Relation of blood pressure variability to carotid atherosclerosis and carotid artery and left ventricular hypertrophy

Exploring the link between blood pressure variability and atrial fibrillation: current insights and future directions

Atrial fibrillation (AF) is the most common heart rhythm disorder, especially in people over the age of 50, which affects more than 40 million people worldwide. Many studies have highlighted the association between hypertension with the development of AF. Blood pressure variability (BPV) is a dynamic size obtained by recording blood pressure oscillations using specific readings and at specific time intervals. A multitude of internal and external factors shape BPV while at the same time constituting a common pathogenetic pathway with the development of AF. Until recently, BPV has been applied exclusively in preclinical and clinical studies, without significant implications in clinical practice. Indeed, even from the research side, the determination of BPV is limited to patients without AF due to doubts about the accuracy of its measurement methods in patients with AF. In this review, we present the current evidence on common pathogenic pathways between BPV and AF, the reliability of quantification of BPV in patients with AF, the prognostic role of BPV in these patients, and discuss the future clinical implications of BPV in patients with AF.

Knowledge fields and emerging trends about extracellular matrix in carotid artery disease from 1990 to 2021: analysis of the scientific literature

BACKGROUND

Stroke is a heavy burden in modern society, and carotid artery disease is a major cause. The role of the extracellular matrix (ECM) in the development and progression of carotid artery disease has become a popular research focus. However, there is no published bibliometric analysis to derive the main publication features and trends in this scientific area. We aim to conduct a bibliometric analysis to reveal current status of ECM in carotid artery disease and to predict future hot spots.

METHODS

We searched and downloaded articles from the Web of Science Core Collection with "Carotid" and "Extracellular Matrix" as subject words from 1990 to 2021. The complete bibliographic data were analyzed by Bibliometrics, BICOMB, gCLUTO and CiteSpace softwares.

RESULTS

Since 1990, the United States has been the leader in the number of publications in the field of ECM in carotid artery disease, followed by China, Japan and Germany. Among institutions, Institut National De La Sante Et De La Recherche Medicale Inserm, University of Washington Seattle and Harvard University are in the top 3. "Arteriosclerosis Thrombosis and Vascular Biology" is the most popular journal and "Circulation" is the most cited journal. "Clowes AW", "Hedin Ulf" and "Nilsson Jan" are the top three authors of published articles. Finally, we investigated the frontiers through the strongest citation bursts, conducted keyword biclustering analysis, and discovered five clusters of research hotspots. Our research provided a comprehensive analysis of the fundamental data, knowledge organization, and dynamic evolution of research about ECM in carotid artery disease.

CONCLUSIONS

The field of ECM in carotid artery disease has received increasing attention. We summarized the history of the field and predicted five future hotspots through bibliometric analysis. This study provided a reference for researchers in this fields, and the methodology can be extended to other fields.

Effects of Gas Embolism On Pulsatile Flow Characteristics within a Human Carotid Artery

Gas embolisms can hinder and disturb standard blood flow patterns and lead to occlusions and ischemia. Atherosclerosis in carotid arteries depends mostly on hemodynamic parameters. To understand how gas embolism affects carotid artery hemodynamics, numerical simulation of coupled Newtonian two-phase laminar flow with interface tracking are performed in an anatomical image-based geometry with flow conditions closely approximating physiological flows. Bubble behavior and Pulsatile flow field changes are quantified. Significant deviation from flow without gas embolism is observed leading to non-standard flow distributions. Results show that gas embolism promotes complex spatio-temporal variations in the carotid artery hemodynamics leading to higher time averaged shear stress values and greater regions of high oscillatory shear index.

Impact of visit-to-visit blood pressure variability on hypertensive-mediated target organ damage and future cardiovascular events: the Campania salute network

BACKGROUND

Exaggerated variability of blood pressure (BP) poses additional stress on cardiovascular system independent of BP average value, increasing risk of target organ damage (HMOD) and cardiovascular events. We assessed the impact of visit-to-visit variability (VVV) of BP on development of cardiovascular events and HMOD.

METHODS

Standard deviation (SD) and coefficient of variability of mean SBP and DBP were calculated in 3555 patients from the Campania Salute Network registry, with available echocardiogram and more than six visits during follow-up. Values from the first visit were excluded. The impact of VVV of BP on cardiovascular events, and mediation of HMOD were assessed at final visit.

RESULTS

Mean number of visits was 11 ± 6 with mean interval between visits of 9.1 ± 3.7 months. Mean visit-to-visit SD during follow-up was 13 ± 5 for systolic and 8 ± 3 mmHg for DBP; coefficients of variability were 9.7 ± 3.5 and of 9.6 ± 3.2, respectively. In multivariable analysis, left ventricular mass at follow-up was correlated with systolic VVV of BP independently of significant effect of age, BMI, mean SBP during follow-up and initial left ventricular mass. Follow-up GFR was inversely associated with systolic and diastolic VVV, independently of significant effect of age, mean glucose and SBP during follow-up, and initial GFR. In Cox regression, high VVV of BP was also associated with increased risk of cardiovascular events (hazard ratio 1.49, 95% confidence interval 1.08-2.06, P = 0.015), independently of significant effect of HMOD.

CONCLUSION

VVV is associated with prevalent HMOD and development of cardiovascular events, independently of mean BP value during follow-up and HMOD.

Fat mass and vascular health in overweight/obese children

BACKGROUND AND AIM

Childhood obesity is one of the most serious public health challenges of the 21st century. Body mass index (BMI), the most widely used marker of body fatness, has serious limitations, particularly in children, since it does not accurately discriminate between lean and fat mass. Aim of our study was to investigate if the estimate of fat mass, as derived by a new prediction model, was associated with carotid intima media thickness (IMT) and the cross-sectional area of the intima media complex (CSA-IMC) in overweight or obese children.

