the mean TIMI frame count in the dipper hypertensive patient group were significantly lower than those of the non-dipper hypertensives (right coronary artery TIMI frame count: 16.83 ± 3.70; 21.63 ± 3.44, p < 0.001; circumflex artery TIMI frame count: 21.28 ± 3.52; 25.65 ± 3.61, p < 0.001; left anterior descending artery TIMI frame count: 34.20 ± 2.80; 37.05 ± 3.30, p = 0.001; corrected left anterior descending artery TIMI frame count: 20.05 ± 1.63; 21.74 ± 1.95, p = 0.001; mean TIMI frame count: 19.31 ± 2.3; 22.94 ± 2.61, p < 0.001). The body mass index (BMI) was 23.79 ± 2.81 kg/m2 in the dipper patient group, while it was 25.47 ± 2.92 in the non-dippers. BMI was found to be significantly higher in the non-dipper group than in the dipper group (p = 0.027).

CONCLUSION

In this study, TIMI frame count, which is a simple, productive, objective and reproducible method for determination of microvascular changes, was found to be higher in non-dipper hypertensive patients than in the dipper patients.

Circadian clock and the onset of cardiovascular events

The onset of cardiovascular diseases often shows time-of-day variation. Acute myocardial infarction or ventricular arrhythmia such as ventricular tachycardia occurs mainly in the early morning. Multiple biochemical and physiological parameters show circadian rhythm, which may account for the diurnal variation of cardiovascular events. These include the variations in blood pressure, activity of the autonomic nervous system and renin-angiotensin axis, coagulation cascade, vascular tone and the intracellular metabolism of cardiomyocytes. Importantly, the molecular clock system seems to underlie the circadian variation of these parameters. The center of the biological clock, also known as the central clock, exists in the suprachiasmatic nucleus. In contrast, the molecular clock system is also activated in each cell of the peripheral organs and constitute the peripheral clock. The biological clock system is currently considered to have a beneficial role in maintaining the homeostasis of each organ. Discoordination, however, between the peripheral clock and external environment could potentially underlie the development of cardiovascular events. Therefore, understanding the molecular and cellular pathways by which cardiovascular events occur in a diurnal oscillatory pattern will help the establishment of a novel therapeutic approach to the management of cardiovascular disorders.

The role of clock genes and circadian rhythm in the development of cardiovascular diseases

The time of onset of cardiovascular disorders such as myocardial infarctions or ventricular arrhythmias exhibits a circadian rhythm. Diurnal variations in autonomic nervous activity, plasma cortisol level or renin-angiotensin activity underlie the pathogenesis of cardiovascular diseases. Transcriptional-translational feedback loop of the clock genes constitute a molecular clock system. In addition to the central clock in the suprachiasmatic nucleus, clock genes are also expressed in a circadian fashion in each organ to make up the peripheral clock. The peripheral clock seems to be beneficial for anticipating external stimuli and thus contributes to the maintenance of organ homeostasis. Loss of synchronization between the central and peripheral clocks also augments disease progression. Moreover, accumulating evidence shows that clock genes affect inflammatory and intracellular metabolic signaling. Elucidating the roles of the molecular clock in cardiovascular pathology through the identification of clock controlled genes will help to establish a novel therapeutic approach for cardiovascular disorders.

Prognostic significance of dipping in older hypertensive patients

BACKGROUND AND AIMS

Arterial hypertension doubles the risk of coronary heart disease, heart and kidney failure, and peripheral arterial disease. Less variation in diurnal ambulatory blood pressure monitoring (ABPM) patterns may affect mortality outcome. Therefore, as hypertension occurs in over 95% of older subjects, the prognostic value of dipping status in older hypertensive patients will be assessed.

METHOD

The retrospective study group consisted of 170 hypertensive patients, aged 75-84 years, enrolled in the years 2005 to 2007. Baseline measures included 24-h ABPM. Diurnal index and dipping status was calculated and stratified the group into dippers (40 patients, 23.5%), non-dippers (65 patients, 38.2%) and reverse-dippers (65 patients, 38.2%).

RESULTS

During a 5-year observation, after baseline we have observed 69 deaths (40.9%) from the whole group of 170 patients with 23 (35.4%) being non-dippers and 36 (55.4%) reverse-dippers. There were significant differences between the groups divided according to diurnal dipping status in survival time, number of recorded deaths and night mean blood pressure. We have identified and confirmed risk factors for the all-cause mortality: age, mean systolic and diastolic blood pressure, diurnal index and dipping status (dipping, non-dipping or reverse-dipping).

CONCLUSION

Reverse-dippers and non-dippers revealed worse prognosis compared with dippers.

