Autonomic nervous system activity in dipper and non-dipper essential hypertensive patients. What about sex differences?

Effect of Liuzijue exercise in different periods on circadian rhythm of blood pressure in patients with essential hypertension: A randomized trial

BACKGROUND

Exercising at different times of the day is a widely employed strategy for treating essential hypertension, aimed at enhancing the circadian rhythm of blood pressure. This study aimed to investigate the effects of Liuzijue exercise in the morning and afternoon on the circadian rhythm of blood pressure in patients with essential hypertension.

METHODS

This clinical randomized trial recruited 36 patients. They were randomly divided into 3 groups: morning exercise, afternoon exercise, and waiting treatment group. Randomization was performed at a ratio of 1:1:1, ensuring an equal distribution of participants among the 3 groups. Based on maintaining routine work and rest and continuing the original drug treatment, the exercise performed Liuzijue exercise for 12 weeks. The exercise time was 9:00 to 10:00 in the morning exercise group and 14:00 to 15:00 in the afternoon exercise group. The waiting treatment group did not perform any form of fitness exercise. The subjects in the 3 groups were monitored by 24-hour ambulatory blood pressure on the day before and after the first day.

RESULTS

After the 12-week Liuzijue exercise intervention, mean systolic blood pressure during the night significantly decreased in the morning exercise group (P < .01). In contrast, the waiting group experienced substantial increases in 24-hour mean systolic blood pressure (24hSBP), 24-hour mean diastolic blood pressure (24hDBP), mean systolic blood pressure during the daytime (dSBP), and mean diastolic blood pressure during the daytime (dDBP) (P < .01). Further analysis showed that the morning exercise group had significantly lower 24hSBP, 24hDBP, dSBP, dDBP, and mean systolic blood pressure during the night than the waiting group (P < .05). Additionally, the morning exercise group had lower 24hSBP and dSBP levels than the afternoon exercise group (P < .05). In contrast, the afternoon exercise group had lower 24hDBP and dDBP than the waiting treatment group (P < .05).

CONCLUSIONS

The 12-week Liuzijue exercise in the morning regimen demonstrated superior efficacy in reducing 24-hour ambulatory blood pressure levels among patients with essential hypertension. Moreover, it facilitates the transition of non-dipper blood pressure patterns to dippers, thereby rectifying aberrant circadian rhythms.

Effects of Nondipping Blood Pressure Changes: A Nephrologist Prospect

Blood pressure (BP) variations depend on various internal, environmental, and behavioral factors. BP fluctuations occur both in normotensive and hypertensive people. Although it fluctuates over the 24-hr day and night, the morning BP increases after waking up and declines throughout sleep. It is typical for BP to decrease by 10% to 20%, while sleeping, known as dipping BP. However, if there is no decrease in nighttime mean systolic BP or a drop of less than 10 mmHg, it is called nondipping BP. Conversely, reverse dipping BP means an increase in mean systolic BP instead of a drop during the night. Reverse dipping is observed in hypertension (HTN), diabetes mellitus (DM), chronic kidney disease (CKD), and obstructive sleep apnea (OSA) syndrome. The introduction of ambulatory BP monitoring (ABPM) led to the emergence of identifying normal and elevated BP patterns. Non-dipping BP increases the risk of cardiovascular system (CVS) complications such as left ventricular hypertrophy, proteinuria, glomerular filtration rate (GFR) reduction, and CKD progression. A loss or blunting of the normal BP profile is recognized as a deleterious variant, and restoring abnormal BP patterns has been reported to significantly impact end-organ damage, morbidity, and mortality. In this non-systematic clinically-oriented, comprehensive review, we aim to update the BP variables and the pathophysiology of nondipping BP and point out the areas which need more investigation from a nephrology perspective because the nondipping BP increases the risk of proteinuria, GFR reduction, and CKD progression. A literature search of PubMed, Google, EMBASE, and Google Scholar was conducted. Checks of selected papers and relevant reviews complemented the electronic search. With improved BP measurement methods, the physiology of BP profile variations is readily detectable during the day and night. A nondipping BP profile is a distinct BP pattern that may have significant end-organ damage effects and therapeutic importance for nephrologists. The pathophysiology of the nondipping BP variant must be clarified to prevent complications, and further investigations are required. Furthermore, there is debate about the best BP index to utilize: systolic BP, diastolic BP, mean arterial pressure, or a mixture of all. All these areas are important and need new research projects.

The Association Between 24-Hour Blood Pressure Profiles and Dementia

Midlife hypertension increases risk for dementia. Around one third of adults have diagnosed hypertension; however, many adults are undiagnosed, or remain hypertensive despite diagnosis or treatment. Since blood pressure (BP) follows a circadian rhythm, ambulatory BP monitoring allows for the assessment of BP over a 24-hour period and provides an important tool for improving the diagnosis and management of hypertension. The measurement of 24-hour BP profiles, especially nocturnal BP, demonstrate better predictive ability for cardiovascular disease and mortality than office measurement. However, few studies have examined 24-hour BP profiles with respect to dementia risk. This is an important topic since improvements in BP management could facilitate the primary prevention of vascular cognitive impairment and dementia. Therefore, this review discusses the evidence linking BP to dementia, with a focus on whether the implementation of 24-hour BP measurements can improve risk prediction and prevention strategies. Pathways linking nocturnal BP to dementia are also discussed as are risk reduction strategies. Overall, limited research suggests an association between 24-hour BP elevation and poorer cognition, cerebral small vessel disease, and dementia. However, most studies were cross-sectional. Further evidence is needed to substantiate 24-hour BP profiles, over and above office BP, as predictors of vascular cognitive impairment and incident dementia.

