The spectrum of circadian blood pressure changes in type I diabetic patients

The many faces of hypertension in individuals with type 1 diabetes

Several disturbed blood pressure (BP) patterns, including disparities between office and out-of-office BP measurements (such as white-coat and masked hypertension), disturbed circadian BP variability (such as abnormal dipping patterns and nocturnal hypertension) and treatment-resistant hypertension, are common in individuals with type 1 diabetes. Consequently, office or home BP measurements alone may not reflect real BP variation and may lead to inadequate diagnosis and treatment of hypertension. The early detection of these disturbed BP patterns is especially crucial in individuals with type 1 diabetes, as these patterns may indicate future development of adverse cardiovascular and renal outcomes. In this review we will describe these disturbed BP patterns and discuss recent findings on their prevalence and outcomes. We will also address critical areas for future research to determine the true prevalence and prognosis of disturbed BP patterns, and to optimize and improve the knowledge and management of high-risk individuals with type 1 diabetes and disturbed BP patterns.

Non-dipping and higher nocturnal blood pressure are associated with risk of mortality and development of kidney disease in type 1 diabetes

AIMS

People with type 1 diabetes have increased risk of cardiovascular (CV) and kidney disease. A 24-hour ambulatory blood pressure (BP) measurement (ABPM) examines diurnal variations in BP. We aimed to determine the prognostic significance of blunted decrease in nocturnal systolic BP of <10 % (non-dipping of nocturnal BP) for CV- and kidney disease and all-cause mortality in type 1 diabetes.

METHODS

From 2009 to 2011, at Steno Diabetes Center Copenhagen, 654 participants with type 1 diabetes had 24-hour ABPM obtained with a tonometric wrist-watch device (BPro, HealthStats, Singapore). In 2017, outcomes (composite CV endpoint; all-cause mortality; decline in estimated glomerular filtration rate (eGFR) ≥30 %; end-stage kidney disease (ESKD); and a composite kidney endpoint including decline in eGFR ≥30 %, ESKD and all-cause mortality) were registered. Hazard Ratios (HR) were calculated using Cox regressions.

RESULTS

Participants were mean ± SD 55 ± 13 years old and had median (IQR) 35 (24-44) years diabetes duration. Mean daytime and nocturnal systolic BP were 133 ± 16 and 121 ± 16 mmHg while 337 (52 %) participants demonstrated non-dipping. After CV risk factor adjustments, non-dipping was associated with all-cause mortality (HR 2.12 (1.09-4.11), p = 0.03) and the composite kidney endpoint (HR 1.92 (1.23-3.00), p = 0.004).

CONCLUSIONS

Non-dipping entailed increased risk of all-cause mortality and kidney disease in type 1 diabetes.

Effect of Chronotherapy of Antihypertensives in Chronic Kidney Disease: A Randomized Control Trial

Introduction:

There is a higher prevalence of non-dipping pattern in hypertensive chronic kidney disease (CKD) patients. Nocturnal hypertension has been shown to predict cardiovascular mortality and morbidity and is often superior to daytime blood pressure. We studied the effect of shifting or adding antihypertensive to night time on blood pressure profile of CKD III-IV patients.

Methods:

In this single-center, prospective, randomized controlled trial, eligible participants were adults from eastern India aged 18–65 years with CKD stages 3 and 4, with a non-dipping pattern on ambulatory blood pressure monitor (ABPM). The intervention group received all the antihypertensives in the night time whereas the standard care group continued to take the medication in the morning. Both groups were followed up for 1 year. The primary outcome was the number of patients changed from non-dippers to dippers in the standard care group and intervention group. Secondary outcomes included a change in estimated glomerular filtration rate (eGFR) and change in the cardiac structure.

Results:

39 patients in the intervention group and 36 patients in the standard care group were analyzed. 10 patients (26%) reverted to dipping pattern in the intervention group as compared to none in the standard care group. Mean changes in eGFR were −2.55 and −0.18 mL/min/1.73 m² in the standard care and intervention group at the end of the study, respectively. Between-group difference in eGFR was significant at 1 year (5.22 [95% CI, 4.3–6.1] ml/min/1.73 m²); (P = 0.03). The cardiac structure showed no significant changes in either group.

Conclusions:

Bedtime administration of antihypertensives reverted non-dippers to dippers and slowed the decline in eGFR in CKD stages 3 and 4 compared to morning administration of antihypertensives.

Association between blood pressure variability, cardiovascular disease and mortality in type 2 diabetes: A systematic review and meta-analysis

AIM

To investigate the associations of blood pressure variability (BPV), expressed as long-term (visit-to-visit) and short-term (ambulatory blood pressure monitoring [ABPM] and home blood pressure monitoring [HBPM]) and all-cause mortality, major adverse cardiovascular events (MACEs), extended MACEs, microvascular complications (MiCs) and hypertension-mediated organ damage (HMOD) in adult patients with type 2 diabetes.

