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Pressure Variability (pressure + variability)
Kinds of Pressure Variability Selected AbstractsLinear and nonlinear measures of blood pressure variability: Increased chaos of blood pressure time series in patients with panic disorderDEPRESSION AND ANXIETY, Issue 2 2004Vikram K. Yeragani M.B.B.S. Abstract Arterial blood pressure (BP) variability increases progressively with the development of hypertension and an increase in BP variability is associated with end organ damage and cardiovascular morbidity. On the other hand, a decrease in heart rate (HR) variability is associated with significant cardiovascular mortality. There is a strong association between cardiovascular mortality and anxiety. Several previous studies have shown decreased HR variability in patients with anxiety. In this study, we investigated beat-to-beat variability of systolic and diastolic BP (SBP and DBP) in normal controls and patients with panic disorder during normal breathing and controlled breathing at 12, and 20 breaths per minute using linear as well as nonlinear techniques. Finger BP signal was obtained noninvasively using Finapres. Standing SBPvi and DBP BPvi (log value of BP variance corrected for mean BP divided by HR variance corrected for mean HR) were significantly higher in patients compared to controls. Largest Lyapunov exponent (LLE) of SBP and DBP, a measure of chaos, was significantly higher in patients in supine as well as standing postures. The ratios of LLE (SBP/HR) and LLE (DBP/HR) were also significantly higher (P < .001) in patients compared to controls. These findings further suggest dissociation between HR and BP variability and a possible relative increase in sympathetic function in anxiety. This increase in BP variability may partly explain the increase in cardiovascular mortality in this group of patients. Depression and Anxiety 19:85-95, 2004. © 2004 Wiley-Liss, Inc. [source] EXAMINATION OF RESPIRATORY AND CIRCULATORY DYNAMICS DURING EXAMINATION USING A THIN GASTROINTESTINAL ENDOSCOPE IN ADVANCED-AGE SUBJECTSDIGESTIVE ENDOSCOPY, Issue 2 2007Miyako Niki Background:, Endoscopic examination influences cardiovascular hemodynamics. Upper gastrointestinal examinations are currently performed with a thin endoscope. In the present study, respiratory and circulatory dynamics and autonomic nervous activity using a thin endoscope (XP260) or a standard endoscope (XQ240) were investigated. Methods:, The subjects were 25 healthy adults aged less than 60 years (middle-aged group) and 15 healthy adults aged 60 years or older (advanced-age group). Percutaneous oxygen saturation, tonometric blood pressure, heart rate, and autonomic nervous activity were evaluated before the examination. After the endoscopic procedure, a questionnaire survey regarding examination-related stress was conducted. Results:, In the questionnaire survey, the proportion of subjects who answered ,very stress free' in the thin endoscope group was significantly higher than that in the standard endoscope group. The low frequency power of blood pressure variability (LFBP), an indicator of sympathetic nervous activity, was significantly lower during the thin endoscopic procedure than during the standard endoscopic procedure. Moreover, the ratio of low frequency power to high frequency power of heart rate variability (LFRR/HFRR), an indicator of sympathetic nervous activity, was significantly lower during thin endoscopic procedure than during the standard endoscopic procedure. The maximum rates of change in the LFBP and HFRR powers in the advanced-age group using thin and standard endoscopic procedures were significantly lower than in the middle-aged group. Conclusions:, The findings, although not in cross-over study, suggest that a thin endoscope has a less marked influence on circulatory kinetics. Gastrointestinal endoscopic examinations using a thin endoscope might reduce complications related to endoscopic screening examinations in advanced-age subjects. [source] Cardioventilatory Coupling in Resting Human SubjectsEXPERIMENTAL PHYSIOLOGY, Issue 6 2003Y. C. Tzeng In 48 conscious resting subjects we examined the temporal coupling of heart beat timing and the onset of inspiration (cardioventilatory coupling), and the