Association between 24-hour ambulatory heart rate and arterial stiffness

Clinical and experimental studies point to a positive association between carotid-femoral pulse wave velocity (PWVcf) and casual heart rate. However, an association with 24-h ambulatory heart rate has never been investigated. Twenty-four hour ambulatory heart rate and PWVcf (automatic computerised technique) were simultaneously measured in 213 subjects with untreated mild-to-moderate essential hypertension. It was found that mean ambulatory heart rate was higher in women than in men but the difference reached statistical significance only in those below 50 years of age during night-time measurements. As well as age and blood pressure, 24-h ambulatory heart rate was also an independent factor influencing PWVcf. Independent of gender, the relationship between PWVcf and ambulatory heart rate was stronger in patients over 50 years of age. Casual heart rate was not a significant determinant of PWVcf in this population. In conclusion, ambulatory heart rate contribution to explain pulse wave velocity is more important than casual heart rate. The relationship between 24-h heart rate and pulse wave velocity is stronger for subjects older than 50 years of age independent of gender.     

The 24-hour heart rate behavior in long-term survivors of cardiac transplantation

A detailed computerized analysis of heart rate (HR) behavior during ambulatory monitoring was performed in 19 long-term survivors of cardiac transplantation (12 orthotopic, 7 heterotopic) and in 10 normal volunteers. Compared with normal hearts, the transplanted denervated and the recipient innervated hearts in the heterotopic group showed higher average HRs over the whole 24 hours, the waking and sleeping periods. The rates of the denervated and the recipient hearts did not differ significantly. The maximal HR was similar in all 3 groups, but the minimal HR was lower in the normal hearts than in denervated and recipient hearts. The 24-hour RR interval variability was greatly reduced in the denervated hearts (60 +/- 22 ms) compared with the recipient (89 +/- 26 ms) and normal (151 +/- 38 ms) hearts. During arousal from sleep, the magnitude, time and rate of the HR change were significantly reduced in the denervated hearts compared with the innervated hearts and in the recipient compared with the normal hearts. These findings demonstrate that denervated hearts can show significant variations in HR during the 24-hour period, but to a lesser extent than normal hearts. The widest deviation from normal occurs during sleep, when the denervated heart shows minimal slowing probably due to lack of parasympathetic innervation. In heterotopic transplant recipients, the patients' own HR responses also are significantly blunted.     

A novel approach to assessment of individual 24-hour heart rate variability

A novel approach to assessment of individual 24-hour heart rate variability (HRV) has been suggested. This approach allows to compare sequences of RR intervals with knowingly nonstationary rhythm and to obtain valuable information on direction (increase or decrease) of HRV changes. The latter was not achievable by existing techniques. Main feature of the novel approach is consideration of dependence of sinus arrhythmia on heart rate on a given time interval (rhythmogram fragment). This became possible due to use of implementation of a new characteristic of 24-hour HRV - mean weighted variation of rhythmogram (MWVR). This parameter repesented a generalization of a previously introduced variation of short rhythmogram fragment (VSRF) and was formed in the following way. Rhythmogram was divided into short fragments and within each fragment VSRF was calculated. Then average variations were averaged for different ranges of HR changes. Each averaged variation was multiplied by weight coefficient which depended on corresponding range of HR changes, and by portion (expressed in percent) of overall number of short rhythmogram fragments belonging to this range. MWVR was determined as sum of resulting multiples. Analysis of rhythmograms from 58 healthy persons showed that MWVR declined with age. In patients with heart failure (n=80) mean MWVR was lower than in healthy persons and decreased with increase of NYHA class of heart failure. Eight patients were restudied while they were classified to a different heart failure class. Transition to a higher class was associated with lowering of MWVR and vice versa. Thus MWVR adequately reflected dynamics of functional state of an individual patient.     