MATERIALS AND METHODS

PubMed, Medline, Embase, Cinahl, Web of Science, ClinicalTrials.gov and grey literature databases were searched for studies including patients with type 2 diabetes, at least one variable of BPV (visit-to-visit, HBPM, ABPM) and evaluation of the incidence of at least one of the following outcomes: all-cause mortality, MACEs, extended MACEs and/or MiCs and/or HMOD. The extracted information was analyzed using random effects meta-analysis and meta-regression.

RESULTS

Data from a total of 377 305 patients were analyzed. Systolic blood pressure (SBP) variability was associated with a significantly increased risk of all-cause mortality (HR 1.12, 95% CI 1.04-1.21), MACEs (HR 1.01, 95% CI 1.04-1.17), extended MACEs (HR 1.07, 95% CI 1.03-1.11) and MiCs (HR 1. 12, 95% CI 1.01-1.24), while diastolic blood pressure was not. Associations were mainly driven from studies on long-term SBP variability. Qualitative analysis showed that BPV was associated with the presence of HMOD expressed as carotid intima-media thickness, pulse wave velocity and left ventricular hypertrophy. Results were independent of mean blood pressure, glycaemic control and serum creatinine levels.

CONCLUSIONS

Our results suggest that BPV might provide additional information rather than mean blood pressure on the risk of cardiovascular disease in patients with type 2 diabetes.

Circadian regulation of renal function

The kidneys regulate many vital functions that require precise control throughout the day. These functions, such as maintaining sodium balance or regulating arterial pressure, rely on an intrinsic clock mechanism that was commonly believed to be controlled by the central nervous system. Mounting evidence in recent years has unveiled previously underappreciated depth of influence by circadian rhythms and clock genes on renal function, at the molecular and physiological level, independent of other external factors. The impact of circadian rhythms in the kidney also affects individuals from a clinical standpoint, as the loss of rhythmic activity or clock gene expression have been documented in various cardiovascular diseases. Fortunately, the prognostic value of examining circadian rhythms may prove useful in determining the progression of a kidney-related disease, and chronotherapy is a clinical intervention that requires consideration of circadian and diurnal rhythms in the kidney. In this review, we discuss evidence of circadian regulation in the kidney from basic and clinical research in order to provide a foundation on which a great deal of future research is needed to expand our understanding of circadian relevant biology.

Nocturnal blood pressure is associated with the progression of microvascular complications and hypertension in patients with type 1 diabetes mellitus

AIMS

To evaluate relationships between early alterations in blood pressure and the progression of microvascular complications of diabetes in clinically-normotensive patients with type 1 diabetes (T1DM).

METHODS

In a prospective observational study of 85 normotensive T1DM patients without microalbuminuria, blood pressure (BP) was monitored over 24h using the ambulatory blood pressure monitoring (ABPM) system at baseline and 7years later. Development or progression of microalbuminuria, retinopathy and hypertension was evaluated.

RESULTS

Initially, 20 patients (24%) were diagnosed with masked hypertension and 31 (37%) with non-dipper pattern as the only pathological findings. At 7years: 1) twenty-seven patients (32%) had progression of retinopathy related to the nocturnal diastolic blood pressure (BPD) (OR:1.122; p=0.034) and final non-dipper pattern (OR:5.857; p=0.005); 2) seven patients (10%) developed microalbuminuria for which nocturnal systolic blood pressure (BPS) was a risk factor (OR:1.129; p=0.007); 3) five of the normotensive patients (9%) progressed to hypertension; historic HbA1c (OR:2.767; p=0.046) and nocturnal BPD (OR:1.243; p=0.046) being the related risk factors. BPD level ≥65mmHg was associated with an increase in progression of retinopathy and hypertension.

CONCLUSIONS

In T1DM patients there is an elevated prevalence of BP alterations, detected using ABPM. Alterations in nocturnal BP predispose to development/progression of microvascular complications and overt hypertension.

Autonomic Dysfunction: How to Identify and When to Treat?

Cardiovascular autonomic dysfunction (AD) is a particular condition that can be detected by means of ambulatory blood pressure monitoring (ABPM). ABPM is helpful to identify some specific characteristics of haemodynamic AD, including non-dipping/reverse-dipping pattern, orthostatic and post-prandial hypotension and elevated blood pressure variability. These characteristics may be misdiagnosed with traditional, clinic blood pressure measurements. AD is relatively common in the real world. By analysing about 1000 recordings in a Cardiology unit, AD was found in 6.8 % of the exams. Several diseases may be the underlying causes of AD. In our sample half of the subjects were diabetic (54.4 %), 17.7 % were patients with alpha-synucleinopathy (Parkinson disease or multiple system atrophy), and 27.9 % had other underlying causes of AD including chronic kidney disease, α-lytic drug assumption and AD from unknown causes. According to the different aetiology, different clinical characteristics can be found, in particular in diabetics these peculiar aspects are less pronounced compared to the other subgroups. These characteristics have been found to be predictors of cardiovascular events, organ damage, and mortality. For these reasons, early identification of these behaviours is important, in order to better define patient's cardiovascular risk profile. As regard treatment of AD, several drugs have been tested, however none of this showed efficacy in all kinds of patients. Another open aspect is "safe" reference values for supine hypertension.