relationship between coupling and spectral indices of autonomic function. Using the proportional Shannon entropy (SH,) of the RI -1 interval (interval between inspiration and the preceding ECG R wave) as a measure of coupling we detected statistically significant coupling in 32 of the 48 subjects. This was confirmed by visual inspection of time series plots of RI intervals, in which coupling was evident as horizontal banding. Coupling resulted in a significant preference for whole number heart rate/respiratory frequency ratios. The strongest coupling was associated with low ventilatory frequency and high heart rate variability in the high (0.15-0.40 Hz) and low (0.04-0.15 Hz) frequency ranges, but was not related to blood pressure variability, or to a spectral measure of baroreflex sensitivity (,-index, low frequency range). There was no difference in coupling strength between males and females. We have previously described cardioventilatory coupling in spontaneously breathing anaesthetised subjects. The current study extends those observations by demonstrating that the qualitative features of coupling seen during anaesthesia are also observed in the conscious state. We conclude that the role of coupling in normal physiological respiratory control needs to be more widely explored. [source] Extracting new patterns for cardiovascular disease prognosisEXPERT SYSTEMS, Issue 5 2009Luis Mena Abstract: Cardiovascular diseases constitute one of the main causes of mortality in the world, and machine learning has become a powerful tool for analysing medical data in the last few years. In this paper we present an interdisciplinary work based on an ambulatory blood pressure study and the development of a new classification algorithm named REMED. We focused on the discovery of new patterns for abnormal blood pressure variability as a possible cardiovascular risk factor. We compared our results with other classification algorithms based on Bayesian methods, decision trees, and rule induction techniques. In the comparison, REMED showed similar accuracy to these algorithms but it has the advantage of being superior in its capacity to classify sick people correctly. Therefore, our method could represent an innovative approach that might be useful in medical decision support for cardiovascular disease prognosis. [source] Sea-level pressure variability in the Po Plain (1765,2000) from homogenized daily secular recordsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2004Maurizio Maugeri Abstract A homogenized 236 year daily regional sea-level pressure (SLP) record is constructed for the Po Plain (north Italy) by means of six station records: Bologna, Genoa, Lugano, Milan, Padua and Turin. Station records are subjected to a first homogenization in order to reduce all observations to sea level and to 0°C and to correct the bias introduced by calculating daily means using different sets of observation hours. A second homogenization is performed by means of comparison with other Italian and European series. After homogenization, the root-mean square error of the yearly station records is evaluated within 0.2 hPa after 1880, whereas for the periods 1834,1880 and 1765,1833 it is estimated as between 0.2 and 0.3 hPa and as around 0.4 hPa respectively. Trend analysis is applied to the annual and seasonal regional records and concerns both SLP and its day-to-day variability. The results show that neither the SLP nor its day-to-day variability have an evident trend when considering the entire 1765,2000 period. However, if the series is divided roughly in two parts, then significant trends can be highlighted. The annual and seasonal regional SLP records are also compared with corresponding regional temperature series. The results show that, especially in spring and in summer, temperature and SLP are in good agreement. Copyright © 2004 Royal Meteorological Society [source] The combination of atenolol and amlodipine is better than their monotherapy for preventing end-organ damage in different types of hypertension in ratsJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2009Ping Han Abstract Combinations therapy is often used in hypertensive patients whether combination therapy is necessary for preventing end-organ damage is not known. The objective