Blood Pressure Variability Parameters Research Articles

The relationship between blood pressure variability, obesity and left atrial phasic function in hypertensive population

We sought to investigate the relationship between blood pressure (BP) variability and left atrial (LA) phasic function assessed by volumetric and speckle tracking method in normal-weight, overweight and obese hypertensive patients. This cross-sectional study included 164 untreated hypertensive subjects who underwent a 24-h ambulatory BP monitoring and complete two-dimensional echocardiographic examination (2DE). All the patients were separated into three groups according to their body mass index (BMI): normal-weight patients (BMI<25kg/m(2)), overweight patients (25≤BMI<30kg/m(2)), and obese patients (BMI≥30kg/m(2)). Daytime, nighttime and 24h BP variability indices were higher in obese hypertensive subjects than in lean patients. Maximum and minimum LA volumes and volume indexes gradually and significantly increased, whereas pre-A LAV decreased, from normal-weight to obese subjects. Total and passive LA emptying fractions, representing LA reservoir and conduit function, gradually reduced from lean to obese individuals. Active LA EF, the parameter of LA booster pump function, increased in the same direction. Similar results were obtained by 2DE strain analysis. BP variability parameters were associated with structural, functional and mechanical parameters of LA remodeling in the whole study population. The parameters of LA reservoir function were negatively related with BP variability indices, whereas the parameters of LA pump function were positively related with BP variability indices. Obesity significantly impacts BP variability and LA phasic function in untreated hypertensive subjects. BP variability is associated with LA remodeling independent of BP, left ventricular systolic and diastolic function.

Assessment of Short-term Blood Pressure Variability in Patients With Ascending Aortic Dilatation.

Blood pressure variability (BPV) is a novel parameter related to adverse cardiovascular findings and events, especially in hypertensive patients. The aim of the present study was to investigate the relationship between short-term BPV and ascending aortic dilatation (AAD). Hypertensive patients with AAD may exhibit higher short-term BPV compared to hypertensive patients with normal diameter ascending aorta and BPV may be correlated with aortic sizes. Seventy-six hypertensive patients with AAD and 181 hypertensive patients with a normal-diameter ascending aorta were retrospectively enrolled in the study. Clinical data, echocardiographic characteristics, and 24-hour ambulatory blood pressure monitoring characteristics were compared between the 2 groups. Standard deviation (SD) and Δ of BP were used as parameters of BPV. Although 24-hour mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) were similar between the 2 groups, the SD of SBP and SD of DBP values were significantly higher in AAD patients (17.2 ± 6.8 vs 13.8 ± 3.5, P < 0.01; and 12.1 ± 5.1 vs 10.7 ± 3.1, P = 0.02, respectively). Daytime SD of SBP values were higher in AAD patients, whereas nighttime SD of SBP values did not differ between groups. In multivariate linear regression analysis, 24-hour SD of SBP, 24-hour Δ SBP, daytime SD of SBP, daytime Δ SBP, and left ventricular mass index were independently correlated with aortic size index. Our study revealed higher levels of short-term BPV in hypertensive patients with AAD. This conclusion warrants further study.

Blood pressure variability and the development of early neurological deterioration following acute ischemic stroke.

Early neurological deterioration (END) is a common condition associated with poor outcome after acute ischemic stroke. We studied association between blood pressure (BP) variability and development of END. In this retrospective observational study, we studied a consecutive series of patients hospitalized for acute ischemic stroke within 24 h of onset. The primary outcome of interest was the development of END according to predefined criteria within the first 72 h of stroke onset. During this period, the mean, maximum (max), and minimum (min) values for the SBP and DBP were measured. The following parameters of BP variability were calculated for the SBP and DBP: the difference between the maximum and minimum (max-min), the SD, and the coefficient of variation. Of the 1161 patients enrolled in the study (mean age, 67.5 ± 13.3 years; 59.6% men), 210 (18.1%) developed END. All of the BP variability parameters were linearly associated with END independent of mean BP and potential clinical variables (P values < 0.05 on likelihood ratio tests for trend), except for SBPmax-min. Among the other BP parameters, SBPmean, SBPmax, DBPmax, and DBPmin were independently associated with END. After adjustments for potential confounders, the odds for END increased 14-21% with each increase of one standard deviation in the BP variability parameter. BP variability is independently and linearly associated with the development of neurologic deterioration in acute stage of ischemic stroke.

