The relationship of electronically monitored physical activity to blood pressure, heart rate, and the circadian blood pressure profile

We studied how closely changes in electronically monitored physical activity are reflected in changes in blood pressure and heart rate in a group of untreated hypertensive subjects. Thirty-nine hypertensive patients (office blood pressure > 140/ 90 mm Hg) of mean age 57 +/- 10 years (mean +/-SD) wore an ambulatory blood pressure monitor and a wrist actigraph simultaneously. Both average and peak activity for 5 min before each valid blood pressure reading were determined, as was average activity for awake and sleep periods, determined by patient kept diaries. For the overall group, awake and 24-h activities were inversely correlated to age (n = 39, r = -0.42; P = 0.01 and n = 39, r = -0.38; P = 0.01, respectively). No correlation was found between group awake activity and group-average blood pressure or heart rate. For individual patients, there was marked variation in the degree of correlation between awake activity measures (both peak and average) and blood pressure and heart rate. The strongest positive correlation was between activity levels and the heart rate-pressure product. Nondipper profile hypertensives had higher sleep activity than dipper hypertensives (44 +/- 28 units/min v 25 +/- 20 units/min, df = 37, t = 2.12; P = 0.04), but awake activity levels were similar. The higher sleep activity remained after adjustment for age. These findings indicate that the relationship between actigraphic activity and hemodynamic parameters is highly variable and that the rate-pressure product is the strongest correlate of short-term activity. Furthermore, hypertensives with the nondipper profile have higher sleep activity than dipper hypertensives. These findings stress the need for further study into the role of day-to-day activity in determining ambulatory blood pressure and heart rate variability.     

Effects of antihypertensive agents on circadian blood pressure and heart rate patterns. Review

Blood pressure and heart rate exhibit a circadian rhythm, with both rising rapidly during the morning hours and then decreasing throughout the day to a nadir around 3 AM. Current evidence suggests a possible link between cardiovascular events, such as myocardial infarction and sudden cardiac death, which have been shown to occur most frequently during the morning hours, and the rapid rise in blood pressure and heart rate during this same time period. We review data from ambulatory blood pressure studies to ascertain which antihypertensive agents provide the most satisfactory control of blood pressure and heart rate during the hours of 6 AM to 12 noon. Of the forms of drug therapy studied, labetalol, a combined alpha- and beta-blocker, and two calcium channel blockers, nifedipine and verapamil, appear to be the most effective in blunting the rise in arterial blood pressure during these critical morning hours.     

Altered circadian blood pressure profile and prognosis

BACKGROUND: In a previous analysis of the Progetto Ipertensione Umbria Monitoraggio Ambulatoriale we found a higher rate of cardiovascular morbid events among hypertensive nondippers than we did among dippers (5.86 versus 1.18 events per 100 person-years, P = 0.0002) for women, whereas the difference between the two groups was smaller and not statistically significant for men (4.15 versus 2.48 events per 100 person-years). These differences held in a multivariate analysis after adjustment for several confounders including average 24 h ambulatory blood pressure. In another analysis, the rate of occurrence of cardiovascular end-points was higher among nondippers than it was among dippers regardless of the definition of day and night (0600-2200 h and 2200-0600 h, awake and asleep, and 1000-2000 h and 2400-0600 h) and of the dividing line between dippers and nondippers (10 versus 0% day-night difference in blood pressure). OBJECTIVE: To test in a subsequent analysis based on a larger sample and a longer follow-up period, for both sexes, the prognostic value of a blunted diurnal rhythm of blood pressure. METHOD: We used the night: day ratio of ambulatory blood pressure, a continuous and normally distributed variable. RESULTS: A night: day systolic blood pressure ratio > 0.899 for men and > 0.909 for women (upper tertiles of distributions) identified a subset of subjects with greater than normal cardiovascular risk for any level of concomitant risk factors, wherease the hight:day diastolic blood pressure ratio was not statistically significant as an independent predictor. The excess risk for subjects in the upper tertile of the night: day systolic blood pressure ratio held after adjustment for several risk markers, including average 24 h ambulatory blood pressure. CONCLUSION: These data suggest that a blunted reduction in blood pressure from day to night predicts an increased cardiovascular morbidity at any level of concomitant risk factors including average 24 h ambulatory blood pressure. Nondippers can be defined in terms of a night: day ambulatory systolic blood pressure ratio > 0.899 for men and > 0.909 for women, regardless of the diastolic blood pressure profile.     

