70Autonomic dysfunction in atrial fibrillation (AF) patients: absent vasomotor reflex to decreased cardiac venous return during af in comparison to sinus rhythm; implications for earlier rhythm control

Abstract Funding Acknowledgements Dr Malik is supported by an Australian Postgraduate Award Scholarship from the University of Adelaide. OnBehalf Centre for Heart Rhythm Disorders, University of Adelaide & Royal Adelaide Hospital Background A bi-directional relationship exists between AF and the autonomic nervous system (ANS). Patients with AF studied in sinus rhythm (SR) have impaired vasomotor responses to decreased cardiac volume. Whether autonomic dysfunction worsens during AF itself, is unknown. Purpose We examined haemodynamic responses to lower body negative pressure (LBNP) in patients with persistent AF compared to AF studied in SR. LBNP decreases cardiac volume, deactivates atrial stretch receptors and induces a reflex to maintain blood pressure by increasing systemic vascular resistance (SVR). Methods 21 consecutive patients with paroxysmal or persistent AF were studied; during AF (n = 8) or SR (n = 13). Anti-arrhythmic and anti-hypertensives were withheld for 5 half-lives. Patients underwent LBNP using a custom-made chamber sealing both lower limbs. Negative pressure at sham (-0 mmHg), low (-20 mmHg) and high level (-40 mmHg) was applied for 5 minutes each. Finger photo plethysmography was used for beat-beat-blood pressure. Computation of SVR during AF is not feasible with this method. Therefore, the right forearm was used to perform venous occlusion plethysmography (VOP); non-invasive, well validated with LBNP and impervious to AF: to estimate forearm blood flow (FBF) and SVR (inversely proportional). Results Baseline characteristics and responses to LBNP are presented in Table 1. MAP was maintained, and HR rose slightly, in the SR group. MAP and HR decreased in the AF group. VOP demonstrates a reduction in FBF in the SR group (vasoconstriction); whereas the vasomotor response to LBNP was absent during AF. Figure 1 (Panels A-C). Conclusion The presence of AF is associated with autonomic dysfunction from impaired cardiac volume regulation. This novel finding may contribute to the known risk of falls and syncope due to AF. Further studies are needed to evaluate whether abnormal cardiac reflexes are involved in atrial remodelling and AF progression. Table 1 Baseline Characteristics During AF During SR P Value Age 65 ± 5 59 ± 3 0.4 AAD & Anti-HTN medications withheld (%) 75 85 0.6 Resting mean arterial pressure (MAP) 109 ± 9 93 ± 6 0.1 Resting heart rate (HR) 94 ± 6 60 ± 4 0.0001* Haemodynamic response to LBNP % Δ MAP due to LBNP -9 ± 5 +0.5 ± 3 0.2 % Δ HR due to LBNP -6 ± 3 +5 ± 3 0.03* % Δ FBF due to LBNP +75 ± 59 -27 ± 8 0.02* AAD Anti-arrhthmic. HTN: Hypertension. Mean +/- SEM. Abstract Figure. Vasomotor response to LBNP: in AF vs SR

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Left atrial 4D flow cardiovascular magnetic resonance: a reproducibility study in sinus rhythm and atrial fibrillation

Journal of Cardiovascular Magnetic Resonance ◽

10.1186/s12968-021-00729-0 ◽

2021 ◽

Vol 23 (1) ◽

Author(s):

Marco Spartera ◽

Guilherme Pessoa-Amorim ◽

Antonio Stracquadanio ◽

Adam Von Ende ◽

Alison Fletcher ◽

...

Keyword(s):