METHODS AND RESULTS

As many as 375 overweight/obese Italian children, 54.7% males, aged 5-15 years, admitted to a tertiary care hospital, were consecutively enrolled in a study on cardiovascular markers of atherosclerosis. All children underwent an ultrasound carotid examination. Mean weight was 62.2 ± 20.8 Kg and fat-mass was 26.2 ± 10.7 Kg. Multiple regression analyses showed a significant association of fat mass with carotid IMT (β 0.156, p 0.01) and CSA-IMC (β 0.216, p < 0.001); these associations remained significant after controlling for the main cardiovascular risk factors (age, sex, blood pressure, HOMA-index, triglycerides, LDL-cholesterol, HDL-cholesterol, birth weight and high-sensitivity C-reactive protein).

CONCLUSION

Fat mass calculated with the new formula is independently associated with subclinical atherosclerosis in overweight/obese children.

Long-Term Blood Pressure Variability in Young Adulthood and Coronary Artery Calcium and Carotid Intima-Media Thickness in Midlife: The CARDIA Study

Recent evidence links long-term (visit-to-visit) blood pressure (BP) variability to the risk of cardiovascular disease, independent of mean BP levels. Potential associations between long-term BP variability and cardiovascular disease risk may be reflected in early life course alterations in coronary artery calcium (CAC) and carotid intima-media thickness. We evaluated 2482 CARDIA study (Coronary Artery Risk Development in Young Adults) participants (mean [SD] age at the year 20 exam [2005-2006] was 45.4 [3.6] years, 43.2% men, and 41.3% black). We included participants with BP assessments across 20-years (year 0, 2, 5, 7, 10, 15, 20 exams) and carotid intima-media thickness and CAC data at the year 20 exam. BP variability was assessed using variability independent of the mean and SD. Adjusted multivariable linear or logistic regression models (as appropriate) were used to assess associations between long-term BP variability measures and carotid intima-media thickness. and CAC (ln [CAC+1] and prevalent CAC). Long-term systolic BP variability independent of the mean (per 1 SD) was positively associated with carotid intima-media thickness (β=10 μm, SE=3, P=0.002). Similarly, long-term diastolic BP variability independent of the mean was associated with carotid intima-media thickness (β=10 μm, SE (3), P=0.001). Long-term BP variability was not associated with either ln [CAC+1] or prevalent CAC. Long-term systolic and diastolic BP variability across early adulthood was positively associated with modest adverse midlife alterations in carotid intima-media thickness but not to CAC. Our findings provide further insights into pathophysiologic mechanisms that link long-term BP variability to cardiovascular disease.

Misclassification of blood pressure of Vietnamese adults when only a single measurement is used

A single clinic measurement of blood pressure (BP) may be common in low- and middle-income countries because of limited medical resources. This study aimed to examine the potential misclassification error when only one BP measurement is used. Participants (n = 14,706, 53.5% females) aged 25-64 years were selected by multistage stratified cluster sampling from eight provinces, each representing one of the eight geographical regions of Vietnam. Measurements were made using the World Health Organization STEPS protocols. Data were analyzed using complex survey methods. For systolic BP, 62.7% had a higher first reading whereas 30.0% had a lower first reading, and 27.3% had a reduction of at least 5 mmHg whereas 9.6% had an increase of at least 5 mmHg. Irrespective of direction of change, increased variability in BP was associated with greater age, urban living, greater body size and fatness, reduced physical activity levels, elevated glucose, and raised total cholesterol. These measurement variations would lead to substantial misclassification in diagnosis of hypertension based on a single reading because almost 20% of subjects would receive a different diagnosis based on the mean of two readings.

The Clinical Importance of Periodic Leg Movements in Sleep

OPINION STATEMENT

Periodic leg movements during sleep (PLMS) are commonly found in patients with restless leg syndrome (RLS), but they may occur in other sleep disorders and several medical conditions. Their prevalence increases with age, but they can also be observed in children. During the last decades, very active research has been devoted to determine and understand the pathophysiology, associated events, and clinical significance of PLMS. This chapter tries to sum up the most relevant PLMS-related findings, focusing on the relationship between PLMS and the cardiovascular system, in order to understand the clinical implication of this complex motor phenomenon. PLMS have been associated with sympathetic overactivity, namely surges in nocturnal blood pressure and heart rate, without modification in global autonomic balance. Also, PLMS have been related to inflammatory cellular pathways, with elevated level of inflammatory markers, which are associated with cardiovascular risk. The PLMS-related modulation of the autonomic system and of inflammation may increase cardiovascular and cerebrovascular risk in subjects with frequent PLMS. Moreover, also, comorbidities associated with PLMS may play a synergic role in worsening the cardiovascular risk and the consequent mortality and morbidity. Furthermore, little is known about pathophysiological correlates in children with PLMS and their chronic implication on the cardiovascular and cerebrovascular systems. A few studies have suggested that treating PLMS with dopaminergic drugs may reduce their associated sympathetic overactivity and modify disease progression. Definitely, further research is needed to assess the clinical impact of PLMS, associated or not with RLS, and above all the long-term impact of treating PLMS on cardiovascular risk, morbidity, and mortality.

Exploring diurnal variation using piecewise linear splines: an example using blood pressure

Background

There are many examples of physiological processes that follow a circadian cycle and researchers are interested in alternative methods to illustrate and quantify this diurnal variation. Circadian blood pressure (BP) deserves additional attention given uncertainty relating to the prognostic significance of BP variability in relation to cardiovascular disease. However, the majority of studies exploring variability in ambulatory blood pressure monitoring (ABPM) collapse the data into single readings ignoring the temporal nature of the data. Advanced statistical techniques are required to explore complete variation over 24 h.