Prognostic significance of dipping in older hypertensive patients

BACKGROUND AND AIMS

Arterial hypertension doubles the risk of coronary heart disease, heart and kidney failure, and peripheral arterial disease. Less variation in diurnal ambulatory blood pressure monitoring (ABPM) patterns may affect mortality outcome. Therefore, as hypertension occurs in over 95% of older subjects, the prognostic value of dipping status in older hypertensive patients will be assessed.

METHOD

The retrospective study group consisted of 170 hypertensive patients, aged 75-84 years, enrolled in the years 2005 to 2007. Baseline measures included 24-h ABPM. Diurnal index and dipping status was calculated and stratified the group into dippers (40 patients, 23.5%), non-dippers (65 patients, 38.2%) and reverse-dippers (65 patients, 38.2%).

RESULTS

During a 5-year observation, after baseline we have observed 69 deaths (40.9%) from the whole group of 170 patients with 23 (35.4%) being non-dippers and 36 (55.4%) reverse-dippers. There were significant differences between the groups divided according to diurnal dipping status in survival time, number of recorded deaths and night mean blood pressure. We have identified and confirmed risk factors for the all-cause mortality: age, mean systolic and diastolic blood pressure, diurnal index and dipping status (dipping, non-dipping or reverse-dipping).

CONCLUSION

Reverse-dippers and non-dippers revealed worse prognosis compared with dippers.

Differences in circadian time structure of diastolic blood pressure between diabetes mellitus and essential hypertension

BACKGROUND

Abnormal circadian blood pressure patterns have been associated with cardiovascular disease in diabetes mellitus. We have described that the acrophase of diastolic blood pressure (DBP) registered in type 1 diabetes (T1D) patients was significantly earlier than normal and DBP ecphasia was more pronounced in patients with lower heart rate variability during deep breathing. The aim of this study was to compare the circadian rhythm characteristics of BP among different groups: normotensive (NT) control subjects, patients affected by T1D and type 2 diabetes (T2D), and patients with essential hypertension (HT).

FINDINGS

We retrospectively evaluated ambulatory blood pressure monitoring records in 30 NT, 20 T1D, 20 T2D, 20 HT whose fasting plasma glucose and HbA1c were contemporaneously measured. The four groups were well-matched regarding age, gender, and BMI.Systolic blood pressure (SBP) and DBP midline-estimating statistic of rhythm were higher in T1D, T2D, and HT groups. DBP ecphasia was present only in the diabetic individuals: the acrophase of DBP occurred four hours earlier than normal in T1D group, whereas two hours earlier in T2D group. In a multiple regression analysis, only HbA1c and SBP acrophase were statistically significant correlates of DBP acrophase.

CONCLUSIONS

People with diabetes mellitus, both type 1 and type 2, have their circadian acrophase of DBP occurring 2-4 hours earlier than normotensive and hypertensive subjects. Altered circadian timing of DBP, potential trigger of cardiovascular events, seems to be a distinguishing feature of diabetes mellitus and correlates with the previous 2-3 months of glycaemic control.

Alterations in arterial pressure in patients with Type 1 diabetes are associated with long-term poor metabolic control and a more atherogenic lipid profile

AIM

To determine the prevalence of alterations in blood pressure (BP) in patients with Type 1 diabetes who are normoalbuminuric and normotensive; and to evaluate the association with genetic, clinical and metabolic factors. MATERIAL/ METHODS: Normoalbuminuric, normotensive Type 1 diabetic patients (no.=85) had their ambulatory blood pressure monitoring (ABPM) performed over 24 h, together with measurement of HbA1c and lipid profile, polymorphisms of the ACE gene, non-midriatic retinography, and the "historical HbA1c" calculated (mean of all the determinations available on the patient).

RESULTS

Of the 85 patients, a mean of 18.8% had pathologic values of BP over the 24 h, 31.8% during active periods and 22.4% during rest periods; in 42% there was a non-dipper pattern in BP. The patients with alterations of BP had higher body mass index (BMI), higher levels of glycemia and of triglycerides, and decreased levels of HDL cholesterol. The "historical HbA1c" was significantly higher in the patients with the non-dipper pattern (8.6 ± 1.4% vs 7.9 ± 1.4%; p=0.046). Pulse pressure was directly associated with male gender (p=0.006) and with BMI (p=0.001). No differences were detected in the distribution of the polymorphisms of the ACE gene as a function of the BP alterations.

CONCLUSIONS

An elevated number normoalbuminuric, normotensive, Type 1 diabetic patients have alterations in BP detected with ABPM over 24 h, and these are associated with a greater BMI, poor long-term metabolic control and a more atherogenic lipid profile.