Sex Differences in Circadian Rhythms

Sex as a biological variable is the focus of much literature and has been emphasized by the National Institutes of Health, in part, to remedy a long history of male-dominated studies in preclinical and clinical research. We propose that time-of-day is also a crucial biological variable in biomedical research. In common with sex differences, time-of-day should be considered in analyses and reported to improve reproducibility of studies and to provide the appropriate context to the conclusions. Endogenous circadian rhythms are present in virtually all living organisms, including bacteria, plants, invertebrates, and vertebrates. Virtually all physiological and behavioral processes display daily fluctuations in optimal performance that are driven by these endogenous circadian clocks; importantly, many of those circadian rhythms also show sex differences. In this review, we describe some of the documented sex differences in circadian rhythms.

Association of nocturnal subconjunctival hemorrhage and non-dipper blood pressure pattern: A benign clue for serious diseases

PURPOSE

To evaluate the association between non-dipper blood pressure pattern and subconjunctival hemorrhage (SCH).

METHODS

Twenty-seven consecutive patients with nocturnal SCH and 27 age, sex-matched controls were enrolled. Demographic, blood parameters, office blood pressure measurements, 24-h ambulatory blood pressure monitoring (ABPM) were evaluated.

RESULTS

Mean diastolic blood pressure (DBP) for nighttime (65.03 ± 7.1 vs. 70.78 ± 10.5, p: 0.22), mean heart rate for nighttime (64.54 ± 8.26 vs. 69.93 ± 9.85, p: 0.034), Minimum Systolic Blood pressure(SBP) and DBP values for nighttime (92.44 ± 9.72 vs. 99.44 ± 10.66, p:0.015 and 51.15 ± 8.31 vs. 57.7 ± 11.2, p: 0.018) were higher, nocturnal fall ratio of SBP and DBP were significantly lower in the SCH ( + ) group compared to SCH (-) group (5.38 ± 8.39 vs. 10.34 ± 6.08, p: 0.016 and 4.26 ± 8.92 vs. 13.78 ± 6.97, p < 0001 respectively). Ten patients (37%) in the SCH (-) group and 18 patients (66.7%) in the SCH ( + ) group were non-dippers (p: 0.029). Mean daytime SBP and DBP were higher compared to office measurements of 4 patients (14.8%) in the SCH (-) group and 11 patients (40.7%) in the SCH ( + ) group (p: 0.033).

CONCLUSION

SCH had a strong association with non-dipper blood pressure pattern, higher nocturnal heart rate and masked hypertension which are precursors of myocardial infarction, stroke and renal failure. So, SCH should be considered as a clue for serious diseases such as coronary artery disease, myocardial infarction, stroke and patients should be evaluated for ABPM.

Clinical risk factors and predictive score for the non-dipper profile in hypertensive patients: a case-control study

Background

Night-time BP, especially non-dipper, is a stronger predictor of adverse cardiovascular outcomes. Ambulatory blood pressure monitoring (ABPM) is a gold standard for the detection of non-dippers but it often is unavailable and expensive. This study aims to determine clinical risk factors that predict non-dipper.

Methods

An exploratory traditional case-control study, exclusive sampling of control was conducted from January 2013 to September 2018 to explore clinical risk factors associated with non-dippers in hypertensive patients. Subgroup analysis was performed in each treated and untreated hypertensive patient. The parsimonious predictive score for non-dippers was constructed.

Results

The study included 208 hypertensive patients receiving 24 h ABPM. There were 104 dippers and 104 non-dippers. Significant clinical risk factors associated with non-dippers were the age of > 65 years, average office diastolic blood pressure (DBP), and fasting plasma glucose of > 5.6 mmol/L. Results of subgroup analysis showed that dyslipidemia, history of coronary artery disease, use of angiotensin-converting enzyme inhibitors (ACEIs) and direct vasodilators, average office DBP, and serum uric acid were associated with non-dippers in treated hypertensive patients, however, there were no risk factors associated with non-dippers in the untreated group. The predictive score for non-dippers in treated group included average office DBP, dyslipidemia, serum uric acid, male, calcium channel blockers and ACEIs use. The area under Receiver Operating Characteristic (AuROC) was 0.723. A cut-off point which was > 0.0701 and prevalence of non-dippers of 46%, this score had a sensitivity of 77.4%, specificity of 65.6%, positive predictive value (PPV) of 66.1%, and negative predictive value (NPV) of 79.6%. For untreated group, age, hemoglobin and body mass index were included in the predictive model. AuROC was 0.74. There was a sensitivity of 51.9%, specificity of 91.2%, PPV of 82.4%, and NPV of 70.5% at the cut-off point of > 0.357, and prevalence of 44%.

Conclusion

There were several significant clinical risk factors associated with non-dippers in treated hypertensive patients. The predictive score might be useful for the detection of non-dippers; however, it cannot replace ABPM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40885-021-00180-4.

Clinical significance of heart rate variability for the monitoring of cardiac autonomic neuropathy in end-stage renal disease patients

BACKGROUND AND AIMS

The aim of this study is to determine whether the measurement of continuous heart rate variability (HRV) is useful in the evaluation of cardiac autonomic neuropathy (CAN) in end-stage renal disease (ESRD) patients.

