Top PDF Characterization of Cardiac Electrogram Signals During Atrial Fibrillation

Characterization of Cardiac Electrogram Signals During Atrial Fibrillation

Characterization of Cardiac Electrogram Signals During Atrial Fibrillation

maintenance regardless of any patient and this hence gave rise to performing circumferen- tial PVI in conjunction with linear lesions at roof and the other standard sites determined based on some pre-defined mechanisms including CFAEs [27] [56]. The common goals of ablation are to prevent AF either by eliminating the trigger that initiates AF or by alter- ing the arrhythmogenic substrate in such a way that it could no longer maintain AF [11]. Typical end-points were established for each procedure such as verification of conduction block using pacing technique and those sites failing the test are again ablated until they form a complete conduction block. However, studies have demonstrated some after-effects of catheter ablation - one of the major consequence of the procedure is the change in atrial size and its electrical properties, the phenomenon of which is called structural remodeling and electrical remodeling (including fibrosis) respectively. Further, current ablation pro- cedures does not guarantee complete recovery of the arrhythmia; as a matter of fact, early recurrence of AF is common post ablation as demonstrated by some studies and inturn call for reablation attempts; but what is alarming is the late recurrence of AF - AF occur- ring later than 1 year. After a single procedure, late incidence have been reported between 11% and 29%, and that after repeated procedures have been between 7% and 24% [11]. Although it is been considered that the dominant mechanism of AF recurrence is PV re- connection because most of the patients undergoing repeated ablation procedures display a PV reconnection, several potential mechanisms such as failure to identify and ablate the non-PV arrhythmogenic sources during the initial procedure also play a major role in AF recurrence. Such non-PV sources can occasionally be even in the form of focal triggers as opposed to rotors, which can however be identified and ablated as performed in case of atrial tachycardia.
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Cardiac Inter Beat Interval and Atrial Fibrillation Detection using Video Plethysmography

Cardiac Inter Beat Interval and Atrial Fibrillation Detection using Video Plethysmography

Despite the fact that these aforementioned studies obtained favorable results for average heart rate estimations, it is known that the output of the ICA method returns the resulting Independent Components in a random order, thus effectively limiting the accurate reconstruction of the plethysmographic signal. The work presented by Tsouri et. al. [21] (2012) expands on the performance limitations introduced by the sorting problem inherent to ICA methods, and proposes a Constrained ICA algorithm as the solution. However, the proposed algorithm requires prior knowledge of the parameter being extracted, thus limiting its application to assess signals with significant variability.
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A new LMS algorithm for analysis of atrial fibrillation signals

A new LMS algorithm for analysis of atrial fibrillation signals

Electrograms were recorded from 20 patients referred to the Columbia University Med- ical Center cardiac electrophysiology (EP) laboratory for catheter ablation of AF. These were obtained prospectively as approved by the Internal Review Board at Columbia University Medical Center, but analyzed retrospectively after the catheter ablation pro- cedures were completed using standard clinical protocols. Ten patients had documen- ted clinical paroxysmal AF, with a normal sinus rhythm as their baseline rhythm in the electrophysiology laboratory. Atrial fibrillation was induced by burst pacing from the coronary sinus or from the right atrial lateral wall, and the arrhythmia persisted for at least 10 minutes for those signals that were included in retrospective analysis. Ten other patients had longstanding persistent AF, and had been in AF without interruption for at least several months prior to the catheter mapping and ablation procedure. Elec- trograms recorded from the distal ablation electrode during arrhythmia were filtered with a single-pole bandpass from 30-500 Hz by the acquisition system to remove base- line drift and high frequency noise, sampled at 977 Hz, and stored (CardioLab, GE Healthcare, Waukesha, WI).
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Assessment of the dynamics of atrial signals and local atrial period series during atrial fibrillation: effects of isoproterenol administration

Assessment of the dynamics of atrial signals and local atrial period series during atrial fibrillation: effects of isoproterenol administration

