Nocturnal fall of blood pressure and silent cerebrovascular damage in elderly hypertensive patients. Advanced silent cerebrovascular damage in extreme dippers

Chronopharmacology and chronotherapy of cardiovascular medications: relevance to prevention and treatment of coronary heart disease

Biological functions and processes, including cardiovascular ones, exhibit significant circadian (24-hour) and other period rhythms. Ambulatory blood pressure assessment reveals marked circadian rhythms in blood pressure both in normotensive persons and hypertensive patients, whereas Holter monitoring substantiates day-night patterns in electrocardiographic events of patients with ischemic heart disease. The concept of homeostasis, that is, constancy of the milieu interne, which has dominated the teaching, research, and practice of medicine during the 20th century,is now being challenged by emerging concepts from the field of chronobiology-the science of biological rhythms. Epidemiologic studies document the heightened morning-time risk of angina, myocardial infarction, and stroke. Circadian rhythms in coronary tone and reactivity, plasma volume, blood pressure, heart rate, myocardial oxygen demand, blood coagulation, and neuroendocrine function plus day-night patterns in the nature and strength of environmental triggers all contribute to this morning vulnerability. Homeostatically devised pharmacotherapies, that is, medications formulated to ensure a near-constant drug concentration, may not be optimal to adequately control diseases that vary in risk and severity during the 24 hours. Moreover, circadian rhythms in the physiology of the gastrointestinal tract, vital organs, and body tissues may give rise to administration-time differences in the pharmacokinetics and effects of therapies. Thus the same medication consumed in the same dose under identical conditions in the evening and morning may not exhibit comparable pharmacokinetics and dynamics. New technology makes possible chronotherapy, that is, increase of the efficiency and safety of medications by proportioning their concentrations during the 24 hours in synchrony with biological rhythm determinants of disease. The chronotherapy of peptic ulcer disease achieved by the evening dosing of H 2-receptor antagonists and of asthma by the evening dosing of special drug delivery forms of theophylline and morning methylprednisolone administration has proven to be beneficial. Controlled-onset extended-release verapamil constitutes the first chronotherapy of essential hypertension and ischemic heart disease; once-a-day bedtime dosing results in a high drug concentration in the morning and afternoon and a reduced one overnight. Studies demonstrate effective 24-hour control of blood pressure, including the attenuation of its rapid rise in the morning, without induction of nighttime hypotension. Moreover, this formulation effectively controls angina, especially in the morning when the risk of ischemia is greatest. Determination of the role of verapamil chronotherapy in the primary prevention of cardiovascular morbidity and mortality awaits the results of the CONVINCE trial now in progress.

Analysis of circadian blood pressure rhythm and target-organ damage in stroke-prone spontaneously hypertensive rats

OBJECTIVE

We compared diurnal patterns of blood pressure in Wistar-Kyoto (WKY) rats, spontaneously hypertensive rats (SHR) and stroke-prone spontaneously hypertensive rats (SHRSP), and analyzed the relationship between the change in diurnal patterns of blood pressure and target-organ damage in SHRSP.

MATERIALS AND METHODS

Blood pressure, heart rate and motor activity in the three groups of rats were continuously monitored by radiotelemetry, from 1100 h on the first measuring day to 1300 h on the third measuring day. The left ventricular weight and the ratio of beta-myosin heavy chain to alpha-myosin heavy chain in the cardiac left ventricle, morphological changes in the glomerular basement membrane in the kidney, 24 h urinary protein excretion and brain weights were also measured in 10-, 12- or 17-week-old SHRSP.

RESULTS

The SHR circadian blood pressure rhythm exhibited a pattern which peaked during the rats' active (light-off or dark) phase, but the peak time was a little closer to the resting (light-on) phase compared with that for WKY rats. Although the circadian blood pressure rhythm for 10-week-old SHRSP was similar to that observed for SHR, the patterns in 12- and 17-week-old SHRSP were shifted further towards the resting phase. Heart and left ventricular weight increased with the progression of hypertension. The ratio of beta- to alpha-myosin heavy chain in the left ventricle was higher in 12- and 17-week-old SHRSP than in 10-week-old SHRSP. Brain weight was increased significantly in 17-week-old SHRSP compared with 10- and 12-week-old SHRSP. Increased urinary protein excretion and morphological changes in the glomerular basement membrane in the kidney were observed in 12- and 17-week-old SHRSP.

