Effect Of Blood Pressure Variability Research Articles

Effect of Blood Pressure Variability on Cardiovascular Outcome in Diabetic and Nondiabetic Patients with Stroke

The association between blood pressure (BP) variability and stroke outcome is controversial, and there are few studies that have focused on the impact of BP variability in diabetic patients with stroke. Therefore, we aimed to examine the impact of BP variability on cardiovascular outcome in diabetic and nondiabetic patients with stroke. A total of 373 ischemic stroke patients with large artery atherosclerosis were recruited and followed up. Ambulatory BP monitoring was performed in all patients and divided according to the 25th and 75th percentiles interval of SD of daytime systolic BP (SBP). Kaplan-Meier analysis and Cox regression were used to assess the relationship between BP variability and cardiovascular outcomes including stroke recurrence, vascular events and cardiovascular death. The 339 patients were included in the final analysis. During an average follow-up of 19.0 ± 5.1 months (.6-26.8 months), 69 (20.4%) cardiovascular events occurred in all patients. Kaplan-Meier analysis found that there were no differences in cardiovascular events-free survival among the different BP variability groups in diabetic patients (P = .995); however, nondiabetic patients with greater BP variability showed a lesser cardiovascular events-free survival (P = .039). Through Cox regression we found the SD of daytime SBP (hazard ratio 1.103; 95% CI 1.011-1.203) was associated with cardiovascular outcomes in nondiabetic patients with stroke. We show that SBP variability is associated with cardiovascular outcomes in stroke patients without diabetes, but we didn't find a correlation between SBP variability and cardiovascular outcomes in stroke patients with diabetes.

Blood pressure variability of two ambulatory blood pressure monitors

There are no data on the evaluation of blood pressure (BP) variability comparing two ambulatory blood pressure monitoring monitors worn at the same time. Hence, this study was carried out to compare variability of BP in healthy untreated adults using two ambulatory BP monitors worn at the same time over an 8-h period. An Accutorr device was used to measure office BP in the dominant and nondominant arms of 24 participants.Simultaneous 8-h BP and heart rate data were measured in 24 untreated adult volunteers by Mobil-O-Graph (worn for an additional 16 h after removing the Spacelabs monitor) and Spacelabs with both random (N=12) and nonrandom (N=12) assignment of each device to the dominant arm. Average real variability (ARV), SD, coefficient of variation, and variation independent of mean were calculated for systolic blood pressure, diastolic blood pressure, mean arterial pressure, and pulse pressure (PP). Whether the Mobil-O-Graph was applied to the dominant or the nondominant arm, the ARV of mean systolic (P=0.003 nonrandomized; P=0.010 randomized) and PP (P=0.009 nonrandomized; P=0.005 randomized) remained significantly higher than the Spacelabs device, whereas the ARV of the mean arterial pressure was not significantly different. The average BP readings and ARVs for systolic blood pressure and PP obtained by the Mobil-O-Graph were considerably higher for the daytime than the night-time. Given the emerging interest in the effect of BP variability on health outcomes, the accuracy of its measurement is important. Our study raises concerns about the accuracy of pooling international ambulatory blood pressure monitoring variability data using different devices.

Visually evoked blood flow responses and interaction with dynamic cerebral autoregulation: Correction for blood pressure variation

Visually evoked flow responses recorded using transcranial Doppler ultrasonography are often quantified using a dynamic model of neurovascular coupling. The evoked flow response is seen as the model's response to a visual step input stimulus. However, the continuously active process of dynamic cerebral autoregulation (dCA) compensating cerebral blood flow for blood pressure fluctuations may induce changes of cerebral blood flow velocity (CBFV) as well. The effect of blood pressure variability on the flow response is evaluated by separately modeling the dCA-induced effects of beat-to-beat measured blood pressure related CBFV changes.Parameters of 71 subjects are estimated using an existing, well-known second order dynamic neurovascular coupling model proposed by Rosengarten et al. [1], and a new model extending the existing model with a CBFV contributing component as the output of a dCA model driven by blood pressure as input.Both models were evaluated for mean and systolic CBFV responses. The model-to-data fit errors of mean and systolic blood pressure for the new model were significantly lower compared to the existing model: mean: 0.8%±0.6 vs. 2.4%±2.8, p<0.001; systolic: 1.5%±1.2 vs. 2.2%±2.6, p<0.001. The confidence bounds of all estimated neurovascular coupling model parameters were significantly (p<0.005) narrowed for the new model.In conclusion, blood pressure correction of visual evoked flow responses by including cerebral autoregulation in model fitting of averaged responses results in significantly lower fit errors and by that in more reliable model parameter estimation. Blood pressure correction is more effective when mean instead of systolic CBFV responses are used. Measurement and quantification of neurovascular coupling should include beat-to-beat blood pressure measurement.