Methods

We use piecewise linear splines in a mixed-effects model with a constraint to ensure periodicity as a novel application for modelling daily blood pressure. Data from the Mitchelstown Study, a cross-sectional study of Irish adults aged 47–73 years (n = 2047) was utilized. A subsample (1207) underwent 24-h ABPM. We compared patterns between those with and without evidence of subclinical target organ damage (microalbuminuria).

Results

We were able to quantify the steepest rise and fall in SBP, which occurred just after waking (2.23 mmHg/30 min) and immediately after falling asleep (−1.93 mmHg/30 min) respectively. The variation about an individual’s trajectory over 24 h was 12.3 mmHg (standard deviation). On average those with microalbuminuria were found to have significantly higher SBP (7.6 mmHg, 95% CI 5.0–10.1) after adjustment for age, sex and BMI. Including an interaction term between each linear spline and microalbuminuria did not improve model fit.

Conclusion

We have introduced a practical method for the analysis of ABPM where we can determine the rate of increase or decrease for different periods of the day. This may be particularly useful in examining chronotherapy effects of antihypertensive medication. It offers new measures of short-term BP variability as we can quantify the variation about an individual’s trajectory but also allows examination of the variation in slopes between individuals (random-effects).

Electronic supplementary material

The online version of this article (doi:10.1186/s12982-017-0055-5) contains supplementary material, which is available to authorized users.

Increased Blood Pressure Variability Prior to Chronic Kidney Disease Exacerbates Renal Dysfunction in Rats

Increased blood pressure variability (BPV), which can be experimentally induced by sinoaortic denervation (SAD), has emerged as a new marker of the prognosis of cardiovascular and renal outcomes. Considering that increased BPV can lead to organ-damage, the goal of the present study was to evaluate the effects of SAD on renal function in an experimental model of chronic kidney disease (CKD). SAD was performed in male Wistar rats 2 weeks before 5/6 nephrectomy and the animals were evaluated 4 weeks after the induction of CKD. Our data demonstrated that BPV was increased in SAD and CKD animals and that the combination of both conditions (SAD+CKD) exacerbated BPV. The baroreflex sensitivity index was diminished in the SAD and CKD groups; this reduction was more pronounced when SAD and CKD were performed together. 5/6 nephrectomy led to hypertension, which was higher in SAD+CKD animals. Regarding renal function, the combination of SAD and CKD resulted in reduced renal plasma and blood flow, increased renal vascular resistance and augmented uraemia when compared to CKD animals. Glomerular filtration rate and BPV were negatively correlated in SAD, CKD, and SAD+CKD animals. Moreover, SAD+CKD animals presented a higher level of glomerulosclerosis when compared to all other groups. Cardiac and renal hypertrophy, as well as oxidative stress, was also further increased when SAD and CKD were combined. These results show that SAD prior to 5/6 nephrectomy exacerbates renal dysfunction, suggesting that previous augmented BPV should be considered as an important factor to the progression of renal diseases.

Blood Pressure Variability and Prediction of Target Organ Damage in Patients With Uncomplicated Hypertension

BACKGROUND

The average of multiple blood pressure (BP) readings (mean BP) independently predicts target organ damage (TOD). Observational studies have also shown an independent relationship between BP variability (BPV) and TOD, but there is limited longitudinal data. This study aimed to determine the effects of changes in mean BP levels compared with BPV on left ventricular mass index (LVMI) and aortic pulse wave velocity (aPWV).

METHODS

Mean BP levels (research-protocol clinic BP (clinic BP), 24-hour ambulatory BP, and 7-day home BP) and BPV were assessed in 286 patients with uncomplicated hypertension (mean age 64±8 SD years, 53% women) over 12 months. Reading-to-reading BPV (from 24-hour ambulatory BP) and day-to-day BPV (from 7-day home BP) were assessed at baseline and 12 months, and visit-to-visit BPV (clinic BP) was assessed from 5 visits over 12 months. LVMI was measured by 3D echocardiography and aPWV with applanation tonometry.

RESULTS

The strongest predictors of the changes in LVMI (ΔLVMI) were the changes in mean 24-hour systolic BPs (SBPs) (P < 0.02). Similarly, the strongest predictors of the changes in aPWV (ΔaPWV) were the changes in mean 24-hour ambulatory SBPs (P < 0.01) and the changes in mean clinic SBP (P < 0.001). However, none of the changes in BPV were independently associated with ΔLVMI or ΔaPWV (P > 0.05 for all).

CONCLUSIONS

Changes in mean BP levels, but not BPV, were most relevant to changes in TOD in patients with uncomplicated hypertension. Thus, from this point of view, BPV appears to have limited clinical utility in this patient population.

Left atrial dimension is related to blood pressure variability in newly diagnosed untreated hypertensive patients

Variability in daily blood pressure (BPV) recorded 24-h ambulatory blood pressure monitoring (ABPM) is known to be related to left ventricular hypertrophy and an increased incidence of cardiovascular events in hypertensive patients. The aim of this study was to evaluate whether left atrium dimension, which increases early in hypertensive subjects, was related to BPV in a group of 167 drug-naive patients (100M/67F, age: 46±11yr). The patients were chosen among those consecutively sent by their general practitioners to confirm the existence of arterial hypertension and afterwards diagnosed as hypertensive (mean 24-h ABPM ⩾130/80 mm Hg). In each patient, the left atrial posteroanterior diameter index for height (LADi) and the left ventricular mass standardized for body surface area (LVMi) were measured using standardized echocardiographic methods. BPV was calculated as the weighted mean of daytime and nighttime systolic and diastolic blood pressure s.d.'s (ws.d.), according to the formula ws.d.=[(daytime s.d. × 10)+nighttime s.d. × 6)]/16. An increase in left atrial dimension (LADi>24 mm m(-1)) was present in 36 patients (21.6% of the total population). In a univariate regression, LVMi was significantly related to systolic BPV (r=0.24; P=0.02) only in men, whereas LADi was significantly related to both systolic and diastolic BPV in both genders. After adjusting for sex, age, BMI, heart rate, diastolic function and estimated glomerular filtration rate, both systolic and diastolic BPV remained significantly related to LADi (P=0.02 for both) but not to LVMi. In conclusion, this study suggests that BVP, as measured as BPws.d., is significantly and independently associated with increased LADi in newly diagnosed, treatment-naive hypertensive patients.