Preserved blood pressure and heart rate circadian rhythm in early stage Alzheimer's disease.

BACKGROUND: This study investigated the blood pressure (BP) values over the day-night period in 11 noninstitutionalized patients affected by probable Alzheimer's disease (AD) in its early stage. The scientific aim was to detect whether the BP circadian rhythm (CR) was preserved, given the fact that CR disruption was observed in advanced or institutionalized AD patients. METHODS: The BP within-day values were gathered via noninvasive ambulatory monitoring. The BP time series were analyzed according to the chronobiological procedure, called Cosinor method with three harmonic components. RESULTS: The biometric analysis was able to document that BP changes over the 24-h scale in AD patients as a function of a significant CR. Such a preserved circadian regulation is, however, compromised in the second and third harmonic component, suggesting that the BP within-day variability is desynchronized by the environmental clues that act as synchronizers during the diurnal part of the day. CONCLUSIONS: The preservation of the BP CR in the early stage of AD suggests using such a finding as a clinical tool for confirming the recent onset of the disease. As a matter of fact, it is presumed that the disease is not evolved enough to reach the suprachiasmatic nuclei, wherein is located the BP circadian pacemaker. The abolition of the ultradian components is another precocious sign that, in turn, indicates early-stage AD patients to be particularly compromised in their synchronization to diurnal cues, such as social routines, meal timing schedule, psycho-physical activity, and occupational schemes.     

Alterations of sleep and circadian blood pressure profile

The organization of sleep activity in stages of different depth is reflected by consistent changes in blood pressure that account for the major part of the day-night blood pressure difference. On the other hand, different mechanisms may underlie dysregulation of nocturnal blood pressure. Cyclic variations in autonomic nervous system activity play an important role in the mediation of the influences of sleep and wakefulness on blood pressure. In addition, several physiologic substances that are knoiwn to induce sleep or arousal are knoiwn to exert actions on blood pressure. Hence, derangements in autonomic nervous system activity, either primitive or secondary to alterations in the circadian rhythm of a variety of neurohumoral factors, are reflected in changes of the circadian blood pressure profile. Important additional influences of sleep on blood pressure may be exerted through respiratory variations, so that sleep-disordered breathing is bound to alter nocturnal blood pressure. Finally, insomnia has to be taken into account as a major cause of sleep-related alteration of the circadian blood pressure profile. The number of medical disorders that can cause insomnia is huge, and includes many if not all of the conditions in which a loss or reversal of the physiologic blood pressure fall at night is found to be prevalent. Unfortunately, objective sleep studies have been performed only in studies of a minority of these disorders, and further studies to assess the pathophysiologic mechanisms actually involved in causing sleep disturbances in each pathologic condition are necessary.     

Altered circadian blood pressure profile and renal damage

Introduction. The relationship between arterial hypertension and renal damage has long been recognized. In 1836, Bright reported an association between cardiac hypertrophy and contraction of the kidney [1] and 40 years later Gull and Sutton [2] suggested that the renal damage in patients with arterial hypertension could be the consequence of vascular hypertensive alterations.     

