scholarly journals Computational Modelling of the Role of Atrial Fibrillation on Cerebral Blood Perfusion.

2021 ◽  
Author(s):  
Timothy Hunter ◽  
Jermiah Joseph ◽  
Sanjay R Kharche ◽  
Daniel Goldman
Keyword(s):  
Atrial Fibrillation ◽  
Cerebral Perfusion ◽  
Control Mechanism ◽  
Computational Modelling ◽  
Blood Perfusion ◽  
Whole Body ◽  
Baroreflex Control ◽  
Computational Work ◽  
The Impact

Atrial fibrillation is a prevalent cardiac arrhythmia, and may reduce cerebral blood perfusion augmenting the risk of dementia. It is thought that cer- ebral arterial geometry variants play an important role in cerebral perfusion. This computational work investigated the role of geometric variants on cerebral blood flow in the presence of cardiac atrial fibrillation.A model consisting of a detailed cerebral and whole-body circulation, along with baroreflex control mechanism was developed. Cerebral perfusion based on vasculature geometry variations, represented by Circle of Willis variants, was simulated in the presence of atrial fibrillation conditions. Perfusion and its heter- ogeneity were quantified using segment-wise hypoperfusion events and mean perfusion at terminals.It was found that cerebral perfusion and the rate of hypoperfusion events strongly depends geometry variation as well as atrial fibrillation induced stochas- tic heart rates. The hypoperfusion events were specific to particular arteries in each variant. Our results, based on biophysical principles, suggest that cerebral vascular geometries modulate the impact of atrial fibrillation in cerebral perfu- sion. Further, our findings suggest potential clinical assessment sites.

scholarly journals Computational Modelling of the Role of Atrial Fibrillation on Cerebral Blood Perfusion

2021 ◽  
pp. 679-686
Author(s):  
Timothy J. Hunter ◽  
Jermiah J. Joseph ◽  
Udunna Anazodo ◽  
Sanjay R. Kharche ◽  
Christopher W. McIntyre ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Computational Modelling ◽  
Blood Perfusion

scholarly journals The Role of Adenosine in Pulmonary Vein Isolation: A Critical Review

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Paolo D. Dallaglio ◽  
Timothy R. Betts ◽  
Matthew Ginks ◽  
Yaver Bashir ◽  
Ignasi Anguera ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
At Risk ◽  
Pulmonary Vein ◽  
Pulmonary Vein Isolation ◽  
Waiting Time ◽  
Critical Review ◽  
Recurrence Rates ◽  
The Impact ◽  
Af Recurrence

The cornerstone of atrial fibrillation (AF) ablation is pulmonary vein isolation (PVI), which can be achieved in more than 95% of patients at the end of the procedure. However, AF recurrence rates remain high and are related to recovery of PV conduction. Adenosine testing is used to unmask dormant pulmonary vein conduction (DC). The aim of this study is to review the available literature addressing the role of adenosine testing and determine the impact of ablation at sites of PV reconnection on freedom from AF. Adenosine infusion, by restoring the excitability threshold, unmasks reversible injury that could lead to recovery of PV conduction. The studies included in this review suggest that adenosine is useful to unmask nontransmural lesions at risk of reconnection and that further ablation at sites of DC is associated with improvement in freedom from AF. Nevertheless it has been demonstrated that adenosine is not able to predict all veins at risk of later reconnection, which means that veins without DC are not necessarily at low risk. The role of the waiting period in the setting of adenosine testing has also been analyzed, suggesting that in the acute phase adenosine use should be accompanied by enough waiting time.

scholarly journals THE ROLE OF INFLAMMATION AND COAGULATION CASCADE IN THE PATHOGENESIS OF ATRIAL FIBRILLATION

ASJ. ◽  
2020 ◽  
Vol 3 (41) ◽  
pp. 8-10
Author(s):  
L. Hazarapetyan ◽  
S. Grigoryan ◽  
A. Sarksyan
Keyword(s):  
Atrial Fibrillation ◽  
Coagulation Cascade ◽  
Control Group ◽  
Atrial Remodeling ◽  
Inflammation Markers ◽  
Reactive Protein ◽  
Gender And Age ◽  
The Impact ◽  
The Relationship