Carotid artery diameter and wall stiffness in proteinuric renal disease without severely reduced kidney function

PURPOSE

To evaluate the carotid artery diameter, and wall thickness and stiffness in patients with glomerulopathy and proteinuria without severely reduced kidney function.

METHODS

We compared 30 control subjects to 30 patients with glomerular disease, proteinuria, and glomerular filtration rate > 30 ml/min/1.73 m(2) : membranous glomerulonephritis (n = 13), minimal change disease (n = 2), focal and segmental glomerulosclerosis (n = 3), IgA nephropathy (n = 5), lupus nephritis (n = 5), antiphospholipid antibody nephropathy (n = 1), cryoglobulinemic glomerulonephritis (n = 1). The laboratory evaluations included carotid artery diameter, intima-media thickness, and stiffness measurements.

RESULTS

Carotid cross-sectional area of intima-media complex was thicker in patients (18.6 ± 1.4 [x ± SEM]) than in controls (14.8 ± 0.6 mm(2) , p = 0.014), as was carotid artery wall stiffness (8.96 ± 0.86 versus 5.65 ± 0.38, [x ± SEM], p < 0.01). This difference remained significant after adjustment for age, sex, and metabolic cardiovascular risk factors: carotid stiffness was 9.19 ± 0.67 (99% confidence interval [CI] 7.40-10.98)] in patients and 4.80 ± 0.75 (99% CI 2.79-7.11) in controls; adjusted mean difference 4.40 (99% CI 1.46-7.34); p <0.001.

CONCLUSIONS

This study showed, for the first time, signs of altered structural and elastic properties of the arterial wall in patients with proteinuria and glomerular disease without severely reduced kidney function.

Short-term blood pressure variability over 24 h and target organ damage in middle-aged men and women

Blood pressure variability (BPV) has been associated with cardiovascular events; however, the prognostic significance of short-term BPV remains uncertain. As uncertainty also remains as to which measure of variability most accurately describes short-term BPV, this study explores different indices and investigates their relationship with subclinical target organ damage (TOD). We used data from the Mitchelstown Study, a cross-sectional study of Irish adults aged 47-73 years (n=2047). A subsample (1207) underwent 24-h ambulatory BP monitoring (ABPM). As measures of short-term BPV, we estimated the s.d., weighted s.d. (wSD), coefficient of variation (CV) and average real variability (ARV). TOD was documented by microalbuminuria and electrocardiogram (ECG) left ventricular hypertrophy (LVH). There was no association found between any measure of BPV and LVH in both unadjusted and fully adjusted logistic regression models. Similar analysis found that ARV (24 h, day and night), s.d. (day and night) and wSD were all univariately associated with microalbuminuria and remained associated after adjustment for age, gender, smoking, body mass index (BMI), diabetes and antihypertensive treatment. However, when the models were further adjusted for the mean BP the association did not persist for all indices. Our findings illustrate choosing the appropriate summary measure, which accurately captures that short-term BPV is difficult. Despite discrepancies in values between the different measures, there was no association between any indexes of variability with TOD measures after adjustment for the mean BP.

The association of Restless Legs Syndrome with hypertension and cardiovascular disease

Restless Legs Syndrome (RLS), is a sensory-motor neurological disorder that appears to be surprisingly common in the community. Periodic limb movements in sleep are typically encountered in more than 80% of RLS patients and comprise involuntary muscular jerks in the lower limbs, such as flexion of the knees or ankles.  Iron deficiency and dopaminergic neuronal dysfunction in the central nervous system are currently thought to be the likely pathophysiological culprits. There is evidence linking RLS to hypertension and cardiovascular disease. This short review will first present a synopsis of epidemiological, clinical and pathophysiological data concerning the syndrome, and then information on the possible links between RLS and cardiovascular disorders.

Effects of nutritional parameters on nocturnal blood pressure in patients undergoing hemodialysis

BACKGROUND

Malnutrition is a common problem in uremic patients. It is unclear whether there is an association between the degree of malnutrition and 24-h ambulatory blood pressure patterns in patients undergoing hemodialysis. In the present study, we observed the relationship between the degree of malnutrition and deterioration of the rhythm of diurnal blood pressure, which are both risk factors for cardiovascular morbidity-mortality and associated with hypervolemia.

METHOD

We observed 148 patients undergoing hemodialysis in the Nephrology Department of Celal Bayar University Hospital. All cases were assessed for body weight alterations, dietary food intake, gastrointestinal symptoms, loss of subcutaneous fat and muscle tissue, presence and severity of comorbidities, functional capacity (subjective global assessment), and anthropometric indices. Ambulatory blood pressure measurements were performed for all cases on the day between the two hemodialysis sessions.

RESULTS

We found that the circadian blood pressure rhythm deteriorated in patients with a high-malnutrition score, and that malnutrition was more common and severe in those subjects with the non-dipper and reverse-dipper blood pressure patterns. Malnutrition score was positively correlated with the nighttime systolic and nighttime mean blood pressures and mean 24-h arterial blood pressure (all p ≤ 0.01). We identified a positive correlation between malnutrition score and the reduction in serum albumin and anthropometric indices.

