Atrial repolarization wave: a new approach using spline-based feature engineering and explainable AI for atrial arrhythmia diagnosis.

BackgroundThe characterization of atrial repolarization (Ta wave) remains largely elusive due to its inherently low amplitude and concealment beneath the dominant QRS complex.ObjectiveThis study aims to witness Ta wave within QRS complex using spline interpolation framework.Methodology10-s ECGs of 50 Sinus Tachycardia (SiT) and 20 Atrial Tachycardia (AT) were recorded using standard 12-lead. Lead-II signals were pre-processed for noise removal and fiducial points detection. Later, three spline models were used to synthesize hidden Ta wave using the datapoints from PR and ST segment. Further, validation analysis was performed to select the optimal spline model with the Ta wave of Atrio-Ventricular Block (AVB) ECG.ResultsIt was noted that the clamped cubic & B-spline interpolation model gave the best SSIM score of 0.7 and lowest power spectrum % difference of 1.33 of interpolated Ta wave within QRS complex. Further, Ta wave voltage and temporal features including Ta dispersion, area, peak location, Ta area/duration, duration/amplitude, and Ta2/Ta1 were crafted. Statistically significant P, Ta & P-Ta features were fed to seven Machine Learning (ML) models. The best ML models, were used to design a stacked ensemble architecture with combined P-Ta features to enhance the classification accuracy 99% and F1 score 0.99.ConclusionThe proposed method demonstrated that along with the existing P wave features, Ta wave features have potential in better classification of atrial arrhythmia, while interpolation model offers ease of implementation and adaptability to diverse clinical applications.

Objective:In the present study, a modified limb lead (MLL) system was used to record the Ta wave in sinus rhythm and with AV block in male patients.Methods:Eighty male subjects (mean age 36±7 years) in sinus rhythm and 20 male patients with AV block (mean age 72±5 years) were included in this study. Standard limb lead (SLL) ECGs and MLL ECGs were recorded for 60 seconds each with an EDAN SE-1010 PC ECG system.Results:In sinus rhythm subjects, the observable Ta wave duration was 109±4.7 ms, the P-Ta duration was 196±5.1 ms, and the corrected P-Ta duration was 238±7.2 ms. The Ta wave peak amplitude was -42±8 pV. In AV block patients, the Ta wave duration was 314±28 ms the P-Ta duration was 418±29 ms and the corrected P-Ta duration was 462±31 ms, while the Ta wave peak amplitude was -37±9 pV. A correlation was found between the P and Ta wave amplitude, and no correlation was found between the P and Ta wave duration or the Ta amplitude and Ta duration in sinus rhythm and AV block subjects.Conclusion:The end of the Ta wave is not observable in sinus rhythm subjects, as it extends into the QRS complex and ST segment. In AV block patients, the Ta wave duration was generally three times longer than the observable Ta duration in sinus rhythm subjects.

In of Sinus Rhythm (SR) volunteers, the atrial repolarization (Ta wave) as a possible indicator for atrial-related diseases is undermined. The presence of Ta wave in exercise stress ECG has been noted previously, however its manifestation during SR is limited in Standard 12-lead system. This study delineates and compares the characteristics of the Ta wave in Sinus Tachycardia (ST) with the SR in terms of amplitude and Ta peak location using the Modified Limb Lead (MLL) system. MLL was recorded for eight SR and fifteen ST volunteers (mean age of 24 years). P-R and S-T segment amplitudes were measured and analyzed. Ta wave-related impact on P-R and S-T segment have been noted and found a 41.60 % increase in P-RST to P-RSR and 49.60% in S-TST to S-TSR using absolute values of P-R and S-T segments. Moreover, the Ta wave peak can be predicted with the change in morphology of the P-R and S-T segments. Determination of Ta wave peak may help to delineate atrial-related disease conditions. A detailed study on Ta wave induced S-T segment depression and elevation helps decrease the false-positive detection of myocardial ischemia and infarction.