Figure 3 shows an example of the distribution of regularity index (R) computed in one patient and in a single record- ing site (electrogram 8) during the four experimental con- ditions. The R values, computed in the six-second segments, are superimposed to their mean value. A signif- icant reduction (p < 0.001) of the index passing from sinus rhythm to AF was detectable. Comparing the results obtained from the same rhythm with and without isopro- terenol, a reduction of R was observed after drug adminis- tration in both sinus rhythm and atrial fibrillation. In this particular case, the decrease during sinus rhythm was sta- tistically significant (p < 0.001). In particular, considering all patients recording sites, we observed 59 reductions (42 with p < 0.05) over 79 recordings passing from SR to SRISO and 40 (17 with p < 0.05) over 77 passing from AF to AFISO. This result reflects the global tendency of entire dataset, as illustrated in Table 1, where the mean value obtained from all patients recording sites is showed, underlining a statistically significant reduction passing both from SR to AF and from SR to SRISO.
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Monitoring Atrial Fibrillation using PPG Signals and a Smartphone

Monitoring Atrial Fibrillation using PPG Signals and a Smartphone

portable ECG have been developed and also have been used with smartphones as external sensors. On the other hand, photoplethysmography (PPG) sensors are today embedded in many mobile devices such as smartphones. The simplest PPG sensor includes a LED and a photodetector that get in contact with the skin surface to moni- tor cardiac activity. Due to their popularity, PPG sensors are often studied to measure their efficacy in terms of heart rate variability (HRV) assessment [6]-[10]. Following this trend, this work develops an algorithm for atrial fibrillation detection using PPG signals. The main goal is to implement an AF monitor system on a mobile device (i.e. smartphone) to facilitate AF monitoring while simultaneously increasing patient com- fort.
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Contemporary therapy of atrial fibrillation

Contemporary therapy of atrial fibrillation

namic and myocardial consequences, such as reduced cardiac output, and heart failure (HF), increased hospi- talizations, reduced quality of life, increased risk of thro- mboembolism and decreased survival [1]. The frequency of AF is estimated that by 2010, approximately 2.6 mil- lion people will be affected in the United States [2], AF accounts for approximately one third of the hospitaliza- tions related primarily to cardiac arrhythmias [3,4]. The prevalence of AF is expected to increase dramatically, by 2050, that number may increase to 10 million patients [2], reflecting the aging US population and rising prevalence of AF risk factors [5,6]. Cross-sectional studies have demonstrated an 8% prevalence among patients older than 80 years [7]. In addition to age, Framingham Study demonstrated that men had a 1.5-fold greater risk of de- veloping AF than women, and hypertension and diabetes were significant independent predictors of AF [8]. De- spite the severe burden of disease and the potential for progression to a permanent state of arrhythmia, AF re- mains a highly treatable disorder, especially with early intervention [1].
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FIBRILLATION ATRIAL 12 INTERNATIONAL. Atrial Fibrillation and Heart Failure: MEETING. Preliminary Program

FIBRILLATION ATRIAL 12 INTERNATIONAL. Atrial Fibrillation and Heart Failure: MEETING. Preliminary Program

A special awards 1.500,00 euro gross will be given to the “Best Abstract” works selected by the Abstract Selection Committee between accepted oral communications and posters. The winners will be announced during the Best Abstract Award event scheduled for the evening of 16 February 2017.

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Post operative atrial fibrillation

Post operative atrial fibrillation

It can be seen that the data to support the hypothesis that A F m ay in part be m ediated by inflam m ation is som ew hat lim ited. W e chose the m odel o f coronary artery bypass surgery because o f the high frequency o f atrial fibrillation follow ing cardiac surgery and the variety o f inflam m atory stim uli associated w ith the surgical undertaking, w e felt that this setting w as one w here the potential im portance o f the role o f inflam m ation in the pathogenesis o f atrial fibrillation could be studied. D espite these advantages cardiac bypass surgery is associated w ith a host o f other features that m ay also increase the potential developm ent o f atrial fibrillation. D uring the surgery these include atrial traum a from handling and cannulation for the extracorporeal bypass circuit, m yocardial ischaem ia during the period o f extracorporeal perfusion and reperfusion injury follow ing the return o f m yocardial perfusion. F ollow ing the surgery features that m ay contribute include haem odynam ic alterations, neuro-horm onal perturbations, the pro-arrhythm ic potential o f inotropes, the deleterious effects o f the acute w ithdraw al o f anti-arrhythm ic drugs including beta-blockers along with
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Phenotypic description of cardiac findings in a population of Dogue de Bordeaux with an emphasis on atrial fibrillation