METHODS AND RESULTS

This cross-sectional study was performed at Seoul St. Mary's hospital between June 2017 and February 2018. Seventy-seven ESRD patients, and 29 healthy controls (HCs) were asked to wear a continuous ambulatory HRV monitor for 24 h. General cardiac function was evaluated using transthoracic echocardiogram (TTE), pulse wave velocity (PWV), coronary calcium scoring (CCS), and 24-h ambulatory blood pressure monitoring (ABPM). HRV parameters of ESRD patients and HCs, and the correlation of HRV parameters with cardiovascular screening methods were observed. All HRV parameters were significantly decreased in ESRD patients compared to HCs (P < 0.001). In the correlation analysis between TTE results and HRV parameters, 24-h standard deviation of all N-N intervals (24SDNN), 24-h standard deviation of sequential 5-min N-N interval means (24DANN) and Low Frequency Power/High Frequency Power (LF/HF) ratio showed negative correlations with E/e', LAVI and TR velocity which are representative indices for the diastolic function of the heart (P < 0.05). HRV parameters showed negative correlations with baPWV, CCS, and 24-h ABPM results as well (P < 0.05). Hemoglobin and serum albumin showed positive correlations with HRV parameters, and glucose, BUN, creatinine, and iPTH levels showed negative correlations (P < 0.05).

CONCLUSION

Continuous HRV monitoring may be a useful tool for the evaluation of CAN in ESRD.

Circulating IL-37 levels are elevated in patients with hypertension

Interleukin-37 (IL-37) has been reported to be closely linked to vascular diseases, including atherosclerosis and aortic calcification. The present study aimed to assess the expression levels of IL-37 in patients with hypertension. Blood samples were collected from control subjects (n=20) and patients with hypertension (n=45). Subsequently, macrophages, lymphocytes and dendritic cells were individually isolated and the mRNA expression of IL-37 was measured. In addition, the circulating IL-37 levels in control subjects (n=30) and patients with hypertension (n=334) were assessed. Furthermore, all patients who were subjected to detection of circulating IL-37 underwent ambulatory blood pressure monitoring. The results suggested that the mRNA levels of IL-37 in macrophages, but not in lymphocytes and dendritic cells, isolated from patients with hypertension were markedly elevated compared with those in cells isolated from control subjects. Circulating IL-37 levels were increased in patients with hypertension compared with those in control subjects and positively correlated with systolic and diastolic blood pressure in patients with hypertension. No differences were observed between patients with dipper hypertension and patients with non-dipper hypertension. In addition, patients with hypertension with a smoking habit, type 2 diabetes mellitus and carotid atherosclerotic plaque (CAP) exhibited higher IL-37 levels. IL-37 levels were positively correlated with creatinine, C-reactive protein and homocysteine levels. Furthermore, the results of a linear regression analysis suggested that IL-37 levels were independently associated with the presence of CAP. In conclusion, IL-37 levels are increased in patients with hypertension and may be associated with the onset of CAP.

The Expression of IL-12 Family Members in Patients with Hypertension and Its Association with the Occurrence of Carotid Atherosclerosis

Background

The interleukin-12 (IL-12) family consists of four members, namely, IL-12, IL-23, IL-27, and IL-35. The aim of this study was to examine the expression of circulating IL-12, IL-23, IL-27, and IL-35 in hypertensive patients.

Methods

Blood samples were collected from hypertensive patients and nonhypertensive (control) subjects, and protein multifactorial monitor kits were used to measure the plasma IL-12, IL-23, IL-27, and IL-35 levels in each sample. In addition, all enrolled subjects underwent ambulatory blood pressure monitoring (ABPM) and vascular stiffness.

Results

Hypertensive patients exhibited higher IL-12, IL-23, and IL-27 levels and lower IL-35 levels than control subjects; IL-12, IL-23, and IL-27 levels were positively correlated with both systolic blood pressure (SBP) and diastolic blood pressure (DBP), while IL-35 levels were negatively correlated with SBP and DBP. IL-12, IL-23, and IL-27 levels gradually increased in patients with grade I, II, and III hypertension, while IL-35 levels gradually reduced. According to the ABPM results, hypertensive patients were divided into the dipper and nondipper hypertension groups; IL-12, IL-23, IL-27, and IL-35 levels showed no differences between the two groups, but IL-12, IL-23, and IL-27 levels in both groups increased compared with those in the control group, while IL-35 levels decreased. Additionally, the expression of these IL-12 family members was influenced by many clinical factors and was independently associated with the occurrence of carotid atherosclerotic plaques.

Conclusions

The changes in IL-12, IL-23, IL-27, and IL-35 levels were not associated with the presence of the nondipper type but were closely associated with the development of carotid atherosclerotic plaque in hypertensive patients.

Assessment of pupillary autonomic functions by dynamic pupillometry in different circadian arterial blood pressure patterns

OBJECTIVE

The aim of the present cross-sectional study was to evaluate the autonomic nervous system by dynamic pupillometry (DP) in normotensive and hypertensive individuals with either a non-dipper-type or a dipper-type circadian rhythm of blood pressure (BP).

PATIENTS AND METHODS

A total of 80 patients were allocated into four groups: normotensive/dipper (n=23), normotensive/nondipper (n=19), hypertensive/dipper (n=18), and hypertensive/nondipper (n=20). Pupil diameters (R0, R1, R2, and R%): latency (Lc), amplitude (Ac), velocity (Vc), and duration (Tc) of pupil contraction: latency (Ld), velocity (Vd), and duration (Td) of pupil dilatation were measured by DP. Among the DP parameters, Vc and Ac were known parasympathetic indices and R% was the major sympathetic index.

