Systemic hemodynamics during sleep in young or middle-aged and elderly patients with essential hypertension

Association of home blood pressure with sleep and physical and mental activity, assessed via a wristwatch-type pulsimeter with accelerometer in adults

This study aimed to examine the associations between home blood pressure (HBP) and sleep and activity assessed using data obtained via a wristwatch-type pulsimeter with accelerometer (Pulsense®) using original software. We recruited 28 elderlies and 40 employees aged 24-81 years who were not on hypotensive agents and sleeping drugs. Sleep, activity, and HBP were measured consecutively over a 5-7-day period. Body mass index (BMI), base heart rate (HR₀), and age showed significant correlation with HBP in a simple and multiple linear regression analysis. HR₀ was positively, and log deep sleep duration, negatively correlated with HBP in the adjusted multiple linear regression analysis. Physical and mental activities were negatively correlated with systolic blood pressure (SBP) in a simple linear regression, but high physical and mental activities tend to reduce deep sleep duration. Self-recorded sleep duration had no relationship with HBP. In conclusion, HR₀, BMI, age, deep sleep duration, and activity showed relationships with HBP. Using this type of wristwatch and observing daily sleep and activity data with HBP measurement may have important clinical implication.

Non-dipping nocturnal blood pressure in psoriasis vulgaris

BACKGROUND

Psoriasis vulgaris is one of the most prevalent chronic, inflammatory skin disorders. Patients with psoriasis carry an excess risk of hypertension and adverse cardiovascular (CV) events. Blood pressure (BP) has a circadian rhythm characterised with lower values at night. A blunted nocturnal BP decline defined as non-dipping accelerates the development of hypertension and CV diseases. The aim of this study is to evaluate circadian variation of blood pressure in normotensive middle-aged patients with psoriasis vulgaris.

METHODS

Seventy adult patients with psoriasis vulgaris (group 1) and 70 age and sex-matched healthy individuals (group 2) were included in the study. Ambulatory BP monitoring was performed in all participants over a 24-h period. Non-dippers are defined as those who show a reduction in BP of less than 10 % between the average day and night systolic BP.

RESULTS

Although mean 24-h BPs were similar in both groups, night-time BPs were significantly higher in psoriatic patients (115.1 ± 7.7 vs. 109.9 ± 6.0 mmHg and 72.1 ± 7.0 vs. 67.6 ± 5.5 mmHg, respectively; p < 0.05). The non-dipping pattern of BP changes was significantly more common in patients with psoriasis vulgaris compared with the control group (65.9 vs. 34.1 %, p < 0.01). Psoriasis severity and BMI are independent predictors of impaired nocturnal BP regulation.

CONCLUSIONS

Patients with psoriasis vulgaris had increased nocturnal BP and heart rate. This is the first study to demonstrate a blunted nocturnal BP decrease in normotensive patients with psoriasis.

Relation Between 24-h Heart Rate Variability and Blood Pressure Fluctuation During Exercise in Stroke Patients

BACKGROUND

In some stroke patients blood pressure (BP) fluctuates extensively during medical rehabilitation, so the present study investigated the influence of autonomic nervous dysfunction on the change in BP during exercise.

METHODS AND RESULTS

The subjects consisted of 55 stroke inpatients (males, 29; mean age, 58.8 years old; ischemic/hemorrhagic etiology, 30/25) who were admitted to the Stroke Center within 2 weeks of their first stroke. The control group consisted of 15 age-matched healthy volunteers. The 24-h heart rate (HR) variability (HRV) and BP variability (BPV) were examined, and then the increase and recovery of BP and HR were measured during bicycle ergometer exercise at 4 METs. Components of 24-h HRV (low-frequency power (LF), high-frequency power (HF), LF/HF, and asleep-awake ratio of LF/HF (LF/HF(d-n)) were lower (p < 0.01) and BPV was greater in the stroke group (p < 0.05) than in the control group. There was a negative correlation between BP change during exercise and LF/HF or LF/HF(d-n) (r = -0.43 or r = -0.58, p < 0.01), and a greater increase in systolic BP (102 +/-9.8 mmHg, n = 7) during exercise was observed in stroke patients with lower LF/HF(d-n) (< or = 1.0).

CONCLUSIONS

Lower HRV in stroke patients may relate to an increase in BP during exercise. HRV is useful for estimating the risk during medical rehabilitation.

Base heart rate during sleep in hypertensive and normotensive subjects

OBJECTIVE

Many studies have reported that the resting heart rate (HR) is intimately related to the prognosis of cardiovascular disease. However, HR in the waking state is influenced by psychological and physical activity and has low reproducibility. To measure the base HR (minimum and stable HR during sleep) with ease, we developed a wristwatch-type HR recorder. We then investigated the pathophysiological significance of the base HR.