Atrial Fibrillation ◽

Blood Pressure ◽

Heart Rate ◽

Cardiovascular Magnetic Resonance ◽

Magnetic Resonance ◽

Sinus Rhythm ◽

Left Atrial ◽

Peak Velocity ◽

4D Flow ◽

Mean Velocity

Abstract Background Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) allows sophisticated quantification of left atrial (LA) blood flow, and could yield novel biomarkers of propensity for intra-cardiac thrombus formation and embolic stroke. As reproducibility is critically important to diagnostic performance, we systematically investigated technical and temporal variation of LA 4D flow in atrial fibrillation (AF) and sinus rhythm (SR). Methods Eighty-six subjects (SR, n = 64; AF, n = 22) with wide-ranging stroke risk (CHA2DS2VASc 0–6) underwent LA 4D flow assessment of peak and mean velocity, vorticity, vortex volume, and stasis. Eighty-five (99%) underwent a second acquisition within the same session, and 74 (86%) also returned at 30 (27–35) days for an interval scan. We assessed variability attributable to manual contouring (intra- and inter-observer), and subject repositioning and reacquisition of data, both within the same session (same-day scan–rescan), and over time (interval scan). Within-subject coefficients of variation (CV) and bootstrapped 95% CIs were calculated and compared. Results Same-day scan–rescan CVs were 6% for peak velocity, 5% for mean velocity, 7% for vorticity, 9% for vortex volume, and 10% for stasis, and were similar between SR and AF subjects (all p > 0.05). Interval-scan variability was similar to same-day scan–rescan variability for peak velocity, vorticity, and vortex volume (all p > 0.05), and higher for stasis and mean velocity (interval scan CVs of 14% and 8%, respectively, both p < 0.05). Longitudinal changes in heart rate and blood pressure at the interval scan in the same subjects were associated with significantly higher variability for LA stasis (p = 0.024), but not for the remaining flow parameters (all p > 0.05). SR subjects showed significantly greater interval-scan variability than AF patients for mean velocity, vortex volume, and stasis (all p < 0.05), but not peak velocity or vorticity (both p > 0.05). Conclusions LA peak velocity and vorticity are the most reproducible and temporally stable novel LA 4D flow biomarkers, and are robust to changes in heart rate, blood pressure, and differences in heart rhythm.

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Pulsed Wave Doppler Ultrasound Is Useful to Assess Vasomotor Response in Patients with Multiple System Atrophy and Well Correlated with Tilt Table Study

The Scientific World JOURNAL ◽

10.1100/2012/548529 ◽

2012 ◽

Vol 2012 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Ke-Vin Chang ◽

Wen-Shiang Chen ◽

Ruey-Meei Wu ◽

Ssu-Yuan Chen ◽

Hsiu-Yu Shen ◽

...

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Correlation Analysis ◽

Multiple System Atrophy ◽

Cardiovascular Response ◽

Vasomotor Response ◽

Tilt Table ◽

Hemodynamic Variables ◽

Pulsed Wave Doppler ◽

Head Up Tilt

The study aim was to assess sympathetic vasomotor response (SVR) by using pulsed wave Doppler (PWD) ultrasound in patients with multiple system atrophy (MSA) and correlate with the tilt table study. We recruited 18 male patients and 10 healthy men as controls. The SVR of the radial artery was evaluated by PWD, using inspiratory cough as a provocative maneuver. The response to head-up tilt was studied by a tilt table with simultaneous heart rate and blood pressure recording. The hemodynamic variables were compared between groups, and were examined by correlation analysis. Regarding SVR, MSA patients exhibited a prolonged latency and less heart rate acceleration following inspiratory cough. Compared with the tilt table test, the elevation of heart rate upon SVR was positively correlated to the increase of heart rate after head-up tilt. The correlation analysis indicated that the magnitude of blood pressure drop from supine to upright was positively associated with the SVR latency but negatively correlated with the heart rate changes upon SVR. The present study demonstrated that blunted heart rate response might explain MSA's vulnerability to postural challenge. PWD may be used to predict cardiovascular response to orthostatic stress upon head-up tilt in MSA patients.

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Noise-Enhanced Heart Rate and Sympathetic Nerve Responses to Oscillatory Lower Body Negative Pressure in Humans

Journal of Neurophysiology ◽

10.1152/jn.2001.86.2.559 ◽

2001 ◽

Vol 86 (2) ◽

pp. 559-564 ◽

Cited By ~ 21

Author(s):

Ichiro Hidaka ◽

Shin-Ichi Ando ◽

Hideaki Shigematsu ◽

Koji Sakai ◽

Soko Setoguchi ◽

...