of this study was to determine in four different hypertensive animal models the necessity of adding the calcium channel blocker amlodipine to therapy with the ß-blocker atenolol to modulate end-organ damage. Spontaneously hypertensive rats, DOCA-salt hypertensive rats, two-kidney, one-clip renovascular hypertensive rats and Lyon genetically hypertensive rats were used to study this objective. These animal models have different sensitivities to atenolol and amlodipine. The dosages of therapy employed were 10 mg/kg atenolol alone, 1 mg/kg amlodipine, 10 mg atenolol + 1 mg/kg amlodipine and 5 mg/kg atenolol+0.5 mg/kg amlodipine. BP was continuously recorded in all animals. After determination of baroreflex sensitivity, rats were sacrificed for end-organ damage evaluation. The combination of amlodipine and atenolol had a synergistic inhibitory effect on blood pressure and blood pressure variability, and end-organ damage as compared with monotherapy with atenolol or amlodipine in all animal models. Baroreflex sensitivity also improved with the combination therapy more than with monotherapy. In conclusion, atenolol and amlodipine combination exerts a superior effect on blood pressure, blood pressure variability, baroreflex sensitivity and end-organ damage. The superior effect of the combination was observed in all four models of hypertension. [source] Ambulatory monitoring and physical health report in Vietnam veterans with and without chronic posttraumatic stress disorderJOURNAL OF TRAUMATIC STRESS, Issue 4 2003Jean C. Beckham Abstract This study investigated the associations among PTSD, ambulatory cardiovascular monitoring, and physical health self-reports in 117 male Vietnam combat veterans (61 with PTSD and 56 without PTSD). PTSD was associated with health symptoms and number of current health conditions beyond the influence of several covariates. PTSD was associated with greater systolic blood pressure variability, and an elevated percentage of heart rate and systolic blood pressure readings above baseline. Higher mean heart rate and an elevated percentage of heart rate above baseline were associated with physical health symptoms. None of the ambulatory monitoring variables mediated the association between PTSD and physical health outcomes. Findings suggest that the interrelationships among ambulatory autonomic responses, PTSD, and physical health deserve more research attention. [source] Blood Pressure Regulation and Vegetarian DietsNUTRITION REVIEWS, Issue 1 2005Susan E. Berkow PhD Hypertension affects approximately 50 million individuals in the United States and approximately 1 billion worldwide. Although heredity plays a role in blood pressure variability, diet and lifestyle exert considerable influence in blood pressure regulation. This report reviews the evidence of the relationship between a vegetarian diet and blood pressure regulation and presents data as to the putative mechanisms of action. [source] Altered Autonomic Cardiac Control Predicts Restenosis After Percutaneous Coronary InterventionPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2006MATTHIAS GOERNIG Background: Early and late restenosis in up to 30% remains a major problem for long-term success after percutaneous coronary intervention (PCI). Compared to bare metal stents, the use of drug-eluting stents reduces restenosis below 10%, but implant coasts have to be considered. In restenosis noninvasive testing lacks diagnostic power. We applied a new approach to identify patients with a high risk for restenosis after PCI by combining heart rate (HR) and blood pressure variability (BPV) analyses. Methods: In 52 patients with clinical suspicion of restenosis and history of PCI, we investigated patterns of cardiovagal autonomic regulation prior to cardiac catheterization. The patients were separated in (i) patients with restenosis (CAD+R) and (ii) patients without restenosis (CAD,R), where restenosis is defined as a stenosis greater than 75% of luminal diameter in at least one main vessel. The following parameters/methods were evaluated: Canadian Cardiovascular Society grade (CCS-grade), vessel disease score (CAD-level), left ventricular ejection fraction (LVEF), heart rate variability (HRV), BPV, baroreflex sensitivity (BRS), as well as HR turbulence