Ambulatory blood pressure in stroke and cognitive dysfunction

We have reviewed the most relevant data regarding ABPM and brain damage, with specific reference to first and recurrent stroke, silent structural brain lesions such as lacunar infarcts and white matter lesions, and cognitive impairment. Only two large studies have evaluated the usefulness of ABPM in relation to antihypertensive treatment in primary stroke prevention. In the Syst-Eur trial, drug treatment reduced ABPM and office BP more than placebo in patients with sustained isolated systolic hypertension (ISH). In contrast, in those patients with white-coat hypertension (WCH) changes in ABPM between the treatment groups were not significantly different. Patients with WCH had a lower incidence of stroke (p < 0.05) during follow-up than patients with sustained ISH, suggesting that WCH is a benign condition. In the HYVET trial 50 % of the very elderly patients included with office systolic BP > 160 mmHg had WCH. However, a significant 30 % stroke reduction was observed in treated patients including those with WCH, indicating that WCH may not be a benign condition in the elderly. In the acute stroke setting, where treatment of hypertension is not routinely recommended due to the lack of evidence and the differing results of the very few available trials, ABPM data shows that sustained high BP during the first 24 h after acute stroke is related to the formation of cerebral edema and a poorer functional status. On the other hand, even when nondipping status was initially related to a poorer prognosis, data indicate that patients with very-large nocturnal dipping, the so-called "extreme dippers", are those with the worse outcomes after stroke. The association between different ABPM parameters (circadian pattern, short-term variability) and poorer performance scores in cognitive function tests have been reported, especially in elderly hypertensives. Unfortunately most of these studies were cross-sectional and the associations do not establish causality.

Comparison of the effects of amlodipine and losartan on blood pressure and diurnal variation in hypertensive stroke patients: a prospective, randomized, double-blind, comparative parallel study

BACKGROUND

Lowering blood pressure (BP) and reducing diurnal variation are important for the prevention of stroke in patients with hypertension.

OBJECTIVE

This study was conducted to compare the BP-lowering and diurnal BP variation effects of amlodipine and losartan on acute stroke patients.

METHODS

Seventy-seven hypertensive patients with acute stroke were enrolled in this randomized, double-blind, single-center clinical trial. They were randomly assigned to receive either amlodipine or losartan daily. To evaluate whether amlodipine was noninferior to losartan, ambulatory BP monitoring was performed before the drugs were first administered and at the end of week 8. BP variables analyzed included the mean awake, sleep, morning, evening, and prewake BP values; the nocturnal dipping status; and the morning surge.

RESULTS

Thirty-nine patients in the amlodipine group and 38 patients in the losartan group completed the follow-up. In the baseline characteristics, mean age was 63.6 years, and 68.8% were male. In the intention-to-treat analysis, the mean (SD) systolic BP decreased 14.82 (11.71) mm Hg in the amlodipine group and 13.11 (12.69) mm Hg in the losartan group, and amlodipine proved noninferior to losartan (mean difference, 1.71 mm Hg [95% CI, -3.83 to 7.26]). However, in the per-protocol analysis, noninferiority was not proven (BP reduction, 16.06 [11.33] vs 17.17 [11.85] mm Hg; mean difference, -1.11 mm Hg [95% CI, -6.88 to 4.65]). Amlodipine had a greater tendency than losartan to produce a blunt morning surge.

CONCLUSIONS

The noninferiority of amlodipine was not confirmed by the per-protocol analysis. However, amlodipine showed a favorable effect on the morning surge. ClinicalTrials.gov identifier: NCT01830517.

Salt sensitivity: a review with a focus on non-Hispanic blacks and Hispanics

The purpose of this review is to summarize the available information regarding salt sensitivity particularly as it relates to non-Hispanic blacks and Hispanics and to clarify possible etiologies, especially those that might shed light on potential treatment options. In non-Hispanic blacks, there is evidence that endothelial dysfunction, reduced potassium intake, decreased urinary kallikrein excretion, upregulation of sodium channel activity, dysfunction in atrial natriuretic peptide (ANP) production, and APOL1 gene nephropathy risk variants may cause or contribute to salt sensitivity. Supported treatment avenues include diets high in potassium and soybean protein, the components of which stimulate nitric oxide production. Racial heterogeneity complicates the study of salt sensitivity in Hispanic populations. Caribbean Hispanics, who have a higher proportion of African ancestry, may respond to commonly prescribed anti-hypertensive agents in a way that is characteristic of non-Hispanic black hypertensives. The low-renin hypertensive phenotype commonly seen in non-Hispanic blacks has been linked to salt sensitivity and may indicate an increased risk for salt sensitivity in a portion of the Hispanic population. In conclusion, increased morbidity and mortality associated with salt sensitivity mandates further studies evaluating the efficacy of tailored dietary and pharmacologic treatment in non-Hispanic blacks and determining the prevalence of low renin hypertension and salt sensitivity within the various subgroups of Hispanic Americans.

Sleep disturbance is associated with decreased daily activity and impaired nocturnal reduction of blood pressure in dementia patients

Our aim was to investigate the relationships between sleep disturbance and activities of daily living (ADL) and 24-h blood pressure patterns in institutionalized dementia patients. Using 107 institutionalized dementia patients (32 males and 75 females, mean age 76.3 years), patients with a mini mental state examination (MMSE) score<24 were classified into four groups based on ADL (normal or declined) and nocturnal reduction in blood pressure (dipper or non-dipper). The sleep/wake state was visually monitored hourly for 14 consecutive days, and daytime and nighttime sleep ratios were determined. MMSE scores were significantly lower in the declined ADL group than in the normal ADL group. The nighttime sleep ratio of the non-dipper/declined ADL group was significantly lower than in the other groups. Sleep disturbance was associated with the deterioration of MMSE scores, low ADL, and impaired nocturnal reduction in blood pressure in dementia patients.