Short-term blood pressure variability in acute stroke: post hoc analysis of the controlling hypertension and hypotension immediately post stroke and continue or stop post-stroke antihypertensives collaborative study trials.

Short-term blood pressure variability (BPV) may predict outcome in acute stroke. We undertook a post hoc analysis of data from 2 randomized controlled trials to determine the effect of short-term BPV on 2-week outcome. Controlling Hypertension and Hypotension Immediately Post Stroke (CHHIPS) was a trial of BP-lowering, enrolling 179 acute stroke patients (onset<36 hours). Continue or Stop Post-Stroke Antihypertensives Collaborative Study (COSSACS) compared a strategy of continuation versus temporarily stopping prestroke antihypertensive therapy in 763 acute stroke patients (onset<48 hours). BPV at baseline (defined as SD, coefficient of variation, variation independent of the mean, and average real variability) was derived from standardized casual cuff BP measures (6 readings<30 minutes). Adjusted logistic regression models were used to assess the relation between BPV and death and disability (modified Rankin scale>3) at 2 weeks. Seven hundred six (92.5%) and 171 (95.5%) participants were included in the analysis for the COSSACS and CHHIPS data sets, respectively. Adjusted logistic regression analyses revealed no statistically significant associations between any of the included BPV parameters with 2-week death or disability in either study data set: COSSACS, odds ratio SD systolic BP 0.98 (0.78-1.23); CHHIPS, odds ratio SD systolic BP 0.97 (0.90-1.11). When derived from casual cuff BP measures, short-term BPV is not a useful predictor of early (2 weeks) outcome after acute stroke. Differing methodology may account for the discordance with previous studies indicating long-term (casual BPV) and short-term (beat-to-beat BPV) prognostic value. COSSACS was registered on the International Standard Randomised Controlled Trial Register; URL: http://www.isrctn.com. Unique identifier: ISRCTN89712435. CHHIPS was registered on the National Research Register; URL: http://public.ukcrn.org.uk. Unique identifier: N0484128008.

Finger volume pulse waveforms facilitate reliable assessment of heart rate variability, but not blood pressure variability or baroreflex function.

BackgroundWe sought to determine whether heart rate variability (HRV), blood pressure (BP) variability, and baroreceptor-heart rate reflex sensitivity can be reliably assessed using finger volume pulse waveforms obtained from the commercially available EndoPAT device.MethodsNon-invasive BP (Finometer Pro as a non-invasive standard) and finger volume (EndoPAT) waveforms were recorded in 65 adults (37 ± 14 years; 60% female) and systolic BP and heart rate (HR) time series were derived after calibrating the EndoPAT signal based on systolic and diastolic BP values obtained by a sphygomomanometer. Transfer function analyses were performed to test for coherence between systolic BP and HR time series derived from the Finometer and EndoPAT devices. Time-domain HRV parameters, frequency domain HR and systolic BP variability parameters, and baroreflex sensitivity (sequence technique) were computed from Finometer- and EndoPAT-derived time series and intraclass correlation coefficients (ICC) were calculated.ResultsSquared coherence between systolic BP time series derived from the Finometer and EndoPAT devices was low, suggesting poor correlation. In contrast, squared coherence between HR time series derived from the two devices was excellent [High Frequency (HF) = 0.80, Low Frequency (LF) = 0.81], with gain values close to 1.0. ICC values for time- and frequency-domain HRV parameters were excellent (>0.9 except for relative HF HRV, which was 0.77), while ICC values for frequency-domain BP variability parameters and baroreceptor-HR reflex sensitivity were low.ConclusionsFinger volume pulse waveforms can be used to reliably assess both time-domain and frequency-domain HR variability. However, frequency domain BP variability parameters cannot be reliably assessed from finger volume pulse waveforms using the simple calibration technique used in this study.