24-hour blood pressure profile in centenarians

OBJECTIVE: Ambulatory blood pressure in the elderly has been studied in the past, the age range most frequently examined being 65 to 80 years. The present study was aimed at determining 24-h blood pressure means and profile in centennial human beings. PATIENTS AND METHODS: Sphygmomanometric blood pressure (average of three values) and 24-h ambulatory blood pressure measurements were performed in 16 centennial subjects (age 101.7 0.4 years, mean SEM) and in 20 healthy normotensives aged 80.7 1.1 years. All subjects were in good clinical and mental conditions for their age. They had no history, signs or symptoms of cardiovascular or non-cardiovascular diseases and were under no drug treatment. RESULTS: In the centennial group sphygmomanometric blood pressure amounted to 131.2 3.0/70.7 2.2 mmHg (systolic/diastolic) and 24-h blood pressure and heart rate average values to 125.6 +/- 3.4/64.8 2.0 mmHg and 77.5 4.3 bpm, respectively. Blood pressure and heart rate showed no difference between daytime and night-time values, i.e. night-time was accompanied by no blood pressure and heart rate fall. In contrast, in all subjects, a significant reduction in blood pressure was observed during the post-prandial period, with no significant heart rate changes. In the octogenarian group, sphygmomanometric and 24-h blood pressure averages were 146.6 4.4/82.8 2.2 and 131.8 2.5/75.3 1.6 mmHg, respectively, with a clearcut reduction in night-time as well as in post-prandial values. CONCLUSIONS: In centenarians 24-h blood pressure values are: (1) lower than sphygmomanometric blood pressures and (2) slightly less than in subjects aged 80 years. At variance with these subjects, however, in centenarians nocturnal hypotension and bradycardia are abolished, presumably because of a derangement in the central sleep influences on the cardiovascular system.     

96例大学生24h心脏节律和窦性心率谱的特征精细分析

目的探讨大学生(集体)24h动态心脏节律及窦性心率谱的特征。方法对刚进入临床课程学习的医学大学生一个大班及部分在读的心血管专业硕士研究生进行24h单导联心电图调查。采用杭州百慧医疗设备有限公司生产的单导心电记录仪记录,记录仪贴附于胸骨柄上端,记录后输入计算机,通过散点图及逆向技术、直方图、事件等程序逐波核实,达到精细分析。结果共96例(大学生84例,研究生12例)完成18.5～24h的监测记录,入选分析,男44例,女52例。记录全程均为窦性心律者18例(18.8%);发生异位心律者78例(81.3%),其中房性早搏者46例,室性早搏者8例,两者兼有者24例;发生二度房室传导阻滞者10例(9例为Ⅰ型、1例兼有Ⅱ型)(10.4%)。房性早搏发生在1～21次者69例,1例发生764次;室性早搏发生在1～13次者28例,37次者1例,71次和601次、3688次者各1例。整体平均心率为(75.3±7.0)次/分;最快为(151.7±12.5)次/分、最慢为(47.7±5.3)次/分。男性平均心率慢于女性,且变化范围大于女性。窦性心率的Lorenz-NN散点图各异,但具有相似性,大体分为二大类:①匀称光滑形;②头大尾小形。减速区散点最大变异性(纵坐标值减横坐标值)大于快速区散点的。男性心率变异大于女性。结论观察的大学生群体异位心律的发生率高(81.3%),但属偶发者和频发(发生次数>0.1%)者少(3.1%),大多数为罕发性(发生次数<0.1%);二度Ⅰ型房室传导阻滞的发生率高(10.4%);平均心率为75次/分,最慢心率为48次/分,最快心率为152次/分。窦性心率的Lorenz-NN散点图各异,但具相似性,减速区散点最大偏移程度大于加速区的。     

Reproducibility of heart rate measured in the clinic and with 24-hour intermittent recorders

This study was undertaken to assess the reproducibility of office versus ambulatory heart rates in 839 hypertensive subjects participating in the Hypertension and Ambulatory Recording Venetia Study (HARVEST). A 24-hour heart rate was recorded twice; this procedure was repeated three months later. Reproducibility was better for ambulatory than for office measurement, and was greater for 24-hour than for daytime heart rate, and lowest for night-time heart rate. Reproducibility of office heart rate was impaired above 85 bpm, and was poorer in subjects with more severe office hypertension. A small but significant decrease in average daytime (−1 bpm, P < 0.0001) and virtually no change in night-time heart rate (−0.3 bpm, NS) were observed at repeat recording. Heart rate reproducibility indices were related to the extent of the heart rate and blood pressure white-coat effect, but did not vary according to age, gender, body mass index, day-night blood pressure difference, or alcohol or tobacco use. Results indicate that heart rate recorded over the 24 hours has a better reproducibility than office heart rate, and could thus be a better prognostic indicator than traditional measurement of resting heart rate in the hospital setting.     