and blood pressure (BP) potentiation caused by premature ventricular complexes. Results: Whereas age, LVEF, CAD-level, CCS-grade, and mean BP did not differ between CAD+R and CAD,R, significant differences were found in (i) BPV: diastolic LF/P, systolic, and diastolic UVLF, (ii) in BRS: slope of tachycardic sequences, and (iii) in extrasystolic parameters: heart rate turbulence onset (HRTO) and potentiation of systolic BP (SBPP). Standard HRV parameters did not show significant differences between the groups. Using the two parameters diastolic LF/P (threshold >0.2) and HRTO (threshold >0) restenosis were predicted in 83.4%. Conclusions: These results demonstrate that indicators of sympathetic activation or vagal depression identify restenosis in patients after PCI, thus opening a perspective for a new noninvasive monitoring. [source] Denervation of Carotid Baro- and Chemoreceptors in HumansTHE JOURNAL OF PHYSIOLOGY, Issue 1 2003Henri J. L. M. Timmers Experimental denervation in animals has shown that carotid baro- and chemoreceptors play an eminent role in maintaining blood pressure and blood gas homeostasis. Denervation of carotid sinus baro- and chemoreceptors in humans may occur as a complication of invasive interventions on the neck or after experimental surgical treatment in asthma. In this topical review, the short- and long-term effects of carotid baro- and chemoreceptor denervation on the control of circulation and ventilation in humans are discussed. Carotid baroreceptor denervation in humans causes a persistent decrease in vagal and sympathetic baroreflex sensitivity and an increase in blood pressure variability; however, carotid denervation does not lead to chronic hypertension. Therefore, although carotid baroreceptors contribute to short-term blood pressure control, other receptors are able to maintain normal chronic blood pressure levels in the absence of carotid baroreceptors. Conversely, carotid chemoreceptor denervation leads to permanent abolition of normocapnic ventilatory responses to hypoxia and reduced ventilatory responses to hypercapnia. [source] 2357: Autonomic nervous system and endothelial peripheral dysfunction in normal tension glaucoma patientsACTA OPHTHALMOLOGICA, Issue 2010J WIERZBOWSKA Purpose To define parameters of autonomic nervous system activity and peripheral vascular reactive hyperemia in normal tension glaucoma patients. Methods Ambulatory 24-hour electrocardiogram and blood pressure (BP) monitoring by using Lifecard CF and SpaceLab 90207-30 combined with occlusion provocation test were carried out in 54 NTG patients (44 women, mean age 59.7) and 43 matched control subjects (34 women, mean age 57.0). Heart rate variability (HRV) time and frequency domain parameters [low-frequency (LF), high-frequency (HR) and LF/HF ratio], and blood pressure variability (BPV) were calculated and analyzed for both study groups. Postocclusive hyperemia response parameters (TM - time to peak flow, TH ,half-time hyperaemia, TR ,time to rest flow, BZ-biological zero and MAX , maximum hyperemic response) were compared for patients with a nocturnal fall in mean BP (MPB) of less than 10% (non-dippers), of 10-20% (dippers) and of more than 20% (over-dippers) Results NTG patients demonstrated higher LF and LF/HF values for 24-hour period, day-time and night time than control subjects. There was no difference in BPV between study groups (10.4 ± 1.9 vs. 10.5 ± 2.1, p=0.790). In NTG patients, TH was significantly higher (79.0 ± 80.9 s vs. 51.5 ± 35.3 s, p=0.028) and BZ was significantly lower (2.3 ± 1.0 vs. 3.1 ± 2.0, p=0.009) as compared to the control group. There was statistically significant difference between NTG non-dippers, dippers and over,dippers in the BZ parameter (2.3 ± 0.9 vs. 2.7 ± 1.3 vs. 1.4 ± 0.4 p=0.024). Conclusion NTG patients exhibit abnormal ANS system activity and a different systemic hyperemia response as compared with healthy subjects. [source] KETANSERIN-INDUCED BAROREFLEX ENHANCEMENT IN SPONTANEOUSLY HYPERTENSIVE RATS DEPENDS ON CENTRAL 5-HT2A RECEPTORSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2007Fu-Ming Shen SUMMARY 1Ketanserin may influence baroreflex function by blocking 5-HT2A receptors and/or ,1 -adrenoceptors through central and/or peripheral mechanisms. 