Cardiovascular disease, chronopharmacotherapy, and the molecular clock

Cardiovascular functions such as heart rate and blood pressure show 24h variation. The incidence of cardiovascular diseases including acute myocardial infarction and arrhythmia also exhibits diurnal variation. The center of this circadian clock is located in the suprachiasmatic nucleus in the hypothalamus. However, recent findings revealed that each organ, including cardiovascular tissues, has its own internal clock, which has been termed a peripheral clock. The functional roles played by peripheral clocks have been reported recently. Since the peripheral clock is considered to play considerable roles in the processes of cardiac tissues, the identification of genes specifically regulated by this clock will provide insights into its role in the pathogenesis of cardiovascular disorders. In addition, the discovery of small compounds that modulate the peripheral clock will help to establish chronotherapeutic approaches. Understanding the biological relevance of the peripheral clock will provide novel approaches to the prevention and treatment of cardiovascular diseases.

Glomerular filtration rate is related to dipping pattern in ambulatory blood pressure monitoring--a cross-sectional population-based study

A non-dipping pattern in ambulatory blood pressure monitoring (ABPM) increases the risk of cardiovascular disease. The association between renal function and the dipping pattern has not been studied in a random middle-aged population. This is a cross-sectional population-based study of 226 males and 234 females aged 40 to 62 years. Renal function was assessed with estimated glomerular filtration rate (eGFR). Non-dipping status was defined as a reduction of <10% between the daytime and the nighttime systolic BP. Non-dippers represented 18.7% of the study population. Their mean eGFR was 79.1 (s.d. 15.7) ml min(-1) per 1.73 m(2) as compared with a mean eGFR of 84.1 (s.d. 16.2) ml min(-1) per 1.73 m(2) in dippers (P=0.005); this difference remained significant after adjustments. Subjects in the lowest and in the middle eGFR tertiles had an independently increased risk of non-dipping in comparison with those in the highest eGFR tertile (odd ratios (OR), 2.34 (95% confidence interval (CI), 1.18 to 4.63) and OR, 2.01 (95% CI, 1.06 to 3.83), respectively). This study showed that even a minor deterioration in renal function is associated with increased risk of non-dipping pattern in ABPM in a random middle-aged population.

Low nocturnal blood pressure is associated with reduced cerebral blood flow in the cohort "Men born in 1914"

BACKGROUND

"Men born in 1914" is a population-based cohort study of the epidemiology of cardiovascular and cerebral disease. Little is known about how diurnal variation in blood pressure (BP) levels influence cerebral perfusion in very elderly populations.

OBJECTIVES

To study the association between systolic (SBP) and diastolic BP (DBP) levels, during the day and at night, expressed through 24 h ambulatory BP monitoring (ABPM) and regional cerebral blood flow (rCBF) disturbances.

METHODS

A cross-sectional study from a population-based cohort of 108 men 81 years of age (born in 1914) was performed in an out-patient university clinic. Cerebral blood flow measurements using (99m)Tc-hexamethylpropyleneamine oxime single photon emission computed tomography and 24 h ABPM were performed. Eleven men were excluded due to incomplete ABPM data.

RESULTS

Mean DBP at night for each tertile was correlated to rCBF for the medial temporal right (P=0.012) and left (P=0.039) regions. Also, DBP during the day was correlated to the medial temporal right region (P=0.025). When analyses were stratified for DBP during the day, subjects with high DBP during the day (greater than 70 mmHg) showed a stronger association between low medial temporal right rCBF and low mean DBP at night (r=0.32, P=0.009) compared with subjects who had a lower daytime DBP. A corresponding positive correlation was noted for the medial temporal left region and daytime SBP, whereas a negative correlation was noted for frontal left region blood flow and SBP at night.

CONCLUSIONS

A significant association was seen between low BP levels, especially at night, and rCBF in subjects with otherwise normal daytime DBP that may indicate a risk for nocturnal cerebral ischemia.

Role of sleep-wake cycle on blood pressure circadian rhythms and hypertension

Stages of different depth characterize the temporal organization of sleep. Each stage exerts an effect on blood pressure (BP) regulation and contributes to its 24-h variation. The main determinant of the circadian influences of sleep and wakefulness on BP is the daytime sympathetic and nighttime parasympathetic prevalence, but many other physiologic mechanisms known either to induce sleep or determine arousal may play an important role in the mediation of sleep influences on BP. Alteration of one or more of such mechanisms may be reflected in altered circadian BP rhythms. Sleep- and arousal-related mechanisms and phenomena that affect circadian BP rhythms include neurohumoral sleep factors (arginine vasopressin, vasoactive intestinal peptide, somatotropin, insulin, steroid hormones and metabolites, and serotonin among others) and waking factors (corticotropin-releasing factor, adrenocorticotropin, thyrotropin-releasing hormone, endogenous opioids, and prostaglandin (E(2))). Pathologic respiratory variations (sleep-disordered breathing) and insomnia are major causes of the sleep-related alteration of the circadian BP profile, including loss of the expected normal decline in BP by 10-20% from the daytime level. A great number of medical disorders can cause insomnia, but objective sleep studies have been performed only in a minority of them. Overall, the sleep-related pathophysiological mechanisms actually involved in causing altered circadian BP rhythms in different normotensive and hypertensive conditions are not completely understood. In any case, changes in the circadian BP rhythm are known to be strongly related to one's risk of cardiovascular morbidity and mortality, thus representing strong prognostic indicators worthy of further investigation.