CONCLUSION

This is the first study to demonstrate an association between malnutrition and deterioration in the circadian blood pressure rhythm in a hemodialysis population. Nutritional disturbance is associated with an increase in night-time blood pressure. Low serum albumin levels and hypervolemia may contribute this situation.

Ambulatory blood pressure variability is associated with restenosis after percutaneous coronary intervention in normotensive patients

BACKGROUND

Previous studies have showed that BP variability is associated with cardiovascular events. However, no data were available regarding binary restenosis as an end-point after percutenous coronary intervention (PCI).

METHODS AND RESULTS

This multicenter study included 100 consecutive normotensive patients with stable coronary artery disease who were planned for PCI. Before the index procedure, office BP and 24-h ambulatory BP measurements were performed. BP variability indices including systolic and diastolic 24-h average, the day and the night values of standard deviation (SD) and variation coefficient (VC) were measured and calculated. All patients underwent repeat coronary angiography at 6-month. According to angiographic results, 2 groups were formed; a restenosis group (n=30) with binary restenosis of the stented segment and a control group (n=70) with a stenosis diameter of <50% in stented segment. Systolic SD and VC values for 24-h average (14.0±2.8mmHg vs. 9.5±1.6mmHg, p<0.001 and 16%±3 vs. 11%±2, p<0.001, respectively), the day (15.2±3.9mmHg vs. 10.6±1.7mmHg, p<0.001 and 17%±4 vs. 12%±2, p<0.001, respectively), and the night (12.8±4.1mmHg vs. 8.4±2.4mmHg, p<0.001 and 14%±5 vs. 11%±3, p=0.004, respectively) values were significantly higher in restenosis group compared to control group. Similarly, diastolic SD and VC values for 24-h average (10.6±2.5mmHg vs. 8.1±1.5mmHg, p<0.001 and 12%±3 vs. 9%±2, p=0.001, respectively), the day (11.1±2.9mmHg vs. 9.0±1.8mmHg, p=0.003 and 12%±3 vs. 10%±2, p=0.006, respectively), and the night (10.0±3.6mmHg vs. 7.2±2.0mmHg, p=0.001 and 11%±5 vs. 9%±3, p=0.059, respectively) values were significantly higher in restenosis group compared to no restenosis group except for diastolic VC night. All systolic and diastolic BP variability indices except diastolic VC night were found to be independent predictors of risk of restenosis in multivariate analysis. In addition, the cut-off values of 11.4mmHg and 13% for 24-h systolic SD and VC, respectively, were found to be highly sensitive (93% for both) and specific (94% and 91%, respectively) for predicting binary restenosis at 6-month after PCI.

CONCLUSIONS

BP variability indices are significantly and independently associated with binary restenosis and higher values can predict restenosis after PCI sensitively and specifically.

Does blood pressure variability modulate cardiovascular risk?

Exactly how hypertension causes end organ damage and vascular events is poorly understood. Yet the concept that underlying "usual" blood pressure (BP) accounts for all BP-related risk of vascular events and for the benefits of BP-lowering drugs has come to underpin clinical guidelines on the diagnosis and treatment of hypertension. This article reviews evidence that variability in BP also predicts risk of stroke and other vascular events independently of mean BP and evidence that drug-class effects on variability in BP explain differences in the effectiveness of BP-lowering drugs in preventing stroke.

Blood pressure variability is significantly associated with ECG left ventricular mass in normotensive Africans: the SABPA Study

The prognostic significance of blood pressure (BP) variability has lately enjoyed considerable attention. The need for early markers of cardiovascular dysfunction is imperative in black South Africans who have a significant risk for cardiovascular disease. We therefore compared 24-h BP variability with various traditional and advanced BP measurements, regarding their association with sub-clinical organ damage in black and white South Africans. The study included 409 African and Caucasian teachers aged 25-60 yrs. We measured office BP, 1-min continuous (finger) BP, ambulatory BP, BP reactivity and determined weighted 24-h BP variability. Albumin-to-creatinine ratio, Cornell product and carotid cross-sectional wall area (CSWA) were measures of organ damage. Africans had higher 24-h BP, BP variability, BP reactivity and sub-clinical organ damage (P<0.001). Correlations of BP variability with organ damage were overall weak when compared with other BP measurements. In normotensive groups, we found an independent association of 24-h systolic BP (SBP) variability with Cornell product only in Africans (r=0.37; P=0.01), confirmed in multiple regression models, with 24-h SBP included in the model. Only in hypertensive Caucasians, a significant correlation between CSWA and 24-h SBP variability was evident (r=0.30; P=0.01), although CSWA indicated stronger correlations with office or 24-h SBP than 24-h SBP variability. To conclude, 24-h SBP variability could potentially be an effective measure for the early detection of normotensive Africans at increased risk for the development of cardiovascular complications. Its usefulness based on associations with target organ damage in hypertensive groups seems to be less than traditional office or 24-h BP measurements.