Introduction: Atrial fibrillation (AF) is associated with prothrombotic or hypercoagulable states, various inflammation markers such as interleukin-6 (IL-6) and hsC-reactive protein (hsCRP) have also been associated with AF. The aim of this study is to investigate the relationship between inflammation markers and the prothrombotic state in the setting of AF and the impact on outcome in patients with AF. Methods: We observed 141 patients with non-valvular AF. As a control group patients similar in gender and age without AF were examined. Clinical, instrumental and laboratory tests were performed on the observed patients. The markers of the coagulation cascade (TF and F) and of inflammatory markers (hsCRP and IL-6) were studied additionally by ELISA on the analyzer "Stat Fax 303 Plus". Studies were conducted using SPSS 13.0 and EXCEL-2013. Results: The obtained results showed that compared to the control group, AF patients had significantly higher levels of IL-6 (p = 0.043), hsCRP (p = 0.002), TF (p = 0.026), and F (p = 0.025). Moreover, levels of hsCRP were higher among AF patients at "high" risk of stroke by CHA2DS2-VASc Score (p = 0.003). Besides, the levels of hsCRP and IL-6 were markedly elevated in patients with dilated left atrium (p = 0.001), poorly functioning left atrial appendage (p = 0.023) and longer duration of AF (p = 0.002). Conclusion: We have demonstrated that the increased plasma levels of IL-6 and hsCRP are related to indices of the coagulation cascade and contribute to structural atrial remodeling in patients with AF.

scholarly journals Benefits of prescribing low-dose digoxin in atrial fibrillation

2021 ◽  
Vol 35 ◽  
pp. 205873842110519
Author(s):  
Ciprian Ilie Rosca ◽  
Nilima Rajpal Kundnani ◽  
Anca Tudor ◽  
Maria-Silvia Rosca ◽  
Violeta-Ariana Nicoras ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Low Dose ◽  
Beta Blockers ◽  
Treatment Protocol ◽  
Factor Xa ◽  
Group 2 ◽  
Clinical Records ◽  
The Impact ◽  
Group 1

Introduction The role of digoxin (cardiac glycoside) in controlling the heart rate (HR) for the treatment of atrial fibrillation (AF) patients has not been explored in depth. Methods To contribute to the limited data, our team conducted retrospective analysis of the clinical records of 1444 AF patients. We divided the AF patients into two groups, wherein group 1 patients were treated with beta-blockers (BB), low-dose digoxin, and an anticoagulant (vitamin K antagonist/factor-IIa inhibitor/factor-Xa inhibitor), and group 2 patients were treated with just BB and an anticoagulant. Our objectives were to compare the impact of combination therapy of BB and digoxin on the resting HR in patients with permanent AF and the patients’ quality of life (QOL) at periodic intervals. Results The findings of our study showed a better control of the resting HR rate (<110bpm) and an improved QOL among the group 1 patients when compared with group 2 patients. Conclusion Our findings are indicative of the favorable clinical outcomes that resulted from the addition of a low-dose of digoxin to the AF treatment regimen. However, larger studies/trials elucidating the outcomes of AF patients treated with the dual rate control therapy are required, to clarify the role of digoxin, guide the choice of agents, and standardize the AF treatment protocol.

scholarly journals Additive effects of heating and exercise on baroreflex control of heart rate in healthy males

2017 ◽  
Vol 123 (6) ◽  
pp. 1555-1562 ◽  
Author(s):  
Tiago Peçanha ◽  
Cláudia L. M. Forjaz ◽  
David. A. Low
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Baroreflex Sensitivity ◽  
Whole Body ◽  
Additive Effects ◽  
Passive Heating ◽  
Baroreflex Control ◽  
Rr Intervals ◽  
Body Heat

This study assessed the additive effects of passive heating and exercise on cardiac baroreflex sensitivity (cBRS) and heart rate variability (HRV). Twelve healthy young men (25 ± 1 yr, 23.8 ± 0.5 kg/m2) randomly underwent two experimental sessions: heat stress (HS; whole body heat stress using a tube-lined suit to increase core temperature by ~1°C) and normothermia (NT). Each session was composed of a preintervention rest (REST1); HS or NT interventions; postintervention rest (REST2); and 14 min of cycling exercise [7 min at 40%HRreserve (EX1) and 7 min at 60%HRreserve (EX2)]. Heart rate and finger blood pressure were continuously recorded. cBRS was assessed using the sequence (cBRSSEQ) and transfer function (cBRSTF) methods. HRV was assessed using the indexes standard deviation of RR intervals (SDNN) and root mean square of successive RR intervals (RMSSD). cBRS and HRV were not different between sessions during EX1 and EX2 (i.e., matched heart rate conditions: EX1 = 116 ± 3 vs. 114 ± 3 and EX2 = 143 ± 4 vs. 142 ± 3 beats/min but different workloads: EX1 = 50 ± 9 vs. 114 ± 8 and EX2 = 106 ± 10 vs. 165 ± 8 W; for HS and NT, respectively; P < 0.01). However, when comparing EX1 of NT with EX2 of HS (i.e., matched workload conditions but with different heart rates), cBRS and HRV were significantly reduced in HS (cBRSSEQ = 1.6 ± 0.3 vs. 0.6 ± 0.1 ms/mmHg, P < 0.01; SDNN = 2.3 ± 0.1 vs. 1.3 ± 0.2 ms, P < 0.01). In conclusion, in conditions matched by HR, the addition of heat stress to exercise does not affect cBRS and HRV. Alternatively, in workload-matched conditions, the addition of heat to exercise results in reduced cBRS and HRV compared with exercise in normothermia. NEW & NOTEWORTHY The present study assessed cardiac baroreflex sensitivity during the combination of heat and exercise stresses. This is the first study to show that prior whole body passive heating reduces cardiac baroreflex sensitivity and autonomic modulation of heart rate during exercise. These findings contribute to the better understanding of the role of thermoregulation on cardiovascular regulation during exercise.

