A5057130869- Heart Rate Variability and Autonomic Control
- Cardiovascular Syncope and Autonomic Disorders
- Non-Invasive Vital Sign Monitoring
- Spaceflight effects on biology
- Neuroscience of respiration and sleep
- Blood Pressure and Hypertension Studies
- Cardiovascular Health and Disease Prevention
- Cardiovascular and exercise physiology
- EEG and Brain-Computer Interfaces
- Hemodynamic Monitoring and Therapy
- Traumatic Brain Injury and Neurovascular Disturbances
- High Altitude and Hypoxia
- Obstructive Sleep Apnea Research
- Cardiovascular and Diving-Related Complications
- Optical Imaging and Spectroscopy Techniques
- Cardiac Health and Mental Health
- Muscle activation and electromyography studies
- Cardiac Arrest and Resuscitation
- ECG Monitoring and Analysis
- Cardiac electrophysiology and arrhythmias
- Cerebrovascular and Carotid Artery Diseases
- Heart rate and cardiovascular health
- Vagus Nerve Stimulation Research
- Cardiovascular Disease and Adiposity
- Advanced Chemical Sensor Technologies
Amsterdam University Medical Centers
2019-2024
University of Amsterdam
2013-2023
Amsterdam UMC Location University of Amsterdam
2008-2017
University College London
2016
MRC Lifecourse Epidemiology Unit
2016
University of Southampton
2016
Karolinska Institutet
1996-2009
Japan External Trade Organization
2006
UNSW Sydney
2006
Delft University of Technology
2005
A beat-to-beat model of the cardiovascular system is developed to study spontaneous short-term variability in arterial blood pressure (BP) and heart rate (HR) data from humans at rest. The consists a set difference equations representing following mechanisms: 1) control HR peripheral resistance by baroreflex, 2) Windkessel properties systemic tree, 3) contractile myocardium (Starling's law restitution), 4) mechanical effects respiration on BP. tested comparing power spectra cross simulated...
ABSTRACT Respiratory sinus arrhythmia (RSA) has received much attention in recent years due to the large body of evidence indicating that variations this phenomenon represent alterations parasympathetic cardiac control. Although it appears respiratory is mediated by vagal mechanisms, extent which well‐known influences (i.e., rate and tidal volume) on (in altering its magnitude) may moderate relationship between RSA tone never been systematically studied. We addressed issue examining...
This study compared spontaneous baroreflex sensitivity (BRS) estimates obtained from an identical set of data by 11 European centers using different methods and procedures. Noninvasive blood pressure (BP) ECG recordings were in 21 subjects, including 2 subjects with established failure. Twenty-one BRS the two main techniques estimates, i.e., spectral analysis (11 procedures) sequence method (7 but also one trigonometric regressive (TRS), exogenous model autoregressive input (X-AR), Z method....
Different methods for spectral analysis of the heart rate signal-considered as series point events-are used in studies on variability. This paper compares these methods, focusing two principal ones: interval spectrum, i.e., spectrum series, and counts, which is related to representation event a spikes (delta functions). Both autospectra are estimated experimental data shown produce similar results. similarity proven analytically, it that small variations length, ratio spectra PI(f)/PC(f) =...
Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans positioning of these above heart level causes them to collapse. An alternative is vertebral plexus. We set out determine effect posture and central pressure (CVP) on distribution over internal plexus, using a mathematical model. Input model was data beat-to-beat blood flow velocity CVP measurements 10 healthy subjects, during baseline rest Valsalva manoeuvre standing position. The model,...
Wave reflections affect the proximal aortic pressure and flow waves play a role in systolic hypertension. A measure of wave reflection, receiving much attention, is augmentation index (AI), ratio secondary rise pulse pressure. AI can be limiting, because it depends not only on magnitude reflection but also shapes timing incident reflected waves. More accurate measures are obtainable after separation its forward (P f ) b components. However, this calculation requires measurement flow. We...