Ambulatory blood pressure variability is increased in diabetic hypertensives

The purpose of this study was to examine the possible difference in the 24-hr BP profile--including short-term BP variability, assessed as the standard deviation--between diabetic and non-diabetic hypertensives. We measured 24-hr ambulatory BP in 11 diabetic hypertensives (diabetic HT) and 10 non-diabetic hypertensives (non-diabetic HT) who were hospitalized for the educational program in our hospital and were under stable salt intake. Renal function and sleep apnea were also estimated. There were no significant differences in 24-hr systolic BP (141 mmHg vs. 135 mmHg, ns), daytime systolic BP (143 mmHg vs. 138 mmHg, ns), and nighttime systolic BP (135 mmHg vs. 130 mmHg, ns) between diabetic HT and non-diabetic HT. The values of 24-hr HR (69.7 beats/min vs. 65.2 beats/min, ns) and 24-hr HR variability (9.9 beats/min vs. 10.1 beats/min, ns) were also similar between the groups. Interestingly, diabetic HT had a significantly greater 24-hr systolic and diastolic BP variability than non-diabetic HT (18.2 mmHg vs. 14.5 mmHg, p < 0.05; 11.5 mmHg vs. 9.6 mmHg, p < 0.05, respectively). The values for creatinine clearance, urinary protein excretion, and apnea-hypopnea index were similar between the groups. Bivariate linear regression analysis demonstrated that fasting blood glucose was the primary determinant of 24-hr diastolic BP variability (r = 0.661, p < 0.01). Multiple stepwise regression analysis revealed that fasting blood glucose was a significant and independent contributor to 24-hr systolic BP variability (r = 0.501, p < 0.05). Taken together, these results demonstrate that BP variability is increased in diabetic hypertensives. Furthermore, it is possible that an elevation of fasting blood glucose may contribute to the enhanced BP variability in hypertensives.

Carotid artery wall hypertrophy in children with metabolic syndrome

Preclinical vascular changes (increased stiffness and/or wall thickness) have been observed in children with known metabolic risk factors. Aim of the present study was to evaluate different carotid parameters, representative of vascular health, in children with and without metabolic syndrome (MS). We studied 38 children with MS (mean age 9.6+/-2.6 years; range 6-14 years) and 45 healthy age-matched subjects. Children who met three or more of the following criteria qualified as having the MS: fasting glucose >110 mg dl(-1), fasting triglyceride concentration >100 mg dl(-1), fasting high-density lipoprotein cholesterol concentration <50 mg dl(-1) for females or <45 mg dl(-1) for the males, waist circumference >75th percentile for age and gender and systolic or diastolic blood pressure >90th percentile for age, gender and height. Carotid B-mode ultrasound examinations were performed and intima-media thickness and diameters were measured in all subjects. Arterial geometry was further characterized by calculation of carotid cross-sectional area. Carotid intima-media thickness and lumen diameters were increased in children with MS as compared to children without MS. Moreover, carotid cross-sectional area was significantly higher in the group of children with MS 9.83+/-1.86 mm(2) [mean+/-s.d.] compared with the control group: 7.77+/-1.72 mm(2), P<0.001, even after adjustment for age, gender and height. Carotid hypertrophy is already detectable in children with MS. High-resolution B-mode ultrasound could provide a valuable tool for the cardiovascular risk stratification of children.

Ambulatory blood pressure, blood pressure variability and the prevalence of carotid artery alteration: the Ohasama study

OBJECTIVES

To investigate the association between ambulatory blood pressure (BP) variables (level, short-term variability, circadian variation and morning pressor surge) and carotid artery alteration in a general population.

METHODS

We measured ambulatory BP every 30 min in 775 participants (mean age 66.2 +/- 6.2 years, 68.8% women) from the Japanese general population. Short-term BP variability during the daytime and night-time were estimated as within-subject standard deviation of daytime and night-time BP, respectively. Circadian BP variation was calculated as the percentage decline in nocturnal BP. Morning pressor surge was defined as morning BP minus pre-waking BP. The extent of carotid artery alteration was evaluated as the average of common carotid intima-media thickness (IMT) and the presence of focal carotid plaque.

RESULTS

Daytime and night-time BP values were more closely associated with carotid artery alteration than casual BP. With mutual adjustment for daytime and night-time BP, the latter (P < 0.0001) was more closely associated with IMT, which represents diffuse arterial thickening and arteriosclerosis, than daytime BP (P = 0.2). Night-time systolic BP variability was positively associated with carotid plaque (focal atherosclerotic lesions) independently of possible confounding factors, including night-time systolic BP (P = 0.01). A diminished nocturnal decline in systolic BP was associated with a greater IMT after adjustment for confounding factors (P = 0.03). A morning pressor surge was not associated with carotid artery alteration.

CONCLUSION

Ambulatory BP levels and BP variability were closely associated with carotid artery alteration, suggesting that these parameters are independent risk factors or predictors of carotid artery alteration.

A possible relationship of nocturnal blood pressure variability with coronary artery disease in diabetic nephropathy

Evidence suggests a relationship between short-term blood pressure (BP) variability and cardiovascular target-organ damage. Although a blunted nocturnal decrease in BP and reduced heart rate variability have been shown to be associated with cardiovascular morbidity in diabetic patients, little information is available on short-term BP variability. In this study, short-term BP variability was assessed in 36 subjects with type 2 diabetes and overt nephropathy who underwent ambulatory BP monitoring, and the factors that correlated with short-term BP variability were examined. The incidence of coronary artery disease (CAD) was significantly greater in the patients with increased 24-h systolic BP variability (67% versus 11%; p < 0.0005), while that of cerebrovascular disease was not significantly affected (61% versus 50%). Multiple stepwise regression analysis revealed that serum cholesterol (cholesterol) and plasma norepinephrine (p-NE) were significant and independent contributors to nighttime systolic BP variability (partial R2 = 0.490, p < 0.001; partial R2 = 0.470, p < 0.001) and demonstrated that body mass index and p-NE were primary determinants of nighttime diastolic BP variability (partial R2 = 0.539, p < 0.0005; partial R2 = 0.304, p < 0.05). Diabetic nephropathy patients with CAD had significantly increased daytime systolic (17.8 mmHg versus 13.1 mmHg, p < 0.0005), nighttime systolic (17.4 mmHg versus 10.5 mmHg, p < 0.0001), and nighttime diastolic (10.4 mmHg versus 7.2 mmHg, p < 0.05) BP variability. Furthermore, logistic regression analysis demonstrated that nighttime systolic BP variability was an independent risk factor for CAD (odds ratio 3.13 [95% CI 1.02-9.61]; p < 0.05). The increase in nighttime BP variability is associated with a proportional sympathetic activation in diabetic nephropathy. Elevated short-term BP variability combined with relative sympathetic prevalence during the night might represent an important risk factor for cardiovascular events in the diabetic population.