Circadian Rhythms in the CNS and Peripheral Clock Disorders: Role of the Biological Clock in Cardiovascular Diseases

The cardiovascular diseases are closely related to circadian rhythm, which is under the control of the biological clock. Clock genes show circadian oscillation not only in the suprachiasmatic nucleus but also in peripheral tissues, suggesting the existence of the peripheral clock. We previously demonstrated that plasminogen activator inhibitor-1 (PAI-1) might be an output gene of the peripheral clock. To further elucidate the functional relevance of the peripheral clock in the cardiovascular system, we screened target genes of the peripheral clock by cDNA microarray analysis. A total of 29 genes including transcription factor, growth factors, and membrane receptors were upregulated by CLOCK/BMAL and showed circadian oscillation. These results suggest that cardiovascular systems have their own peripheral clocks, and at least in part, they may regulate the circadian oscillation of cardiovascular function directly. These results potentially provide a molecular basis for the circadian variation of cardiovascular function and novel strategies for the prevention and treatment of cardiovascular diseases.

Utility of ambulatory blood pressure monitoring in children and adolescents

Diagnosis of hypertension is critically dependent on accurate blood pressure measurement. "Accurate" refers to carefully following the guidelines for blood pressure measurement laid out for children and adults to minimize observer and subject errors that commonly occur in clinical blood pressure measurement. Accurate blood pressure measurement is more important in children and adolescents as the misdiagnosis of hypertension may have a life-long adverse impact on insurability and employment. Automated blood pressure measurement offers multiple advantages in achieving high-quality blood pressure determinations by reducing observer errors. The most commonly used form of automated blood pressure measurement is 24-h ambulatory blood pressure measurement (ABPM). Information on ABPM in children has grown exponentially over the last decade. Normative data exists for diagnosis of hypertension in children using ABPM including a novel method for determining normal values with the LMS method. There is further information about the utility of different determinants of 24-h blood pressure such as dipping status, morning surge and blood pressure load. ABPM has been able to detect significant differences in blood pressure in many disease states in children including chronic renal failure, polycystic kidney disease, solitary functioning kidney, and after renal transplantation. Increasingly nonambulatory automated blood pressure determinations have been used in management of hypertension in children. Although nonambulatory automated readings lack information about nocturnal blood pressure or blood pressure during daily activity, studies have suggested that home automated blood pressure measurements are a helpful adjunct to the usual office blood pressure reading.

Applications of 24-hour Noninvasive Ambulatory Blood Pressure Monitoring

Casual blood pressure (CBP) measurements using a standard sphygmomanometer have traditionally constituted the principal modality for the assessment and management of hypertension. However, CBP measurement has shortcomings. Ambulatory blood pressure monitoring (ABPM) provides abundant information on blood pressure (BP), including heart rate, all BP readings for test periods, BP average, BP variability, BP load, load index, distribution pattern of BP, reduction percentage of BP, trough/peak ratio, and summary statistics for overall 24-hour, daytime and nighttime periods. Over the last three decades, ABPM has evolved from a research device to an established and valuable clinical tool for assessment and management of hypertension. This technology has been proven to be useful in terms of the distribution pattern of BP, characterization of BP profiles in normotensive and hypertensive patients, evaluation of patients with mild or labile hypertension, physiologic and psychologic factors for fluctuation of BP, load index study, study of white coat hypertension, etiology of hypertension, prognosis of hypertension, and assessment of antihypertensive management. Nevertheless, the technology remains underused due to lack of insurance reimbursement in most countries. Accordingly, insurance reimbursement is crucial to promote increased utility of ABPM. Clinicians should be familiar with the role of this technology in the care of patients with abnormal BP. This review is an attempt to increase clinicians' understanding of ABPM and the appropriate use of this technology.

Cardiac remodeling in systemic hypertension

Experimental and clinical studies provide evidence that hypertension is causally related to adverse cardiac structural changes, such as LA enlargement, LV hypertrophy and myocardial fibrosis, and functional changes inclusive of LV systolic and diastolic dysfunction. These changes are induced by both hemodynamic and nonhemodynamic factors. There is accumulating evidence from several small and large clinical trials that various classes of antihypertensive therapy prevent and regress LVH and myocardial fibrosis. Prevention and reversal of LVH are associated with an improvement in cardiac function and with a decline in risk of adverse cardiovascular outcomes. Prevention of LVH should be a priority in subjects with hypertension. In patients with hypertensive heart disease, the components of therapy must comprise optimization of BP and regression of LVH. Future targets of therapy in hypertensive heart disease may include regression of myocardial fibrosis, normalization of LA size, and improvement in LV diastolic function.