Effect of blood pressure variability on endothelial function assessed by brachial artery flow mediated dilatation

Purpose: To examine the influence of blood pressure variability on endothelial function assessed by brachial artery flow mediated dilatation. Methods: We screened 190 individuals without history of cardiovascular disease in a primary prevention program recording age (45,62±8,72 years), sex (48,4% males), body mass index (BMI = 27,03±4,79 kg/m2), waist circumference (94,42±14,16 cm), total cholesterol (214,30±41,87 mg/dl), LDL-cholesterol (136,59±37,73 mg/dl), HDL-cholesterol (47,99±13,24 mg/dl), triglycerides (150,02±108,15 mg/dl), blood glucose (92,28±28,18 mg/dl), number of smoked cigarettes/day. We determined the brachial artery FMD according to the guidelines for the ultrasound assessment of endothelial-dependent flow-mediated vasodilation. All subjects underwent a 24-hour Ambulatory Blood Pressure Monitoring (ABPM) on a working day, performing usual daily activities and avoiding heavy physical exercise. Blood pressure and heart rate readings were obtained every 15 minutes during daytime and every 30 minutes during nighttime. We recorded mean systolic and diastolic Blood Pressure (BP) and BP variability calculated as the Standard Deviation (SD) of mean blood pressure. After data collection we investigated the correlations (Pearson's r) between FMD values, classical risk factors and ABPM records, defining the magnitude of correlation as weak (r = 0,1 to 0,3), moderate (0,3 to 0,5) and high (0,5 to 1). Results: The uppermost observed correlations of brachial artery FMD values were in the moderate range, with systolic BP variability (r=-0,399, p<0,001), mean systolic BP (r=-0,372, p<0,001) and waist circumference (r=-0,360, p<0,001). We found weak significant correlations between FMD and mean diastolic BP (r=-0,288, p<0,001), age (r=-0,254, p<0,001), BMI (r=-0,290, p<0,001), number of smoked cigarettes/day (r=-0,223, p=002), HDL-cholesterol (r=0,168, p=0,021), triglycerides (r=-0,181, p=0,012) and blood glucose (r=-0,235, p=0,001). Moreover, the persons with endothelial dysfunction defined as a brachial artery FMD value less than 7,5% have significantly increased systolic blood pressure variability as compared with those with normal endothelial function (14,29±3,41 mmHg vs. 11,48±2,40 mmHg, p<0,001). Conclusions: Our study indicates that systolic blood pressure variability determined by ambulatory blood pressure monitoring is one of the most important factors that impacts on endothelial function.

Exploring the link between hypertension and dementia: Effects of blood pressure variability on brain perfusion and cognition in an elderly population

Exploring the link between hypertension and dementia: Effects of blood pressure variability on brain perfusion and cognition in an elderly population

The Significance of Blood Pressure Variability for the Development of Hemorrhagic Transformation in Acute Ischemic Stroke

Elevated blood pressure (BP) is commonly observed in acute ischemic stroke and is known to be associated with hemorrhagic transformation (HT). However, the effect of BP variability on the development of HT is not known well. A consecutive series of patients with acute ischemic stroke, who were hospitalized within 24 hours of onset and showed no HT on initial gradient echo MRI, were enrolled in this study. BP measurements during the first 72 hours were obtained, and BP variability of each patient was described using various summary parameters: SD, maximum (max), minimum (min), difference between max and min (max-min), average squared difference between successive measurements (sv), and maximum sv (svmax). Of 792 patients meeting the eligibility criteria, 70 (8.8%) developed HT. Among BP variability parameters categorized into quartiles, SBP(max), SBP(min), SBP(max-min), SBP(svmax), DBP(SD), DBP(max), DBP(min), DBP(max-min), and DBP(svmax) were significantly associated with HT independent of mean SBP, age, interval from onset to arrival, initial stroke severity, diabetes mellitus, stroke subtype, thrombolysis, initial glucose, and total cholesterol (P<0.05 on likelihood ratio test of trend). The analyses about the interaction between thrombolysis and variability parameters showed that the effects of BP variability on the development of HT did not differ by whether patients received thrombolysis or not. Our study suggests that we may consider not only the absolute level of BP but also its variability to prevent hemorrhagic transformation.