Objective: This study aims to characterize P and Ta wave of Modified Limb Lead (MLL) Electrocardiogram (ECG) in Normal Sinus Rhythm (NSR) and Atrioventricular Block (AVB). Methods: ECGs were recorded using MLL configuration from 100 NSR volunteers (mean age 31 years, 35 women) and 20 male AVB patients (mean age 72 years). Amplitudes and durations of P, Ta wave, and PTa Interval (PTaI) were measured, plotted, and analyzed for both the groups. Results: P-wave amplitudes were larger in AVB, and also P, Ta waves correlated significantly in both groups with higher correlation in AVB (NSR: [Formula: see text]; AVB: [Formula: see text]). Ta-wave duration ([Formula: see text][Formula: see text]ms) was longer than P-wave duration ([Formula: see text][Formula: see text]ms) in AVB patients and was opposite to P-wave polarity in all the leads. PP Interval (PPI) correlated significantly with P wave (NSR: [Formula: see text]; AVB: [Formula: see text]), Ta wave ([Formula: see text]; [Formula: see text]), PTaI ([Formula: see text]; [Formula: see text]), and corrected PTaI ([Formula: see text]; [Formula: see text]). Conclusion: P-wave right axis shift leads to the higher P-wave amplitude in AVB which may be due to the advancing age and atrial chamber enlargement. In NSR, the duration of observable Ta wave was longer than P wave, whereas in AVB, the Ta wave duration was 3–3.5 times longer than P wave.

Modified Limb Lead (MLL) ECG recording systems are in use during exercise stress test and for enhancing the a trial ECG components (i.e.) P and Ta wave (atrial repolarization). Though the MLL system improves the amplitude and signal to noise ratio of a trial ECG components, information on the temporal aspects of these waves are scarce. Therefore, the aim of this study is to delineate the effects of a trial sinus rate in P wave and observable segment of the Ta wave in normal sinus rhythm (NSR) subjects efficiently. MLL ECGs were recorded from 50 NSR subjects (mean age 27 years, 20 women). The amplitude and duration of P wave and observable Ta wave were measured and analyzed. The P and Ta wave amplitudes correlated significantly (r = 0.28, p 0.05). Atrial sinus cycle length (PP interval) and heart rate variability (HRV) mainly affected the repolarization segment.

The standard 12-lead Electrocardiogram (ECG) system is the most commonly used technique for obtaining the electrocardiographic signal to evaluate the heart’s electrical activity. In the surface ECG, atrial repolarization (Ta wave) is not observed. However, during the exercise stress test, ST-segment depression validates the existence of Ta wave.To record the Ta wave and enhance atrial depolarization (P wave) in Sinus Rhythm (SR) ECG, Modified Limb Lead (MLL) system is used. PTa Interval (PTaI) represents the duration from the beginning of P wave to the end of Ta wave. This study aims to develop a corrected PTaI (PTac) formula to correct the PTaI from MLL ECGs for different heart rates. ECGs were recorded from 35 volunteers in SR and Sinus Tachycardia (ST) condition of mean age 24 ± 5 years using EDAN PC ECG system. Regression analysis was implemented on the recorded data to derive the slope for PP Interval (PPI) vs. PTaI plots in both groups. In SR group, PPI correlated well with PTaI (r = 0.48) compared to the ST group (r = 0.17). A new corrected PTaI (\({\text{PTa}}_{\text{c}} {\text{N}}\)) formula was developed from the slope values of SR and ST and compared with the previously developed PTac formula. The developed PTac formula of this study showed accurate results with the least slope in different heart rates. Implementation of new PTac formula in automatic algorithms further improves the clinical diagnosis related to atrial ECG components.

To characterize the electrocardiographic features of the atrial repolarization (Ta) wave in dogs with third-degree atrioventricular (AV) block. ECGs of 36 dogs with third-degree AV block and no identifiable structural heart diseases. Standard 12-lead ECGs were acquired with a digital system, and measurements were manually edited. 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. 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.