Atrial Fibrillation and Cognitive Impairment: An Associated Burden or Burden by Association?

Angiology ◽  
2020 ◽  
Vol 71 (6) ◽  
pp. 498-519
Author(s):  
Theodora A. Manolis ◽  
Antonis A. Manolis ◽  
Evdoxia J. Apostolopoulos ◽  
Helen Melita ◽  
Antonis S. Manolis
Keyword(s):  
Risk Factors ◽  
Atrial Fibrillation ◽  
Cognitive Impairment ◽  
Control Strategies ◽  
Brain Magnetic Resonance Imaging ◽  
Cerebral Hypoperfusion ◽  
The Impact ◽  
Vascular Oxidative Stress ◽  
Prior Stroke

Growing evidence suggests that atrial fibrillation (AF), in addition to its thromboembolic risk, is a risk factor for cognitive impairment (CI) via several pathways and mechanisms, further contributing to morbidity/mortality. Prior stroke is a contributor to CI, but AF is also associated with CI independently from prior stroke. Silent brain infarctions, microemboli and microbleeds, brain atrophy, cerebral hypoperfusion from widely fluctuating ventricular rates, altered hemostatic function, vascular oxidative stress, and inflammation may all exacerbate CI, particularly in patients with persistent/permanent rather than paroxysmal AF and with increased duration/burden of the arrhythmia. Brain magnetic resonance imaging is an important screening tool in eliciting and monitoring vascular and nonvascular lesions contributing to CI. Evidence is also emerging about the role of genetics in CI development. Anticoagulation and rhythm/rate control strategies may protect against CI preventing or slowing its progression or conversion to dementia, particularly at the early stages when CI may still be a treatable condition. Importantly, AF and CI share many common risk factors. Thus, screening for these 2 conditions and searching for and managing modifiable risk factors and potentially reversible causes for both AF and CI remains an important step toward prevention or amelioration of the impact incurred by these 2 conditions.

Biomarkers Determining Prognosis of Atrial Fibrillation Ablation

2019 ◽  
Vol 26 (5) ◽  
pp. 925-937 ◽  
Author(s):  
Dimitris Tsiachris ◽  
George Giannopoulos ◽  
Spyridon Deftereos ◽  
Charis Kossyvakis ◽  
Constantinos Tsioufis ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Catheter Ablation ◽  
Inflammatory Markers ◽  
Persistent Atrial Fibrillation ◽  
Atrial Fibrillation Ablation ◽  
Oxidative Stress Biomarkers ◽  
Specific Patient ◽  
Term Administration ◽  
The Impact

Catheter ablation for rhythm control is recommended in specific patient populations with paroxysmal, persistent, or long-standing persistent atrial fibrillation. Pulmonary vein isolation is the cornerstone of the ablative therapy for atrial fibrillation. However, relapse is still common since the single procedure efficacy of atrial fibrillation ablation was estimated to be 60-80% in paroxysmal and 50-70% in persistent atrial fibrillation. It is important to identify predictors of successful atrial fibrillation patients ablation. In the present review, we will assess the role of available biomarkers to predict responders of an initial atrial fibrillation catheter ablation. Emphasis has been given on the role of myocardial injury biomarkers, natriuretic peptides and traditional inflammatory markers. Novel inflammatory markers, oxidative stress biomarkers and microRNAs have also been examined as predictors of a successful atrial fibrillation procedure. Notably, the impact of procedural and short-term administration of steroids, as well as the role of colchicine on preventing atrial fibrillation recurrence after ablation is thoroughly presented.