Hypertension

The field of hypertension has enjoyed some remarkable successes in recent years. Better blood pressure management has been an important contributor to the recent rapid decline in the age-adjusted death rates for coronary heart disease (CHD) and stroke.1 Yet, there is yet so much more that could be accomplished through better blood pressure management. CHD and stroke remain the first and third leading causes of death in the United States.2 And only slightly more than a third of those with hypertension in the United States achieve recommended treatment goal blood pressure levels.3 Control rates are even worse in most other countries.4 Better blood pressure management can save many lives. Here, some pathways to success are considered. Few measurements in medicine are done as poorly and inconsistently as blood pressure measurement. Methods used today in clinical practice and in clinical trials are little changed from the earliest days of measurement.5 Though there is a clear recognition of biological variability, we continue to make decisions largely on measurements taken at random times under poorly controlled conditions. The measurement process is less regulated than measurement of most other major risk factors. Just compare the quality control process for glucose or cholesterol measurement with that for blood pressure measurement in your own local setting. There are not readily available solutions for this issue. Substantial investments in research in this area should be made by government and commercial entities. We must have reliable, reproducible, convenient, and precise measurement tools for blood pressure. These tools should allow for measurement of the important components of blood pressure and mechanisms for integrating and interpreting influence of time of day, activity, …

Cardiac autonomic control buffers blood pressure variability responses to challenge: a psychophysiologic model of coronary artery disease.

This article presents a model that identifies effects of blood pressure variability (BPV) as a possible mechanism by which psychological/psychiatric factors and health behaviors confer increased risk of coronary artery disease (CAD) and acute coronary syndromes. Recent research in vascular biology and dynamics of coronary artery blood flow suggests that BPV may have pathogenic effects on the coronary endothelium, plaque formation, and plaque stability. Thus, BPV may be a risk factor for cardiovascular disease independent of mean arterial pressure. The model proposes that autonomic control of the heart exerts a buffering or inhibitory influence on oscillations in blood pressure. Established psychological/behavioral risk factors for CAD, such as depression, hostility, and anxiety, as well as physical deconditioning and aging, are associated with diminished autonomic control of the heart, which may disinhibit pathogenic BPV. Together, these data suggest a coherent, testable psychophysiological model of CAD. In this article, we review these data and make recommendations for research to examine the model.

Influence of short-term blood pressure variability on blood pressure determinations.

To evaluate the effect of blood pressure variability on Riva Rocci Korotkoff blood pressure determinations, we studied the intra-arterial pressure during Riva Rocci Korotkoff determinations in 25 patients. In 50 measurements with a cuff deflation rate of 2.5 mm Hg/sec, the systolic intra-arterial pressure at Korotkoff phase 1 was 2.1 (95% confidence interval 1.2-3.0) mm Hg higher than the average systolic intra-arterial pressure in the 20 seconds surrounding this moment (p less than 0.01). This elevation was shown to increase with increasing blood pressure variability, as expressed by the standard deviation of the systolic blood pressure. The elevation caused by the proposed mechanism was amplified when a slow cuff deflation rate of 1.5 mm Hg/sec was used. No significant difference was noted in the diastolic intra-arterial pressure at Korotkoff phase 5, when a normal deflation rate of 2.5 mm Hg/sec was used. A slow cuff deflation rate caused a small elevation in diastolic pressure at the moment of Korotkoff phase 5. We conclude that even normally occurring blood pressure variability might lead to a consistent elevation of systolic Riva Rocci Korotkoff blood pressure measurements. This effect is reinforced by an increasing blood pressure variability and by a slower cuff deflation rate.

Decreased blood pressure in borderline hypertensive subjects who practiced meditation

A prospective investigation was designed to test whether the altered behavior of the regular practice of a relaxation, meditational technique might lower blood pressure in 22 borderline hypertensive subjects. The investigation was unbiased with regard to the presence of antihypertensive agents; subject familiarity with blood pressure measurement or with the observer; observer error; and the effects of blood pressure variability. During the control period, blood pressures averaged 146.5 mm Hg systolic and 94.6 diastolic. During the experimental period, they decreased to 139.5 mm Hg systolic ( p < 0.001) and 90.8 mm Hg diastolic (0.001 < p < 0.002). The results of this relaxation, meditational technique are consistent with a hypothesized integrated hypothalamic response associated with decreased sympathetic nervous system activity. It is possible that the decreased blood pressures are unrelated to the proposed mechanism of decreased sympathetic nervous system activity and represent, instead, a placebo effect. Regardless of mechanism, the described relaxation, meditational technique is an effective method of lowering borderline hypertensive blood pressures. The relaxation technique is learned easily and inexpensively, practiced at no cost, and has no pharmacologic side effects.