Highly variable blood pressure as a predictor of poor cognitive outcome in patients with acute lacunar infarction.

Many patients develop cognitive impairment after an acute stroke. It is not clear whether blood pressure variability is a prognostic factor for cognitive impairment. We aimed to determine the association between blood pressure variability on hospital admission and cognitive outcome in patients with acute lacunar infarction. We performed a retrospective analysis on 22 men and 14 women (mean age, 61.8 years) who had completed a cognitive evaluation 3 months after onset of an acute lacunar infarction. The patients had no previous functional disability or dementia, stenosis in major cerebral arteries, cardiac embolic sources, or infarct in strategic territories for cognition. We used standard deviation and coefficient of variance as parameters of blood pressure variability, and each cognitive function test z score as an outcome parameter. We performed linear regression analysis to assess the relationship between blood pressure variability and cognition, adjusted for vascular risk factors, severity of neurologic deficits, and mean blood pressure. High variability of both systolic and diastolic blood pressure was significantly associated with low z scores on the Controlled Oral Word Association Test and the Digit Symbol Coding test (P<0.01). High variability of diastolic blood pressure was significantly associated with low z scores on the Korean Mini-Mental State Examination and Seoul Verbal Learning Test delayed recall (P<0.01). Highly variable blood pressure on admission for acute lacunar infarction may predict poor cognitive outcomes, especially frontal lobe dysfunction.

Impact of multi-electrode renal sympathetic denervation on short-term blood pressure variability in patients with drug-resistant hypertension. Insights from the EnligHTN I study

BackgroundTransluminal renal sympathetic denervation (RDN) has been shown to reduce blood pressure (BP) in patients with treatment-resistant hypertension. MethodsWe assessed the effect of multi-electrode RDN on short-term BP variability indexes in resistant hypertensives. Thirty-one patients with drug-resistant uncontrolled hypertension, participants in the EnligHTN I study, underwent ambulatory BP measurements at baseline and 6months after RDN using the EnligHTN ablation catheter (St. Jude Medical). Twelve resistant hypertensives matched for office BP served as control group. ResultsAt 6months post-RDN, office BP and 24-hour BP were reduced by 25.6/10.3mmHg and by 10.2/6mmHg (p<0.001 for all cases), respectively. No significant changes were observed 6months post-RDN in standard short-term BP variability indexes including 24-hour systolic and diastolic average real variability. The rates of systolic and diastolic 24-hour BP variation were decreased 6months after RDN, (from 0.40/0.30 to 0.34/0.24, p=0.030/0.006, respectively), especially in the responders group (n=23, 74.2%). No significant differences in BP and BP variability parameters in the control group were detected. ROC analysis revealed an area under the curve for prediction of response to RDN by systolic time rate of 66.8% (95% CI: 46.7% to 87%; p=0.16) and by diastolic time rate of 76.1% (95% CI: 58.2% to 93.9%; p=0.030). ConclusionsAlthough standard BP variability indexes remained unchanged, the rate of systolic and diastolic BP variation was significantly decreased 6months after RDN in patients with drug-resistant hypertension. These novel indexes might also be useful as predictors of response.

Cardiovascular variability in Mexican patients with Parkinson's disease.

Cardiovascular variability (CVV) has been evaluated in patients with Parkinson's disease (PD) in other countries and exhibit ethnic differences. We investigated heart rate variability (HRV) and blood pressure variability (BPV) in Mexican patients with PD. We further compared HRV and BPV between this group and young healthy controls (YHC) in order to estimate, for the first time in our country, the magnitude of the difference. Twenty patients were examined. Time- and frequency-domain CVV parameters were studied during supine rest (SR), active standing (AS) and controlled breathing. These measurements were compared to those of 20 YHC. In the three conditions tested, our study showed a decrease in almost all HRV parameters in PD patients; on the contrary, decreased BPV parameters were found less frequently and only during SR and AS. Our results indicate that HRV is impaired in PD. Some BPV parameters are also diminished.