Nocturnal blood pressure fall as predictor of diabetic nephropathy in hypertensive patients with type 2 diabetes

BACKGROUND

Hypertensive patients with reduced blood pressure fall (BPF) at night are at higher risk of cardiovascular events (CVE).

METHODS

We evaluated in hypertensive diabetic patients, if a reduced nocturnal BPF can precedes the development of diabetic nephropathy (DN). We followed 70 patients with normal urinary albumin excretion (UAE) for two years. We performed 24-hours ambulatory BP monitoring in baseline and at the end of the study.

RESULTS

Fourteen (20%) patients (GI) developed DN (N = 11) and/or CVE (n = 4). Compared to the remaining 56 patients (GII) in baseline, GI had similar diurnal systolic (SBP) and diastolic BP (DBP), but higher nocturnal SBP (138 +/- 15 vs 129 +/- 16 mmHg; p < 0.05) and DBP (83 +/- 12 vs 75 +/- 11 mmHg; p < 0,05). Basal nocturnal SBP correlated with occurrence of DN and CVE (R = 0.26; P < 0.05) and with UAE at the end of the study (r = 0.3; p < 0.05). Basal BPF (%) correlated with final UAE (r = -0.31; p < 0.05). In patients who developed DN, reductions occurred in nocturnal systolic BPF (12 +/- 5 vs 3 +/- 6%, p < 0,01) and diastolic BPF (15 +/- 8 vs 4 +/- 10%, p < 0,01) while no changes were observed in diurnal SBP (153 +/- 17 vs 156 +/- 16 mmHg, NS) and DBP (91 +/- 9 vs 90 +/- 7 mmHg, NS). Patients with final UAE < 20 microg/min, had no changes in nocturnal and diurnal BP.

CONCLUSIONS

Our results suggests that elevations in nocturnal BP precedes DN and increases the risk to develop CVE in hypertensive patients with T2DM.

Prognostic value of subdivisions of nighttime blood pressure fall in hypertensives followed up for 8.2 years. Does nondipping classification need to be redefined?

To evaluate the long-term prognostic significance of different ranges of the percentage fall in nighttime blood pressure (BP) of the nondipping pattern, 1200 hypertensive patients (645 women, age 51+/-12 years) underwent ambulatory BP monitoring under stabilized therapy. The occurrence of cardiovascular (CV) events was followed for 9833 patient-years and analyzed by the Cox hazard model. There were 152 CV fatal/nonfatal events (79 strokes, 51 coronary events, 22 others) during the 15.2 years of follow-up. According to nighttime BP fall (%) the authors noted: <0% (reverse-dippers [RD], n=83); 0%-4.9% (nondippers 1 [ND1], n=207); 5%-9.9% (nondippers 2 [ND2], n=311), 10%-19.9% (dippers [D], n=523); and > or =20% (extreme dippers [ED], n=76). After adjustment for confounding variables, hazard ratios (95% confidence interval) of CV event and stroke in RD vs D were 2.29 (1.31-3.99) and 2.46 (1.11-5.49); of ND1 vs D were 1.42 (1.12-1.79) and 1.62 (1.17-2.23); and of ND1 vs ND2 were 2.24 (1.33-3.75) and 2.30 (1.15-4.58). No differences were found in RD vs ND1 and ND2 vs D. Nondippers have a higher CV risk than dippers but only for a nighttime BP fall <5% suggesting that the limits for nondipping should be redefined for a stratification of CV risk.

The natural progression of kidney injury in young type 1 diabetic patients

Diabetes is the most common cause of end-stage renal disease in industrialized countries. This article describes the structural changes in early diabetic nephropathy and the relationship with renal functional parameters, blood pressure, and albumin excretion. The detrimental influence of sustained hyperglycemia and/or glycemic fluctuations on renal structural change has been well documented. Tight glycemic control is paramount to preventing the development, and even the regression, of renal lesions. As much of the renal injury from diabetes occurs in clinical silence before symptoms or laboratory findings of renal injury are evident, finding early markers of risk is imperative so that nephropathy can be prevented. Currently, the only clinical surrogate marker of diabetic renal injury available is microalbuminuria. However, given the reports of regression of microalbuminuria back to normoalbuminuria, the reliability of this tool as an indicator of risk has been questioned. The need for alternative, noninvasive surrogate markers is described in this report.

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.

Glomerular filtration rate is related to dipping pattern in ambulatory blood pressure monitoring--a cross-sectional population-based study

A non-dipping pattern in ambulatory blood pressure monitoring (ABPM) increases the risk of cardiovascular disease. The association between renal function and the dipping pattern has not been studied in a random middle-aged population. This is a cross-sectional population-based study of 226 males and 234 females aged 40 to 62 years. Renal function was assessed with estimated glomerular filtration rate (eGFR). Non-dipping status was defined as a reduction of <10% between the daytime and the nighttime systolic BP. Non-dippers represented 18.7% of the study population. Their mean eGFR was 79.1 (s.d. 15.7) ml min(-1) per 1.73 m(2) as compared with a mean eGFR of 84.1 (s.d. 16.2) ml min(-1) per 1.73 m(2) in dippers (P=0.005); this difference remained significant after adjustments. Subjects in the lowest and in the middle eGFR tertiles had an independently increased risk of non-dipping in comparison with those in the highest eGFR tertile (odd ratios (OR), 2.34 (95% confidence interval (CI), 1.18 to 4.63) and OR, 2.01 (95% CI, 1.06 to 3.83), respectively). This study showed that even a minor deterioration in renal function is associated with increased risk of non-dipping pattern in ABPM in a random middle-aged population.