Phenotypic description of cardiac findings in a population of Dogue de Bordeaux with an emphasis on atrial fibrillation

heart rate of 200 bpm at presentation, with 17/19 (89%) of these dogs having a heart rate ≥ 160 bpm. Three (15.8%) non-CHDN dogs with AF did not have any chamber dilatation and were considered not to have structural cardiac heart disease, although one was classified with systolic dysfunction. Only one of these three dogs had a heart rate < 160 bpm (84 bpm). Four non-CHDN dogs in sinus rhythm had systolic dysfunction, with 2/4 demonstrating >1000 VPCs/24 h on Holter. Overall, 18/34 (52.9%) non- CHDN dogs demonstrated systolic dysfunction and 18/34 (52.9%) demonstrated right sided dilatation (atrial or ventricular), with 38% showing evidence of both systolic dysfunction and right sided dilatation. Of non-CHDN dogs with AF, 13/19 (68.5%) had systolic dysfunction and 14/19 (73.7%) had right sided dilatation. No non-CHDN dogs in sinus rhythm had right sided dilatation without concurrent systolic dysfunction (Fig. 4). Left heart dilatation and systolic dysfunction were present in 9/34 (26%) non-CHDN dogs and five (55%) of these had AF. Normalised left ventricular dimensions and indexed left atrial dimensions within the non-CHDN dogs are displayed in Fig. 5. Pulmonary hypertension was identified in six non-CHDN dogs, four with mild and two with moderate severity; the latter two had AF and right sided atrial/ventricular dilatation. The prevalence of collapse did not differ between sinus, SVT or AF rhythm (P = 0.958).
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Atrial fibrillation and physical activity

Atrial fibrillation and physical activity

H.R., a 60-year-old man, visits you in the office. He has been a runner for 20 years and has just completed his 15th marathon. His physical examination findings show no abnormalities and he has an unremarkable medical history. His father had atrial fibrillation (AF) and died following a stroke at the age of 79. Three of his friends in his running club have recently developed AF and have been advised to reduce their levels of exercise. H.R. wants to know whether it is safe to continue his current train- ing schedule of 50 to 60 km per week.

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Is atrial fibrillation a risk factor for in-hospital cardiac arrest?: a Swedish retrospective cohort study

Is atrial fibrillation a risk factor for in-hospital cardiac arrest?: a Swedish retrospective cohort study

All patients admitted to the Karolinska University Hospital between 1 January 2014 and 31 December 2015 were eligible for this study. Patients under the age of 18 were excluded. In cases where individual patients had been admitted to the hospital on multiple occasions during the study period, only the first occasion was included. The definition of IHCA used by SRCR was used, that is, a hospitalised patient who is unresponsive with apnoea (or agonal, gasping respiration) where cardiopulmonary resuscitation (CPR) and/or defibrillation is initiated. 16

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Life-threatening intestinal ischaemia and necrosis in a patient with cardiac arrest and atrial fibrillation

Life-threatening intestinal ischaemia and necrosis in a patient with cardiac arrest and atrial fibrillation