SUBJECTS AND METHODS

The subjects were 158 patients (82 men and 76 women) with essential hypertension (HT) on no medication and 204 normotensive (NT) subjects (105 men and 99 women, matched for age). On the basis of pulse waves from the wristwatch-type photoelectric plethysmograph, using a blue sensor with a wavelength of 450 nm, HR was recorded easily minute by minute during sleep time. In addition, 40 (23 men and 17 women) of the HT patients were hospitalized. Their cardiac index (CI) and stroke volume index (SVI) were measured by means of the cuvette method during waking time and night-time deep sleep when their HR had reached a minimum level.

RESULTS

Mean base HR (HRo) in NT subjects was 49+/-4 beats per minute (bpm) and tended to rise with increasing age (r = 0.51, P < 0.01). In HT patients, HR0 was significantly higher: 60+/-7 bpm (P < 0.01). CI of HT patients, measured during night-time deep sleep, maintained a stable value of 2.45+/-0.36 l/min per m2. SVI in patients whose HR0 was above 60 was significantly lower than that in patients whose HR0 was below 60 (37+/-4.5: 45+/-4.8 ml/m2, P < 0.01). Corresponding differences in mean HR and SVI during waking or night-time, became smaller.

CONCLUSIONS

These findings suggest that there is a close relation between base HR and cardiac function caused by such conditions as age and hypertension. This relation became indistinct during waking time. Moreover, the wristwatch-type HR recorder appears to be a useful tool for measuring base HR.

Diurnal variation of hemodynamic indices in non-dipper hypertensive patients

The purpose of this study was to elucidate the underlying mechanisms of blunted nocturnal blood pressure reduction in non-dipper hypertensive patients. We studied the diurnal variations in systemic hemodynamic indices and baroreflex sensitivity. In 45 subjects with essential hypertension (24 men; mean age, 49+/-1 years), intra-arterial pressure was monitored telemetrically. Non-dippers were defined as those with a nocturnal reduction of systolic blood pressure of less than 10% of daytime systolic blood pressure. Stroke volume was determined using Wesseling's pulse contour method, calibrated with indocyanine green dilution. Baroreflex sensitivity was calculated as deltapulse interval/deltasystolic blood pressure on spontaneous variations. The mean values of the hemodynamic parameters were calculated every 30 min. Twenty-six subjects were classified as non-dippers. Daytime blood pressure was not significantly different between dippers (149+/-4/87+/-3 mmHg) and non-dippers (147+/-3/82+/-2 mmHg), while the nighttime blood pressure was significantly reduced in dippers (131+/-3/77+/-2 mmHg) but not in non-dippers (145+/-3/80+/-2 mmHg). Nocturnal decreases in both cardiac index and stroke index were smaller in non-dippers (-12.0+/-1.2% and 1.5+/-1.0%) than in dippers (-17.5+/-1.4% and -2.2+/-1.1%). Baroreflex sensitivity significantly increased at nighttime both in dippers (6.5+/-0.6 to 8.0+/-0.7 ms/mmHg) and in non-dippers (5.1+/-0.3 to 6.4+/-0.4 ms/mmHg). Neither daytime nor nighttime baroreflex sensitivity was significantly different between the groups. We conclude that the hemodynamics of non-dipper essential hypertension are characterized by an inadequate nocturnal decrease in cardiac index and stroke index, suggestive of relative volume expansion or malsuppressed sympathetic activity.

The 24-hour rhythm of blood pressure differs from that of leg hemodynamics in orthotopic heart transplant recipients

BACKGROUND

This study was aimed at investigating whether a circadian rhythm of peripheral resistance exists in patients with orthotopic cardiac transplantation (OCT) and whether it parallels that of blood pressure (BP).

METHODS

BP and leg flow and resistance (plethysmography) were monitored for 24 hours in 13 denervated OCT recipients and 13 control patients with native heart, matched for casual blood pressure.

RESULTS

On the basis of BP trend, control patients showed a BP reduction during sleep, whereas OCT recipients did not. Leg resistance was significantly lower and leg flow significantly higher during sleep than during waking in all patients, and the extent of the nocturnal decrease was similar in the two categories.

CONCLUSIONS

The decrease in leg resistance in patients confined to bed for 24 hours is caused by peripheral mechanisms and does not depend on the autonomic control of the heart. The nocturnal decline in BP depends, on the contrary, on cardiac control and is lost in patients with denervated heart.