Determination of the spatial and intensity properties of atrial repolarization potentials in the dog

Data on human atrial repolarization are scarce since the QRS complex normally obscures its ECG trace. In the present study, consecutive patients with third-degree AV block were studied to better describe the human Ta wave. Forty patients (mean age 75 years, 17 men) were included. All anti-arrhythmic drugs were discontinued before ECG recording. Standard 12-lead ECGs were recorded, transformed to orthogonal leads and studied using signal-averaged P wave analysis. The average P wave duration was 124 +/- 16 ms. The PTa duration was 449 +/- 55 ms (corrected PTa 512 +/- 60 ms) and the Ta duration (P wave end to Ta wave end) was 323 +/- 56 ms. The polarity of the Ta wave was opposite to that of the P wave in all leads. The Ta peaks were located at 196 +/- 55 ms in Lead Y, 216 +/- 50 ms in Lead X, and 335 +/- 92 in Lead Z. No correlation was found between P wave duration and Ta duration, or between Ta peak amplitude and Ta duration. The morphology of the Ta wave was similar regardless of the interatrial conduction. The Ta wave has the opposite polarity, and the duration is generally two to three times that, of the P wave. Although the Ta peak may occasionally be located in the PQ interval during normal AV conduction, it is unlikely that enough information can be obtained from analysis of this segment to differentiate normal from abnormal atrial repolarization. Hence, an algorithm for QRST cancellation during sinus rhythm is needed to further improve analysis.

The prevalence of adult congenital heart disease (ACHD) has risen markedly over the past 2 decades, with the number of adults now rivaling the number of children with severe defects.1 This is, perhaps, not surprising given that current care allows nearly 90% of infants born with heart defects to thrive into their adult years.1,2 This remarkable triumph is tempered, however, by the realization that early interventions were reparative and not curative. Numerous complications may surface years after uneventful childhood courses, justifying vigilant clinical follow-up throughout adulthood. The 12-lead ECG remains an invaluable cornerstone in the clinical appraisal of adults with congenital heart disease that, in certain circumstances, provides diagnostic and/or prognostic information. The present review imparts a clinical perspective to ECG interpretation in ACHD, emphasizing practical and pathogenomonic findings in the more frequently encountered congenital defects in adults. Anatomic features of the conduction system relevant to ECG findings in ACHD are summarized, including variations in the location of the sinus node, atrioventricular (AV) node, and His-Purkinje system. Thereafter, pertinent ECG features are highlighted for common subtypes of ACHD (Table). Examples are provided throughout for illustration. View this table: Table. Typical ECG Features in Common Forms of ACHD ### Sinus Node In the morphologically normal heart, a crescent-shaped sinus node is characteristically located epicardially along the lateral aspect of the superior cavoatrial junction. It generates a P-wave axis typically between 15° and 75°. Most patients with ACHD have normally positioned atrial chambers, called atrial situs solitus, with normal sinus node location. The position of the sinus node may, however, vary with the atrial chambers and their appendages. #### Juxtaposition of the Atrial Appendages In juxtaposition of the atrial appendages, both appendages are on the same side of the arterial pedicle rather than each being ipsilateral to its respective atrium. Left juxtaposition, with left-sided atrial appendages, frequently accompanies tricuspid atresia and has …

Atrial repolarization in patients with left ventricular dysfunction.

