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Atrial rate is known to modulate ventricular response during atrial fibrillation (AF). The resulting pulse irregularity translates into widely varying inter-beat intervals (IBIs) extracted from recorded surface electrocardiogram (ECG) activity. In AF, the random nature of the IBIs makes them difficult to analyze using traditional methods, and little work has investigated the relationship between ventricular response and persistent AF (persAF) disease progression. In this paper, we propose nonlinear approaches for characterizing IBI dynamics in patients undergoing catheter ablation for the treatment of persAF.

Telemedicine is a legitimate entity for applying the use of modern information and communications technologies to deliver health services to remote patients. Telecardiology is one of the fastest growing fields in telemedicine. The use of mobile applications between cardiac patients and healthcare providers is an effective way to rescue cardiac patients from heart attack. The main objective of this work is developing a mobile application for remote exchange of data between cardiac patients and their consultants to help in fast diagnosing and monitoring. In the proposed application, the main parameters of heart signals are extracted and sent to the consultant including: Ventricular, Atrial rate, PR, QRS, QT QTC and PR Axis. The consultant in turn send a diagnosis for such case along with its medicine. The application has been implemented and tested in collaboration with the King Faisal Center for the heart of the King Faisal Specialist Hospital.

This thesis treats of the problematic of patients with atrial fibrillation who undergo a catheter ablation. It comports two main objectives. The first one is to implement an algorithm capable of compute the atrial rate of a patient during the procedure from the detection of the A peaks on the patient's atrial rhythm signal. The second one is to find a way to predict the catheter ablation outcome (i.e. the absence of recurrence of the pathology) from the patient's characteristics. An empirical method has been implemented to detect the atrial rate, since the traditional frequency-based methods were unsuccessful. This method is based on finding the peaks of a signal and keeping the ones with some specificities. Those are determined by three parameters: the minimum height, the minimum peak separation and the minimum peak prominence. The first parameter is fixed, while the two other ones have to be selected. The user can either find these parameters manually (which gives a very good result) or use a suggested set of parameters (which can either give a good result or lead to a very big error). The learning has been conducted on 66 patients and 45 features. Among these features, the atrial rate and the maximum AA interval could not have been used, since those data where highly incomplete. Three algorithms have been considered: CART algorithm, Random Forest algorithm or $K$-Nearest Neighbours algorithm. The feature selection has been produced by two different methods: ReliefF and mutual information. Only the CART algorithm was able to output acceptable results with a BCR =0.73, while the other algorithms were not satisfying at all, giving BCR near 0.5 (total uncertainty) Master [120] : ingénieur civil en mathématiques appliquées, Université catholique de Louvain, 2018

Atrial flutter is an aberrant, reentrant atrial tachycardia. The ECG shows characteristic “sawtooth” p-waves with a rate of about 300 bpm. Since the conduction abnormality is above the AV node, the QRS complexes are normal. In atrial fibrillation, multiple ectopic atrial pacemakers fire in a disorganized fashion, resulting in an atrial rate of 450 or more. The AV node blocks most impulses, resulting in a completely irregular (sometimes called irregularly irregular) ventricular rhythm.

1. Identify a QRS complex that falls on a vertical line bordering a large square; the HR is calculated by dividing 300 by the number of large squares that separate it from the next QRS complex. 2. By dividing 60,000 (milliseconds in 1 min) by the interval—in milliseconds—between two P waves (atrial rate) or between two QRS complexes (ventricular rate) (Fig. 4.1).

The electrocardiogram (ECG) interpretation in patients with cardiac resynchronization therapy (CRT) may be challenging. The difficulty increases if not well-known pacemaker algorithm is turned on. We show a T-wave protection algorithm (LVTP) in a patient with CRT. Accelerated sinus rhythm and intermittent oversensing in left ventricular channel resulted in loss of CRT pacing. The restoration of biventricular pacing occurred when atrial rate decreased. We provide detailed descriptions of the electrocardiogram and intracardiac electrogram. LVTP may confuse ECG examination interpretation, especially in patients with accelerated atrial rhythm and oversensing in left ventricular channel.