In the present case, a 68-year old man with known chronic coronary artery disease survived sudden cardiac arrest following successful CPR, but subsequently had intestinal ischaemia and necrosis requiring surgical intervention. The cause of the ischaemia is most likely an embolism to the SMA. If patients develop atrial fibrillation and abdominal symptoms following successful resuscitation from a cardiac arrest, then intestinal ischaemia should be ruled out. However, atrial fibrillation, whether related to cardiac arrest or other factors, may cause an embolus and possible intestinal ischaemia. These patients must undergo immediate medical imaging, and physicians must initiate immediate treatment in order to reduce the high mortality rates of this condition.
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Metformin therapy and postoperative atrial fibrillation in diabetic patients after cardiac surgery

Metformin therapy and postoperative atrial fibrillation in diabetic patients after cardiac surgery

Background: Postoperative atrial fibrillation (AF) commonly occurs in cardiac surgery patients. Studies suggest inflammation and oxidative stress contribute to postoperative AF development in this patient population. Metformin exerts an anti-inflammatory effect that reduces oxidative stress and thus may play a role in preventing postoperative AF. Methods: We conducted a matched, retrospective cohort study of diabetic patients ’ age ≥ 18 undergoing a coronary artery bypass graft (CABG) and/or cardiac valve surgery from January 1, 2009, to November 30, 2014. We extracted data from The Society of Thoracic Surgeons National Adult Cardiac Surgery Database. Primary exposure was ongoing metformin use at a dose of ≥ 500 mg in effect before cardiac surgery as captured before admission. Primary study outcome was postoperative AF incidence. Matching was used to reduce selection bias between metformin and non-metformin groups. Comparison between the groups after matching was accomplished using the McNemar test or paired t test.
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Dronedarone in the management of atrial fibrillation

Dronedarone in the management of atrial fibrillation

Atrial fibrillation is a growing medical problem with increasing prevalence. Hence, improved therapeutic approaches are needed, among which dronedarone may prove useful, especially in the long-term treatment of AF with fewer adverse effects. Many other drugs like propafenone SR, azimilide, tedisamil, other atrial selective drugs such as AZD7009, AVE0118, and some serotonin-5HT 4 receptor antagonists (which reduce the calcium load in the myocardial cells) are under investigation for the treatment of AF. Although attempts are made to cure AF by catheter ablation techniques, it remains questionable whether this technique will ever be applicable to the majority of the patients. Dronedarone proves to be safe and effective for all types of AF and for all the age groups. It is likely that various forms of AF therapy will optimally be tailored to specific patient populations. This is an area of major ongoing investigation that provides hope for major improvements in AF management over the next decade.
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Oral anticoagulation in atrial fibrillation

Oral anticoagulation in atrial fibrillation

AF—atrial fibrillation, APPRAISE—Apixaban for Prevention of Acute Ischemic Events, ARISTOTLE—Apixaban for Reduction in Stroke and Other ThromboemboLic Events in AF, ASA—acetylsalicylic acid, CAD—coronary artery disease, CrCl—creatinine clearance, CYP—cytochrome P450, DM—diabetes mellitus, GI—gas- trointestinal, HF—heart failure, HTN—hypertension, INR—international normalized ratio, LVEF—left ventricular ejection fraction, MI—myocardial infarction, NNT—number needed to treat, NSAID s —nonsteroidal anti-inflammatory drugs, NYHA—New York Heart Association, RELY—Randomized Evaluation of Long-term Anticoagulation Therapy, ROCKET-AF—Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonist for Prevention of Stroke and Embolism Trial in AF, TIA—transient ischemic attack, TTR—time in therapeutic range for patients taking warfarin.
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Chronic Atrial Fibrillation in the Elderly

Chronic Atrial Fibrillation in the Elderly

The trial, which randomized elderly chronic AF patients to attempted maintenance of sinus rhythm or to treatment with rate-controlling drugs, clearly demonstrated that rhythm control offers no survival advantage over rate control after a mean followup of 3.5 years. Moreover, patients in the rhythm-control group required more hospitalizations and suffered more adverse drug reactions. There was no difference in the number of ischemic strokes between the two groups; 70% of patients in the rhythm-con- trol group continued on warfarin. The majority of strokes occurring during the trial were due to discontinuing warfarin or a subtherapeutic INR.
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Atrial Fibrillation Symptom Clusters