CONCLUSIONS

These data suggest that SHRSP have an abnormal circadian blood pressure rhythm associated with hypertensive target-organ damage. This rat strain may therefore be a useful model in which to investigate the mechanisms responsible for the alteration in the circadian blood pressure rhythm, and to analyze the relationship between the abnormal circadian rhythm and target-organ damage.

Effects of alcohol restriction on 24-hour ambulatory blood pressure in Japanese men with hypertension

PURPOSE

Restriction of alcohol intake is widely recommended in the treatment of hypertension. However, we have observed that alcohol may have biphasic effects on blood pressure in Japanese men with hypertension.

METHODS

Hypertensive men (n = 34) who habitually drank alcohol were randomly assigned to keep their drinking habits constant for 4 weeks, or to abstain (or reduce alcohol intake to a maximum of 15 mL/day) for 4 weeks in a crossover design. Amount of alcohol intake was recorded by each patient throughout the study. Office and 24-hour ambulatory blood pressure were measured at the end of both periods.

RESULTS

After alcohol restriction, mean (+/-SD) ethanol intake decreased from 66+/-26 mL/day to 11+/-10 mL/day. Office systolic blood pressure decreased slightly from 142+/-12 mm Hg to 139+/-11 mm Hg, and diastolic blood pressure decreased significantly from 95+/-7 mm Hg to 93+/-7 mm Hg in the low-alcohol period. Daytime systolic blood pressure fell by 3+/-9 mm Hg (P <0.05), but nighttime systolic blood pressure rose by 4+/-9 mm Hg (P <0.05) with restriction of alcohol intake. Thus, average 24-hour blood pressure did not change, although 24-hour heart rate and day-night difference in blood pressure decreased significantly in the low-alcohol period.

CONCLUSION

In Asian men with hypertension, restriction of alcohol intake reduces daytime blood pressure but not night-time or 24-hour blood pressure.

Plasma levels of natriuretic peptides and adrenomedullin in elderly hypertensive patients: relationships to 24 h blood pressure

OBJECTIVE

The aim of this study was to investigate the relationships between levels of natriuretic peptides and adrenomedullin and 24 h blood pressure levels in elderly hypertensives.

DESIGN AND METHODS

We performed both 24 h ambulatory blood pressure monitoring and measurement of plasma levels of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and adrenomedullin in 118 asymptomatic hypertensive elderly (> 60 years old) patients. We classified the subjects into groups with isolated clinic hypertension (n = 40) and sustained hypertension (n = 78). We also measured the levels of these peptides in 37 elderly normotensive subjects.

RESULTS

Plasma ANP and BNP levels were slightly increased in patients with isolated clinic hypertension compared with elderly normotensives. Among the hypertensives, plasma ANP and BNP levels were more closely related to 24 h blood pressure levels than to office blood pressure levels. Sustained hypertensives showed significantly increased plasma levels of ANP and BNP compared with isolated clinic hypertensives, while adrenomedullin levels were similar in the two groups. Elderly hypertensives with left ventricular hypertrophy detected by electrocardiography had significantly higher levels of ANP and BNP, and higher BNP/ANP ratios than those without left ventricular hypertrophy, while there was no significant difference in adrenomedullin levels between the two groups.

CONCLUSIONS

Our results suggest that measurements of ANP and BNP may be useful in detecting left ventricular hypertrophy and in differentiating isolated clinic hypertension from sustained hypertension in elderly hypertensive patients.

Circadian blood pressure changes and myocardial ischemia in hypertensive patients with coronary artery disease

OBJECTIVES

We sought to evaluate whether different circadian blood pressure (BP) changes could influence the occurrence of ischemic episodes in untreated and treated hypertensive patients with stable coronary artery disease (CAD).

BACKGROUND

In hypertensive patients with CAD the occurrence of myocardial ischemia could be influenced by either high or low BP values. Ambulatory monitoring has shown that circadian BP profile is not uniform in hypertensive patients.

METHODS

Twenty-one patients with a nighttime BP fall < 10% ("nondippers"), 35 with a nighttime BP fall between > 10% and < 20% ("dippers") and 14 with a nighttime BP fall > 20% ("overdippers") with CAD underwent simultaneous ambulatory BP and electrocardiographic monitoring before and during drug therapy with nitrates and atenolol or verapamil in a prospective, randomized, open, blinded end point design.