Clinical variables associated with non-dipping of nocturnal blood pressure in type 2 diabetes

Aim

Non-dipping of nocturnal BP (blood pressure) is common in people with type 2 diabetes and is associated with increased risk of cardiovascular morbidity and mortality. This study aimed to identify the factors associated with nocturnal non-dipping of BP in people with type 2 diabetes.

Methods

Data were examined from 100 people with type 2 diabetes who had undergone ambulatory BP monitoring. Dippers were defined as those with a systolic night-time BP dip over 15%, and non-dippers as those with a systolic night-time BP dip of under 5%.

Results

There was no significant difference between the mean awake systolic BP in the dipping (142.9 mmHg) and the non-dipping (142.0 mmHg) groups (p=0.77). Non-dippers were significantly older (p<0.0001) with a higher prevalence of albuminuria (p=0.003) and of macrovascular disease (p=0.008) when compared with the dipping group. After adjustment for age, albuminuria remained more prevalent within the non-dipping group (p=0.007). There was no significant difference in glycaemic control, type of diabetes treatment, smoking status, or gender between the groups.

Conclusion

Albuminuria is strongly associated with non-dipping of nocturnal BP in people with type 2 diabetes.

Ambulatory blood pressure monitoring and target organ damage in pediatrics

The prevalence of hypertension in children and adolescents is rising in association with the increasing rate of childhood obesity, and it is associated with early target organ damage. Published guidelines on high blood pressure in children and adolescents, focused on the early and accurate diagnosis of hypertension, resulted in improved ability to identify children with hypertension. Although auscultation using a mercury sphygmomanometer remains the method of choice for evaluation of hypertension in children, accumulating evidence suggests that ambulatory blood pressure monitoring is a more accurate method for diagnosis, and it is more closely associated with target organ damage. In addition, ambulatory blood pressure monitoring is a valuable tool in the assessment of white-coat hypertension, and masked hypertension in children and adolescents. Masked hypertension in children and adolescents is associated with a similar risk of target organ damage as in established hypertension.

Impaired diurnal blood pressure variation and all-cause mortality

BACKGROUND

Most healthy people exhibit a decrease in systolic blood pressure (SBP) at night. A drop of <10% from mean daytime values, "non-dipping," is associated with kidney disease and cardiovascular events. We hypothesized that non-dipping would predict all-cause mortality.

METHODS

Consecutive patients referred for ambulatory blood pressure (BP) monitoring at the Cleveland Clinic between 1994 and 2004 were included. Mean daytime (6 AM-11 PM) and nighttime (11 PM-6 AM) SBP values were calculated. We examined diurnal BP variation as a continuous variable, ((Mean daytime SBP - Mean nighttime SBP)/(Mean daytime SBP)) x 100%, and also as a categorical variable, defining "non-dipping" as a nocturnal SBP drop of <10%; subjects who exhibited non-dipping were defined as "non-dippers" and the others as "dippers." All-cause mortality was ascertained from the Social Security Death Index.

RESULTS

Of the 621 patients included in the study, 261 were dippers and 360 were non-dippers. Non-dippers were older (P < 0.0001), more likely to be non-white (P < 0.05), and had higher rates of smoking, diabetes, hypertension, coronary artery disease, congestive heart failure, and renal insufficiency (P < 0.01 for all). Over a mean follow-up of 6.3 years, 61 patients died, including 10 dippers (3.8%) and 51 non-dippers (14.2%). The unadjusted hazard ratio for death based upon a decrement in the dipping percentage from the 75th to 25th percentile was 2.22 (95% confidence interval 1.64-2.95; P < 0.0001). This was attenuated after adjustment for comorbid conditions, including mean 24-h SBP and renal function: adjusted hazard ratio 1.62 (1.14-2.24; P < 0.005).

CONCLUSIONS

Blunted diurnal BP variation is a strong predictor of death, but this may be accounted for, in large part, by its association with other cardiovascular risk factors.

Non-dipping blood pressure in the metabolic syndrome among Arabs of the Oman family study

OBJECTIVE

The objective was to examine the circadian changes in blood pressure and their relation to the metabolic syndrome and its components in Omani Arabs.

RESEARCH METHODS AND PROCEDURES

Ambulatory blood pressure (ABPM) was recorded in 1124 subjects from 5 large, extended, consanguineous, and young Arab pedigrees. According to the International Diabetes Federation's definition, 264 subjects had the metabolic syndrome, a prevalence of 23%. Subjects were defined as non-dippers when their nocturnal systolic blood pressure (SBP) fell by <10% from daytime SBP.