2In the present study, we tested the hypothesis that the baroreflex sensitivity (BRS)-enhancing effects of ketanserin are mediated by central 5-HT2A receptors in spontaneously hypertensive rats (SHR). 3Using a conjugate of a monoclonal antibody to the serotonin reuptake transporter (SERT) and the toxin saporin (anti-SERT-SAP), which specifically eliminates the neurons that express SERT, the effects of ketanserin (0.3 and 3.0 mg/kg, i.g.) on BRS, blood pressure (BP), heart period (HP) and blood pressure variability (BPV) were compared between conscious intact SHR and SHR pretreated with anti-SERT-SAP. 4Immunochemistry showed that, 2 weeks after intracerebroventricular injection of the toxin, 5-HT expression was strikingly attenuated in the brain, whereas values of BRS, BPV and BP were similar to those in the sham group. In intact SHR, 0.3 mg/kg ketanserin significantly improved BRS (191% control) and reduced BPV without affecting BP; at 3.0 mg/kg, ketanserin significantly increased BRS (197% control) and decreased BPV and BP. In toxin-pretreated SHR, only the high dose of ketanserin improved BRS (132% control), neither of the ketanserin doses reduced BPV, but both significantly decreased BP. 5We conclude that the BRS-enhancing effects of ketanserin are mediated largely by central 5-HT2A receptors, whereas the antihypertensive effect of ketanserin persists even after destruction of serotonergic neurons in the central nervous system. [source] IDENTIFICATION OF BLOOD PRESSURE CONTROL MECHANISMS BY POWER SPECTRAL ANALYSISCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2007Harald M Stauss SUMMARY 1Blood pressure and organ perfusion are controlled by a variety of cardiovascular control systems, such as the baroreceptor reflex and the renin,angiotensin system (RAS), and by local vascular mechanisms, such as shear stress-induced release of nitric oxide (NO) from the endothelium and the myogenic vascular response. Deviations in arterial blood pressure from its set point activate these mechanisms in an attempt to restore blood pressure and/or secure organ perfusion. However, the response times at which different cardiovascular mechanisms operate differ considerably (e.g. blood pressure control by the RAS is slower than blood pressure control via the baroreceptor reflex). 2Owing to these different response times, some cardiovascular control systems affect blood pressure more rapidly and others more slowly. Thus, identifying the frequency components of blood pressure variability (BPV) by power spectral analysis can potentially provide important information on individual blood pressure control mechanisms. 3Evidence is presented that the RAS, catecholamines, endothelial-derived NO and myogenic vascular function affect BPV at very low frequencies (0.02,0.2 Hz) and that low-frequency (LF) BPV (0.2,0.6 Hz) is affected by sympathetic modulation of vascular tone and endothelial-derived NO in rats. In humans, LF BPV (0.075,0.15 Hz) is affected by sympathetic modulation of vascular tone and myogenic vascular function. The impact of the RAS and endothelial-derived NO on BPV in humans requires further investigation. 4In conclusion, power spectral analysis is a powerful diagnostic tool that allows identification of pathophysiological mechanisms contributing to cardiovascular diseases, such as hypertension, heart failure and stroke, because it can separate slow from fast cardiovascular control mechanisms. The limitation that some cardiovascular control mechanisms affect the same frequency components of BPV requires the combination of blood pressure spectral analysis with other techniques. [source] EARLY STRUCTURAL CHANGES OF AORTIC WALL IN SINOAORTIC-DENERVATED RATSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2006Fu-Ming Shen SUMMARY 1The present work was designed to observe the early structural changes in the aortic wall in Sprague-Dawley rats 1, 2 and 4 weeks after sinoaortic denervation (SAD). 2Rats were examined 1, 2 and 4 weeks after SAD. Blood pressure (BP) was recorded in the conscious state. The thoracic aortas were taken for investigations, including: light microscopy, electron microscopy, immunohistochemistry and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labelling (TUNEL). 