RESULTS

Vc and Ac were higher in the dipper normotensives with respect to nondipper normotensives (Vc=5.19±0.85 vs. 4.58±0.71, P=0.017; Ac=1.66±0.27 vs. 1.49±0.28, P=0.048). Vc and Ac were higher in dipper hypertensives with respect to the nondipper subgroup of hypertensive cases (Vc=4.44±0.81 vs. 3.94±0.45, P=0.024; Ac=1.47±0.26 vs. 1.27±0.11, P=0.004). R% was higher in the nondipper subgroup of hypertensives than the dipper subgroup of hypertensive cases (36.7±4.8 vs. 33.5±3.8, P=0.033). Correlation analyses showed moderate positive correlations of night-time decline in BP with Vc (r=0.460, P=0.001) and Ac (r=0.420, P=0.001). There was also a negative correlation between night-time decline in BP and R% (r=-0.259, P=0.001).

CONCLUSION

Nondipping in BP is associated with lower parasympathetic activity both in normotensive and in hypertensives cases. Furthermore, in the nondipper subgroup of hypertensive cases, there is higher sympathetic activity than the dipper subgroup.

Reversal of nocturnal non-dipping of blood pressure after Levothyroxine therapy in patients with subclinical hypothyroidism

AIMS

To study the loss of diurnal variation in blood pressure in normotensive patients with Subclinical/overt hypothyroidism and effect of Levothyroxine (L-T4) treatment.

MATERIALS AND METHODS

In this interventional study Eighty patients between 17- 50 years with newly detected OH and SCH (74 women and 6 men) and nine euthyroid subjects (all men) with blood pressure <140/90 were recruited. All patients underwent 24h ambulatory blood pressure monitoring (ABPM) using ABPM machine before and after treatment with L-T4. Diurnal index (DI), Percent time elevation (PTE), Hyperbaric impact (HBI) were studied pre and post L-T4 treatment.

RESULTS

Of the 89 subjects (22 SCH, 58 OH and 9 controls), 7 of the SCH and 30 of OH subjects reported back in follow up after L-T4 supplementation for evaluation. DI, HBI and PTE when compared at baseline between different groups (SCH- OH, SCH- control, OH- control) were insignificant. After L-T4 supplementation DI, HBI and PTE varied significantly with p value 0.007, 0.003 and 0.003 respectively between SCH- OH only. Post L-T4 analysis in SCH group was statistically insignificant (p-value 0.102) but a trend toward improvement in DI was noted (baseline and post treatment DI mean 7.00 and 13.00 respectively).

CONCLUSION

Loss of nocturnal dipping was found in patients with OH and SCH which was restored after L-T4 therapy only in patients with SCH and not with OH.

TREATMENT

of SCH patients with high cardiovascular risk may be beneficial in this setting and can be a new indication for LT4 therapy in SCH.

Muscle microcirculation alterations and relation to dipping status in newly diagnosed untreated patients with arterial hypertension-A pilot study

OBJECTIVE

The importance of abnormalities observed in the microcirculation of patients with arterial hypertension (AH) is being increasingly recognized. The authors aimed to evaluate skeletal muscle microcirculation in untreated, newly diagnosed hypertensive patients with NIRS, a noninvasive method that evaluates microcirculation.

METHODS

We evaluated 34 subjects, 17 patients with AH (13 males, 49±13 years, BMI: 26±2 kg/m² ) and 17 healthy controls (12 males, 49±15 years, BMI: 25±3 kg/m² ). The thenar muscle StO₂ (%) was measured by NIRS before, during and after 3-minutes vascular occlusion to calculate OCR (%/min), EF (%/min), and RHT (minute). The dipping status of hypertensive patients was assessed.

RESULTS

The RHT differed between AH patients and healthy subjects (2.6±0.3 vs 2.1±0.3 minutes, P<.001). Dippers had higher EF than nondippers (939±280 vs 710±164%/min, P=.05).

CONCLUSIONS

The study suggests an impaired muscle microcirculation in newly diagnosed, untreated AH patients.

Circadian blood pressure pattern and right ventricular and right atrial mechanics: A two- and three-dimensional echocardiographic study

The purpose of this investigation was to evaluate right ventricular (RV) and right atrial (RA) function and mechanics in untreated hypertensive patients with different blood pressure (BP) patterns by using two-dimensional (2DE) speckle tracking analyses and three-dimensional echocardiography (3DE). This cross-sectional study included 174 recently diagnosed hypertensive patients. All patients underwent a 24-hour ambulatory BP monitoring and complete 2DE and 3DE examination, including 2DE speckle tracking analysis. Our results showed that 2DE RV global longitudinal strain was significantly lower in the non-dippers. Similar results were obtained for 2DE RV systolic and early diastolic strain rate. The RA longitudinal strain, as well as RA systolic and early diastolic strain rate, was decreased in non-dippers. Our results revealed that 3DE RV end-diastolic and end-systolic volumes were increased, whereas 3DE RV ejection fraction was reduced in non-dipper hypertensive patients. Similar results were obtained for RA volumes and RA ejection fraction estimated by 2DE. Independent predictors of 3DE RV ejection fraction, 2DE RV and RA global longitudinal strain were left ventricular mass index and RV wall thickness. An additional independent predictor of the RV longitudinal strain was 3DE RV ejection fraction, and for RA longitudinal strain, an additional independent predictor was tricuspid E/é ratio. Two-DE speckle tracking evaluation and 3DE examination revealed that the RV and RA function and mechanics were more deteriorated in the non-dipper patients than in dipper untreated hypertensive patients.