HomeCirculationVol. 133, No. 8ECG Response: February 23, 2016 Free AccessResearch ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessResearch ArticlePDF/EPUBECG Response: February 23, 2016 Originally published23 Feb 2016https://doi.org/10.1161/CIRCULATIONAHA.116.021443Circulation. 2016;133:764ECG Challenge: A 47-year-old woman with a history of palpitations that occur after exercise presents to an emergency department with palpitations that have persisted for several hours. An ECG (A) is obtained. Several minutes later the palpitations abruptly stop and an ECG (B) is repeated.Download figureDownload PowerPointECG A shows a regular rhythm at a rate of 120 bpm. The QRS complex duration is increased (0.12 s) and there is a morphology consistent with a right bundle-branch block with a tall an RR′ wave in V1 (←) and a broad terminal S wave in leads I and V5 to V6 (→). The axis is extremely leftward between –30° and –90° (positive QRS complex in lead I and negative complex in leads II and aVF). There are 2 causes for an extreme left axis; that is, an old inferior wall myocardial infarction (which has a deep initial Q wave in leads II and aVF) or a left anterior fascicular block (which has an rS morphology in leads II and aVF). Because the QRS complexes in leads II and aVF have an rS morphology, this is a left anterior fascicular block. The QT/QTc intervals are prolonged (360 ms/510 ms) but are normal when corrected for the wide QRS complex duration (340 ms/480 ms). There is a P wave seen before each QRS complex (+), most obvious in leads I, II, aVF, and V5 to V6. The P waves are positive in these leads, consistent with a sinus mechanism. The PR interval is constant, although prolonged (0.26 s). This represents a first-degree atrioventricular (AV) conduction delay (or first-degree AV block. Therefore, it appears that this is a sinus tachycardia with a first-degree AV conduction delay (first-degree AV block).After the palpitations stopped, ECG B shows a regular rhythm at a rate of 85 bpm. There are 2 premature complexes (*). The QRS complex duration is normal and there is a normal morphology. The axis is normal between 0° and +90° (positive QRS complex in leads I and aVF) and the QT/QTc intervals are normal (340 ms/400 ms). There is flattening of the ST segment (↑) in leads I, aVL, and V5 to V6, which are nonspecific changes. There is a P wave (+) before each QRS complex with a constant PR interval (0.20 s). The P wave is positive in leads I, II, aVF, and V4 through V6. Hence, this is a normal sinus rhythm. The 2 premature QRS complexes (*) have the same morphology as the sinus complexes; they are both preceded by a P wave (^), but the P wave is different than the sinus P wave. These are premature atrial complexes. Although ECG A appears to show a sinus tachycardia with a first-degree AV conduction delay, ECG B shows a normal sinus rhythm with a PR interval that is shorter (0.20 s) than the PR interval during the tachycardia (0.26 s). The PR interval stays the same or shortens with sinus tachycardia. Sinus tachycardia is attributable to enhanced sympathetic tone or increased catecholamines, which results in more rapid impulse conduction through the AV node and, hence, a shortening of the PR interval. Therefore, a longer PR interval with a faster heart rate is not consistent with a sinus mechanism, but is consistent with an atrial tachycardia. With an atrial tachycardia, which is not the result of enhanced sympathetic tone, there is generally a slowing of conduction through the AV node (and, hence, a longer PR interval) as a result of decremental AV conduction. When the AV node is stimulated at a more rapid rate (in the absence of sympathetic stimulation), conduction through the node is slower. In addition, the P waves seen in ECG A are different than those seen with sinus rhythm (ECG B). Therefore, the rhythm in ECG A is an atrial tachycardia. Last, the QRS complex during the atrial tachycardia has a right bundle-branch block morphology and a left anterior fascicular block, whereas these features are not seen during normal sinus rhythm. Hence, these conduction abnormalities are rate-related changes.Please go to the journal’s blog, OpenHeart, for more ECG Challenges: http://goo.gl/tQPNFp. Challenges are posted on Tuesdays and Responses on Wednesdays.FootnotesCorrespondence to Philip J. Podrid, MD, West Roxbury VA Hospital, Section of Cardiology, 1400 VFW Pkwy, West Roxbury, MA 02132. E-mail [email protected] Previous Back to top Next FiguresReferencesRelatedDetails February 23, 2016Vol 133, Issue 8 Advertisement Article InformationMetrics © 2016 American Heart Association, Inc.https://doi.org/10.1161/CIRCULATIONAHA.116.021443PMID: 26903019 Originally publishedFebruary 23, 2016 PDF download Advertisement