Treadmill gait training improves baroreflex sensitivity in Parkinson’s disease

Partial weight supported treadmill gait training (PWSTT) is widely used in rehabilitation of gait in patient with Parkinson’s Diseases (PD). However, its effect on blood pressure variability (BPV) and baroreflex sensitivity (BRS) in PD has not been studied. To evaluate the effect of conventional and treadmill gait training on BPV components and BRS. Sixty patients with idiopathic PD were randomized into three groups. Twenty patients in control group were on only stable medication, 20 patients in conventional gait training (CGT) group (Stable medication with CGT) and 20 patients in PWSTT group (Stable medication with 20 % PWSTT). The CGT and PWSTT sessions were given for 30 min per day, 4 days per week, for 4 weeks (16 sessions). Groups were evaluated in their best ‘ON’ states. The beat-to-beat finger blood pressure (BP) was recorded for 10 min using a Finometer instrument (Finapres Medical Systems, The Netherlands). BPV and BRS results were derived from artifact-free 5-min segments using Nevrocard software. BRS showed a significant group with time interaction (F = 6.930; p = 0.003). Post-hoc analysis revealed that PWSTT group showed significant improvement in BRS (p < 0.001) after 4 weeks of training. No significant differences found in BPV parameters; systolic BP, diastolic BP, co-variance of systolic BP and low frequency component of systolic BP. Four weeks of PWSTT significantly improves BRS in patients with PD. It can be considered as a non-invasive method of influencing BRS for prevention of orthostatic BP fall in patients with PD.

Abstract T MP75: Effect of Subacute BP Variability on Subsequent Vascular Events in Patients with Acute Ischemic Stroke

Objectives: We recently reported that blood pressure variability (BPV) during a subacute stage of ischemic stroke may affect functional outcome. This study aimed to test a hypothesis whether subacute BPV increases a risk of subsequent vascular events following acute ischemic stroke. Methods: From a prospective stroke registry database, consecutive ischemic stroke patients hospitalized within 48 h of onset were identified. Subacute BPV parameters were defined as maximum 2 -minimum, standard deviation (SD) and coefficient of variation (CV) of systolic BP (SBP) from 72 hours after onset to discharge. Primary outcome was a time to a subsequent vascular event (SVE), which was a composite of stroke, myocardial infarction and other vascular death. The BPV parameters were categorized into tertiles and dose-response relationships between BPV parameters and SVE were examined. The hazard ratios (HRs) of BPV parameters were estimated using Cox proportional hazard models with adjustments for predetermined confounders. Result: Of 3047 patients (mean age, 66.4 years and median NIHSS score, 3); BP was measured by median 46 times per person during the subacute stage (median 7 days). Median follow-up duration was 352 days (interquartile range, 112 to 389 days) and cumulative SVE rates were 7.0%. SVE rates differed by the tertiles of BPV parameters; SVE rates of lower, middle and upper thirds of maximum-minimum were 5.2%, 6.4% and 9.6%, those of SD were 5.4%, 8.5% and 7.9% and those of CV were 4.9%, 8.4% and 7.6%, respectively (P’s &lt; 0.05 on log rank test). There were significant dose-response relationships of SVE with maximum-minimum and SD (P &lt; 0.01 and 0.01), not with CV (P = 0.14) independent of mean SBP, age, sex, history of stroke, hypertension, diabetes mellitus, hyperlipidemia, atrial fibrillation and stroke subtypes. Adjusted HRs of one-SD of maximum-minimum, SD and CV of SBP were 1.24 (95% confidence interval, 1.09-1.40), 1.16 (1.01-1.32) and 1.15 (1.01-1.30), respectively. Conclusion: This study suggests that the increase of blood pressure variability at subacute stage of ischemic stroke may increase the risk of subsequent vascular events.