Impact of the time rate of blood pressure variation on left ventricular mass

OBJECTIVES

Blood pressure (BP) changes are steeper in hypertensive than in normotensive individuals, whereas an increased rate of BP fluctuations is associated with medial hypertrophy of the carotid arteries. We evaluated the association between the rate of BP variation derived from ambulatory blood pressure monitoring (ABPM) data analysis and left ventricular mass (LVM).

METHODS

ABPM and echocardiographic measurements of LVM were performed in 365 normotensive, 185 white-coat hypertensive (WCH) and 448 uncomplicated hypertensive individuals.

RESULTS

The daytime and night-time rate of systolic blood pressure (SBP) and diastolic BP variation were significantly higher in hypertensive than in normotensive (P < 0.001) and WCH (P < 0.05) individuals. In the entire study population multiple linear regression models revealed independent determinants of LVM in the following rank order: body mass index (beta + 0.266, P < 0.001), daytime SBP (beta + 0.264, P < 0.001), male sex (beta +0.220, P < 0.001), age (beta + 0.203, P < 0.001), daytime heart rate (HR; beta - 0.191, P < 0.001), daytime rate of SBP variation (beta + 0.167, P < 0.001), and SBP dipping (beta - 0.132, P < 0.001). A 0.1 mmHg/min increase in the daytime rate of SBP variation correlated with an increment of 7.087 g (95% confidence interval 4.775-9.399) in the LVM. The addition of the daytime rate of SBP variation in the multiple regression model for the prediction of LVM significantly increased the adjusted model R [R change 0.024 (2.4%); P for change < 0.001].

CONCLUSION

Steeper BP variations may produce a greater stress on the left ventricular wall and may have an additive role to body habitus, BP and HR levels in the detection of cardiac hypertrophy. Target-organ damage in hypertensive patients, in addition to BP levels, dipping status and BP variability, may also be related to a steeper rate of BP oscillations.

Organisational injustice and impaired cardiovascular regulation among female employees

OBJECTIVES

To examine the relation between perceived organisational justice and cardiovascular reactivity in women.

METHODS

The participants were 57 women working in long term care homes. Heart rate variability and systolic arterial pressure variability were used as markers of autonomic function. Organisational justice was measured using the scale of Moorman. Data on other risk factors were also collected.

RESULTS

Results from logistic regression models showed that the risk for increased low frequency band systolic arterial pressure variability was 3.8-5.8 times higher in employees with low justice than in employees with high justice. Low perceived justice was also related to an 80% excess risk of reduced high frequency heart rate variability compared to high perceived justice, but this association was not statistically significant.

CONCLUSIONS

These findings are consistent with the hypothesis that cardiac dysregulation is one stress mechanism through which a low perceived justice of decision making procedures and interpersonal treatment increases the risk of health problems in personnel.

A New Technique for Detecting Sleep Apnea-Related "Midnight" Surge of Blood Pressure

Patients with obstructive sleep apnea syndrome (OSAS) have been reported to be at greater risk for cardiovascular events, and midnight surge of blood pressure (BP) may be a mechanism of sleep apnea-related cardiovascular risk. However, there has been no accurate noninvasive technique to detect intermittent BP surge at the time of each sleep apnea episode. We therefore developed an experimental system to detect apnea-related short-term BP surge based on BP measurement triggered by peripheral (finger-tip) oxygen desaturation (a desaturation-triggered BP monitoring system). In 16 patients with OSAS, this new system successfully detected BP surges at the time of the sleep apnea, and the BP values were found to be significantly higher than those detected using a conventional fixed interval BP monitoring system (systolic BP [SBP] difference: 13 +/- 5.8 mmHg, p = 0.039; diastolic BP [DBP] difference: 10 +/- 6.8 mmHg, p = 0.032). The maximum SBP time rate (velocity of BP surge) showed a strong positive correlation with the apnea-hypopnea index (r = 0.855, p < 0.0001). In conclusion, we developed a noninvasive oxygen desaturation-triggered BP monitoring system that can successfully detect sleep apnea-related BP surge. The midnight BP surge detected by this new method was significantly associated with the severity of OSAS.

Blood pressure variability and prognosis in uncomplicated mild hypertension

BACKGROUND

The independent prognostic value of blood pressure (BP) variability in essential hypertension and particularly in uncomplicated mild hypertension is not yet completely clear. We investigated the relationship between BP variability, evaluated by noninvasive monitoring, and cardiovascular outcome in uncomplicated mild hypertension patients.

METHODS

The occurrence of fatal and nonfatal cardiovascular events was evaluated in 1088 uncomplicated mild hypertension patients, 626 with low BP variability (SD of daytime systolic BP below the mean of the study population) and 462 with high BP variability (SD of daytime systolic BP above the mean of the study population).

RESULTS

During the follow-up (4.74 +/- 2.4 years, range 0.5-9.7 years), the event rates per 100 patient-years in subjects with low and high BP variability were 0.72 and 1.5, respectively. Event-free survival was significantly different between the groups (P = .01). However, after adjustment for other covariates in a Cox multivariate analysis, the adverse prognostic relevance of high BP variability was no longer detectable, whereas age, daytime systolic BP, low-density lipoprotein cholesterol, and smoking habit resulted as independent predictors of cardiovascular events.

CONCLUSIONS

In uncomplicated mild hypertension population, BP variability evaluated by noninvasive monitoring is not an independent predictor of outcome.