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Stochastic Resonance ◽

Negative Pressure ◽

Sympathetic Nerve ◽

Carotid Sinus ◽

Lower Body Negative Pressure ◽

Arterial System ◽

Lower Body ◽

Cardiopulmonary Baroreceptors

By injecting noise into the carotid sinus baroreceptors, we previously showed that heart rate (HR) responses to weak oscillatory tilt were enhanced via a mechanism known as “stochastic resonance.” It remains unclear, however, whether the same responses would be observed when using oscillatory lower body negative pressure (LBNP), which would unload the cardiopulmonary baroreceptors with physically negligible effects on the arterial system. Also, the vasomotor sympathetic activity directly controlling peripheral resistance against hypotensive stimuli was not observed. We therefore investigated the effects of weak (0 to approximately −10 mmHg) oscillatory (0.03 Hz) LBNP on HR and muscle sympathetic nerve activity (MSNA) while adding incremental noise to the carotid sinus baroreceptors via a pneumatic neck chamber. The signal-to-noise ratio of HR, cardiac interbeat interval, and total MSNA were all significantly improved by increasing noise intensity, while there was no significant change in the arterial blood pressure in synchronized with the oscillatory LBNP. We conclude that the stochastic resonance, affecting both HR and MSNA, results from the interaction of noise with the signal in the brain stem, where the neuronal inputs from the arterial and cardiopulmonary baroreceptors first come together in the nucleus tractus solitarius. Also, these results indicate that the noise could induce functional improvement in human blood pressure regulatory system in overcoming given hypotensive stimuli.

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Baseline characteristics of the 1149 patients recruited into the Rapid Intervention with Glyceryl trinitrate in Hypertensive stroke Trial-2 (RIGHT-2) randomized controlled trial

International Journal of Stroke ◽

10.1177/1747493018816451 ◽

2018 ◽

Vol 14 (3) ◽

pp. 298-305 ◽

Cited By ~ 1

Author(s):

Philip M Bath ◽

Polly Scutt ◽

Jason P Appleton ◽

Mark Dixon ◽

Lisa J Woodhouse ◽

...

Keyword(s):

Blood Pressure ◽

Glyceryl Trinitrate ◽

Acute Stroke ◽

Controlled Trial ◽

Nitric Oxide Donor ◽

Main Trial ◽

Randomized Controlled ◽

Baseline Characteristics ◽

The Uk ◽

Stroke Trial

Background High blood pressure is common in acute stroke and associated with a worse functional outcome. Glyceryl trinitrate, a nitric oxide donor, lowers blood pressure in acute stroke and may improve outcome. Aims Rapid Intervention with Glyceryl trinitrate in Hypertensive stroke Trial-2 (RIGHT-2) tested the feasibility of performing a UK multicenter ambulance-based stroke trial, and the safety and efficacy of glyceryl trinitrate when administered by paramedics before hospital admission. Methods Paramedic-led ambulance-based multicenter prospective randomized single-blind blinded-endpoint parallel-group controlled trial of transdermal glyceryl trinitrate (given for four days) versus sham in patients with ultra-acute (<4 h) presumed stroke. Data are number (%), median (interquartile range) or mean (standard deviation). Results Recruitment ran from October 2015 to 31 May 2018. A total 1149 patients were recruited from eight UK ambulance services and taken to 54 acute hospitals. Baseline characteristics include: mean age 73 (15) years; female 555 (48%); median time from stroke to randomization 70 (45, 115) min; face-arm-speech scale score 2.6 (0.5); and blood pressure 162 (25)/92 (18) mmHg. The final diagnosis was ischemic stroke 52%, hemorrhagic stroke 13%, Transient Ischemic Attack (TIA) 9%, and mimic 25%. The main trial results will be presented in quarter 4 2018. The results will also be included in updated Cochrane systematic reviews, and individual patient data meta-analyses of all relevant randomized controlled trials. Conclusion It was feasible to perform a multicenter ambulance-based ultra-acute stroke trial in the UK and to treat with glyceryl trinitrate versus sham. The relatively unselected cohort of stroke patients is broadly representative of those admitted to hospital in the UK. Trial registration ISRCTN26986053.

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A data-zone scoring system to assess the generalizability of clinical trial results to individual patients

European Journal of Preventive Cardiology ◽

10.1177/2047487318815967 ◽

2018 ◽

Vol 26 (6) ◽

pp. 569-575 ◽

Cited By ~ 6

Author(s):

Luke J Laffin ◽

Stephanie A Besser ◽

Francis J Alenghat

Keyword(s):