RESULTS

Non-dippers with the metabolic syndrome were 131 of 264 (50%), compared with 265 of 860 (31%) without the metabolic syndrome. Of the non-dippers, 99 of 131 (76%) were females and 32 of 131 (24%) were males. Daytime and nighttime SBP and DBP and nighttime pulse pressure were significantly higher in non-dipper subjects with the metabolic syndrome. The important determinants of a non-dipping BP in this cohort were high BMI and high serum triglycerides.

DISCUSSION

We hypothesize that obesity and nocturnal volume-dependent hypertension may be involved in the pathophysiology of non-dipping in the metabolic syndrome. This study showed that non-dipping BP was common in subjects with the metabolic syndrome. Higher 24-hour blood pressure load may add to the indices of the overall cardiovascular burden already associated with the metabolic syndrome.

Reproducibility of dipping/nondipping pattern in untreated essential hypertensive patients: impact of sex and age

OBJECTIVE

We aimed to evaluate the intrasubject short-term reproducibility of nocturnal blood pressure patterns (dipping/nondipping) in essential hypertensive patients in relation to age (<50 and > or =50 years) and sex.

METHODS

A total of 619 never-treated essential grade 1 and 2 hypertensive patients (383 men, 236 women) underwent the following procedures: (1) repeated clinic blood pressure measurements, (2) routine examinations, (3) ambulatory blood pressure monitoring over two 24-h periods within 4 weeks. Dipping pattern was defined as a 10%, or more, reduction in average systolic blood pressure/ diastolic blood pressure at night compared to daytime values.

RESULTS

Of the 407 patients showing a dipping pattern during the first ambulatory blood pressure monitoring period, 329 (80.1%) had the same pattern during the second ambulatory blood pressure monitoring recording. Of the 212 patients with a nondipping pattern during the first ambulatory blood pressure monitoring period, 140 (65.9%) confirmed the same pattern during the second ambulatory blood pressure monitoring period. Overall, 149 patients (24.1%) changed their initial nocturnal pattern at the second ambulatory blood pressure monitoring recording, without significant age and sex-related differences. Lower reproducibility rates of the nondipping as compared to the dipping pattern were found in the whole population as well as in men regardless of age and in younger but not in older women.

CONCLUSIONS

These findings indicate that nocturnal blood pressure patterns have a limited short-term reproducibility in the whole study population as well as in different age and sex subgroups. As variability of nocturnal blood pressure patterns is not predicted by easy available clinical data, such as sex and age, a reliable classification of patients according to circadian blood pressure patterns should be obtained by repeating ambulatory blood pressure monitoring.

Prognostic significance of the white coat hypertension in patients with type 1 diabetes mellitus

Despite the high prevalence of white coat hypertension (WCH) in diabetes mellitus and the evidence that hypertension is a clear risk factor for the development of microalbuminuria (MA) in these patients, there is no information on the long-term prognostic significance of this condition in the diabetic population. We studied the evolution of 40 patients with type 1 diabetes mellitus (Type 1 DM). Twenty patients with WCH (office blood pressure> or =140/90mmHg associated with mean daytime blood pressure<135/85mmHg) classified as the WCH group and 20 patients with type 1 DM with a similar age and disease evolution, but who were normotensive, (office blood pressure<140/90mmHg associated with mean daytime blood pressure<135/85mmHg) classified as the normotensive control group. After 5 years of follow-up, MA appeared in four subjects and sustained hypertension in another, with a total of 31% of events in the WCH group, with none in the normotensive group. Kaplan-Meier analysis showed that the relative risk of developing these hypertensive events was 25% higher in the WCH group. At baseline, the night time systolic and diastolic blood pressure levels were significantly higher in patients who further developed MA and sustained hypertension. The findings in this study highlight the clinical importance of careful follow-up of type 1 diabetic patients with WCH.

The early natural history of nephropathy in Type 1 Diabetes: III. Predictors of 5-year urinary albumin excretion rate patterns in initially normoalbuminuric patients