Blood pressure variability and stress management training for essential hypertension

The purpose of this study was to determine whether stress management training reduces blood pressure (BP) variability in hypertensive patients. Previous literature suggests that cardiovascular risk is not only a function of BP levels, but also of BP variability, and this partially depends on changes induced by the stress of everyday life. The authors reanalyzed data from a previous study of 43 male patients with essential hypertension who were randomly assigned to 2 groups (stress management training and waiting list). Patients in the stress management group lowered their self-measured BP variability significantly from pretreatment to the 4-month follow-up examination, showing a mean reduction of 2.6/1.5 mm Hg in the standard deviation of systolic/diastolic BP (SBP/DBP), and a mean decrease of 1.84/1.59% in the coefficient of variation of SBP/DBP. For SBP, these reductions were significantly greater than those showed by the control group. These results suggest that stress management training is effective in reducing day-to-day BP variability, providing an additional reduction in cardiovascular risk for hypertensive patients.

A reliable index for the prognostic significance of blood pressure variability

OBJECTIVES

This study presents a reliable index inspired by the total variability concept of real analysis in mathematics, called average real variability (ARV), for the prognostic significance of blood pressure variability (BPV) overcoming the pitfalls of the commonly used standard deviation (SD).

BACKGROUND

Recent studies have suggested that an increase in BPV is associated with an increase in subsequent cardiovascular events/complications. However, there are other studies where the cited association was not found or was lost in the presence of other well-known risk factors. An explanation for these apparently contradictory results may be the selection of the variability index used (SD).

METHODS

Ambulatory blood pressure monitoring in 312 subjects aged > or = 55 years. Logistic regression models and survival methods were used to establish the prognostic significance of awake systolic BPV: in particular, (i) the performance of ARV versus SD, and (ii) the value of BPV relative to other well-known risk factors.

RESULTS

The analyses using the ARV index show a statistically significant relative risk equal to 4.548 (P = 0.006) for the group with high BPV with respect to the low BPV group (reference level); in contrast, the corresponding relative risk associated to the SD index was not statistically significant. Furthermore, ARV exhibited a similar predictive value to systolic blood pressure.

CONCLUSIONS

The proposed ARV index is a more reliable representation of time series variability than SD and may be less sensitive to the relative low sampling frequency of the ambulatory blood pressure monitoring devices. The results suggest that ARV adds prognostic value to the ABPM and could prompt the use of therapeutic measures to control BPV.

Relationship between birth weight and blood pressure variability in children

This cross-sectional study investigates the relationship between birth weight, 24-h blood pressure and blood pressure variability in childhood. Blood pressure was measured in 976 schoolchildren, free from cardiovascular disease, aged between 6 and 16 years. Blood pressure variability was estimated as the standard deviation of the 24-h mean (systolic and diastolic) blood pressure values. Linear regression showed that variation in systolic or diastolic blood pressure was not significantly associated with birth weight. Similarly, no association was found between blood pressure variability and birth weight when using the birth weight groups used by a previous study. Adjusting for other covariates, including mean 24-h blood pressure, made little difference to the observed results. No interactions were observed between birth weight and either gender or age on blood pressure variability. The results of this study do not support the suggestion of a significant association between birth weight and blood pressure variation in childhood. This might suggest that blood pressure variability is influenced mainly by environmental or lifestyle factors, but as little research has been published in this area, further investigation is required and in particular it would be important to assess the use of other measures of blood pressure variation.

Regression dilution of systolic and diastolic blood pressure in patients with established cerebrovascular disease

BACKGROUND AND OBJECTIVE

Blood pressure (BP) is a major risk factor for stroke and cardiovascular events. To quantify its effect, it is necessary to correct for regression dilution bias (RDB). RDB has been estimated from repeated measurements of BP in population-based studies, but there are no data in patients with established vascular disease.

METHOD

We analyzed repeat measurements of BP from three large studies of patients with cerebrovascular disease: UK-TIA trial (n=2098), Dutch TIA trial (n=2953), and the European Carotid Surgery Trial (n=2646). The regression dilution ratio (RDR) was estimated by parametric and nonparametric methods at follow-up intervals ranging from 4 months to 6 years.

RESULTS

After an interval of only 4-5 months, nonparametric RDRs of 0.56, 0.40, and 0.45 for systolic BP and 0.45, 0.33, and 0.31 for diastolic BP were observed in the three studies, respectively. These values are much smaller than those reported in population-based studies, indicating greater within-person variability in BP.

CONCLUSION

RDRs from population-based studies cannot necessarily be applied to cohorts with established vascular disease.

Serum cholesterol affects blood pressure regulation

A close relationship between abnormalities of the lipid metabolism and arterial hypertension has been observed in several epidemiological studies. The aim of the present study was to investigate whether serum cholesterol might affect blood pressure (BP) levels at rest, during ambulatory monitoring or during sympathetic stimulation-independently of other variables such as body weight or serum insulin-thus influencing the outcome of hypertensive complications. Seventy-three patients with sustained newly-discovered and never-treated hypertension were divided into tertiles according to their serum cholesterol levels and their resting BP, 24-h BP and BP during isometric exercise (handgrip) were compared. Cardiac mass and carotid wall thickness were measured by echographic technique. The results were that tertiles were similar for body weight, blood glucose and serum insulin, but different for serum cholesterol and triglycerides. BP at rest and during 24-h monitoring was similar in the three groups, whilst a significant difference was detected during sympathetic stimulation by handgrip, with systolic and diastolic BP increasing by 16/12, 28/19 and 30/23 mm Hg (P < 0.01) in lower, medium and higher tertiles, respectively. Intima-media layer of the carotid arteries was also significantly thickened in the groups with higher cholesterol levels (0.54 +/- 0.07, 0.67 +/- 0.14, 0.68 +/- 0.15, P < 0.05). These data support the conclusion that even in patients with recently discovered hypertension, cholesterol levels may influence the BP response to adrenergic stimulation as well as the outcome of target organ disease.