3Blood pressure variability (BPV) was significantly increased in the SAD groups 1, 2 and 4 after the operation when compared with the sham-operated ones. 4Two weeks after SAD the percentage proportion of smooth muscle cell density (SMC%) was obviously increased. 5Four weeks after SAD: the SMC%, percentage proportion of collagen density (CD%) and aortic wall thickness (WT) were obviously increased with vascular smooth muscle cells blebbing concomitantly. Endothelial cells showed degenerative changes and swelling with blebbing of the cell membrane and increased condensation of peripheral nuclear chromatin and cytoplasmic vacuolization. It was also found that the number of apoptotic endothelial cells was increased and expression of eNOS was reduced. 6This is the first study that shows the time-course of aortic wall and endothelial cell changes induced by SAD. Increased BPV might be the priming factor in the development of organ damage induced by SAD. [source] Ketanserin stabilizes blood pressure in conscious spontaneously hypertensive ratsCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2003Chao-Yu Miao Summary 1.,It has been demonstrated that blood pressure variability (BPV) is increased in hypertension and related to organ damage. It will be important to lower BPV in the treatment of hypertension. The present study was designed to investigate the effect of ketanserin, a 5-HT2A receptor antagonist with a weak ,1 -adrenoceptor blocking effect, on BPV in conscious spontaneously hypertensive rats (SHR). 2.,It was found that ketanserin decreased blood pressure (BP) and BPV in SHR when administered intravenously (3 mg/kg, i.v.). Ketanserin decreased BPV, but not the BP level, when administered intracerebroventricularly (50 µg/rat, i.c.v.). 3.,Prazosin, an ,1 -adrenoceptor antagonist, lowered BP but did not affect BPV when given either i.v. (0.5 mg/kg) or i.c.v. (30 ug/rat). Ritanserin (0.625 mg/kg, i.v.; 40 'ug/rat, i.c.v.), a 5-HT2A receptor antagonist, decreased BPV only when administered i.c.v. and did not modify the BP level. 4.,Ketanserin enhanced arterial baroreflex function in SHR when given either i.v. or i.c.v. 5.,The stabilizing effect of ketanserin on BP was persistent when administered intragastrically. This administration route is similar to oral administration clinically. 6.,It is concluded that ketanserin is an antihypertensive agent with an effect of reducing BPV. This effect is mainly mediated by central 5-HT2A receptors and is probably attributable to the restoration of arterial baroreflex function. [source] Respiratory effects on the reproducibility of cardiovascular autonomic parametersCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 4 2007Éva Zöllei Summary 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. [source] Effects of local arteriosclerosis on carotid baroreflex sensitivity and on heart rate and arterial pressure variability in humansCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2006Ola Eiken Summary The study examined whether the alterations in heart rate variability (HRV) and baroreflex sensitivity (BRS) observed in patients with coronary artery disease can also be discerned in otherwise healthy subjects with mild-to-moderate arteriosclerosis in the carotid artery bifurcation. Based on the results of carotid duplex ultrasonography, subjects were designated as either having no arteriosclerotic lesions (n = 18), unilateral (n = 19) or bilateral lesions (n = 18) in the bifurcation. Electrocardiograms were recorded and simultaneous and continuous records of arterial pressure were obtained. Resting HRV was determined by calculating the spectral power density in three frequency bands: 0,0·05 Hz [very low frequency (VLF) band], 0·05,0·15 [low frequency (LF) band] and 0·15,2 Hz (high frequency band), whereas the arterial pressure variability (APV) was determined from spectral power density of the VLF and LF bands. Carotid BRS was evaluated by measuring R-R intervals during application of pulse-synchronous graded pressures (40 to ,65 mmHg) in a neck-chamber device. Analysis of variance revealed no effect of mild-to-moderate carotid arteriosclerosis on the spectral components of HRV and APV or on BRS. It thus appears that mild-to-moderate asymptomatic carotid arteriosclerosis does not affect carotid BRS, APV or HRV at rest. [source] |