Predictors of Blood Pressure Reduction With Nocturnal Continuous Positive Airway Pressure Therapy in Patients With Obstructive Sleep Apnea and Prehypertension

Previous studies showed that treatment of obstructive sleep apnea syndrome (OSAS) with continuous positive airway pressure (CPAP) significantly reduced the blood pressure (BP) in hypertensive patients. We investigated the predictors of BP change in normotensive patients with OSAS who underwent CPAP. A total of 24 patients with OSAS (19 male; age: 48.7 ± 10.4 years) were enrolled. The 24-hour mean BP (24 hMBP), subjective sleepiness, fasting venous blood samples, and anthropometric measurements were assessed at baseline, 6th week and 12th week of CPAP treatment. The 24 hMBP fell at 12 weeks from 89.2 ± 8.4 to 82.9 ± 7.3 mm Hg ( P < .0001) irrespective of the severity of disease. Also, both daytime and nighttime BP showed significant reduction after CPAP. Male gender, Epworth sleepiness scale, body mass index, smoking, alcohol use, and baseline 24 hMPB were the independent predictors of a fall in 24 hMBP. The CPAP therapy may provide benefit even in the absence of overt hypertension by reducing both daytime and nighttime BP.

Wrist skin temperature, motor activity, and body position as determinants of the circadian pattern of blood pressure

Although the circadian blood pressure (BP) pattern has been extensively studied, the determinants of this rhythm are not fully understood. Peripheral vasodilatation is a regulatory mechanism for BP maintenance. However, it remains to be established whether the increase of nocturnal distal skin temperature associated with heat loss could also reflect the dipping status. For the first time, this paper investigates the relationship between BP and skin wrist temperature (WT), to evaluate whether the WT circadian rhythm can serve as screening procedure to detect dipping/non-dipping BP patterns. In addition, the authors compare the relationship between WT and other variables previously described as determinants of the BP pattern, such as physical activity and body position. Measurements of WT, motor activity, and body position for 5 d, plus ambulatory BP for 24-h during that span, were obtained from 28 diurnally active normotensive volunteers. WT was negatively correlated, whereas activity and body position were positively correlated, with systolic and diastolic BPs. However, these relationships were stronger during the rest than activity phase. In addition, a 78.6% concordance was detected between the observed dips in BP and the predicted BP pattern calculated based on the WT rhythm. Thus, these results suggest that the increase in WT produced by heat loss during the rest phase through peripheral skin blood vessels is the result of blood vessel vasodilatation reflexes in response to a shift from a standing to a supine position, together with shift in the circadian sympathetic/parasympathetic balance (nocturnal parasympathetic activation). In conclusion, WT could be considered as a potential new screening procedure to implement the diagnosis of non-dipping BP pattern.

Can acupuncture affect the circadian rhythm of blood pressure? A randomized, double-blind, controlled trial

OBJECTIVES

The objective of the study was to investigate the effect of acupuncture on the circadian rhythm of blood pressure (BP) in patients with hypertension.

DESIGN

The study was designed as a randomized, double-blind, controlled trial. Subjects were randomly divided into an active acupuncture group and a sham acupuncture group. Each patient received real or sham acupuncture treatment twice a week for 8 weeks. Acupuncture needles were inserted at bilateral ST 36 plus PC 6; placebo points.

SUBJECTS

Thirty-three (33) patients with essential hypertension were the subjects.

OUTCOME MEASURES

Twenty-four (24)-hour ambulatory BP was assessed before and after treatment.

RESULTS

After the treatment period, there was a significant increase in nocturnal diastolic BP dipping compared to that at baseline (10.20±7.56 mm Hg versus 5.21±10.19 mm Hg, p=0.038) in the active acupuncture group but not in the sham acupuncture group. The nocturnal diastolic BP dipping response to active acupuncture treatment was significantly different from the response seen with the sham acupuncture treatment (p=0.041). The number of dippers also increased from 4 to 8 in the active acupuncture group. Average systolic and diastolic BP was not changed significantly except for nighttime diastolic BP (90.32±11.47 mm Hg to 87.83±9.16 mm Hg, p=0.041).

CONCLUSIONS

It is suggested that acupuncture treatment could be useful for improving the circadian rhythm of BP in patients with hypertension.

Nighttime hospital blood pressure--a predictor of death, ESRD, and decline in GFR

Nighttime systolic blood pressure (BP) from ambulatory blood pressure monitoring (ABPM) is more predictive than clinic BP for cardiovascular disease, stroke, and death even after controlling for clinic BP. However, ABPM is expensive and burdensome to obtain regularly. BPs obtained in the hospital may provide a window into nighttime BP. We conducted a retrospective cohort study of all hypertensive patients admitted to the Louis Stokes Cleveland Department of Veterans Affairs Medical Center (LSCDVAMC) in 2002 and 2003 with one or more BP recorded between midnight and 6 am on the day of or the day before discharge. The mean age of the study population (n = 1085) was 62 years and 96% were male. Twenty-two percent had coronary artery disease (CAD) and 34% had diabetes. The mean nighttime systolic BP was 132 mmHg and baseline glomerular filtration rate (GFR) was 83 mL/min per 1.73 m(2). Over a median follow-up period of 4.3 years, 266 subjects died, 22 developed end-stage renal disease (ESRD), 99 had a 50% decline in GFR, and 136 developed myocardial infarction (MI). The adjusted hazard ratios (HRs) associated with a 10 mmHg increase in nighttime systolic BP were 1.03 (95% confidence interval, 0.93-1.15) for death, 1.30 (0.94-1.80) for ESRD, 1.26 (1.08-1.47) for a 50% decline in GFR, 1.07 (0.92-1.23) for myocardial infarction, and 1.12 (1.03-1.23) for a composite of death, ESRD, or a 50% decline in GFR. In conclusion, nighttime systolic BP in hospitalized patients is an independent predictor of important clinical outcomes such as a composite of death, ESRD, or a 50% decline in GFR.