Background Atrial flutter ( AFL ) has been identified to be equivalent to atrial fibrillation ( AF ) in terms of preventing ischemic stroke, although differences exist in atrial rate, substrate, and electrophysiological mechanisms. This study aimed to investigate differences in clinical outcomes between nonvalvular AF and AFL . Methods and Results AF and AFL patients without any prescribed anticoagulation were enrolled from a 13‐year national cohort database. Under series exclusion criteria, ischemic stroke, heart failure hospitalization, and all‐cause mortality were compared between the groups in real‐world conditions and after propensity score matching. We identified 175 420 patients in the AF cohort and 6239 patients in the AFL cohort, and the prevalence of most comorbidities and frequency of medications were significantly higher in the AF group than the AFL group. In the real‐world setting the AF patients had higher incidence rates of ischemic stroke, heart failure hospitalization, and all‐cause mortality than the AFL patients (all P AF cohort was 1.63‐fold higher than in the AFL cohort ( P AF cohort was 1.70‐fold higher than in the AFL cohort ( P AF cohort was 1.08‐fold higher than in the AFL cohort ( P =0.002). Conclusions There were differences between AF and AFL in comorbidities and prognosis with regard to ischemic stroke, heart failure hospitalization, and all‐cause mortality.

This review focuses on the manifestations of the three triggered atrial upper rate functions of St Jude Medical cardiac implantable electronic devices. The occurrence of repetitive nonreentrant ventriculoatrial synchrony (RNRVAS) is also evaluated as a basis for the development of automatic mode switching (AMS) and as a trigger for atrial tachycardia/atrial fibrillation (AT/AF) event recordings. RNRVAS is a common trigger for AMS because all the atrial events or intervals are used to calculate the filtered atrial rate interval (FARI). Once AMS is initiated, it will also effectively stop RNRVAS because entry into AMS also shortens the postventricular atrial refractory period (PVARP). Recent design developments to eliminate or minimize unusual upper rare responses include the following: (1) P waves in the PVARP are no longer counted towards the FARI if they are followed by an atrial paced event. (2) In new devices the AT/AF detection algorithm substitutes the Moving Average Interval (a relatively complex calculation) with the new FARI average. (3) Improved design of the rate-responsive PVARP with a far more aggressive response than in the past (enhanced atrial protection interval).

In this meta-analysis we systemically evaluated the evidences regarding the association of subclinical events of rapid atrial rate episodes (AHRE) detected by implanted devices, with risk of stroke. Pubmed, Medline and other databases were searched for trials that reported relation between

Objective—To characterize the electrocardiographic features of the atrial repolarization (Ta) wave in dogs with third-degree atrioventricular (AV) block. Sample—ECGs of 36 dogs with third-degree AV block and no identifiable structural heart diseases. Procedures—Standard 12-lead ECGs were acquired with a digital system, and measurements were manually edited. Results—A Ta wave was detectable in all dogs for at least 1 ECG lead. The Ta wave had negative polarity in leads I, II, III, and aVF and positive polarity in leads aVL and aVR, with a mean electrical axis of −114.26°. Mean duration and mean amplitude of the Ta wave in lead II were 140.2 milliseconds and −0.09 mV, respectively, with the ratio for the Ta-to-P wave duration of 2.3 and the ratio of Ta-to-P wave amplitude of −0.35. Significant correlations were found between the Ta wave duration and duration of the P-Ta interval, Ta wave amplitude and the ECG lead, Ta wave duration and body weight, and duration of the P-Ta interval and atrial rate. Measurements of the Ta wave were repeatable. Conclusions and Clinical Relevance—Measurements of the Ta wave in dogs with third-degree AV block were repeatable. The values for the Ta wave reported here can be used as reference values for dogs with AV conduction disturbances and an echocardiographically normal atrial size. Further studies are needed to validate these results in dogs with structural heart diseases.

Background The dominant atrial frequency is a key parameter for the analysis of atrial fibrillation (AF) from intracardiac recordings. The preprocessing approach employed by Botteron et al. in an early work is able to retrieve this frequency. The preprocessing steps are: (1) 40–250-Hz band-pass filtering, (2) rectification, and (3) 20 Hz low-pass filtering. Methods and results The theoretical aspects of this process are addressed. Moreover, its time-domain and frequency-domain properties are evaluated using both simulations and real electrogram (EGM) recordings. The fundamental frequency is emphasized, due to the rectification step. As the interval between consecutive activations becomes more irregular, fundamental frequency detection becomes less robust. In the case of fractionated EGM, this approach fails. In time-domain, the waveform of the atrial beats are dramatically modified, hence hindering any further analysis on the morphology of the activations. Conclusions Botteron preprocessing succeeds in estimating the dominant atrial rate in most EGMs during AF. However, this approach presents some limitations and improved methods are required.