大医院重症监护科室女护士心率血压及其节律的变化

目的：分析大医院重症监护科室女性护士群体血压夜间值及昼夜节律表现。方法：选择在辽宁省肿瘤医院重症监护室的47例女护士为观察对象（ICU组）,白班对照组为同一医院门诊科室白班女护士51例。两组入选对象均接受了24h动态血压（ABPM）监测。结果：24hABPM数据分析显示：白班对照组比较,ICU组的平均夜间收缩压[nSBP,（103．29±11．94）mmHg比（115．86±12．29）mmHg]、夜间舒张压[nDBP,（72．11±8．96）mmHg比（74．37±8．45）mmHg]和夜间心率[nHR,（67．05±7．16）次／min比（72．69±9．30）次／min]均显著升高（P均〈0．05）,夜间收缩压下降率FSBPF,（7．90±1．72）％比（5．75±1．21）％]、夜间舒张压下降率[nDBPF,（7．15±1.43）％比（5．39±0．84）％]和夜间心率下降率[nHRF,（6．04±1．15）％比（4．88±0．70）％]均显著降低（P均〈0．01）,SBP、DBP和HR非杓型比例显著升高（P〈0．05或〈0．01）。结论：大医院重症监护科室女护士存在明确的心率、夜间血压及昼夜节律的异常表现。     

Inverse relationship between heart rate and blood pressure variabilities in rats

The interplay of heart rate variability, baroreceptor control of heart rate, and blood pressure (BP) variability was examined in chronically instrumented, unanesthetized, freely moving rats in which the efferent neural influences on heart rate were pharmacologically altered. In each rat, BP was recorded continuously for 90 minutes in the control condition and in one or more of the following conditions: 1) beta-adrenergic receptor blockade by propranolol, 1 mg/kg; 2) cholinergic blockade by atropine, 0.75 mg/kg, and 3) combined blockade by propranolol plus atropine. Each BP recording was analyzed beat-to-beat by a computer that calculated heart rate and BP variabilities, both expressed as variation coefficients. In addition, under each condition the sensitivity of the arterial baroreceptor control of heart rate was assessed by measuring the reflex changes in pulse interval in response to BP changes induced by bolus i.v. injections of phenylephrine and nitroprusside. As compared with the control condition, 1) propranolol (n = 10) reduced heart rate variability by 23 +/- 4% (p less than 0.01), only slightly impaired baroreceptor reflex sensitivity, and did not significantly modify BP variability (+11 +/- 7%); 2) atropine (n = 11) reduced heart rate variability by 30 +/- 7% (p less than 0.01), drastically impaired baroreceptor reflex sensitivity, and increased BP variability (+40 +/- 8%, p less than 0.01); 3) combined blockade (n = 10) caused variability and baroreceptor reflex changes similar to those induced by atropine alone. Thus, heart rate variability depends on both vagal and sympathetic influences. However, only the former component affects BP variability, that is, it plays an antioscillatory role.(ABSTRACT TRUNCATED AT 250 WORDS)     

Blood pressure circadian rhythm and heart rate turbulence in hypertensive patients: relationship with left ventricular hypertrophy

Objective To investigate the relationship of blood pressure circadian rhythm with myocardial hypertrophy and the changes of autonomic nerve function in patients with essential hypertension (EH). Methods Eighty-two female patients with essential hypertension (EH) underwent 24-hours ambulatory blood pressure monitorings (ABPM), dynamic electrocardiogram (Holter) and echocardiography examination. Patients were classified into non-dipping group (n=40) and dipping group (n=42) according to the result of ABPM. Left ventricular mass index (LVMI), heart rate variability (HRV) in time domain (including SDNN, SDANN, rMSSD, PNN50) and heart rate turbulence (HRT) parameters (including turbulence onset [TO] and turbulence slope [TS]) were measured. Results Compared with those in dipping group, patients in non-dipping group have higher incidence of LVH (19.0% vs 52.5%, P<0.01), greater mean LVMI (112.39±12.79 g/m2 vs 121.98±13.35 g/m2, P<0.01), decreased PNN50 and rMSSD. TS value was decreased while TO was increased in non-dipping group compared with those in dipping group (both P <0.01); patients with LVH showed decreased TS and increased TO, compared with those without LVH. Conclusion In female patients with EH, non-dipping blood pressure circadian is associated with higher incidence of LVH. The HRV and HRT were more remarkably blunted in non-dipping patients, as well as those with LVH.     