Cardiovascular prognostic value of ambulatory blood pressure monitoring in a Portuguese hypertensive population followed up for 8.2 years

AIM

We investigated the cardiovascular (CV) prognostic value of 24-h ambulatory blood pressure (ABP) and blood pressure (BP) during the six 4-h periods of the 24-h ABP length in a cohort of 1200 Portuguese hypertensive patients (aged 51±12 years) without earlier CV events.

METHOD

The presence of CV events were followed for 9.833 patient years and analyzed using a cox hazard model.

RESULTS

During the 15.2 (mean 8.2) years follow-up, there were 152 CV events (11% fatal) including 79 strokes and 52 coronary events. After adjustment for risk factors and office BP (OBP), a 1-standard deviation increment of 24-h, daytime and night-time systolic BP (SBP) significantly predicted any CV event with hazard ratios (HR) 1.41, 1.33 and 1.57, respectively, and stroke with HR 1.67, 1.58, 1.67, respectively (all P<0.01), but not coronary events. Prognostic significance of these SBP values and of night-time ABP persisted after adjustment for diastolic BP and daytime ABP, respectively, whereas the opposite did not occur. SBP night-time fall (%) inversely predicted total CV events after adjustment for diastolic BP night-time fall. Among all six 4-h periods of 24-h, increment of SBP during the first 4 h of night-time was the most powerful predictor of any CV event (HR 1.64) and stroke (HR 2.02) (both P<0.01) even after adjustment for daytime and 24-h BP.

CONCLUSION

In predicting CV events and stroke, ABP is superior to office BP, ABP systolic is superior to ABP diastolic, and night-time BP is superior to daytime BP particularly during the first 4 h of sleep.

Melatonin for nondippers with coronary artery disease: assessment of blood pressure profile and heart rate variability

The aim of this study was to assess the effects of 5 mg melatonin before sleep in patients with coronary artery disease (CAD) and with an abnormal circadian pattern of blood pressure (BP) on changes in circadian BP profile and heart rate variability (HRV). Sixty patients with CAD, nondippers aged 48-80 years (male 75%), were included. In addition to previous treatment, they were randomly allocated to melatonin or placebo. After 90 days, a second 24-h BP monitoring was carried out. Each patient had two sessions (before randomization and at the end of study) of 24-h ECG monitoring to assess the changes in HRV. Inclusion of melatonin led to BP pattern normalization in 35% of patients in the melatonin group and in 15% of controls (P=0.609). This effect was reached not only by a decrease in nighttime BP, but also by an increase in daytime BP (significant in the melatonin group). A nonoptimal effect for BP profile was observed in 12.5% of patients: extreme- or reverse dippers. In patients with conversion from nondippers to dippers (responders), an increase in standard deviation of normal-to-normal intervals between initial and final HRV analyses was observed. Nonresponders represented an increase in the mean circadian heart rate. To avoid nonoptimal effects, the inclusion of melatonin in pharmacotherapy of patients with CAD should be based on monitoring of circadian BP profile, before and during treatment. As melatonin caused not only a nocturnal decrease in BP but also a daytime increase, it should not be recommended in patients with 'high normal' values of BP because of the danger of induction of arterial hypertension.

Effects of angiotensin II type 1 receptor blocker on ambulatory blood pressure variability in hypertensive patients with overt diabetic nephropathy

Previous studies have shown increases in ambulatory short-term blood pressure (BP) variability to be related to cardiovascular disease. In this study, we examined whether the angiotensin II type 1 receptor blocker (ARB) would improve ambulatory short-term BP variability in hypertensive patients with diabetic nephropathy. A total of 30 patients with type II diabetes, along with hypertension and overt nephropathy, were enrolled in this randomized, two-period, crossover trial of 12 weeks of treatment with losartan (50 mg daily) and telmisartan (40 mg daily). At baseline and at the end of each treatment period, 24-h ambulatory BP monitoring with power spectral analysis of heart rate and measurements of proteinuria, estimated glomerular filtration rate and brachial-ankle pulse wave velocity (baPWV) were performed. After 12 weeks of treatment, 24-h, daytime and nighttime short-term BP variability, assessed on the basis of the coefficient of variation of ambulatory BP, was significantly decreased by telmisartan. Both losartan and telmisartan reduced urinary protein excretion and baPWV. However, compared with losartan, telmisartan significantly decreased urinary protein excretion, baPWV and low-frequency (LF)-to-high-frequency (HF) ratio, an index of sympathovagal balance. Multiple regression analysis showed significant correlations between urinary protein excretion and baPWV, 24-h LF-to-HF ratio, nighttime systolic BP and 24-h short-term systolic BP variability. These results suggest that ARB, particularly telmisartan, is effective in reducing proteinuria in hypertensive patients with overt diabetic nephropathy, partly through inhibitory effects on ambulatory short-term BP variability and sympathetic nerve activity, in addition to its longer duration of action on nighttime BP reduction.