The impact of CD4+CD28null T-lymphocytes on atrial fibrillation and mortality in patients with chronic heart failure

2017 ◽  
Vol 117 (02) ◽  
pp. 349-356 ◽  
Author(s):  
Patrick Sulzgruber ◽  
Lorenz Koller ◽  
Max-Paul Winter ◽  
Bernhard Richter ◽  
Steffen Blum ◽  
...  
Keyword(s):  
Heart Failure ◽  
Atrial Fibrillation ◽  
T Cells ◽  
Chronic Heart Failure ◽  
Cytotoxic T Cells ◽  
Supplementary Material ◽  
The Impact ◽  
Pro Inflammatory Cytokines

SummaryAtrial fibrillation (AF) represents the most common cardiac arrhythmia. Especially in patients with chronic heart failure (CHF) the development of AF represents a severe complication resulting in haemodynamic deterioration. While pro-inflammatory cytokines proved to have a pivotal role in the development and progression of both AF and CHF, less attention has been paid to the cellular immunity. Therefore we prospectively enrolled 112 patients with CHF and performed fluorescein-activated cell sorting (FACS). Patients were stratified in two subgroups according to patients presenting with AF (n=56) and patients free of AF (n=56). Comparing AF to non-AF patients we found a significantly lower fraction of regulatory T cells (p<0.001) in patients presenting with AF. However there was a higher fraction of CD4+ cells (p=0.007) and more specifically a significantly higher number of cytotoxic T cells characterised by the loss of CD28 within CD4 T cells (CD4+CD28null; p=0.035) in individuals with AF. After a mean follow-up time of 4.5 years 32 (28.6 %) patients died due to cardiovascular causes. CD4+CD28null cells were significantly associated with cardiovascular mortality in patients presenting with AF, with an adjusted HR per one standard deviation (1-SD) of 1.59 (95 % CI 1.13–2.24; p=0.008), but not in patients free of AF with an adjusted HR per 1-SD of 1.27 (95 % CI 0.86–1.87; p=0.216). We found that the fraction of CD4+CD28null cells proved to be predictive on outcome in CHF-patients presenting with AF. Our results might indicate a potential role of CD4+CD28null cells in the pathogenesis of AF which needs to be confirmed in future studies.Supplementary Material to this article is available online at www.thrombosis-online.com.

scholarly journals Using a Human Circulation Mathematical Model to Simulate the Effects of Hemodialysis and Therapeutic Hypothermia

2021 ◽  
Author(s):  
Jermiah J. Joseph ◽  
Timothy J. Hunter ◽  
Clara Sun ◽  
Daniel Goldman ◽  
Sanjay R. Kharche ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Blood Pressure ◽  
Mathematical Model ◽  
Heart Rate ◽  
Renal Failure ◽  
Blood Flow ◽  
Standard Deviation ◽  
Therapeutic Hypothermia ◽  
Whole Body ◽  
Baroreflex Control

AbstractBackgroundThe human blood circulation is an intricate process regulated by multiple biophysical factors. Our patients often suffer from renal disease and atrial fibrillation, and are given treatments such as therapeutic hypothermia, exercise, and hemodialysis. In this work, a hemodynamic mathematical model of human circulation coupled to a representative dialysis machine is developed and used to explore causal mechanisms of our recent clinical observations.MethodsAn ordinary differential equation model consisting of human whole body circulation, baroreflex control, and a hemodialysis machine was implemented. Experimentally informed parameter alterations were used to implement hemodialysis and therapeutic hypothermia. By means of parameter perturbation, four model populations encompassing baseline, dialysed, hypothermia treated, and simultaneous dialysed with hypothermia were generated. In model populations, multiple conditions including atrial fibrillation, exercise, and renal failure were simulated. The effects of all conditions on clinically relevant non-invasive measurables such as heart rate and blood pressure were quantified. A parameter sensitivity analysis was implemented to rank model output influencing parameters in the presented model.ResultsResults were interpreted as alterations of the respective populations mean values and standard deviations of the clinical measurables, both in relation to the baseline population. A clinical measurable’s smaller standard deviation (in comparison to baseline population) was interpreted as a stronger association between a given clinical measure and the corresponding underlying process, which may permit the use of deducing one by observation of the other.The modelled dialysis was observed to increase systolic blood pressure, vessel shear, and heart rate. Therapeutic hypothermia was observed to reduce blood pressure as well as the intra-population standard deviation (heterogeneity) of blood flow in the large (aorta) and small (kidney) vasculature. Therapeutic hypothermia reduced shear in vessels, suggesting a potential benefit with respect to endothelial dysfunction and maintenance of microcirculatory blood flow. The action of therapeutic hypothermia under conditions such as atrial fibrillation, exercise, and renal failure was to reduce total blood flow, which was applicable in all simulated populations. Therapeutic hypothermia did not affect the dialysis function, but exercise improved the efficacy of dialysis by facilitating water removal.ConclusionsThis study illuminates some mechanisms of action for therapeutic hypothermia. It also suggests clinical measurables that may be used as surrogates to diagnose underlying diseases such as atrial fibrillation.

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