The Diagnosis

HomeCirculation: Arrhythmia and ElectrophysiologyVol. 11, No. 3February 26th Question Free AccessArticle CommentaryPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessArticle CommentaryPDF/EPUBFebruary 26th Question Pasquale Santangeli, MD, PhD Pasquale SantangeliPasquale Santangeli Search for more papers by this author Originally published26 Feb 2018https://doi.org/10.1161/CIRCEP.118.006249Circulation: Arrhythmia and Electrophysiology. 2018;11:e006249See Answer to February 19th Following QuestionA 71-year-old male with history of persistent atrial fibrillation, who underwent a prior ablation procedure, presents with recurrent drug-refractory atrial tachycardia. The tracing in the Figure is recorded in the electrophysiology laboratory, with pacing performed from the cavotricuspid isthmus. What is the mechanism of the arrhythmia?Download figureDownload PowerPointFigure. Surface and intracardiac tracings. A recording is shown with overdrive stimulation delivered from the cavotricuspid isthmus (CTI) during tachycardia. Also shown are three surface electrocardiogram (III, V1, V6) and coronary sinus (CS) electrograms. CS 1,2 is distal and CS CS 9,10 is proximal close to CS ostium.Answer OptionsA. Dual loop macroreentrant atrial tachycardiaB. Macroreentrant atrial tachycardiaC. Microreentrant atrial tachycardiaD. Focal automatic atrial tachycardiaE. Need more dataANSWER TO FEBRUARY 19th QUESTIOND. Sinus rhythm with second-degree type I AV block, bifascicular (right and left superior fascicle) block, and rate-related pseudonormalization of QRSExplanationThe Figure shows a part of lead II rhythm strip overlaid with ladder diagrams to explain the cardiac rhythm. There are regular P waves marching through the tracing (sinus rhythm). There is a repetitive pattern of 3 P waves associated with 2 QRS complexes. The top shows a P wave conducted with a long PR interval. There is no QRS complex following the next P wave. This suggests second-degree atrioventricular (AV) block. The third P wave is followed after a shorter PR interval by a wider QRS complex, potentially an escape ventricular complex (asterisk). However, this explanation is not provided among the available answer options.The bottom is an alternative explanation for the ECG rhythm (Option D). There is prolongation of PR interval from first to second P wave, with block of third P wave, consistent with second-degree type I (Wenckebach) 3:2 AV block. The first QRS complex is aberrant as the right bundle branch conduction is delayed compared with the left posterior fascicle. The second QRS complex occurs with a shorter preceding RR interval that can lead to rate-related delay in conduction through the left posterior fascicle, which now coincides with the conduction through the right bundle branch (pseudonormalization of QRS).Option A is incorrect because first-degree AV block fails to explain the prolongation of PR interval and block of the third P wave that fails to generate a QRS complex. Further, it is less likely for premature junctional complexes to have normal narrow QRS in presence of underlying bifascicular block, although as described above, pseudonormalization could occur due to rate related delay in left posterior fascicle. Option B again fails to explain the PR prolongation and block of the third P wave. Further, the aberrant QRS complexes are not premature. Second-degree type I AV block can explain the block of the third P wave in the AV node; however, option C is incorrect because the aberrant QRS complex occurs after a longer, not a shorter (rate related), preceding RR interval. As there is a consistent temporal relationship between the P waves and the QRS complexes, complete AV block invoked by option 5 is incorrect.Download figureDownload PowerPointFigure. Electrocardiogram lead II from the February 12th Question. The overlaid ladder diagrams show the two possible explanations for the electrocardiographic findings. LPF indicates left posterior fascicle; and RB, right bundle branchFootnotesCirc Arrhythm Electrophysiol is available at http://circep.ahajournals.org. Previous Back to top Next FiguresReferencesRelatedDetails March 2018Vol 11, Issue 3 Advertisement Article InformationMetrics © 2018 American Heart Association, Inc.https://doi.org/10.1161/CIRCEP.118.006249PMID: 29483099 Originally publishedFebruary 26, 2018 PDF download Advertisement SubjectsArrhythmiasCatheter Ablation and Implantable Cardioverter-DefibrillatorElectrophysiology

The atrial repolarization wave: A newly described finding in the electrocardiogram of the mouse (Mus musculus)