Alcohol and its relationship to blood pressure

Ethanol is a molecule of enduring research interest because its consumption has important social as well as medical implications. With excessive ethanol consumption, there is higher prevalence for hypertension, stroke, cardiomyopathy, and arrhythmias. A principal mechanism by which ethanol exerts these cardiovascular effects is through modulation of blood pressure. In this article, we focus on recent research that pursues information on the effects of alcohol on blood pressure in human subjects, regardless of whether they have hypertension or not. Known means by which alcohol exerts hemodynamic effects are briefly covered, and insights on novel biomediators, such as endothelin and gene-based mechanisms, are presented. Newer tools, such as the Alcohol Use Disorders Identification Test-Consumption Questions (AUDIT-C) survey and carbohydrate-deficient transferrin (CDT) serum test, are also covered. Reducing excessive alcohol intake can produce a reduction in blood pressure of up to 4 mm Hg, on average, which could substantially affect the rates of stroke and ischemic heart disease.     

高血压病患者心率变异的变化及其与室性心律失常的相关性研究

目的 探讨高血压病(EH)者24h心率变异性(HRV)的变化及其与室性心律失常(VA)的关系.方法 采用动态心电图(DCG)记录96例患者(A组)和40例对照者(B组)的24h心电信号,分析其HRV变化及其与VA的发生情况.结果 EH者HRV各项时城指标和额域指标中的LF、VLF、HF均较B组显著降低,并有随着VA程度的加重而降低的趋势;时域指标中的SDNN、SDANN、ASDNN、PNN50与VA程度呈弱负相关(P<0.05);SDANN为EH者VA的保护因素.结论 EH者HRV明显降低,HRV与EH者VA程度呈弱负相关.SDANN为EH者VA的保护因素.早期对自主神经功能紊乱进行干预治疗,可能有利于减少EH者VA的发生.     

高血压患者脉压与血压负荷、心率变异性及心律失常关系的探讨

目的探讨原发性高血压(EH)患者24h平均脉压(PP)与血压负荷、心率变异性(HRV)及心律失常的相关性。方法随机选择EH患者86例,同时行动态血压(ABPM)与动态心电图检查,以PP<60mmHg(A组,n=42),PP≥60mmHg(B组,n=44)分为两组,对其进行分析。结果PP增加主要因收缩压(SBP)增加所致;随PP增加,SBP血压负荷增加,HRV时域法指标均降低,而复杂性、恶性心律失常的发生率也明显增加,两组数据经统计学处理,有明显的统计学意义(P<0.05,P<0.01)。结论EH患者PP与血压负荷、HRV时域法指标及心律失常有关,临床在对其治疗中要注意缩小PP,并将PP作为评价高血压危险度和降压效果的重要指标。     

心悸患者年龄与心率并房性心律失常的关系

目的了解各年龄段心悸患者的平均心率和房性心律失常的发生率。方法将1864例心悸患者按年龄分为青年组(≥18岁,<40岁)334例、中年组(≥40岁,<60岁)780例和老年组(≥60岁,<80岁)750例。所有患者均行远程心电监测,分析其平均心率及房性心律失常的发生情况。结果青年组、中年组和老年组平均心率的均值分别为(77.2±10.2)次/min、(74.3±9.3)次/min和(71.0±10.0)次/min(P<0.001),房性心律失常的发生率分别为23.4%、35.6%和68.3%(P<0.001)。结论随年龄的增加,心率降低,房性心律失常增加。     

高血压患者静息心率与血压昼夜节律的相关性

目的探讨原发性高血压患者的静息心率(RHR)与血压昼夜节律的相关性。方法选择210例汉族中年原发性高血压患者,按RHR水平分为3组,RHR1组:RHR<70bpm(53例),RHR2组:70bpm相似文献   

Effects of interferon on circadian changes in blood pressure and heart rate variability in patients with chronic hepatitis.