Blood pressure variability parameters and the risk of developing hypertension in healthy young males: 5-year follow-up study

Purpose: Few prospective studies have evaluated increase Blood Pressure Variability (BPV) as a risk factor for onset hypertension in young populations. We conducted a prospective cohort study to examine the relationship of BPV to the onset of hypertension in healthy young males depending on family hypertensive anamnesis. Methods: Apparently healthy males aged 18-35 (n=366) without prevalent hypertension at baseline were enrolled in 2003-2005 years. All subjects took an annual medical checkup including Blood Pressure (BP) measurement, Ambulatory 24 hour Blood Pressure Monitoring (ABPM) and veloergometry - at baseline only; medical interview until 2010. The participants were categorized into 2 groups according to family anamnesis of hypertension (1st – positive family anamnesis, 2nd – negative one). Incident hypertension was defined as newly detected BP ≥140/90 mmHg and/or initiation of antihypertensive drugs. The incident hypertension was analyzed in each group. Results: During a median follow-up time of 4.6 years, there were 77 cases (21.0%) of incident hypertension. The incident hypertension rate of the 1st group was significantly higher than of the 2nd group (36.4% vs. 7.3%). The patients of the 1st group with incident hypertension in 5-year follow up had significant increased diastolic BP in veloergometry in comparison with men remained normotension. The range of morning systolic BP surge in ABPM was also higher (38.3±8.9 mmHg vs. 51.1±10.1 mmHg, p=0.039). In the 2nd group significant difference for these parameters was not revealed. The relative risks (RR) (95% confidence interval) adjusted for body mass index, excess salt intake, smoking status, and alcohol intake for incident hypertension in the 1st group in morning systolic BP surge by ABPM ≥50 mmHg was 1.43 (1.29–1.59); in the range diastolic BP in veloergometry >0% – 1.56 (1.29–1.59). Conclusions: Even if BP was within normal range, some parameters of blood pressure variability (systolic blood pressure morning surge in ABPM and elevated diastolic blood pressure in veloergometry) was a predictor of future hypertension in a healthy young-aged male population with positive family hypertensive anamnesis.

Blood pressure variability and multiple organ damage in primary hypertension

Organ damage (OD) is an indicator of increased cardiovascular risk. Blood pressure variability (BPV) is related to greater incidence of events, regardless of the severity of hypertension. We investigated the relationship between ambulatory blood pressure monitoring (ABPM)-derived indices of BPV and the presence of multiple OD in primary hypertension (PH). One hundred and sixty-nine untreated patients with PH were evaluated. Systolic (SBP) and diastolic blood pressure (DBP) variability were assessed as the crude and weighted (w.) standard deviation (s.d.), and average real variability (ARV) of the mean value of 24-h, awake and asleep ABPM recordings. Left ventricular mass index, intima-media thickness, estimated-glomerular filtration rate and urinary albumin excretion were assessed as indices of cardiac, vascular and renal damage, respectively. Risk profile progressively increased starting from patients without OD to patients with only one sign of OD, and then to those with multiple OD. In addition to greater severity of the organ involvement, the only variables that were found to significantly differ between subjects with multiple and single OD were office SBP (160 ± 14 vs 154 ± 11 mm Hg, P=0.0423) and DBP (101 ± 7 vs 97 ± 8 mm Hg, P=0.0291), ambulatory arterial stiffness index (AASI) (0.60 ± 0.10 vs 0.50 ± 0.17, P=0.0158) and indices of BPV (24-h SBP s.d., 23 ± 5 vs 20 ± 6 mm Hg, P=0.0300; awake SBP s.d., 22 ± 6 vs 19 ± 6 mm Hg, P=0.0366; 24-h SBP w.s.d., 20 ± 5 vs 17 ± 5 mm Hg, P=0.0385; and 24-h SBP ARV, 18 ± 4 vs 15 ± 5 mm Hg, P=0.0420). All the above mentioned BPV parameters turned out to be determinants of multiple OD, regardless of several confounding variables, including BP levels. Therefore, in hypertensive patients increased SBP variability is associated with multiple signs of OD, regardless of BP values.