Introduction: Atrial fibrillation (AF) induces substantial self-promoting remodeling related to the rapid atrial rate. There is evidence that changes in nuclear Ca 2+ content alter ion channel gene expression and thereby effect electrophysiological changes that increase AF vulnerability and maintenance. However, the ways in which AF affects atrial cardiomyocyte (ACM) nuclear Ca 2+ disposition are unknown. Here, we studied the effects of AF-related remodeling on ACM nuclear structure and Ca 2+ handling. Methods and Results: ACMs were isolated from control (CTL) dogs and dogs subjected to 1 week of AF maintained by atrial tachypacing at 600 bpm (n=7, 6 respectively). We used nuclear imaging with Fluo-5N AM and nucleoplasmic and cytoplasmic calcium transient (CaT) recordings from intact ACMs loaded with Fluo-4 AM. AF significantly decreased the number of nuclear invaginations (NIV) normalized to nuclear envelope (NE) circumference, and increased nuclear length and perimeter in ACMs (Figure A). Diastolic [Ca 2+ ] nuc and [Ca 2+ ] cyto increased in AF vs CTL (Figure B, by 110%*, 89%* respectively, *P2+ transient amplitude decreased significantly with AF, but simultaneously measured cytoplasmic transient amplitude did not change (Figure C). Relaxation time from peak of the Ca 2+ transient to 50% decline (TD 50 ) of nucleoplasmic and cytoplasmic CaTs were significantly prolonged in AF. The addition of a physiological nuclear Ca 2+ transient enhancer, endothelin (200 nM), increased diastolic [Ca 2+ ] nuc and [Ca 2+ ] cyto in both CTL (by 25±6%, 21±6%) and AF (by 40±4%, 31±2 ) ACMs. The IP3 receptor blocker 2-aminoethoxydiphenyl borate (2-APB, 5 μM) abolished endothelin effects on [Ca 2+ ] nuc . Conclusions: AF-related remodeling alters atrial cardiomyocyte nuclear structure and nucleoplasmic [Ca 2+ ] handling. These alterations may play an important role in associated gene-expression changes that produce the AF substrate.

We studied the Medtronic Thera and Kappa 400 dual chamber pacemakers to determine the causes and mechanism of shortening of the sensed AV delay during normal sinus rhythm. When the sensed AV delay shortens to less than its programmed value, it lengthens gradually and returns to its programmed duration after a number of pacing cycles. This behavior is linked to the relatively slow automatic mode switching algorithm (AMS) and was observed when a transient increase in the sensed atrial rate failed to reach the point where AMS was activated and also upon exit from the AMS mode.

Multifocal atrial tachycardia (MAT; also known as chaotic atrial tachycardia) is an unusual arrhythmia in children. The defining characteristics—P-waves of three or more distinct morphologies with irregular P–P intervals, an isoelectric baseline, and an atrial rate greater than 100 beats per minute—are the same as those in adults.

The causal relationship between atrial and ventricular activities during human atrial fibrillation (AF) is poorly understood. This study analyzed the effects of an increase in atrial rate on the link between atrial and ventricular activities during AF. Atrial and ventricular time series were determined in 14 patients during the spontaneous acceleration of the atrial rhythm at AF onset. The dynamic relationship between atrial and ventricular activities was quantified in terms of atrioventricular (AV) coupling by AV synchrogram analysis. The technique identified n: m coupling patterns ( n atrial beats in m ventricular cycles), quantifying their percentage, maximal length, and conduction ratio (= m/ n). Simulations with a difference-equation AV model were performed to correlate the observed dynamics to specific atrial/nodal properties. The atrial rate increase significantly affected AV coupling and ventricular response during AF. The shortening of atrial intervals from 185 ± 32 to 165 ± 24 ms ( P < 0.001) determined transitions toward AV patterns with progressively decreasing m/ n ratios (from conduction ratio = 0.34 ± 0.09 to 0.29 ± 0.08, P < 0.01), lower occurrence (from percentage of coupled beats = 27.1 ± 8.0 to 21.8 ± 6.9%, P < 0.05), and higher instability (from maximal length = 3.9 ± 1.5 to 2.8 ± 0.7 s, P < 0.01). Advanced levels of AV block and coupling instability at higher atrial rates were associated with increased ventricular interval variability (from 123 ± 52 to 133 ± 55 ms, P < 0.05). AV pattern transitions and coupling instability in patients were predicted, assuming the filtering of high-rate irregular atrial beats by the slow recovery of nodal excitability. These results support the role of atrial rate in determining AV coupling and ventricular response and may have implications for rate control in AF.