Causes and mechanisms of nondipping hypertension

Growing evidence indicates that nondippers have worsened cardiovascular outcomes than dippers. Ambulatory blood pressure monitoring with a lack of nocturnal BP fall (nondipping) have also been shown to be more closely associated with target organ damage and worsened cardiovascular outcome than in patients with essential hypertension with dipping pattern. The underlying pathogenetic mechanisms potentially linking nondipping with cardiovascular disease are not fully understood. There are multiple possible underlying pathophysiologic mechanisms in the impaired BP decline during the night. Extrinsic and intrinsic factors including abnormal neurohormonal regulation, lack of physical activity, nutritional factors such as increased dietary sodium intake, and smoking of tobacco have been implicated for blunted circadian rhythm of BP. Certain diseases such as diabetes and chronic renal diseases also affect the circadian BP rhythm. Currently, the clinical importance of nondipping is known well; however, the relationship between certain disease states and nondipping has not been fully explained yet. This paper will attempt to address to clarify the underlying basis for nondipping and the specific associations with various disease states.

Circadian variation of blood pressure: the basis for the chronotherapy of hypertension

Ambulatory blood pressure (BP) measurements present a close correlation with target organ damage and cardiovascular events, including myocardial infarction, stroke and cardiovascular mortality. With the use of this measurement technique, a significant circadian variation has been shown to characterize BP. This circadian BP variation, although affected by a variety of external factors, represents the influence of internal factors such as ethnicity, gender, autonomic nervous system tone, vasoactive hormones, and hematologic and renal variables. In most individuals, BP presents a morning increase, a small post-prandial valley, and a deeper descent during nocturnal rest. However, under certain pathophysiological conditions, the nocturnal BP decline may be reduced or even reversed. This cannot be determined by traditional clinical or home BP assessments. Subjects with a diminished nocturnal BP decline (non-dipper pattern) have a significantly worse prognosis than the ones with a normal dipper pattern. In particular, the non-dipper circadian BP pattern represents a risk factor for left ventricular hypertrophy, microalbuminuria, cerebrovascular disease, congestive heart failure, vascular dementia and myocardial infarction. The normalization of the circadian BP pattern to a dipper profile is a novel therapeutic goal, and accumulating medical evidence suggests this can delay the progression towards the renal and cardiovascular pathology known to be a consequence of the non-dipper BP pattern. The features of the circadian BP profile have direct implications for improving the drug-delivery of antihypertensive therapies as well as the qualification of patients for medication trials and assessment.

Chronotherapy in hypertensive patients: administration-time dependent effects of treatment on blood pressure regulation

Ambulatory blood pressure measurements (ABPM) correlate more closely with target organ damage and cardiovascular events than clinical cuff measurements. ABPM reveals the significant circadian variation in BP, which in most individuals presents a morning increase, small post-prandial decline, and more extensive lowering during nocturnal rest. However, under certain pathophysiological conditions, the nocturnal BP decline may be reduced (nondipper pattern) or even reversed (riser pattern). This is clinically relevant since the nondipper and riser circadian BP patterns constitute a risk factor for left ventricular hypertrophy, microalbuminuria, cerebrovascular disease, congestive heart failure, vascular dementia and myocardial infarction. Hence, there is growing interest in how to best tailor and individualize the treatment of hypertension according to the circadian BP pattern of each patient. Significant administration-time differences in the kinetics and in the beneficial and adverse effects of antihypertensive medications are well known. Thus, bedtime dosing with nifedipine gastrointestinal therapeutic system (GITS) is more effective than morning dosing, while also significantly reducing adverse effects. The therapeutic coverage and efficacy of doxazosin GITS are dependent on the circadian time of drug administration. Moreover, valsartan administration at bedtime, as opposed to upon wakening, results in an improved diurnal/nocturnal BP ratio, increased percentage of controlled patients, and significant reduction in urinary albumin excretion in hypertensive patients. Chronotherapy provides a means of individualizing the treatment of hypertension according to the circadian BP profile of each patient, and constitutes a new option to optimize BP control and reduce the risk of cardiovascular disease.

Relationship between base blood pressure during sleep and health-related quality of life in healthy adults

There are many reports indicating that night time blood pressure (BP) is closely associated with target organ damage. However, BP in the waking period is influenced by physical activity and also by the psychological status. Recently, base BP (BP0: minimum and stable BP during sleep) has been reported to correlate with organ damage in hypertensives. However, little is known about the implications of BP0. We examined how BP0 is associated with BP, heart rate variability and health-related quality of life (HRQOL) in healthy subjects. One hundred and thirty-five participants, composed of 88 male and 47 female (age: 21-33 years) underwent a 24-h ambulatory BP monitoring (ABPM). Sympathetic nervous activity (ratio of low-frequency to high-frequency component: LF/HF) and parasympathetic nervous activity (high-frequency component: HF) were calculated by electrocardiogram monitoring. BP0 was calculated as previously reported. HRQOL was assessed by Medical Outcome Study Short-Forum 36-Item Health Survey. Base systolic BP (SBP0) positively correlated with 24-h systolic BP (SBP) (r=0.662, P<0.0001) and night time SBP (r=0.810, P<0.0001). SBP0 positively correlated with 24-h LF/HF (r=0.214, P<0.02) and night time LF/HF (r=0.326, P<0.001). Moreover, SBP0 negatively correlated with the scores of body pain (r=-0.223, P<0.02). Multiple linear regression analysis showed that SBP0 correlated with gender (P<0.01), night time LF/HF (P<0.04) and the scores of body pain (P<0.04). In conclusion, SBP0 correlated with BP, LF/HF and the scores of body pain (HRQOL). SBP0 may be a useful indicator for assessing 24-h BP, sympathetic nervous functions and HRQOL in healthy subjects.