RESULTS

Daytime BP was not significantly different among the groups both before and during therapy. Nighttime BP was different by definition. Treatment significantly reduced BP values in each group (p < 0.05). Daytime ischemic episodes did not differ among the groups either before or during therapy. Drug therapy significantly reduced daytime ischemia (p < 0.05). In untreated patients, nighttime ischemia was more frequent in nondippers than in dippers and overdippers (p < 0.05). Drug therapy significantly reduced nocturnal ischemia in nondippers (p < 0.05), had no significant effect in dippers and significantly increased nighttime ischemia in overdippers (p < 0.05). During treatment, nighttime ischemia was more frequent in overdippers than in dippers and nondippers (p < 0.05). The same results were achieved when ischemic episodes were defined with more restrictive criteria (ST segment depression > or = 2 mm).

CONCLUSIONS

Circadian BP changes can influence the occurrence of myocardial ischemia in untreated and treated hypertensive patients with CAD. Nocturnal ischemia was found to be more frequent in nondippers among untreated patients and in overdippers among treated patients, potentially suggesting different therapeutic approaches based on circadian BP profile.

Comparison of effects of controlled onset extended release verapamil at bedtime and nifedipine gastrointestinal therapeutic system on arising on early morning blood pressure, heart rate, and the heart rate-blood pressure product

We assessed the differential effects of a chronotherapeutic agent (controlled-onset extended release [COER] verapamil), administered at bedtime versus a conventional, homeostatic therapy (nifedipine gastrointestinal therapeutic system [GITS]) taken in the morning, on early morning and 24-hour blood pressure (BP), heart rate (HR), and the HR x systolic BP product. The study was a multicenter (n = 51), randomized, double-blind prospective clinical trial with a 10-week treatment period. Dose titration was performed by study investigators based on systolic and diastolic BP values at the doctor's office. Ambulatory BP monitoring was performed at placebo baseline, after 4 weeks of stable double-blind therapy, and at end of the study. Twenty-four-hour BP profiles were studied in 557 hypertensive patients. Changes in BP, HR, slope of the rate of rise of BP and HR, and the HR-systolic BP product during the 4 hours from 1 hour before to 3 hours after awakening were evaluated. The study was powered to show equivalence between the 2 regimens, predefined as a difference between treatment groups in mean change from baseline in early morning BP of +/- 5 mm Hg systolic and +/- 3 mm Hg diastolic. Changes in the early morning BP fell within the definition of equivalence for the 2 treatment strategies (-12.0/-8.2 mm Hg for COER-verapamil and -13.9/-7.3 mm Hg for nifedipine GITS). Changes in both the early morning HR and rate-pressure product were significantly greater following COER-verapamil therapy versus nifedipine GITS (HR, -3.8 beats/minute vs +2.6 beats/minute, p < 0.001 and HR-systolic BP product, -1,437 beats/min x mm Hg vs -703 beats/min x mm Hg, respectively, p < 0.001). Changes in ambulatory BP demonstrated clinically similar reductions for the awake period, but nifedipine GITS lowered systolic BP to a greater extent than COER-verapamil during sleep (-11.0 vs -5.8 mm Hg, p < 0.001). COER-verapamil and nifedipine GITS had equivalent effects (+/- 5/3 mm Hg) on early morning BP. In addition, both extended-release calcium antagonists effectively lowered 24-hour BP. However, COER-verapamil had greater effects than nifedipine GITS on early morning hemodynamics (HR, HR-systolic BP product, rate of rise of BP and HR) and lesser effects during sleep due to its intrinsic pharmacologic properties and chronotherapeutic delivery system.