Predictors of albumin excretion rate (AER) abnormalities could provide earlier indicators of diabetic nephropathy risk. Data from the Natural History Study, a prospective 5-year observation of renal structure and function in young type 1 diabetic patients, were examined for predictors of AER patterns in normoalbuminuric type 1 diabetic patients. Included were 170 patients (96 females) (aged 16.7 +/- 5.9 years, duration of diabetes 8.0 +/- 4.3 years) with normal blood pressure, normoalbuminuria (AER <20 microg/min), and eight or more follow-up visits over 5 years. AER, blood pressure, and HbA1c (A1C) were determined quarterly and glomerular filtration rate (GFR) annually. Persistent microalbuminuria (PMA) was defined as 20-200 microg/min in two of three consecutive values within 6-12 months. Four different AER patterns were identified. Group 1 (n = 99): all values <20 microg/min. Group 2 (n = 49): intermittent levels >20 microg/min but not meeting microalbuminuria criteria. Group 3 (n = 14): PMA during follow-up but normoalbuminuria at study exit. Group 4 (n = 8): microalbuminuria at study exit. Group 4 (497 +/- 95 nm, P < 0.01) and group 3 (464 +/- 113 nm, P = 0.03) patients had greater baseline glomerular basement membrane (GBM) width versus group 1 (418 +/- 67 nm). Baseline GFR in group 4 (163 +/- 37 ml.min(-1). 1.73 m(-2)) was higher than group 1 (143 +/- 28 ml.min(-1) . 1.73 m(-2), P = 0.04). A1C was higher in group 2 (9.0 +/- 1.2%) than group 1 (8.4 +/- 1.1%, P = 0.008). Thus, greater increases in GBM width and GFR were predictors of PMA. Since 64% of the patients that developed microalbuminuria reverted to normoalbuminuria, the risk of diabetic nephropathy as defined by current microalbuminuria criteria is unclear.

The normal circadian pattern of blood pressure: implications for treatment

Blood pressure fluctuates over 24 h following a circadian rhythm that reaches a peak in the morning shortly after awakening. The onset of many acute cardiovascular and cerebrovascular events shows a synchronous cyclical pattern, with the highest incidence of morbidity and mortality in the early morning hours. Strong, although circumstantial, evidence suggests that the early morning surge in blood pressure may contribute to the onset of acute cardiovascular episodes. Sustained blood pressure control that blunts the early morning blood pressure surge may help to reduce the incidence of these events. Antihypertensive agents are needed that provide smooth and sustained blood pressure control for the full 24 h, including the risky early morning hours. The angiotensin II receptor blocker telmisartan given once daily, because of its long half-life and mechanism of action, is likely to confer benefit in terms of 24-h blood pressure control and may reduce cardiovascular risk at the time of greatest patient vulnerability.

Relation of diurnal blood pressure variation and triglyceride-to-high-density lipoprotein cholesterol ratio in patients without diabetes mellitus

A night-time decrease in systolic blood pressure that differs <10% from mean daytime values ("nondipping") is associated with increased rates of cardiovascular morbidity and mortality. We hypothesized that insulin resistance would be associated with nondipping in patients who did not have frank diabetes mellitus or hypertension. We included 106 consecutive outpatients who had been referred for 24-hour ambulatory monitoring of blood pressure. Our data suggest that insulin resistance, defined as a high ratio of triglyceride to high-density lipoprotein, is associated with blunted diurnal blood pressure variation (odds ratio 6.3, 95% confidence interval 2.6 to 16.4, p <0.0001) before the development of abnormal levels of fasting blood glucose.

Predictors of progression in hypertensive renal disease in children

In hypertensive renal disease in children, several risk factors influence the development and the rate of progression of renal damage, including blood pressure levels, proteinuria, lipid disorders, and genetic differences. The impact of blood pressure on renal structures, the most important of the factors, depends not only on blood pressure levels, but also on the persistence of the blood pressure levels over time, mainly during the hours when the patient is resting or sleeping. Abnormal circadian variability is frequently observed in patients with renal damage, and nocturnal blood pressure reduction should be a major therapeutic objective to protect against a decline in renal function. Proteinuria is a guide for establishing targets and for monitoring treatment. It should be reduced as much as possible to obtain maximal renoprotective effect. The role of the other factors, such as lipid disorders and genetics, remains elusive.

Nondipping and its relation to glomerulopathy and hyperfiltration in adolescents with type 1 diabetes

OBJECTIVE

To determine whether there is a relation between dipping/nondipping status and end-organ damage (measured as renal glomerulopathy) and long-term renal function in order to predict the development of nephropathy in normoalbuminuric patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Analysis of renal biopsy and ambulatory blood pressure measurements was done in relation to renal function tests performed during a 10-year period. Forty unselected patients (16 girls), with a mean age of 17.7 years and a mean duration of 10.7 years, were studied. The renal biopsies were examined by electron microscopy. Ambulatory blood pressure was monitored (Space Labs 90 207). Systolic nondippers were defined as a <7%, diastolic nondippers as a <14%, and mean arterial blood pressure (MAP) nondippers as a <12% fall in blood pressure during the night. Renal function was evaluated every other year by clearances of inulin (glomerular filtration rate [GFR]) and para-amino hippurate (effective renal plasma flow [ERPF]), and filtration fraction (GFR/ERPF) was calculated. Overnight urinary albumin excretion rate and long-term mean HbA(1c) were measured.

RESULTS

MAP (27% of the patients) and diastolic nondippers (12%) had a significantly thicker basement membrane; larger mesangial matrix volume fraction; and higher long-term GFR, nighttime heart rate, and mean HbA(1c) than dippers.

CONCLUSIONS

Nondipping status was related to more renal morphological changes and long-term hyperfiltration in normoalbuminuric adolescents and young adults, despite a short duration of type 1 diabetes. Nondipping status may be an early predictor of later nephropathy.