Because of the inherent risks intra-arterial blood pressure monitoring a new non-invasive device, Finapres, which measures continuously in finger, was evaluated 14 hypertensive and one normotensive subject. Brachial finger pressures were compared during control period subsequent Valsalva manoeuvre. Visually, measured by Finapres faithfully reproduced recordings all subjects. From each signal beat to systolic, diastolic, mean values their differences obtained time course response its...
To test a new method (cross-correlation baroreflex sensitivity, xBRS) for the computation of time-domain sensitivity on spontaneous blood pressure and heart interval variability using EUROBAVAR data set.We applied xBRS to 42 records in set, obtained from 21 patients lying standing positions. One patient had recent transplant one was diabetic with evident cardiac autonomic neuropathy. computes correlation between beat-to-beat systolic R-R interval, resampled at 1 Hz, sliding 10 s window,...
Background— In patients with a malignant hypertension, immediate parenteral treatment blood pressure–lowering agents such as intravenous sodium nitroprusside (SNP) is indicated. this study, we evaluated static and dynamic cerebral autoregulation (CA) during acute pressure lowering SNP in these patients. Methods Results— 8 mean arterial (MAP) >140 mm Hg grade III or IV hypertensive retinopathy at hospital admission, middle artery velocity (MCA V) were monitored. Dynamic CA was expressed...
We addressed whether dynamic cerebral autoregulation (dCA) is affected in middle artery (MCA) territory (MCAS) and lacunar ischemic stroke (LS).Blood pressure (MAP) MCA velocity (V) were measured 10 patients with large MCAS (National Institutes of Health Stroke score, 17+/-2; mean+/-SEM), LS (score, 9+/-1), reference subjects. dCA was evaluated time (delay the Vmean counter-regulation during changes MAP) frequency domains (cross-spectral Vmean-to-MAP phase lead).In subjects, latencies for...
BackgroundHeart rate variability (HRV) is a validated method to establish autonomic nervous system (ANS) activity. Rheumatoid arthritis (RA) accompanied by ANS imbalance. We hypothesized that dysfunction may precede the development of RA, which would suggest it plays role in its etiopathogenesis.MethodsFirst, we assessed HRV parameters supine (resting) and upright (active) position healthy subjects (HS, n = 20), individuals at risk developing (AR subjects, 50) RA patients (RA, 20). Next,...
Background — After experimental carotid sinus denervation in animals, blood pressure (BP) level and variability increase markedly but normalize to preoperative levels within 10 14 days. We investigated the course of arterial BP after bilateral baroreceptors humans. Methods Results studied 4 women (age 41 63 years) who were referred for evaluation baroreflex function because clinical suspicion attributable body tumor resection. The was assessed from repeated office 24-hour ambulatory...
The objective of this study was to determine the effect aging on beat-to-beat blood pressure and pulse interval variability in resting conditions sympathetic vagal influence cardiovascular system by power spectral analysis interval. We studied three groups healthy, normotensive subjects: young (10 15 years, n = 16), adult (20 40 elderly (70 90 25). Beat-to-beat measured Finapres during 20 minutes supine 10 standing. Overall systolic diastolic pressures were determined as SD coefficient...
The background of this study was the hypothesis that respiratory variability is influenced by chemoreflex regulation. In search for periodicities in due to instability control system, spectral analysis applied breath-to-breath variables 19 healthy subjects at rest. During room-air breathing, coherent oscillations end-tidal CO2 (Pet ) and mean inspiratory flow (Vi/Ti) were found 15 with frequencies mostly below 0.15 cycles per breath. Coherent Pet Vi/Ti expressed gain (0.13 0.34 L/second ·...
Noninvasive cardiac output (CO) measured by arterial pulse analysis was compared with that inert gas rebreathing in six healthy male volunteers. Pulse contour applied to the pressure wave of a Finapres, which noninvasively measures continuous finger. Data were collected before, during, and after 10-day 6 degrees head-down tilt experiment. Intravenous saline loading lower body negative stimuli varied CO over 2.8–9.6 l/min, as technique. Because provides only relative changes CO, obtain...