Circadian variation of haemodynamics in patients with essential hypertension

Kawano, Yuhei; Tochikubo, Osamu; Minamisawa, Kohsuke; Miyajima, Eiji; Ishii, Masao

doi:10.1097/00004872-199412000-00014

Cited by 45 publications

(29 citation statements)

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“…However, in rats, a trend has been identified in which BP rises during periods of darkness and falls during periods of exposure to light. This is thought to be due to the nature that humans are diurnal, sleeping during the night and active throughout the day, whereas rats are nocturnal, active during periods of darkness and sleeping during periods of exposure to light [1,7,9,12,[15][16][17]. It has been recognized in humans that shift-workers who work at night show the high BP values at night [1,23].…”

Section: Discussionmentioning

confidence: 99%

“…In order to solve these problems, it is necessary to measure the BP under awake, unbound and no stress conditions. The stress is usually caused by drugs used at the time of measurement, artificial and environmental factors, and the BP measurement per se.Although it is already known that there exists a circadian BP variation in both rats and humans [1,7,12,[15][16][17], no detailed reports regarding dogs have been published. For this reason, we examined these diurnal variations by measuring the BP across a long period of time in normal awake dogs who were unbound, using the telemetry system which makes 24 hr continual observation possible without stress.…”

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Diurnal Variations of Blood Pressure in Dogs

Mishina

Watanabe

Matsuoka

et al. 1999

The Journal of Veterinary Medical Science

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ABSTRACT. Using the telemetry system, we measured the blood pressure (BP) invasively in seven adult mongrels while unanesthetized and unbound. Post-operative BP after implanting the telemetry BP transmitter showed temporarily high values due to the invasive nature of the surgery. It was, however, observed that BP gradually decreased thereafter, and showed settled trends from the eighth day postoperatively. When we took the average of the systolic, mean and diastolic BP at hourly intervals for each of the dogs once their BP had settled, a twin peak diurnal variation (at 8:00 and 19:00) was observed. Moreover, significantly high values (p<0.05) were identified in active state compared with when sleeping or at rest. The 24 hr BP measured by the telemetry system in seven normal dogs resulted in the following values: systolic 123.4 ± 7.9 mmHg, mean 91.1 ± 5.6 mmHg, and diastolic 74.5 ± 4.9 mmHg.-KEY WORDS: blood pressure, canine, diurnal variation.J. Vet. Med. Sci. 61(6): 643-647, 1999 were exposed under anesthesia, and BP measuring transmitter (model TL10M2-D70) catheter was indwelled. The transmitter body was implanted into a subcutaneous pocket that had created first. After examining the BP by use of transmitter, the digital signal was received by a receiver (RLA2000), and was sent in turn to a consolidation matrix (BCM-100), and a universal adapter (UA10). Finally, the digital signal was converted to an analogue signal by the universal adapter, and output to an analytical computer system (Softron ECG Processor SBP4.8:Softron Co., Tokyo, Japan) (Fig. 1). Further, the systolic, mean and diastolic BP were calculated from the continuous BP readings input for approximately 10 sec at a time at 5 min intervals, and the average were taken to be the systolic, mean and diastolic values for each hour. These measurements were taken continuously for 24 hr, and the following examinations were conducted. Examination of the BP changes after implanting transmitter:We examined the effect of the invasive surgery on BP after the transmitter had been implanted for 14 days post-operatively. For the BP examination, we used the total and average values (24 hr BP) taken every 24 hr using the systolic, mean and diastolic pressure measured at 5 min intervals.Examination into the diurnal BP variations: We examined the diurnal BP variations in normal dogs for a period of seven days after at least one month had passed since the transmitter were implanted. First of all, the systolic, mean and diastolic BP were measured at 5 min intervals and totaled in hourly blocks and examined using their average values. In order to observe the relationship between BP and activity, a comparison was made among the sleeping period (1:00-6:00), the resting period (12:00-17:00), awaking but comparatively settled period, and the periods of intense activity (7:00-9:00 and 18:00-20:00). In addition, comparisons were also made with both the 24 hr BP and For measuring blood pressure (BP) in awake dogs, there are either invasive method by arterial puncture or nonin...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Diurnal Variations of Blood Pressure in Dogs

Mishina

Watanabe

Matsuoka

et al. 1999

The Journal of Veterinary Medical Science

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“…However, little research has been devoted to changes in hemodynamics in the morning. In a previous study we observed that peripheral vascular resistance was greater in the morning than in the evening in patients with essential hypertension (24). Although other researchers have also reported higher forearm vascular resistance (25) and increased coronary artery tone due to sympathetic nervous activity in the morning (19), none have analyzed hemodynamics continuously over a 24-h period in hypertensive patients.…”

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Circadian Variation of Hemodynamics and Baroreflex Functions in Patients with Essential Hypertension.