Circadian and orthostatic blood pressure is abnormal in the carotid sinus syndrome

The authors' objective was to determine circadian blood pressure behavior and the prevalence of orthostatic hypotension in patients with cardioinhibitory carotid sinus syndrome. A prospective consecutive series of 160 patients (mean age, 72 [65-83]) with recurrent syncope attributed to cardioinhibitory carotid sinus syndrome was recruited. Mean maximal slowing of heart rate was 4.5 seconds (3.0-5.5 seconds) during carotid sinus massage. Patients had cardiovascular assessments, including 24-hour ambulatory blood pressure measurements (recordings every half-hour during daytime, hourly at night) and morning orthostatic blood pressures before pacemaker implants. Ambulatory measurements were compared with those of 98 age- and sex-matched controls. Nocturnal systolic blood pressure (130.0+/-21.0 vs. 122.1+/-16.7 mm Hg; p<0.005), diastolic blood pressure (72.8+/-12.5 vs. 68.7+/-9.7 mm Hg; p<0.005), and heart rate (66.5+/-9.4 vs. 65.2+/-9.7 bpm; p<0.005), were significantly higher in patients and independent of cardiovascular medication, cardiovascular diagnoses, and orthostatic hypotension. Almost one half of carotid sinus syndrome patients also had orthostatic hypotension. Blood pressure behavior is abnormal in patients with carotid sinus syndrome as represented by altered nocturnal blood pressures and high prevalence of orthostatic hypotension.

Circadian changes in blood pressure and their relationships to the development of microalbuminuria in type 1 diabetic patients

Diabetic nephropathy in type I diabetic patients, as it is currently understood, progresses in a stepwise fashion from normoalbuminuria to microalbuminuria, then to overt proteinuria and progression to chronic renal failure, and ultimately to end-stage renal disease. The role of early blood pressure changes in relation to diabetic nephropathy is now better understood in light of recent data using ambulatory blood pressure monitoring as a means to monitor blood pressure changes noninvasively throughout the day. Cross-sectional studies with type I diabetic patients with microalbuminuria have shown that the normal nocturnal blood pressure often fails to fall normally during sleep. The question of which comes first, microalbuminuria or a rise in blood pressure in patients with type I diabetes, was recently addressed in a prospective study. An increase in systolic blood pressure during sleep precedes the development of microalbuminuria and may play a causative role in its development.

Circadian pattern of blood pressure, heart rate, and double product in liver glycogen storage disease

The objective of this study was to determine systolic, diastolic, and mean arterial blood pressure (SBP, DBP, and MAP), heart rate (HR), double-product (DP: SBP x HR), and activity levels and their 24h pattern in liver glycogen storage disease (LGSD) patients. A case series of 12 (11 pediatric and one adult) diurnally active LGSD (seven type I, three type III, and two type IX) subjects were simultaneously assessed by 24h ambulatory blood pressure monitoring and wrist actigraphy. Nine subjects were judged to be hypertensive based on the criterion of an elevated 24h mean SBP and/or DBP being elevated beyond reference standards or the SBP and/or DBP load (percentage of time BP exceeds normal values) being greater than 25%. Two of the three other subjects, not viewed as hypertensive based on their 24h average SBP or DBP, exhibited daytime or nighttime SBP and/or DBP load hypertension. Each study variables displayed statistically significant (p < 0.001) group circadian rhythmicity. The SBP, DBP, and MAP displayed comparable 24h patterns of appreciable amplitude (total peak-trough variation equal to 17.7, 23.6, and 19.6%, respectively, of the 24h mean) with highest values (orthophase) occurring approximately 11 h after the commencement of daytime activity. The sleep-time trough (bathyphase) occurred approximately 4.5 h before morning awakening. The statistically significant (p < 0.006) circadian rhythms of HR (amplitude equal to 33.2% of the 24h mean) and DP (amplitude equal to 49.4% of the 24h mean) peaked earlier, approximately 7.4 h into the daytime activity span. The sleep-time trough occurred approximately 3 h before morning awakening. The 24h pattern in the cardiovascular variables was correlated with the 24h pattern of activity, with r ranging from 0.50 for DBP to 0.39 for HR.

Overview of ambulatory blood pressure monitoring in childhood and pregnancy

Despite the fact that the study and applicability of ambulatory blood pressure in children and pregnant women share characteristics which limit the potential development of knowledge for their use, advances produced in the last few years provided the present knowledge regarding the significance and the potential use of ambulatory blood pressure in children and in the pregnant women. In children ambulatory blood pressure monitoring is useful for the diagnosis of mild hypertensives, assessment of refractory hypertension, therapeutic trials with antihypertensive drugs, and clinical investigation when BP is one of the parameters to be taken into account and/or when subtle BP abnormalities are the objective of the study. In pregnant women, the main applicability is to assess the maternal and fetal risk in the hypertensive disorders of pregnancy.