The purpose of this study was to determine if intraatrial electrograms (EGMs) are required to diagnose specific types of atrial tachyarrhythmias detected by pacemaker diagnostics. DDD pacemakers in 56 patients were programmed to store episodes of atrial tachyarrhythmias. Some episodes had a stored atrial EGM snapshot of the atrial tachyarrhythmia. The EGMs were analyzed to confirm whether the stored episodes were true atrial tachyarrhythmias or other pacemaker-sensed events. EGM confirmation of atrial tachyarrhythmias correlated with increasing duration and rate of episodes. In particular, using EGMs, 8 (18%) of 44 episodes10 seconds in duration confirmed atrial tachyarrhythmias compared to 16 (89%) of 18 episodes5 minutes in duration (P0.001). Only 10 (18%) of 56 detected atrial arrhythmia episodes at rates250 complexes per minute were confirmed by the atrial EGM as true arrhythmias compared to 33 (57%) of 58 detected episodes at rates250/min (P0.001) Twenty-nine (91%) of 32 EGM confirmed episodes of atrial fibrillation/flutter had an atrial rate250 complexes per minute and were a minimum of 10 seconds in duration. Fifteen (88%) of 17 episodes meeting the combined stored data criteria of250 complexes per minute and duration5 minutes were confirmed as atrial fibrillation or flutter by stored EGMs. Atrial EGMs identified that 71 (62%) of 114 stored high atrial rate (HAR) episodes were events other than true atrial tachyarrhythmias. Pacemaker diagnostic data with intraatrial EGMs can diagnose specific atrial tachyarrhythmias and identify other pacemaker-sensed events. Stored episodes250 complexes per minute and5 minutes in duration had a high correlation with atrial fibrillation and flutter.

Reports have indicated that maternal administration of ritodrine increased the ventricular rate and thus ameliorated signs of heart failure in a fetus with complete atrioventricular block (CAVB). A fetus from a mother without the anti-SS-A/SS-B antibody had CAVB, with atrial rate 148–154 bpm and ventricular rate 53–57 bpm. After maternal administration of ritodrine, the ventricular rate increased to 60–65 bpm, and then sinus rhythm resumed. Ritodrine may not only increase the ventricular rate but also induce sinus rhythm in a fetus with CAVB.

WOOD, M.A., et al. Influence of Autothreshold Sensing and Sinus Rate on Mode Switching Algorithm Behavior. Mode switching is beneficial to pacemaker patients with paroxysmal atrial tachyarrhythmias. However, the optimal mode switching algorithm is still in evolution. Mode switching algorithms and atrial sensing circuitry can influence mode switching behavior. This study compared the mode switching behavior of four Medtronic, Inc. implantable devices: Thera DR model 7960 pacemaker, Kappa 700 model KDR701 pacemaker, Gem DR model 7271 dual chamber pacing defibrillator, and Jewel AF model 7250 dual chamber pacemaker atrial and ventricular defibrillator. The Thera and Gem DR use the same mean atrial rate mode switch algorithm. The Kappa and Jewel AF use four of seven short atrial intervals and an atrial fibrillation evidence counter algorithm, respectively. The Thera and Kappa devices use fixed gain sensing and the Gem DR and Jewel AF use autothreshold atrial sensing. Digitally recorded atrial electrograms from 52 episodes of human atrial fibrillation were fed into each device with differing simulated sinus rates before and after the atrial fibrillation. The percent of appropriate mode switching was highest for the Kappa 700 (94%) and lowest for the Thera (85%) (P = 0.046). The time to mode switching was significantly longer for the Thera and Gem DR compared to the Kappa 700 or Jewel AF (all P < 0.05). The time to mode switching was shorter for the Gem DR (9.0 ± 1.6 s) using autothreshold atrial sensing than for the fixed gain Thera (11.1 ± 2.1 s, P < 0.05). The mean atrial electrogram amplitude and cycle length were not correlated with the time to mode switching for any device. Faster sinus rates shortened the time to mode switching and prolonged the time to resynchronization in the two devices using the mean atrial interval algorithm. In conclusion, (1) mode switching function among these devices is influenced by algorithms and sensing circuitry, (2) the time to mode switching among these devices is influenced by the algorithm and use of autothreshold atrial sensing, and (3) the sinus rate before and after episodes of atrial fibrillation greatly influences the times to mode switching and resynchronization in devices using the mean atrial interval algorithm.