Blood Pressure ◽

Clinical Trial ◽

National Health ◽

Hazard Ratio ◽

Trial Participant ◽

Nutrition Examination Survey ◽

Specific Patient ◽

Health And Nutrition ◽

Baseline Characteristics ◽

Event Rates

Introduction Evaluating the applicability of a clinical trial to a specific patient is difficult. A novel framework, the Trial Score, was created to quantify the generalizability of a trial's result based on participants' baseline characteristics and not on the trial's inclusion and exclusion criteria. Methods For each Systolic Blood Pressure Intervention Trial (SPRINT) participant, the Euclidean distance in six-dimensional space from the theoretical “average” participant was calculated to produce an individual Trial Score that incorporates multiple distinct continuous-variable baseline characteristics. We prospectively defined the “data-rich,” “data-limited,” and “data-free” zones as Trial Scores < 90th percentile, the 90th–97.5th percentile, and >97.5th percentile, respectively. Trial Scores were then calculated for National Health and Nutrition Examination Survey participants to map data zones of the general population. Individual participant data from the Action to Control Cardiovascular Risk in Diabetes blood pressure trial (ACCORD-BP) was used to test if participants further from the average SPRINT participant behave differently than the overall SPRINT results. Results The National Health and Nutrition Examination Survey cohort and the ACCORD-BP trial demonstrate large percentages of participants in SPRINT's data-free and data-limited zones. Time-to-event rates seen with intensive and standard blood pressure control in SPRINT were the same as ACCORD-BP participants within SPRINT's data-rich zone (hazard ratio 0.97, p = 0.84 and hazard ratio 0.95, p = 0.70). However, these rates were significantly different than those of ACCORD-BP participants outside SPRINT's data-rich zone (hazard ratio 0.64, p < 0.01 and hazard ratio 0.77, p < 0.01). Conclusions ACCORD-BP participants with SPRINT Trial Scores in the 90th percentile or below have similar event rates to SPRINT participants in both the intensive and standard blood pressure groups. Quantifying the difference between an individual patient and the average clinical trial participant holds promise as a tool to more precisely determine applicability of a specific trial to individual patients.

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Isolated superfused rats atrial model for the investigation of atrial fibrillation mechanisms and treatment

European Heart Journal ◽

10.1093/eurheartj/ehab724.3321 ◽

2021 ◽

Vol 42 (Supplement_1) ◽

Author(s):

S Glatstein ◽

M Ghiringhelli ◽

L Maizels ◽

E Heller ◽

E Maor ◽

...

Keyword(s):

Atrial Fibrillation ◽

High Resolution ◽

Sinus Rhythm ◽

Optical Mapping ◽

Ex Vivo ◽

Anatomical Landmarks ◽

Ex Vivo Model ◽

Electrophysiological Properties ◽

Custom Made ◽

Isolated Atria

Abstract Background One of the major barriers to an improved mechanistic understanding of atrial fibrillation (AF), and thus in the pipeline of drug development, has been a lack of appropriate tissue models, especially in small animals. Aim We propose an advanced anatomical ex-vivo model based on rat atria for acute assessment of AF susceptibility. This novel model could yield a better understanding of arrhythmia mechanisms as well as the development of potential therapeutic strategies for the prevention or termination of atrial arrhythmias. Methods Wistar rats atria (N=25) were isolated, flattened and pinned to a custom-made silicon plate. Atria were superfused with an oxygenized Tyrode's solution. Tissues were then loaded with a voltage-sensitive dye and mapped using a high-resolution optical mapping system. AF was induced with 1uM carbamylcholine (N=23) coupled with pacing maneuvers and treated with 30uM Vernakalant (N=10) or 10uM Flecainide (N=10). Finally, the feasibility of a new ablation technique (electroporation) was evaluated. Results Optical mapping results suggested that the superfusion procedure led to a fast atrial recovery. Sinus activity was conserved for all atria for a long period. All the anatomical landmarks were clearly visualized. The acquired optical signals were analyzed during sinus rhythm and pacing, which allowed the creation of detailed activation maps and measurements of action potential duration (APD) and conduction velocity (CV) at different pacing rates. The resulting APD restitution curves revealed electrical excitation at high pacing rates (cycle length between 50ms and 300ms) with a relatively flattened curve. AF was successfully induced and optically mapping confirmed the presence of reentrant activity. AF was successfully treated using Vernacalant and Flecainide. Finally, we demonstrated the feasibility of a new ablation approach (electroporation) for creation of a continuous linear lesion serving as a functional block. Conclusion The isolated superfused atria model, coupled with voltage-sensitive dyes, can be utilized for long-term high-resolution functional imaging of the atria during sinus rhythm, pacing and arrhythmogenic activity. This allows the study of the atrial electrophysiological properties, the mechanisms involved in AF initiation, perpetuation, and termination as well as the study of drug and new ablation modalities. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Research Council (ERC) Spontaneous activation of isolated atria

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Effects of a Custom-Made Pillow on Sleep and Blood Pressure Circadian Rhythm

Journal of Hypertension Open Access ◽

10.4172/2167-1095.1000183 ◽

2013 ◽

Vol 03 (06) ◽

Author(s):

Seiko Miyata Akiko Noda

Keyword(s):

Blood Pressure ◽

Circadian Rhythm ◽

Custom Made

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Abstract 18895: Utility of Remote Monitoring Using a Mobile Phone in Patients with Heart Failure: the REMOTE-HF-1 Study

Circulation ◽

10.1161/circ.130.suppl_2.18895 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Marcus Stahlberg ◽

Satish C Govind ◽

Nicole M Orr ◽

Aasha S Gopal ◽

Justine S Lachmann ◽

...