Atrial Fibrillation Symptom Clusters

sociodemographic and clinical factors potentially associated with cluster membership. Methods: This was a cross-sectional secondary data analysis of 335 Australian community-dwelling adults with chronic (recurrent paroxysmal, persistent, or permanent) atrial fibrillation. We used self- reported symptoms and agglomerative hierarchical cluster analysis to determine the number and content of symptom clusters present. Results: There were slightly more male participants (52%) than female, with a mean age of 72 (±11.25) years. Three symptom clusters were evident, including a vagal cluster (nausea and diaphoresis), a tired cluster (fatigue/lethargy, weakness, syncope/dizziness, and dyspnea/breathlessness), and a heart cluster (chest pain/discomfort and palpitations/fluttering). We compared patient characteristics between those with all the symptoms in the cluster, those with some of the symptoms in the cluster, and those with none of the
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Review. Management of atrial fibrillation

Review. Management of atrial fibrillation

The non-dihydropyridine (or rate-limiting) calcium- channel blockers, verapamil and diltiazem, extend the AV nodal refractory period to slow AV nodal conduction, and are eff ective agents for ventricular rate control during atrial fi brillation. Since intravenous verapamil has more potent negative inotropic and peripheral vasodilator eff ects, intravenous diltiazem has became more popular for the control of acute ventricular rate during atrial fi brillation, especially in patients with mild left-ventricular (LV) dysfunction or hypotension. Intravenous β blockers (esmolol, metoprolol, or propranolol) are also eff ective AV nodal blocking drugs through their sympatholytic properties. The β blockers are especially eff ective in conditions in which the rapid ventricular rate is due to heightened adrenergic tone, such as in the postoperative periods. Apart from esmolol, all the β blockers have a slower onset of action than diltiazem. Intravenous esmolol has a very short half-life that needs careful monitoring and titration of dose. Both β blockers and calcium-channel blockers should be used with caution in patients with hypotension or heart failure.
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Atrial Fibrillation: Pharmacological Therapy

Atrial Fibrillation: Pharmacological Therapy

to a revision of the current ACC/AHA guidelines that recommend the ventricular rates of 60-80 bpm during rest and 90-115 bpm during exercises when rate control strategy is employed for AF management. 10 Choices for rate control are limited. Candidates include ␤ -blockers (class II), calcium channel blockers (class IV), and digoxin. Some of these agents have additional antihypertensive properties and their selection may serve multiple purposes. All ␤ -blockers are effective in rate control for AF, particularly in AF associated with adrenergic drive. They prevent shortening of refractoriness at all levels in the heart. They block adrenergic activation of calcium channels and thereby prolong the refractoriness of the AV node as conduction through the AV node is calcium dependent. The effectiveness of ␤ -blockers as first-line drugs for rate control was demonstrated in the AFFIRM substudy. 41 Overall rate control was achieved in 70% of patients given ␤ -blockers as the first drug (with or without digoxin), 54% with calcium channel blockers (with or without digoxin), and 58% with digoxin. In the acute setting, intravenous esmolol, metoprolol, propanolol, or atenolol has a rapid onset and can be given in a postoperative or acute setting. Esmolol may be given as a continuous infusion and has a short half-life, which is beneficial in critically ill patients. The choice and route of administration should be based on the patient’s hemodynamics and other comorbidities. ␤ -Block- ers should be used with caution in patients who are hypotensive or have heart failure.
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while the incidence of atrial fibrillation

while the incidence of atrial fibrillation

ever, it should be stressed that only 22.3% of the pa- tients in the study had heart failure, while the au- thors recommended that control of the ventricular response to atrial fibrillation should be preferred to cardioversion in the elderly, in patients with coronary artery disease and in patients who do not have heart failure. Perhaps a future meta-analysis of the AF- FIRM study, or a newer study, such as the AF-CHF study that is currently in progress, may be able to of- fer more information, especially concerning patients with atrial fibrillation and heart failure. 33
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