Profile Analysis of 24‐Hours Measurements of Blood Pressure

A method is proposed for classifying subjects according to their convex, flat, or concave change patterns of 24-hours blood pressure measurements. To obtain such a classification is useful for detecting subjects who show abnormal change patterns and giving them appropriate medical treatments. Therefore, an appropriate statistic is proposed for detecting a systematic change along the time axis, as well as a statistic with its inverse characteristic appropriate for evaluating the noise variation. The method is based on the ratio of those two types of statistics; it is verified to work well on real data, giving a classification of subjects into four types of subgroups: extreme dipper, dipper, nondipper, and inverted dipper. It also suggests that there might be an ultra-extreme dipper subgroup.

Reduced nocturnal fall in blood pressure, assessed by two ambulatory blood pressure monitorings and cardiac alterations in early phases of untreated essential hypertension

To investigate whether in recently diagnosed essential hypertensives a reduced nocturnal fall in blood pressure (BP), established on the basis of two 24-h ambulatory blood pressure monitorings (ABPM) is related to a greater cardiovascular damage. In all, 355 consecutive, recently diagnosed, never-treated essential hypertensives referred for the first time to our outpatient clinic were included in the study. Each patient underwent the following procedures: (1) two 24-h ABPMs performed within 3 weeks, (2) 24-h urinary collection for microalbuminuria, (3) nonmydriatic photography of ocular fundi, (4) echocardiography, (5) carotid ultrasonography. We defined nondipping profile as a night-day systolic and diastolic fall < or =10 % (mean of two ABPMs). A dipper BP profile was found in 238 patients, whereas in 117 patients a nondipper profile was present. The two groups were similar for age, gender, body mass index, smoking habit, clinic BP, 48-h BP and heart rate, while, by definition, night-time systolic and diastolic BP were significantly higher in nondippers than in dippers (130/81 vs 121/74 mmHg, P < 0.0001).The prevalence of left ventricular hypertrophy (LVH) defined by four different criteria: (a) LV mass index (LVMI) > or = 125 g/m(2) in both genders; (b) LVMI > or = 134 gm(2) in men and > or = 110 in women; (c) LVMI> or = 125 g/m(2) in men and > or = 110 g/m(2) in women; (d) LVMI > or = 51 g/m(2.7) in men and > or = 47 g/m(2.7) in women was significantly higher in nondippers than in dippers (a: 12 vs 7%, P < 0.05; b: 16 vs 7%, P < 0.01; c: 20 vs 11%, P < 0.01; d: 35 vs 23% P < 0.02) and this finding was associated with a significant increase in aortic root and left atrium dimensions. There were no differences between the two groups in the prevalence of carotid and retinal changes and microalbuminuria. In conclusion our findings suggest that never-treated hypertensives with a reduced BP fall in the night time, defined on the basis of two ABPMs, have a higher prevalence of TOD than dippers, in terms of echocardiographic LVH. In this population setting, cardiac structural alterations are a more sensitive marker of the impact of the nocturnal BP load on cardiovascular system than other extracardiac signs of TOD.

Hepatocyte growth factor and 24-hour ambulatory blood pressure monitoring

In recent years, many growth factors and cytokines have been shown to be related to arteriosclerosis, and hepatocyte growth factor (HGF) has been reported to be associated with hypertension. In the present study, we investigated the relationship between HGF and hypertension by measuring the serum HGF concentration and performing 24-h ambulatory blood pressure monitoring (ABPM) in 47 randomly selected male and female subjects who underwent a medical examination for cardiovascular disease. The results were as follows. 1) The mean serum HGF concentration in the subjects was 0.35+/-0.14 ng/ml. 2) The serum HGF concentration was positively correlated with both the nighttime systolic and diastolic blood pressures (r=0.42, p<0.05 and r=0.47, p<0.01, respectively). 3) No correlation was found between serum HGF concentration and daytime systolic or diastolic blood pressure. 4) When subjects were divided into two groups based on the difference between daytime and nighttime systolic blood pressure, i.e., a group in which the difference was less than 10 mmHg and a group in which the difference was 10 mmHg or more, the HGF concentration was significantly higher in the former group (0.39+/-0.14 vs. 0.30+/-0.12 ng/ml, p<0.05); similarly, when subjects were divided into a group in which the difference between daytime and nighttime diastolic blood pressure was 5 mmHg and a group in which the difference was 5 mmHg or more, the HGF concentration was significantly higher in the former group (0.42+/-0.15 vs. 0.31+/-0.12 ng/ml, p<0.05). The results indicated that there is a relationship between blood pressure measured by ABPM and serum HGF concentration, and that this relationship might be an index of damage to blood vessels in patients with hypertension.

The influence of work- and home-related stress on the levels and diurnal variation of ambulatory blood pressure and neurohumoral factors in employed women