Within-visit blood pressure variability: relevant factors in the general population

The objective of this study was to use a nationwide epidemiological survey to investigate the factors that affect within-visit blood pressure (BP) variability. We analyzed the Korean National Health and Nutrition Examination Survey (KNHNES) data for 2005 (n=5488). We examined three within-visit BP variability parameters that include the following: the alarm reaction (AR), defined as the first BP reading minus the third BP reading; the BP discrepancy, defined as the maximal BP reading minus the minimal BP reading (ΔBPmax); and the s.d. (BPSD). Age, fasting glucose, eGFR, total cholesterol, LDL cholesterol, and the metabolic syndrome (MetS) score were the relevant factors that affected the systolic AR, ΔSBPmax and SBPSD. Multiple linear regression models revealed that age (P<0.0001), the office systolic BP (SBP) level (P<0.0001), the MetS score (P<0.0001), the female gender (P=0.007) and the eGFR (P=0.049) were independently associated with the systolic AR, whereas age (P<0.0001), the office SBP level (P<0.0001), and the female gender (P=0.024 and 0.022) were independently associated with ΔSBPmax and SBPSD, respectively. Within-visit BP variability, especially the variability associated with the SBP, was significantly associated with increased age, female gender and cardiovascular risk factors, such as hypertension, low eGFR and adverse glucose and lipid profiles. In addition, increased age, female gender, the eGFR and the MetS score were independently relevant factors that affected the systolic AR. Systolic within-visit BP variability and systolic AR are associated with cardiovascular risk factors.

MODERN VIEWS ON THE VARIABILITY OF BLOOD PRESSURE

Nowadays conception of blood pressure (BP) variability (BPV) includes a number of indicators related to various physiological factors. All the indexes are calculated with the standard deviation (SD) or more complex formulas, including SD. BPV main varieties are considered a 24-hour BPV (measured by ambulatory BP monitoring – ABPM), midterm BPV (BP self-control or home BP – HBP), and long-term, visit-to-visit, BPV (traditional BP measurement or office BP – OBP). The 24-hour BPV was the main subject of study for many years. Recently significant attention has been paid to the visit-to-visit BPV assessment. Retrospective meta-analysis showed that in a cohort of patients after stroke or transient ischemic attack, this index was a strong and independent (from the average BP level) predictor of stroke. In ASCOT-BPLA study visit-to-visit systolic BPV also was a strong predictor of stroke and coronary events. Long-term BPV in patients of amlodipine/perindopril treatment group was significantly lower than this in patients of atenolol/diuretic group during the follow-up that was associated with a lower risk of cardiovascular complications. However , the concept of visit-to-visit BPV use for risk stratification and monitoring of antihypertensive therapy efficacy is associated with significant limitations (basic data is obtained in the post hoc analysis, difficulties in objective evaluation of prognostic significance of indicators, their dependence on medication adherence, etc.). The HBP self-control is a promising approach to the BPV analysis; it may be the happy medium between ABPM and OPB. New-designed prospective comparative studies are needed to evaluate the clinical significance of the various BPV parameters.