Quantitative analysis of the 24-hour blood pressure and heart rate patterns in young men

To characterize the normal nycterohemeral blood pressure and heart rate profiles and to delineate the relative roles of sleep and circadian rhythmicity, we performed 24-hour ambulatory blood pressure monitoring with simultaneous polygraphic sleep recording in 31 healthy young men investigated in a standardized physical and social environment. Electroencephalographic sleep recordings were performed during 4 consecutive nights. Blood pressure and heart rate were measured every 10 minutes for 24 hours starting in the morning preceding the fourth night of recording. Sleep quality was not significantly altered by ambulatory blood pressure monitoring. A best-fit curve based on the periodogram method was used to quantify changes in blood pressure and heart rate over the 24-hour cycle. The typical blood pressure and heart rate patterns were bimodal with a morning acrophase (around 10:00 AM), a small afternoon nadir (around 3:00 PM), an evening acrophase (around 8:00 PM), and a profound nocturnal nadir (around 3:00 AM). The amplitude of the nycterohemeral variations was largest for heart rate, intermediate for diastolic blood pressure, and smallest for systolic blood pressure (respectively, 19.9%, 14.1%, and 10.9% of the 24-hour mean). Before awakening, a significant increase in blood pressure and heart rate was already present. Recumbency and sleep accounted for 65-75% of the nocturnal decline in blood pressure, but it explained only 50% of the nocturnal decline in heart rate. Thus, the combined effects of postural changes and the wake-sleep transition are the major factors responsible for the 24-hour rhythm in blood pressure. In contrast, the 24-hour rhythm of heart rate may reflect an endogenous circadian rhythm, amplified by the effect of sleep. We conclude that modulatory factors different from those controlling nycterohemeral changes in blood pressure influence the 24-hour variation in heart rate.     

24 h平均心率对老年冠心病患者全因死亡的影响

目的探讨24 h平均心率(AHR)对老年冠心病(CHD)患者全因死亡的影响。方法连续入选2010年6月至2012年6月在北京市海淀医院老年内科住院的老年CHD患者262例。根据出院前24 h动态心电图(holter)检查,以24 h AHR 75次/min为切点分为24 h AHR≥75次/min组71例和24 h AHR75次/min组191例。对入选患者进行随访,2010年12月1日开始,每6个月进行一次,至2016年6月31日结束,以全因死亡为主要研究终点。收集并比较患者出院前24 h的基线资料、化验指标,以及随访期间的死亡原因。采用SPSS 19.0软件对数据进行分析。根据数据类型,组间比较采用t检验、Wilcoxon秩和检验或χ~2检验。组间累计生存率分析采用Kaplan-Meier生存曲线。采用多因素Cox比例风险模型评价随访期间CHD患者全因死亡的各种可能危险因素。结果入选患者中位随访40.7个月,患者资料完整。与24 h AHR75次/min组比较,24 h AHR≥75次/min组患者白细胞计数、低密度脂蛋白胆固醇和尿微量白蛋白显著升高,差异有统计学意义(P0.05)。随访期间患者总死亡率为6.87%(18/262)。与24 h AHR75次/min组比较,24 h AHR≥75次/min组患者全因死亡率[15.49%(11/71)vs 3.66%(7/191),P=0.002]、CHD死亡率[9.86%(7/71)vs 1.57%(3/191),P=0.005]均显著升高,差异有统计学意义。Kaplan-Meier生存分析显示,24 h AHR≥75次/min组患者累计生存率显著低于24 h AHR75次/min组(P=0.001)。多因素Cox比例风险模型分析显示,校正混杂因素后,24 h AHR≥75次/min(HR=4.604,95%CI 1.343～15.784;P=0.015)和吸烟(HR=3.943,95%CI 1.009～15.412;P=0.049)是老年CHD患者全因死亡的独立危险因素。结论 24 h AHR≥75次/min的老年CHD患者全因死亡率明显升高,通过控制24 h AHR和戒烟可能会降低老年CHD患者全因死亡率。     

24-hour electrocardiographic study of heart rate and rhythm patterns in population of healthy children.

Twenty-four hour electrocardiographic recordings were made on 104 randomly selected, healthy 7 to 11-year-old children. Ninety-two were technically adequate and suitable for analysis. The mean highest heart rate measured by direct electrocardiographic analysis over nine beats was 164 +/- 17. The mean lowest heart rates were 49 +/- 6 over three beats', and 56 +/- 6 over nine beats' duration. The maximum duration of heart rates less than 55/minute was 40 minutes. At their lowest heart rates 41 children (45 per cent) had junctional escape rhythms, the maximum duration of which was 25 minutes. Nine children showed PR intervals greater than or equal to 0.20 s and included three with Mobitz type I second degree atrioventricular block. Nineteen (21%) had isolated supraventricular or ventricular premature beats (less than 1/hour). Sixty subjects (65%) had sinus pauses that could not be distinguished on the surface electrocardiogram from those previously described as sinuatrial exit block or sinus arrest. The maximum duration of sinus pause measured over 24 hours on each child was 1.36 +/- 0.23 seconds. Thus apparently healthy children show variations in heart rate and rhythm over 24 hours hitherto considered to be abnormal.     