Keyword(s):

Heart Failure ◽

Blood Pressure ◽

Mobile Phone ◽

Monitoring System ◽

Primary Endpoint ◽

Remote Monitoring ◽

Nyha Class ◽

Drop Out ◽

Remote Monitoring System ◽

Custom Made

Objective: To investigate the clinical feasibility (technical feasibility and patient-/clinician adherence) of remote telemonitoring, using a mobile phone, in an international and diverse HF population. Methods: HF patients from five centers in the USA, India and Sweden were equipped with a blood pressure apparatus, digital weight scale and a mobile phone device with custom made software for remote telemonitoring (Vitalbeat®). Patients were asked to record and transmit daily information on body weight, blood pressure and pulse rate as well as symptoms and adherence to medical therapy for 90 days. The primary endpoint, for assessment of general feasibility was defined as % of days with a combination of successful data transmission from patients and data read by clinicians. Acceptable clinical feasibility was a priori set as ≥ 66% of days meeting the primary endpoint. A survey was used to assess patients’ opinions about the remote monitoring system. Data was analyzed according to Intention to treat. Results: 46 HF patients were included (India=20, USA=13, Sweden=13; 59±16yrs; 84% male; NYHA-class 2.4±0.8) and followed for a total of 4410 days. The primary endpoint occurred in 3178 days (77%) and 34/46 patients (74%) exceeded the cut-off ≥ 66% of days meeting endpoint criteria. In the majority of patients (n=28; 61 %) the primary endpoint was met ≥ 90% of the days, and in 6 patients (13%) 66-89% of the days.Twelve patients (26%) opted to drop out of the study prematurely or were hospitalized for HF related causes. Compared to patients with acceptable clinical feasibility (≥ 66%), patients with less than acceptable feasibility (< 66%) were older (72±12 vs. 56±15 yrs, p=0.003) and more likely to be followed at a center in USA or Sweden (p=0.02 vs. Indian centers). The monitoring system was described as user friendly by 91 % of patients. Conclusion: This study shows that remote telemonitoring using a mobile phone is clinically feasible in an international and diverse heart failure population. However, monitoring was less feasible in elderly patients and depended on the geographic location. Further studies are warranted to assess whether clinical feasibility can improve with improved software/hardware design and/or patient selection.

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Contactless Monitoring of Microcirculation Reaction on Local Temperature Changes

Applied Sciences ◽

10.3390/app9224947 ◽

2019 ◽

Vol 9 (22) ◽

pp. 4947 ◽

Cited By ~ 4

Author(s):

Volynsky ◽

Margaryants ◽

Mamontov ◽

Kamshilin

Keyword(s):

Blood Flow ◽

Skin Temperature ◽

Polarized Light ◽

Thermal Exposure ◽

Thermal Impact ◽

Vasomotor Response ◽

Temperature Changes ◽

Custom Made ◽

Electrocardiogram Ecg ◽

System Operating

Assessment of skin blood flow is an important clinical task which is required to study mechanisms of microcirculation regulation including thermoregulation. Contactless assessment of vasomotor reactivity in response to thermal exposure is currently not available. The aim of this study is to show the applicability of the imaging photoplethysmography (IPPG) method to measure quantitatively the vasomotor response to local thermal exposure. Seventeen healthy subjects aged 23 ± 7 years participated in the study. A warm transparent compress applied to subject’s forehead served as a thermal impact. A custom-made IPPG system operating at green polarized light was used to monitor the subject’s face continuously and simultaneously with skin temperature and electrocardiogram (ECG) recordings. We found that the thermal impact leads to an increase in the amplitude of blood pulsations (BPA) simultaneously with the skin temperature increase. However, a multiple increase in BPA remained after the compress was removed, whereas the skin temperature returned to the baseline. Moreover, the BPA increase and duration of the vasomotor response was associated with the degree of external heating. Therefore, the IPPG method allows us to quantify the parameters of capillary blood flow during local thermal exposure to the skin. This proposed technique of assessing the thermal reactivity of microcirculation can be applied for both clinical use and for biomedical research.

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