Increased heart rate variability during nondirective meditation

Meditation practices are in use for relaxation and stress reduction. Some studies indicate beneficial cardiovascular health effects of meditation. The effects on the autonomous nervous system seem to vary among techniques. The purpose of the present study was to identify autonomic nerve activity changes during nondirective meditation. Heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity (BRS) were monitored in 27 middle-aged healthy participants of both genders, first during 20 min regular rest with eyes closed, thereafter practising Acem meditation for 20 min. Haemodynamic and autonomic data were collected continuously (beat-to-beat) and non-invasively. HRV and BPV parameters were estimated by power spectral analyses, computed by an autoregressive model. Spontaneous activity of baroreceptors were determined by the sequence method. Primary outcomes were changes in HRV, BPV, and BRS between rest and meditation. HRV increased in the low-frequency (LF) and high-frequency (HF) bands during meditation, compared with rest (p = 0.014, 0.013, respectively). Power spectral density of the RR-intervals increased as well (p = 0.012). LF/HF ratio decreased non-significantly, and a reduction of LF-BPV power was observed during meditation (p < 0.001). There was no significant difference in BRS. Respiration and heart rates remained unchanged. Blood pressure increased slightly during meditation. There is an increased parasympathetic and reduced sympathetic nerve activity and increased overall HRV, while practising the technique. Hence, nondirective meditation by the middle aged may contribute towards a reduction of cardiovascular risk.

Autonomic activity and baroreflex sensitivity in patients submitted to carotid stenting

Arterial baroreflex and cardiac autonomic control play important roles in hemodynamic instability after carotid artery stenting (CAS). Spontaneous baroreflex sensitivity (BRS), heart rate variability (HRV) and blood pressure variability (BPV) are established tools for the assessment of arterial baroreflex and cardiac autonomic activity. Aim of the study was to evaluate cardiac autonomic activity (by means of HRV, BPV and BRS) after CAS and to explore the impact of internal carotid artery stenosis on BRS changes after CAS. 37 patients (68±10.45 years) with internal carotid stenosis underwent CAS. HRV, BPV and BRS were measured in all subjects before and at 1 and 72h after CAS. ANOVA was performed to compare BRS, HRV and BPV parameters before and after CAS. Spearman analysis was performed to determine a possible correlation between carotid stenosis degree (or carotid plaque diameter) and BRS changes (ΔBRS). LF/HF (index of sympatho-vagal balance) decreased during postoperative period, in comparison with baseline (2.32±1.70 vs 1.65±1.40, p<0.05). There was a significant negative correlation between carotid stenosis degree and ΔBRS (r=−0.35, p=0.03) and between carotid plaques thickness and ΔBRS (r=−0.36, p=0.02). CAS procedure may cause an alteration of carotid wall mechanical properties, increasing baroreflex sensitivity. BRS does not increase in all the patients, because arterial wall damage and nerve destruction determined by atherosclerotic plaque may reduce ΔBRS.

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.

BLOOD PRESSURE VARIABILITY: DOES IT PREDICT CARDIOVASCULAR OUTCOME?: PP.14.27

Objective: To evaluate blood pressure variability (BPV) and its relation to the occurrence of cardiovascular events (CE) in hypertensive patients. Design and Methods: Retrospective study. We selected 100 consecutive hypertensive patients who performed ambulatory blood pressure monitoring (ABPM) from Jul/2004 to Jun/2005. Studied variables: gender, age, cardiovascular risk factors (CRF), parameters of ABPM, occurrence of CE in the next two years. BPV was evaluated based on the standard deviation (SD) of the mean of the various ABPM parameters. Results: Half of the patients were males and the mean age was 60 ± 13 years. At the beginning, mean BP was 154–87mmHg. Two years later, mean BP was 141–82mmHg and 34% of patients had developed CE. The averages of the maximal (max) values and the mean values of systolic blood pressure (SBP) and mean blood pressure (MBP) in the 24 h, daytime and nighttime were higher in patients who developed CE. The SD of SBP in the 24 h and daytime were higher in patients who developed CE. The SD of MBP in the daytime was higher in patients who developed CE. The weighted average of the SD of the SBP (daytime/nighttime) was also higher in patients who developed CE. There was no difference concerning gender, CRF or previous CE between patients who developed CE or not (p > 0.05). However, patients who developed CE were older (p = 0.012). Nevertheless, the association between the following parameters of BP and BPV and the occurrence of CE remained independent of age (SBP max - 24 h: p = 0.001; daytime: p = 0.001; nighttime: p = 0.005) (SBP mean - 24 h: p = 0.002; daytime: p = 0.003; nighttime: p = 0.004) (SBP – SD 24 h: p = 0.003; SD daytime: p = 0.001) (SBP – weighted average of SD in daytime/nighttime: p = 0.002) (MBP max - 24 h: p = 0.001) (MBP – SD daytime: p = 0.004). Conclusion: An association between BPV and CE was observed in hypertensive patients, which suggests that BPV may be a relevant prognostic factor in these patients.