The purpose of this study was to examine the effects of self-reported perceived stress at work and home on the levels, variation and co-variation of ambulatory blood pressure (BP), pulse rate (PR) and urinary catecholamine, cortisol, and aldosterone excretion measured at work, home and during sleep in women employed outside the home. The subjects of the study were 134 women (mean age 34.4 +/- 9.6 years, range 18 to 64 years) who were employed in managerial, technical or clerical positions at the same work place. Perceived stress at work and home was self-reported on a scale from 0 (low) to 10 (high). BP, PR and the urinary rates of excretion of epinephrine, norepinephrine, cortisol and aldosterone were averaged in the daily work environment from 11 AM to 3 PM, in the daily home environment from approximately 6 PM to 10 PM, and during sleep from approximately 10 PM to 6 AM the following morning. The results showed that systolic and diastolic BP (SBP and DBP) and the rates of urinary catecholamine, cortisol, and aldosterone excretion measured in the work environment were significantly higher than corresponding measurements taken in the home environment. SBP measured at work was also positively correlated with the difference in perceived stress between work and home (p < 0.05). PR (p < 0.001) and the rate of urinary norepinephrine excretion (p < 0.05) measured in the home environment were positively correlated with stress at home. When the subjects were divided into groups based on whether the work or home environment was perceived to be most stressful, women reporting greater stress at work (n=85) had higher work SBP (p < 0.005), work DBP (p < 0.05), and sleep SBP (p < 0.005) than women who perceived the home environment to be more stressful (n=34). There were no differences in the urinary hormonal excretion rates between these perceived-stress groups. Among women with greater perceived stress at home, the home-stress score was positively correlated with sleep SBP level (r = 0.310, p < 0.05), its variation (SD of sleep SBP: r = 0.402, p < 0.01) and home pulse rate ( r= 0.414, p < 0.01). These findings suggest that among employed women, work stress may increase ambulatory BP levels throughout the day, while home stress may induce additional sympathetic activation at home. In addition, they also show that among employed women who perceive greater stress at home than at work, higher home stress levels may also elevate sleep BP levels.

Psychological and physical stress-induced cardiovascular reactivity and diurnal blood pressure variation in women with different work shifts

There is increasing evidence that diurnal blood pressure (BP) variation, in addition to high BP per se, is related to target organ damage and the incidence of cardiovascular events. However, the determinants of diurnal BP variation are not adequately understood. This paper tests the hypothesis that cardiovascular reactivity to acute stress and/or delayed recovery predicts greater diurnal BP variation (i.e., a lower sleep/awake BP ratio). We studied the relationship of diurnal BP variation (assessed by ambulatory BP monitoring) to mental stress (mental arithmetic and anger recall tasks) and physical stress (treadmill)-induced cardiovascular reactivity and recovery in 87 female nurses who worked different shifts. The sleep/awake systolic BP (SBP) ratio was negatively correlated with relative SBP reactivity (maximum SBP increase/baseline SBP: r = -0.21, p = 0.06) and relative stress response (average of SBP during stress/baseline SBP:r = -0.23, p = 0.04) induced by anger recall, while the correlations of the sleep/awake SBP ratio with other parameters of reactivity or recovery in the anger recall or mental arithmetic task were not significant. When subjects were divided into day-shift workers (n=54) and night-shift workers (n = 33), the sleep/awake SBP ratio was negatively correlated with relative SBP reactivity (r = -0.41, p = 0.02) and relative stress response of SBP (r = -0.48, p = 0.006) induced by anger recall, and positively correlated with recovery rate (r = 0.34, p = 0.06) in the latter group, while these correlations were not significant in the former group. The sleep/awake SBP ratio was inversely correlated with the exercise-induced SBP increase in the day-shift workers (r = -0.30, p = 0.03), while this association was not found in the night-shift workers. In conclusion, cardiovascular reactivity triggered by psychological and physical stress in the laboratory may be a weak, but significant, determinant of diurnal BP variation; in addition, work shift (day or night) appears to moderate the relationship between these two pressor mechanisms.

Neurohumoral characteristics of older hypertensive patients with abnormal nocturnal blood pressure dipping

Abnormal patterns of diurnal blood pressure (BP) variation have been reported to be related to advanced target organ damage and poor cardiovascular prognosis. However, the neurohumoral characteristics of patients with such variation have not been fully investigated. We measured BP and plasma levels of neurohumoral factors (norepinephrine [NE], epinephrine, renin, and arginine vasopressin [VP]) during the 70 degree head-up tilt test (10 min supine and 15 min tilting) in 120 older subjects (mean age 71 years) who had sustained hypertension as determined by ambulatory BP monitoring. They who were subclassified according to the nocturnal systolic BP fall as follows: 28 extreme dippers with >20% nocturnal BP fall; 78 dippers with >0% but <20% fall; and 14 nondippers with <0% fall. Plasma renin activity (r = 0.22, P = .02) and VP level (r = 0.36, P < .0001) after tilting were positively associated with the nocturnal systolic BP fall. Plasma NE levels were significantly higher in nondippers than in dippers in both the supine and tilting positions (supine 519 v 315 pg/mL, P = .001; tilting 803 v 550 ng/mL, P < .01), whereas the increase of NE induced by tilting was comparable in the two groups. Plasma renin activity in both the supine and tilting positions was comparable in the three groups, but the increase of this activity caused by tilting was less marked in the nondippers than in the extreme dippers (0.05 v 0.26 ng/mL/min, P = .02) and dippers (0.21 ng/mL/min, P = .07). Plasma VP was markedly increased after tilting in the extreme dippers compared with dippers (3.8 v 2.6 pg/mL, P < .001) and nondippers (v 2.0 pg/mL, P < .001), whereas the levels in the supine position were comparable in the three groups (2.0 pg/mL for extreme dippers, 1.9 pg/mL for dippers, 1.6 pg/mL for nondippers). In conclusion, diurnal BP variation in elderly hypertensive individuals was significantly associated with neurohumoral factors regulating circulating blood volume. Increased VP after tilting in extreme dippers might counteract reduced circulating blood volume, whereas nondippers appear to have alpha- and beta-adrenergic subsensitivity that may be induced by their chronic exposure to high NE levels.