We have determined the effects of interferon therapy on circadian changes in blood pressure and heart rate variability in normotensive hospitalized patients with chronic active hepatitis. Body temperature and pulse rate increased for the initial few days of interferon therapy without significant change in casual or ambulatory blood pressure. Interferon therapy failed to elicit any significant changes in the power spectrum of R-R intervals. In addition, urinary excretion of norepinephrine did not differ between before and during the therapy. These results suggest that interferon therapy caused transient increases in body temperature and pulse rate, but that it did not change either sympathetic or parasympathetic outflow, or the circadian rhythm of blood pressure and heart rate variability, in normotensive subjects.     

The relationship between beta-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 beta-adrenergic receptor functioning in normotensive people. In addition, the authors evaluated the influence of beta-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, beta-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 beta-adrenergic receptors. This desensitization may contribute to blunted nocturnal blood pressure and increased heart rate recovery as measured at 2 minutes following exercise testing.     

Differential effects of morning and evening dosing of nisoldipine ER on circadian blood pressure and heart rate

The time of administration of once-daily antihypertensive agents may have a significant impact on blood pressure control during awake and sleep periods. Using 24-h ambulatory monitoring, we compared the effects of morning and evening dosing of the long-acting dihydropyridine calcium channel blocker, nisoldipine extended-release (ER), on circadian blood pressure (BP) and heart rate in patients with mild-to-moderate hypertension. After completing a 3-week placebo run-in period, 85 patients were randomized to morning versus evening nisoldipine ER treatment at a fixed 20-mg dose. Patients were treated for 4 weeks, followed by crossover to the alternate dosing regimen for 4 additional weeks. Twenty-four–hour ambulatory monitoring was performed at baseline and at 4 and 8 weeks after randomization. Awake and sleep times were determined by electronic activity recorders (Actigraphy). Similar least-squares (±SE) mean changes from baseline in 24-h BP (systolic BP/diastolic BP: −11.9/−7.4 ± 0.6/0.5 v −11.6/−6.5 ± 0.6/0.5 mm Hg) and heart rate (1.0/1.7 ± 0.4/0.4 beats/min) occurred with morning and evening administration, respectively. A significantly greater effect on awake diastolic BP (systolic BP/diastolic BP: −12.6/−8.1 ± 0.7/0.4 v −11.3/−6.4 ± 0.7/0.4 mm Hg; P = .16/.01) was observed with morning dosing compared with evening dosing. In addition, small increases in sleep and early morning heart rate were seen with evening compared with morning administration of nisoldipine (sleep, 3.1 ± 0.4 v 0.4 ± 0.4 beats/min; P < .001; early morning, 3.5 ± 0.7 v 0.5 ± 0.7 beats/min; P = .002). These differential effects on awake BP and sleep heart rate were also observed in patients who had normal (dippers) and elevated (nondippers) BP values during sleep. Appropriate evaluation of the efficacy and safety of long-acting antihypertensive agents is essential when evening administration is being considered. In the present study, the timing of nisoldipine ER administration had no effect on mean changes in BP and heart rate over a 24-h period. However, nisoldipine ER had some differential effects during sleep and awake periods with morning relative to evening dosing.     

Intermittent ventricular parasystole with observations on its relationship to extrasystolic bigeminy

1. 1. Two cases of intermittent parasystole are described in which there is alternate extrasystolic and parasystolic impulse formation from the same focus; transitions between the two rhythms are repeatedly observed.

2. 2. It seems that intermittence results when the parasystolic focus is subjected to the enhancing effect of the sinus discharge whereby the automatic beat is prematurely precipitated, thus becoming a forced beat.

3. 3. This phenomenon can be explained on the basis of a property of automatic centers; namely, that their resting potentials exhibit a gradual upward “slope” of depolarization. With critical timing, the terminal part of the “slope” (i.e. its near threshold level) may encounter the enhancing effect of the preceding sinus beat and thus be precipitated prematurely.

4. 4. It is suggested that the form of extrasystolic bigeminal rhythm described may constitute a link between parasystolic and extrasystolic rhythm.