Different Effects of Volatile Anesthetics on Cardiovascular Neural Regulation of the Autonomic Nervous System in the Streptozotocin-induced Diabetic Rat

Objective Inhalation anesthetics increase heart rate (HR) in vivo in both animals and humans but decrease heart rate in isolated hearts. Clinical studies indicate that insulin-dependent diabetes mellitus is associated with alterations in autonomic nervous system control of cardiovascular function. The specific aim of this study was to elucidate the effects of different inhalation anesthetics on cardiovascular autonomic function in diabetic rats. Materials and Methods We measured blood pressure variability (BPV) in streptozotocin (STZ, 60 mg/kg, i.p.)-induced diabetic Sprague-Dawley rats and vehicle control groups exposed to different inhalation anesthetics (halothane, desflurane and sevoflurane) and BPV was recorded until the recovery stage. Frequency-domain analysis of telemetric systemic arterial pressure and pulse-pulse interval were applied to quantify the parameters of BPV. High frequency power (HF) was regarded as cardiac vagal modulation. Low frequency power of BPV (BLF) was referred to as vascular sympathetic modulation. Normalized low-frequency power (LF%) of the spectrogram of the RR interval was regarded as cardiac sympathetic modulation. Results STZ-induced diabetes was associated with a significant reduction of HR but not consistently with a higher HF among these volatile anesthetics. BLF was significantly decreased at one minimum alveolar concentration (MAC) of desflurane when compared with halothane and sevoflurane in the STZ-induced diabetic group. We found an early recovery of the BLF to awake stage baseline values 30 minutes post-anesthesia for sevoflurane, although it was not significant when compared with the other two anesthetics. However, the LF% significantly recovered to 80% of awake baseline values with desflurane and sevoflurane when compared with halothane 30 minutes post-anesthesia. Conclusion The components of sympathetic regulation (BLF and LF%) may be an early sign of hemodynamic recovery to the awake stage during anesthesia in STZ-induced diabetic rats. Our results provide an indication for clinical anesthetic choice in diabetes patients receiving anesthesia.

Respiratory effects on the reproducibility of cardiovascular autonomic parameters

The aim of this study was to assess the influence of breathing pattern on the reproducibility of the most commonly used heart rate and blood pressure variability parameters and baroreflex indices. 5-5 min ECG and blood pressure recordings were made and repeated for 10 healthy volunteers in supine rest on 10 consecutive days during spontaneous and 6 min(-1) patterned breathing. We investigated the following parameters: mean RR interval (RRI); the standard deviation of RR intervals (SDRR); the root mean square of successive differences in RRI (RMSSD); the percentage of RRIs which differed by 50% from the proceeding RRI (PNN50); mean systolic arterial pressure (SAP); the standard deviation of SAP (SAP SD); mean mean arterial pressure (MAP); mean diastolic blood pressure (DAP) and baroreflex indices from spontaneous sequence method (upBRS and downBRS) and from cross spectral analysis (LF alpha, HF alpha). To assess reproducibility for each parameter within- and between-subject variability values were calculated and the ratio of within- and between-subject variability was assessed. In addition, we calculated intraclass correlation coefficient (ICC). Compared to spontaneous respiration during 6 min(-1) patterned breathing the heart rate and blood pressure variability increased; upBRS, LF alpha and HF alpha increased, downBRS did not change. However, ICC showed good reproducibility for most parameters, which did not improve further with controlled breathing. In conclusion, respiration had a strong influence on the most widely used cardiovascular autonomic parameters. The controlling of breathing did not result in consistent improvement in their reproducibility.