Altered diurnal variation of blood pressure in elderly subjects with decreased activity of daily living and impaired cognitive function

Activity of daily living (ADL) and cognitive are indices of physical and psychological activity in elderly subjects. The present study was performed to clarify the relationship among ADL, cognitive function, and ambulatory blood pressure (ABP) in the elderly. Study subjects were 77 females and 22 males (aged 60 to 101 years) with various levels of ADL and cognition, who were in nursing homes or geriatric hospitals. ABP was recorded every 30 min for 24 h by a noninvasive device. Mini-mental state examination (MMSE) and Barthel index measurement were used to evaluate cognitive function and ADL, respectively. Both the MMSE and Barthel index values showed a significant positive correlation with daytime ABP but not with nighttime ABP. The dip in nighttime BP correlated negatively with age, and positively with MMSE and Barthel index. In the multiple regression analysis, age and Barthel index values remained significant determinants of the dip in nighttime BP. Presence of stroke and MMSE became significant when the Barthel index values were removed from the analyses. When subjects were classified by tertiles of MMSE or Barthel index, subjects in the lowest MMSE group and those in the lowest Barthel index group had both lower daytime ABP and smaller nighttime BP dip than those of the other groups. A low BP level during the daytime was associated with altered diurnal variation of BP in elderly subjects with greater age, impaired cognitive function, and/or decreased ADL. ADL had a greater influence on diurnal BP variation than did cognitive function.

[Nocturnal drop of arterial blood pressure: determinant factors and relationship with organic damage secondary to hypertension]

OBJECTIVES

To evaluate the night-time drop in blood pressure in patients with light hypertension and to determine its possible relationship with damage in key organs.

DESIGN

Cross-sectional study.

SETTING

Eight urban health centres.

PATIENTS

Four hundred and eighteen adults with light-moderate hypertension.

INTERVENTIONS

a) Blood pressure reading on three visits; b) ambulatory monitoring of pressure for 24 hours; c) echocardiograph (in 219 patients); d) albuminuria determination (in 134 patients). A night-time drop in blood pressure was defined as the difference between day and night ambulatory pressures; and relative drop, as the night-time pressure drop as a percentage of the day-time pressure.

RESULTS

Night-time drop in systolic and diastolic pressures was 13.6 (10.7) and 12.1 (8.6) mmHg, respectively. The predictive factors of night-time drop in blood pressure were, directly, daily ambulatory blood pressure (p < 0.05) and female gender (p < 0.05) and, inversely, age (p < 0.05). No association was observed between night-time drop in blood pressure and left ventricular mass. Only in women was an independent relationship found, inversely, between night-time drop in blood pressure and urinary excretion of albumin (p < 0.05).

CONCLUSIONS

Relative night-time drop in blood pressure is greater in women than in men, diminishes with age and depends on the day-time ambulatory pressure. In women a minor night-time drop in blood pressure is associated with greater organic damage.

Prospective analysis of the value of 24-hour ambulatory blood pressure on renal function after kidney transplantation

BACKGROUND

No prospective study has been performed to determine the prognostic value of 24-hr ambulatory blood pressure (24-hr ABP) versus casual blood pressure (CBP) in patients after kidney transplantation. We have addressed this issue by analyzing renal graft function in patients for the first 5 years after transplantation.

METHODS

The 24-hr ABP (SpaceLabs 90207) was monitored 6 and 18 months after transplantation in 46 renal transplant recipients without any acute episodes of rejection. Combined study endpoints were death of patients, need for dialysis, second transplantation, and doubling of serum creatinine.

RESULTS

Six months after transplantation systolic and diastolic 24-hr ABP correlated with serum creatinine (r=0.41, P=0.005 and r=0.37, P<0.01, respectively) although CBP did not. Divided into tertiles according to average 24-hr ABP (lower tertile: < or =91 mmHg; middle tertile: 92-97 mmHg; upper tertile: > or =98 mmHg) serum creatinine significantly differed between the three groups (1.26 +/- 0.38 vs. 1.32 +/- 0.25 vs. 1.65 +/- 0.39 mg/dl, respectively; analysis of variance, P< 0.01). Confounding factors of renal function such as age, body weight, cold and warm ischemic time, cytomegaly virus status, methylprednisone and cyclosporine dosages, cyclosporine concentrations, as well as concomitant antihypertensive medication did not differ among the three groups. In the long-term follow-up (5 years), combined endpoints were reached in 3 of 15 of the lower tertile group, in 3 of 15 of the median tertile group, and in 8 of 16 of the upper tertile group (log-rank test, P<0.01). No relation to long-term out come was found when patients were stratified according to their CBP.

CONCLUSION

In our small but homogenous study cohort 24-hr ABP was more closely related to renal function in patients after transplantation than CBP suggesting that 24-hr ABP is superior for evaluation of hypertension-related renal graft dysfunction.