Nonsymmetrical double logistic analysis of ambulatory blood pressure recordings

We developed an asymmetric double logistic curve-fitting procedure for circadian analysis that can determine the rate of change in variables during the day-to-night separately from the night-to-day transition for use in animal studies. We now have applied this procedure to 24-h systolic (SAP) and diastolic arterial pressure (DAP) and heart rate ambulatory recordings from 302 patients. In 292 cases, all parameters showed a pattern of higher day and lower night values. In men there was a similar rate of transition between day and night or from night to day for both SAP and DAP that lasted 3–4 h, indicating a symmetrical diurnal pattern. By contrast, women showed a faster rate of decrease in mean arterial pressure in the evening compared with men ( P < 0.05) and therefore showed an asymmetric diurnal SAP pattern. For both men and women, there was a markedly greater rate of morning increase in heart rate compared with the rate of evening decrease (2.2- and 1.9-fold, respectively, P < 0.001). The logistic method provided a better fit than the square-wave or the cosinor method ( P < 0.001) and more appropriately detected nondippers. We conclude that analysis of ambulatory recordings by a new logistic curve-fitting method reveals more rapid reductions in evening SAP in women than men but both have two- to threefold more rapid morning rates of tachycardia. The ability of the double logistic method to determine the diurnal blood pressure rates of change independently is key to determining new markers for cardiovascular risk.

Contrasting circadian rhythms of blood pressure among inbred rat strains: recognition of dipper and non-dipper patterns

OBJECTIVE

The non-dipper pattern, i.e. the lack of nocturnal blood pressure (BP) fall, carries a high risk of cardiovascular complications, both in hypertensive and normotensive subjects. Without genetic engineering, experimental demonstration of the non-dipper phenomenon is lacking. The purpose of this study was to assess the haemodynamic and behavioural daily parameters among various strains of rats - spontaneously hypertensive rats (SHR), Wistar-Kyoto (WKY) and Fischer 344 (F344) - in order to characterize their circadian patterns and to detect a non-dipper animal model.

METHODS

Changes in BP, heart rate (HR), and spontaneous locomotor activity (SLA) were recorded continuously for 11 days using telemetry in freely moving 10-week-old male SHR, WKY and F344 rats, in standardized laboratory conditions. Variations in haemodynamic and behavioural parameters were assessed in terms of day/night differences and spectral power corresponding with the 24-h period.

RESULTS

All rats exhibited clear circadian variations in HR and in SLA, in synchrony with the light cycle. Light/dark differences in BP were significantly lower in F344 compared with those of SHR and WKY. The smaller circadian changes in BP observed in F344 were also demonstrated using spectral analysis: the peak detected at 24-h was reduced in F344 compared with SHR and WKY.

CONCLUSION

The inbred F344 strain lacks the typical circadian BP rhythm while oscillations of HR and SLA are maintained, suggesting different regulatory mechanisms. The F344 strain may represent a useful animal model for studying the effects of drugs aimed at restoring the dipper status.

Relationship between physical activity and blood pressure in dipper and non-dipper hypertensive patients

BACKGROUND

The lack of nocturnal decline in blood pressure has been associated with an increase in end-organ damage and cardiovascular events, although results remain controversial, partly because of the inability to reproduce correctly, over time, the classification of patients into dippers and non-dippers. Moreover, the non-dipping status has been frequently related to an increase in nocturnal activity, differences in quality of sleep, or both.

OBJECTIVE

To assess the relationship between activity and blood pressure in patients with hypertension.

METHODS

We studied 306 mild-to-moderately hypertensive patients (130 men), 53.7 +/- 14.0 years of age (mean +/- SD). Blood pressure and heart rate were measured for 48 consecutive hours, at 20-min intervals during the day and at 30-min intervals at night, using an ambulatory device, and physical activity was simultaneously evaluated at 1-min intervals by wrist actigraphy. Circadian parameters of blood pressure, heart rate and activity established by population multiple-components analysis were compared between dippers and non-dippers, by non-parametric testing. Diurnal and nocturnal means of blood pressure and activity were computed for each patient according to individual resting hours determined by actigraphy, and compared among groups by analysis of variance.

RESULTS

Despite highly statistically significant differences between dippers and non-dippers with respect to nocturnal means and in each hourly nightly mean of blood pressure, there were no differences between them for the same parameters during activity, whether or not the patients were receiving medication at the time of monitoring. The average duration of sleep and the 24-h mean and standard deviation of activity were also similar between the groups.

CONCLUSIONS

The highly significantly different circadian variation in blood pressure between dippers and non-dippers with essential hypertension is not related to a significant increase in nocturnal physical activity. Differences in blood pressure could, however, be related to the absence of 24-h therapeutic coverage in most non-dipper patients receiving antihypertensive medication.

Nocturnal non-dipping: what does it augur?

The non-dipping pattern of blood pressure (defined as a nocturnal fall of less than 10%) occurs in about 25% of hypertensives, with increased prevalence in certain sub-groups such as diabetics, African-Americans, and patients with renal disease. It almost certainly has multiple causes, including factors such as the levels of activity and arousal during both the day and the night, the depth and quality of sleep, and the activity of the sympathetic nervous system, among others. In patients with uncomplicated hypertension, the reproducibility is relatively low. There is evidence suggesting that the non-dipping pattern may have an adverse prognosis: thus, it appears to predict the progression of renal disease, to be associated with increased target-organ damage (in some studies), and also to predict increased cardiovascular morbidity. Antihypertensive drug treatment can normalize the non-dipping pattern, but the therapeutic consequences of this are unknown.