Determinants of circadian blood pressure variation: a community-based study in Ohasama

We investigated factors affecting the nocturnal decline in blood pressure (BP). A cross sectional study was done in 706 community-based untreated subjects > or = 20 years of age. Screening and ambulatory BPs were measured and the effects of age and the ambulatory BP on the nocturnal decline were examined. Bivariate analysis demonstrated that the magnitude of the decline and the percent decline in the nocturnal BP increased with increase in daytime ambulatory BP and decreased with increase in nighttime ambulatory BP. Although the magnitude of the nocturnal decline in BP increased with increasing daytime BP, the nocturnal BP in hypertensives was still higher than those in normotensives. The magnitude decreased with increasing age in men but not in women, while the percent decline decreased with increasing age in both men and women. Since bivariate analysis demonstrated that the daytime BP, nighttime BP, and standard deviation of the 24-hour BP strongly correlated with the magnitude of the nocturnal decline, these parameters were excluded as independent variables from the multivariate analysis. In the multivariate analysis the nighttime pulse pressure was negatively and daytime pulse pressure was positively associated with the magnitude of the decline and the percent decline in the nocturnal BP. A non-dipping circadian variation was frequently observed in elderly normotensive men but the rate of nondipper was rather low in hypertensive individuals in the general population. A marked dipping pattern was frequently observed in hypertensive women > or = 70 years of age. The nocturnal BP levels in subjects with daytime hypertension are higher than those in subjects with daytime normotension. Therefore, BP must ideally be lowered over 24-hour period in hypertensive subjects. The diminished magnitude of the decline and the decrease in the percent decline in the nocturnal BP in the elderly may be mediated by the disturbed baroreflex function due to the decrease in compliance of large elastic artery. However, in some elderly hypertensive women, excess nocturnal decline in BP is observed. In such subjects, we should take care of the nocturnal BP levels during treatment.

Isolated office hypertension and end-organ damage

BACKGROUND

Patients with elevated blood pressure levels in the doctor's office but normal blood pressures at other times have recently been described as having 'isolated office hypertension' (IOH). There is debate concerning whether this condition is really benign and thus not in need of treatment. Most of the previous studies on this topic included patients who had already been administered antihypertensive treatment, which unavoidably alters their cardiovascular profile.

OBJECTIVE

To evaluate whether recently discovered and never-treated patients with isolated office hypertension have structural or functional abnormalities in comparison with normotensive controls.

METHODS

Patients included in the study underwent 24 h ambulatory blood pressure monitoring, M-mode echocardiography and high-resolution echography of carotid arteries. Parameters of lipid and carbohydrate metabolism were also determined.

RESULTS

We investigated 76 patients (20 with IOH and 56 with sustained hypertension) who had recently been diagnosed hypertensive but never been administered antihypertensive treatment and 32 matched controls. No changes were detected in left ventricular mass (LVM h2.7, 41.5 +/- 11, 44.5 +/- 10 and 41.5 +/- 10 g/cm2.7 in IOH, sustained hypertension and controls, respectively) and in intimal-medial thickness (IMT, 0.54 +/- 0.13, 0.59 +/- 0.14 and 0.55 +/- 0.16 mm, respectively). However, the left ventricular diastolic function was significantly different (E/A = 1.08 +/- 0.3, 1.04 +/- 0.3 and 1.43 +/- 0.3, respectively, P = 0.02) and the carotid diameter significantly lower than that expected from the pressure-diameter relationship for normotensives.

CONCLUSIONS

These results, at variance with those of others, suggest that IOH affects the cardiovascular system even during the early phases of the disease and indicate the need for prospective clinical trials to evaluate the benefit from early treatment of IOH patients.

Nocturnal fall in blood pressure in the elderly is related to presence of hypertension and not age

AIMS

To determine whether the reduced nocturnal fall in blood pressure (BP) reported in elderly hypertensives is due to ageing or to the presence of hypertension.

METHODS

Twenty-four hour ambulatory BP recordings of 68 normotensive elderly were compared with those of 55 elderly treated hypertensives, aged 63-88 years. Mean night-time BPs were calculated from the average of readings during sleep and mean daytime BPs from the remaining recordings. The maximum day-night BP differences were calculated. Plasma renin, aldosterone and noradrenaline were measured.

RESULTS

Normotensive subjects were aged 72.0 +/- 4.7 years and treated hypertensives 73.7 +/- 4.9 years (p = 0.049). Normotensives had lower systolic BP (SBP) than hypertensives (125 +/- 12 mmHg versus 135 +/- 14 mmHg, p < 0.01). The fall in SPB at night was greater in normotensives than in hypertensives (18 +/- 9 versus 14 +/- 9 mmHg, p < 0.02). Non-dipping occurred in 24% of all subjects, with 59% of these being hypertensives. The nocturnal fall in SBP was not related to age (beta = -0.04, p < 0.62) but was inversely related to a history of hypertension (chi (2) = 5.82, p = 0.02). Serum noradrenaline was significantly related to nocturnal SBP fall (beta = 0.28, p = 0.01).