The relationship between change in blood pressure, blood pressure and time

Physiological homeostatic mechanisms and interventions by anaesthetists attempt to moderate excessive change in many biological variables during anaesthesia. These mechanisms may have fast or slow response times. This study describes how mean arterial blood pressure changes with time and how the change is dependent upon the pre-existing blood pressure. The results demonstrate the 'regression towards the mean' concept; low arterial blood pressures increase and high pressures decrease. The data are the result of all interactions and have been used to produce an 'envelope' into which 80% of all changes fall. Alarm systems using this envelope could warn of excessive changes that occur within short time intervals.

Ambulatory physical activity as a determinant of diurnal blood pressure variation

There are reports that indicate that diurnal blood pressure (BP) variation, in addition to high BP per se, is related to target organ damage and the incidence of cardiovascular events. However, the determinants of diurnal BP variation are not adequately understood. We used actigraphy and ambulatory BP monitoring to study the diurnal variation of BP and physical activity in 160 adults. Within individuals, activity was more strongly related to pulse rate than to BP. The correlation between BP and activity was stronger during sleep than when awake, but the correlation between activity and pulse rate was higher during the awake period than during sleep. Between individuals, the sleep/awake ratio of systolic BP (SBP) was correlated with mean sleep activity (r=.17, P<0.05), mean awake activity (r=-0.16, P<0.05), and, especially, the ratio of sleep/awake activity (r=.24, P<0.01). Awake BP variability (SD of awake SBP) was positively correlated with awake activity (r=.16, P<0. 05). In regard to the effect of position, the standing-supine SBP difference was negatively correlated with the sleep/awake SBP ratio (r=-0.39, P<0.01) and positively correlated with awake SBP variability (r=.33, P<0.01). When we divided the subjects into 3 groups, 19 extreme dippers (with a sleep SBP decrease of >/=20% of awake SBP), 102 dippers (with decreases of >/=10% to <20%), and 39 nondippers (with decreases of <10%), no significant differences existed in awake activity among the groups. However, the nondippers exhibited greater sleep activity than extreme dippers (P<0.05) and an increased sleep/awake activity ratio compared with extreme dippers and dippers (P<0.01). Extreme dipping may also be associated with increased BP variability (P=0.08). Individual SBP responses to activity (the within-person slope of awake SBP regressed on activity) did not differ significantly among the 3 subgroups. In conclusion, physical activity is one of the determinants of ambulatory BP and its diurnal variation. We hypothesize that the association of sleep activity to sleep BP and dipping reflects differences in sleep quality.

Effects of potassium on blood pressure in salt-sensitive and salt-resistant black adolescents

This study examined the effects of increasing dietary potassium on ambulatory blood pressure nondipping status (<10% decrease in blood pressure from awake to asleep) and cardiovascular reactivity in salt-sensitive and salt-resistant black adolescents. A sample of 58 normotensive (blood pressure, 101/57+/-9/4 mm Hg) black adolescents (aged 13 to 16 years) participated in a 5-day low sodium diet (50 mmol/24 h) followed by a 10-day high sodium diet (150 mmol/24 h NaCl supplement) to determine salt-sensitivity status. Participants showed a significant increase in urinary sodium excretion (24+/-19 to 224+/-65 mmol/24 h) and were identified as salt-sensitive if their mean blood pressure increase was >/=5 mm Hg from the low to high sodium diet. Sixteen salt-sensitive and 42 salt-resistant subjects were then randomly assigned to either a 3-week high potassium diet (80 mmol/24 h) or usual diet control group. Urinary potassium excretion significantly increased in the treatment group (35+/-7 to 57+/-21 mmol/24 h). At baseline, a significantly greater percentage of salt-sensitive (44%) compared with salt-resistant (7%) subjects were nondippers on the basis of diastolic blood pressure classifications (P<0.04). After the dietary intervention, all of the salt-sensitive subjects in the high potassium group achieved dipper status as a result of a drop in nocturnal diastolic blood pressure (daytime, 69 versus 67 mm Hg; nighttime, 69 versus 57 mm Hg). No significant group differences in cardiovascular reactivity were observed. These results suggest that a positive relationship between dietary potassium intake and blood pressure modulation can still exist even when daytime blood pressure is unchanged by a high potassium diet.

Clinical significance of nocturnal blood pressure monitoring

Although there are certain technical problems in determining nocturnal BP by ambulatory BP monitoring, the information provided on nocturnal BP has possible clinical significance. Short-term BP variability, an elevated BP during sleep and amplitude and sleep of nocturnal BP decline might be responsible for cardiovascular mortality. Furthermore, circadian BP variation might also be responsible for cardiovascular morbidity and mortality. The nocturnal BP level, even in extreme dippers with diurnal hypertension, is equivalent to or higher than that in normotensive subjects. Antihypertensive effects of drugs with different pharmacologic properties positively correlate with basal ambulatory BP. Therefore, there is a critical BP level at which the antihypertensive effect disappears. The critical BP level for each drug is in normal BP range but not in the hypotensive range. Therefore, an antihypertensive regimen would be safe even in extreme-dipper hypertension without excessive nocturnal hypotension, and might even be beneficial because of the decreasing amplitude and speed of the nocturnal BP decline. We conclude that an antihypertensive drug regimen should control BP throughout a 24-h period regardless of circadian BP variation.