Effect of ramipril on 24-hour variability of blood pressure and heart rate in essential hypertension

Nonrestricted blood pressure recording was performed invasively or noninvasively, using new portable devices, for a period of 24 hours in 4 patients with essential hypertension before and after 6- to 17-day treatment with ramipril at an initial dosage of 1.25 mg daily. Ramipril produced a steady decrease in blood pressure without changing heart rate. Before initiation of ramipril treatment, the blood pressure was lower during the night than during the day. This day to night difference was not affected by ramipril. In addition, analysis of the standard deviation of the mean for each time point examined during 24 hours revealed no effect of ramipril on circadian variation of blood pressure.     

Exclusion of meal periods from ambulatory 24-hour pH monitoring May improve diagnosis of esophageal acid reflux

Distal esophageal pH less than 4 is frequently seen during meal ingestion in 24-hr ambulatory pH monitoring for the diagnosis of gastroesophageal reflux disease (GERD). The characteristics of this meal-related apparent reflux without diet restriction was evaluated. Data from normal volunteers (N=21) and consecutive patients (N=66) referred with heartburn and/or chest pain were studied with ambulatory pH monitoring. The median percent times pH<4 in the distal esophagus were significantly greater in symptomatic patients than controls for total 24-hr, upright, and supine periods, and postprandial periods of 30, 60, 90, 120, and 150 min (P values of 0.007–0.03). However, the median percent time pH<4 during the meal periods was the same for patients (4.4%) and for controls (6.6%) withP=0.23. Excluding the meal periods from analysis resulted in greater separation between controls and patients with abnormal acid exposure when compared to the conventional method. Patients should maintain their usual routine without diet restriction during 24-hr ambulatory pH studies in the clinical setting. Furthermore, exclusion of meal periods can eliminate meal-time pH variabilities without affecting postprandial acid exposure and improve the diagnosis of GERD.     

自主神经功能对糖尿病患者24小时动态血压和心率的影响

采用２４小时动态心电图和血压同步监测７５例糖尿病患者和３５例正常对照组。结果显示：随ＳＤＮＮ（２４小时内全部正常Ｒ－Ｒ间期的标准差）的降低，糖尿病患者的２４小时平均血压和心率、白昼收缩压和心率，夜间血压和心率均明显递增，昼夜血压差和心率差递减；２４小时血压波动曲线由类似双峰双谷逐渐变为失去正常节律，且夜间血压高于白昼的血压曲线；视网病变和肾病的发生率也随之增高，结论：糖尿病患者高血压的发生、发展和     

Prolonged (48-hour) modest hyperinsulinemia decreases nocturnal heart rate variability and attenuates the nocturnal decrease in blood pressure in lean, normotensive humans

CONTEXT: Heart rate variability (HRV), an index of cardiac vagal activity, is decreased in individuals with metabolic disease. The relationship between decreased HRV and metabolic disease is unclear. OBJECTIVE: The objective of this study was to determine whether experimentally induced glucose intolerance decreases HRV in a circadian relevant manner in healthy individuals. DESIGN: This was a within-subject, randomized design study with subjects infused for 48 h with saline (50 ml/h) or 15% glucose (200 mg/m2.min). HRV was evaluated using time domain measurements taken over the 48-h period. Blood pressure and heart rate were monitored, and blood samples were taken. SETTING: This study was performed at the General Clinical Research Center of the Hospital of the University of Pennsylvania. PATIENTS: Sixteen healthy subjects (eight men and eight women; 18-30 yr old; mean body mass index, 21.7 +/- 1.6 kg/m2) were studied. RESULTS: After glucose infusion, mean plasma glucose was increased by 16.8% (P < 0.0001), and plasma insulin was increased by 99.4% (P < 0.0001) compared with after saline infusion. Significant decreases in homeostasis model assessment indicated a decrease in insulin sensitivity (saline, 0.52 + 0.13; glucose, 0.34 + 0.12; P < 0.0001). The nocturnal root mean square successive difference, an index of cardiac vagal activity, was significantly decreased (P < 0.01), and nocturnal HR (P < 0.001) and blood pressure were significantly elevated (saline, 107.4 +/- 2.7; glucose, 112.5 +/- 3.3 mm Hg; P < 0.05) compared with the saline control. The change in homeostasis model assessment due to glucose infusion was significantly correlated with the change in root mean square successive difference (r = 0.48; P < 0.01). CONCLUSIONS: Prolonged mild hyperinsulinemia disrupts the circadian rhythm of cardiac autonomic activity. Early changes in the neural control of cardiac activity may provide a potential mechanism mediating the pathophysiological link between impaired glucose tolerance and cardiovascular disease.     