The Medtronic Thera®/Thera®-i (and Kappa® 400) pacemakers utilize a mode switching algorithm that switches from the DDD/R mode to the DDIR mode in the presence on an atrial tachyarrhythmia. To accomplish this, the pacemaker keeps track of a mean atrial rate (MAR) which is a weighted index of the atrial rate. Once the MAR is greater than the programmed mode switch rate the pacemaker mode switches to the nontracking mode. Because the algorithm weights faster atrial rates more heavily than slow atrial rates, the algorithm is sensitive to a wide variety of atrial tachyarrhythmias, including those with varying amplitudes. Additionally, the algorithm provides a long PVARP and a rate adaptive (RA) AV interval. These not only help ensure that a wide range of atrial rates will be detected, but may also limit the time the patient tracks at the upper rate before mode switching. In order to assess the effectiveness of the algorithm, the Thera®-i provides detailed diagnostics which provide information on the date, time, duration, and rate of the mode switch episodes. Additionally, more detailed beat-to-beat information is provided for each episode which can help determine its appropriateness and can assist in making programming changes.

This paper reviews the rationale for and key features of the automatic mode switching algorithms in the Pacesetter Trilogy DR+ and Affinity DR dual chamber rate-modulated pulse generators along with the subtile differences between these two devices. Critical parameters include independently programmable maximum tracking, maximum sensor and atrial tachycardia detection rates and the post-ventricular atrial blanking period. Guidance is provided as to the assessment of the presence or absence of a far-field R-wave, details as to how the filtered atrial rate interval is calculated in the presence of increasing and decreasing atrial rates and the impact of this calculation on entering or exiting mode switching. Guidelines are provided in programming the sensor using the prediction model. Various methods of assessing the behavior of the mode switch algorithm are provided using multiple different event counters including the automatic mode switch histogram, the event histogram, the event record, and the patient triggered event record and/or event snapshot. The use of these event counters to assess the effectiveness of any therapeutic intervention, be it pharmacologic or a change in the pacing parameters, is discussed.

In this report we describe the case of a 56-year-old woman with normal 1:1 AV conduction at rest who developed 2:1 AV block during treadmill exercise testing. Electrophysiological study documented 2:1 AV block proximal to the His bundle with reappearance of 1:1 AV conduction at a higher pacing atrial rate. A gap phenomenon involving a proximal and distal part of the AV node may be a likely explanation of paradoxical AV conduction in our case.

The relationship between the atrioventricular (AV) conduction ratio and systolic blood pressure or right atrial pressure during atrial pacing was investigated before and after phamacological autonomic nervous blockade (PAB) in horses. The increase in the pacing rate decreased the AV conduction ratio. Systolic blood pressure increased when the AV conduction ratio became low, but the relevancy of the both stopped being recognized after PAB. Also right atrial pressure decreased with a decrease in the AV conduction ratio irrespective of the presence of PAB. These findings indicate that the onset mechanism of dropped beats involves an interaction among atrial rate, AV conduction, autonomic nervous system, and hemodynamics in horses with a second degree AV block.

We read with interest the clinical study by Lim et al. [(1)][1] in which rapid atrial rate and atrial fibrillation (AF) both resulted in increased platelet activation and thrombin generation in humans, but AF additionally induced endothelial dysfunction and inflammation. They concluded that