Cardiovascular morbidity in obstructive sleep apnea

The repetitive respiratory events that characterize obstructive sleep apnea (OSA) are each followed by abrupt increases in heart rate and in pulmonary and systemic artery pressure and by sudden decreases in right and left ventricular stroke volume. The changes in systemic pressure may be profound, with patients who are normotensive while awake having systolic pressures approaching 300 mm Hg after apnea termination. Because of these dramatic hemodynamic oscillations during sleep, many clinicians and investigators have postulated a connection between sleep-disordered breathing and cardiovascular morbidity and even mortality. This review critically examines the evidence for such a causal relationship. We begin, however, by reviewing the normal hemodynamic changes that occur during sleep. We then describe the acute hemodynamic events associated with OSA. Finally, we summarize the evidence for and against a causal connection between sleep apnea and cardiovascular morbidity.

Patterned cardiovascular responses to sleep and nonrespiratory arousals in a porcine model

Patients with obstructive sleep apnea experience marked cardiovascular changes with apnea termination. Based on this observation, we hypothesized that sudden sleep disruption is accompanied by a specific, patterned hemodynamic response, similar to the cardiovascular defense reaction. To test this hypothesis, we recorded mean arterial blood pressure, heart rate, iliac blood flow and vascular resistance, and renal blood flow and vascular resistance in five pigs instrumented with chronic sleep electrodes. Cardiovascular parameters were recorded during quiet wakefulness, during non-rapid-eye-movement and rapid-eye-movement sleep, and during spontaneous and induced arousals. Iliac vasodilation (iliac vascular resistance decreased by -29.6 +/- 4.1% of baseline) associated with renal vasoconstriction (renal vascular resistance increased by 10.3 +/- 4.0%), tachycardia (heart rate increase: +23.8 +/- 3.1%), and minimal changes in mean arterial blood pressure were the most common pattern of arousal response, but other hemodynamic patterns were observed. Similar findings were obtained in rapid-eye-movement sleep and for acoustic and tactile arousals. In conclusion, spontaneous and induced arousals from sleep may be associated with simultaneous visceral vasoconstriction and hindlimb vasodilation, but the response is variable.

Statistical base value of 24-hour blood pressure distribution in patients with essential hypertension

The purpose of this study was to calculate statistically the minimum (base) blood pressure (BP) of nighttime (sleep-time) BP values obtained by ambulatory BP monitoring (ABPM) and to investigate its clinical significance. Twenty-four-hour recording of ECG with ABPM was performed directly (n=89) or indirectly (n=117) in 206 patients with essential hypertension. A telemeter was used for the direct method and a multi-biomedical recorder (TM2425) was used for indirect measurement. First, minimum heart rate (HR0=60/RR0) was determined from sleep-time ECG. The mean product of sleep-time diastolic BP (DBP) and pulse interval (RR) was divided by RR0 to obtain DBP0 [DBP0=(DBPxRR)s/RR0]. The correlation between systolic BP (SBP) and DBP was used to determine SBP0 corresponding to DBP0. Statistical base mean BP (MBP0) was calculated from these values, and its reproducibility and relation to hypertension severity were investigated. MBP0 values were similar to true base values of sleep-time MBP obtained by the direct method (mean+/-SD difference, 2.0+/-4.2 mm Hg). Direct MBP0 criteria predicted hypertension severity (mild, moderate, or severe target organ damage) more accurately (predictive accuracy, 89%) than daytime MBP criteria (53%, P<0.01). Almost the same results were obtained using indirect MBP0 criteria. Day-to-day indirect MBP0 variation (mean absolute difference) was smaller (2.4+/-1.8 mm Hg) than day-to-day daytime and nighttime MBP variation (6.3+/-5.3 and 5.4+/-3.4 mm Hg, respectively; n=61, P<0.01), and the correlation coefficient between day-to-day variations of daytime MBP and physical activity (measured by an acceleration sensor) was 0.38 (P<0.05). In conclusion, statistical base BP was almost equal to true base (minimum) BP of sleep-time BP distribution. It was closely related to the severity of hypertensive organ damage, was highly reproducible, and is considered likely to serve stochastically and physiologically as a representative BP value in an individual subject.

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.