Relationship of 24-hour ambulatory blood pressure and heart rate with markers of hepatic function in cirrhotic patients

Background  

There is evidence that in cirrhotic patients, certain hemodynamic parameters, such as blood pressure and heart rate, are related to the severity of liver disease. This study investigated whether non-invasive 24-hour ambulatory blood pressure and heart rate are more closely associated with markers of liver disease severity than conventional office measurements.     

Hormone replacement therapy and 24-hour blood pressure profile of postmenopausal women

Menopause is associated with an increase in blood pressure (BP) and a decrease in physiologic nocturnal BP fall. These factors may play a role in the increased risk of cardiovascular events after menopause. Some studies indicate that transdermal estrogen replacement therapy may help restore the 24-h BP profile, but data on the effect of oral conjugated estrogens are lacking. We compared 24-h ambulatory BP profiles of 42 postmenopausal women not receiving hormone replacement therapy (HRT) and 20 women receiving HRT. HRT was associated with a significant increase in the proportion of dippers (50% in women not receiving HRT and 80% in women receiving HRT, P = .048). Increase in nocturnal dipping may account, in part, for the beneficial cardiovascular effects of HRT.     

The 24-hour profile of adrenocorticotropin and cortisol in major depressive illness

The 24-h profile of plasma ACTH and cortisol levels was determined in 18 men suffering from major depressive illness (8 with unipolar depression and 10 with bipolar depression) as well as in 7 age-matched normal men. Blood was sampled every 15 min. The circadian variation and episodic fluctuations were analyzed for each individual profile. Both unipolar and bipolar depressed patients had higher 24-h mean cortisol levels (P less than 0.01) than normal men, but no significant difference in 24-h mean ACTH level was found. The nadir of cortisol secretion occurred almost 3 h earlier in older normal subjects and patients with unipolar depression, regardless of age, than in younger normal subjects. This shift paralleled a similar advance of the ACTH nadir. Early timing of the quiescent period of ACTH-cortisol secretion was also found in several patients with bipolar depression, but did not reach significance at the group level. The hypercortisolism in the depressed patients was associated with an increase in the magnitude, but not the number, of cortisol secretory episodes. About 90% of the cortisol pulses could be related to a concomitant ACTH pulse in normal subjects as well as in both groups of depressed patients. However, concomitant ACTH and cortisol pulses were less correlated in magnitude in depressed patients than in normal subjects. These results indicate that major depressive illness is associated with disturbances of pituitary-adrenal function. The early timing of the nadir of ACTH-cortisol secretion suggests that disorders of circadian time keeping may characterize major endogenous depression.     

Blood pressure and heart rate responses during 24-hour ambulatory monitoring and exercise in men with diabetes mellitus

The heart rate (HR) variation of 25 normotensive and asymptomatic men, mean age 58 +/- 7 years, with diabetes mellitus (group I) was studied during deep respiration. Thirteen subjects (52%) had a variation of 10 beats/min or less, consistent with an autonomic neuropathy (AN) (group IA); 12 had variation in HR of more than 10 beats/min and were considered to have no neuropathy (group IB). The 24-hour ambulatory HR and systolic blood pressure (BP) values of group I were compared with those of 13 healthy men, mean age 48 +/- 8 years (group II). The mean of 5 maximal HR measurements during the 24-hour period was higher for group IA (106 +/- 11 beats/min) than for group IB (100 +/- 13 beats/min) or for group II (92 +/- 9 beats/min) (p less than 0.01). The mean of 5 maximal BP measurements was greater for group I (149 +/- 28 mm Hg) than for group II (128 +/- 13 mm Hg) (p less than 0.01), but no difference was observed between groups IA and IB. Maximal treadmill exercise was performed with 22 of the patients (11 with and 11 without AN), and no difference in HR was observed between the 2 groups during all stages of exercise or at maximal exertion. The increase in systolic BP and duration of exercise in these 2 groups were also similar. Seventeen of 25 diabetic men had peripheral neuropathy (PN). Of 13 patients with AN, 10 had PN; of 12 without AN, 7 had PN and 5 did not.(ABSTRACT TRUNCATED AT 250 WORDS)