et al. 1997

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It is well known that cardiovascular accidents such as myocardial infarction frequently occur in the morning, but their triggering mechanisms are not clear. The present study investigated circadian variations of hemodynamics and baroreflex functions. Twenty-three patients with essential hypertension were studied. Direct blood pressure (BP) and ECG were recorded by telemeter over 24 h, and then computeranalyzed. The pulse-contour method was used to measure cardiac output (CO) and total peripheral vascular resistance (TPR). The ratio of low to high frequency components (LF/HF) of the RR-interval on ECG was calculated by power spectral analysis. The baroreflex sensitivity index (BR!) was measured on the basis of the ratio d RR/LI Ps (zl Ps= spontaneous decrease in systolic BP, zl RR = change in RR). Furthermore, 24-h BP changes were transformed algebraically into positive load component (PC) and negative load component (NC) by using a Windkessel model. The circadian variation of hematocrit (Ht) was also measured. The least squares method was used to determine the time at which the maximum and minimum value of each measurement occurred. Whereas the maximum values for BP and CO occurred in the evening (18:30, 17:00), the maximum values for TPR and LF/HF occurred between 06:30 and 08:00, and the minimum value for BRI occurred at 08:00. PC significantly correlated with Ps, heart rate, and CO (r=0.81, 0.92, 0.67), and NC significantly correlated with BRI and LFIHF (r=0.71, 0.64). PC (related to cardiovascular function) reached a maximum and NC (related to baroreflex function) reached a minimum in the late morning (11:00). Ht was highest immediately after the subjects got out of bed. These hemodynamic imbalances may negatively influence coronary blood flow in the morning. (Hypertens Res 1997; 20: 157-166)

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“…For this reason, BP is often taken both at the hospital (casual BP) and home (home BP) for reliable evaluation. In addition, ambulatory blood pressure monitoring (ABPM) has been clinically tested for over 10 years and proven for its effectiveness [1,10,11,18,23]. Given these situations, we aimed to establish the standard BP range and variations in unanesthetized and unrestrained cats by using the telemetry ]* ]* * * system, an invasive but direct BP measurement method.…”

Section: Discussionmentioning

confidence: 99%

Diurnal Variations of Blood Pressure in Cats

Mishina

Watanabe

2006

The Journal of Veterinary Medical Science

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ABSTRACT. Blood pressure (BP) was analyzed invasively using the telemetry system in unanesthetized, unrestrained healthy adult mongrel cats. After surgical implantation of a telemetry transmitter, BP was transiently elevated due to the invasive nature of the surgery, but it was gradually decreased. BP was largely stabilized seven to ten days postsurgery. Once BP was settled, systolic, diastolic and mean BPs 2 were obtained at 5-min intervals in individual cats. Hourly averages of these BP values revealed a diurnal variation with two peaks at 8:00 and 19:00. We also found that BP was significantly higher when cats were active compared to when they were sleeping or at rest (p<0.05). The average 24-hr BP in 20 healthy cats was 118.4 ± 11.0 (systolic), 78.0 ± 8.7 (diastolic) and 94.8 ± 9.5 mmHg (mean) by the telemetry system. KEY WORDS: blood pressure, feline, diurnal variation.J. Vet. Med. Sci. 68(3): 243-248, 2006 Currently blood pressure (BP) is commonly measured in cats by noninvasive methods such as oscillometry and Doppler ultrasonography in the clinical setting [3,12,13,15]. Accurate and stable BP measurements, however, have been difficult with these indirect techniques, because cuff placement and restraint can be very stressful to animals and may interfere with BP readouts. The results may also be variable among methods and operators. In addition, because BP is constantly affected by various factors, it is difficult to reliably evaluate BP of an animal based on a single measurement. To solve these problems, it is necessary to understand the diurnal pressure pattern in cats.Circadian rhythmic or diurnal variations of BP have been known in humans and mice [1,22,23]. We have previously shown that dogs also have diurnal BP variations using a telemetry system that continuously monitors BP for 24 hr without anesthetizing or restraining the animals [16]. On the other hand, only a handful of studies have documented circadian BP patterns in healthy, unrestrained cats. Brown et al. have reported changes in diurnal BP patterns in six healthy cats after administration of certain vasoactive agents [7]. The study by Sei et al. has focused on BP changes during paradoxical sleep and slow-wave sleep in cats [19]. In this study, we monitored BP in 20 healthy cats continuously for a long term by using the stress-free telemetry system. Obtained data were analyzed for diurnal and nocturnal circadian rhythmic patterns and for influences by daily activities. We also addressed whether the 24-hr BP obtained in this study represented the baseline BP in healthy cats. MATERIALS AND METHODS Animals:Twenty adult mixed-breed cats (four males and 16 females) weighing 2.0 to 4.0 kg were used. No abnormalities were found in these animals by general physical examination and blood, serology and urinary tests. They were individually housed in cages for several months prior to the study (for acclimatization) and during the study period under a 12L/12D cycle (light on at 8:00 and off at 20:00). They were given water ad libitum and fed twice da...

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Circadian variation of haemodynamics in patients with essential hypertension

Cited by 45 publications

References 0 publications

Diurnal Variations of Blood Pressure in Dogs

Diurnal Variations of Blood Pressure in Dogs

Circadian Variation of Hemodynamics and Baroreflex Functions in Patients with Essential Hypertension.

Diurnal Variations of Blood Pressure in Cats

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