CONCLUSIONS

Elderly normotensives have a greater decline in nocturnal SBP than treated elderly hypertensives. The failure of SBP to fall at night appears to be more a feature of hypertension than of ageing. Early morning noradrenaline estimations are higher in patients with a greater nocturnal blood pressure fall.

Effects of controlled-onset extended-release verapamil on nocturnal blood pressure (dippers versus nondippers). COER-Verapamil Study Group

Approximately 1 in 4 patients with systemic hypertension have a 24-hour blood pressure (BP) profile characterized by a blunted or absent nocturnal decline in pressure. We evaluated the effects of a chronotherapeutic delivery system of controlled-onset extended-release (COER) verapamil hydrochloride and placebo in 257 hypertensive patients according to their circadian BP pattern in an 8-week prospective, multicenter, randomized, and double-blind clinical trial. Patients were stratified into 193 dippers (>10% decline in BP during the period of 10 P.M. to 5 A.M. compared with the hours of 5 A.M. to 10 P.M.) and 64 nondippers (<10% decline in BP during nighttime). During daytime, placebo-subtracted BP was similarly decreased in dippers and nondippers by COER verapamil. During nighttime, the placebo increased nocturnal BP in dippers (baseline nocturnal BP, 133/78 mm Hg) by 3/3 +/- 2/2 mm Hg and reduced BP by -5/-3 +/- 2/2 mm Hg in nondippers (baseline nocturnal BP, 152/94 mm Hg) (p = NS between groups). After controlling for age, gender, ethnicity, and the regression to the mean observed on placebo for all doses, COER verapamil reduced nocturnal BP more in nondippers than dippers -5.8/-2.4 mm Hg, p <0.0001 for systolic BP and p = 0.09 for diastolic BP). Additionally, a significant dose-related reduction in systolic and diastolic nocturnal BP (r = 0.56, p <0.0001 for systolic BP and r = 0.62, p <0.0001 for diastolic BP) was observed with COER verapamil after controlling for baseline covariates. These data demonstrate that nocturnal BP is decreased by a greater extent in nondipper hypertensives than in dipper hypertensives following treatment with COER verapamil HCL.

Factors affecting the nocturnal decrease in blood pressure: a community-based study in Ohasama

OBJECTIVE

To investigate factors affecting the nocturnal decrease in blood pressure.

DESIGN

A cross-sectional study of 823 community-based untreated subjects aged > 20 years. Screening and ambulatory blood pressures were measured and the effects of age and the ambulatory blood pressure on the nocturnal decrease were examined.

RESULTS

The magnitude of the decrease and the percentage decrease in the nocturnal blood pressure increased with increasing daytime ambulatory blood pressure and decreased with increasing night-time ambulatory blood pressure. Although the magnitude of the nocturnal decrease in blood pressure increased with increasing daytime blood pressure, the nocturnal blood pressure levels in hypertensives were still higher than those in normotensive subjects. The magnitude decreased with increasing age for men but not for women, whereas the percentage decrease decreased with increasing age both for men and for women. The SD of the 24 h blood pressure correlated strongly to the magnitude of the nocturnal decrease (systolic blood pressure r = 0.62, P < 0.0001; diastolic blood pressure r = 0.52, P < 0.0001), suggesting that the SD of the 24 h blood pressure is representative of the nocturnal decrease. A minimal nocturnal decrease was observed frequently in elderly normotensive men but infrequently in hypertensive individuals from the general population. A marked nocturnal decrease was observed frequently in hypertensive women aged > 70 years.

CONCLUSION

Although the magnitude of the nocturnal decrease in blood pressure increased with increasing daytime blood pressure, the nocturnal blood pressure levels increased with increasing daytime ambulatory blood pressure. Therefore, the blood pressure in hypertensive subjects should essentially be lowered throughout the 24 h period. A marked nocturnal decrease in blood pressure in some elderly hypertensive women was observed without treatment. The nocturnal blood pressure levels of such subjects should be considered during treatment.