Hemodynamic factors regulating blood pressure during sleep in patients with mild essential hypertension

Blood pressure (BP) values (systolic BP = Ps, diastolic BP = Pd, heart rate = HR) fluctuate widely throughout the day, and are at their lowest levels during sleep (sleep-Ps = PS0, sleep-Pd = Pd0, sleep-HR = HR0). We analyzed the relationships among these values using the Windkessel model (logarithmic gradient of diastolic pressure decay A = E/R, E = elastic modulus, R = vascular resistance). Intra-arterial BP and ECG were recorded throughout 24 hours in 23 patients with mild essential hypertension (EH) by telemetry, and EEG was monitored during the night. The waveform of each BP pulse was analyzed by computer. The dye-function method was used to obtain the cardiac output while the subjects were awake, recumbent and during slow-wave sleep on the EEG. A high correlation coefficient (r) was observed between mean BP and square root of E x square root of R during sleep (r = 0.88, p < 0.001). Sleep-HR was determined from the waveform that most effectively permitted peripheral blood flow. Furthermore, the simple algebraic relationships Pd not equal to phi x Pd0 and phi not equal to FI + a1(BI) + b1 (a1, b1 = constant) were observed between Pd0 and different 24 h Pd values [FI = eA(RR0-RR); BI = baroreflex index = RR x Pd(RR0 x Pd0)-1, which was significantly correlated with the baroreflex sensitivity, r = 0.79; RR0 and RR are the RR intervals in Pd0 and Pd waves]. The mean r between Pd0 x phi and the actual Pd over 24 h was 0.91 +/- 0.02 (SD). We conclude that sleep-BP and sleep-HR depend mainly on square root of E x square root of R, m [m = log(e)(Ps/Pd)] and E/R, whereas BP variability (phi) over a 24 h period is related to HR variation, the baroreflex index and E/R in mild EH patients.

Relationships of cardiac function and structure to blood pressure rhythms

It is well known that hemodynamic load is one of the most important determinants of cardiac structure and function. Circadian variations in blood pressure (BP) values are usually accompanied by consensual changes in peripheral resistance and/or cardiac output. In recent years, in hypertensive patients with left ventricular hypertrophy (LVH), a reduction in the circadian variations of BP and, in particular, a lack of nocturnal decline were observed; patients with only a small reduction in BP or none at all during the night were considered "non-dippers." In patients in whom a regression of LVH was obtained after prolonged antihypertensive therapy, restoration of the circadian rhythm of BP was also observed. However, the division of patients into "dippers" and "non-dippers" is arbitrary and poorly standardized and repeatable, and in the recent SAMPLE study, most hypertensive patients with LVH were dippers. Therefore, we should be particularly cautious about the conclusions drawn using this index. On the other hand, in patients with LVH, reduced activity of the low pressure cardiopulmonary baroreceptors and impaired day-to-night modulation of autonomic nervous system activity were observed. Therefore, cardiac structural alterations may possibly impair BP modulation; on the other hand, the opposite could also be true: a primarily altered BP modulation, through a persistently elevated afterload, could increase cardiac mass. Therefore, the interrelationships between cardiac structure and BP modulation are complex, and as a result, new and more specific methods of evaluation circadian changes in BP are needed to better clarify their reciprocal influences.

Nocturnal blood pressure and silent cerebrovascular lesions in elderly Japanese

BACKGROUND AND PURPOSE

We conducted a cross-sectional epidemiological survey using ambulatory blood pressure monitoring and brain MRI in a cohort from northern Japan to determine whether an inappropriately low nocturnal blood pressure, or an excess fall in nocturnal blood pressure, might be responsible for silent cerebrovascular lesions in the elderly.

METHODS

Untreated subjects over 55 years and under 64 years of age (late middle age; 24 men and 46 women, 60% of eligible people) and over 65 years and under 75 years of age (elderly; 29 men and 52 women, 91% of eligible people) participated in the study. We evaluated the relationship between the amplitude (Daytime Average-Nighttime Average) or the rate ([Daytime Average-Nighttime Average]/Daytime Average) of the fall in nocturnal blood pressure and the incidence of silent cerebrovascular lesions on MRI (number of lacunar infarctions or extent of periventricular hyperintensity).

RESULTS

The amplitude or the rate of the fall in nocturnal blood pressure in elderly women with one or two lacunar infarctions was significantly higher than that in those without such infarctions. There was a significant positive correlation between the amplitude or the rate of the fall in nocturnal blood pressure and the extent of periventricular hyperintensity in the elderly women. This relationship was observed in women, but not in men, of late middle age; this was not seen in elderly men.

CONCLUSIONS

Results indicate that an inappropriately low nocturnal blood pressure, or an excessive fall in nocturnal blood pressure, is associated with ischemic silent cerebrovascular lesions, at least in elderly women. Treatment of hypertension in such women should be administered with care and with regard to nocturnal blood pressure.