Electrocardiographic analysis of ectopic atrial activity obscured by ventricular repolarization: P wave isolation using an automatic 62-lead QRST subtraction algorithm

INTRODUCTION: Atrial activity on the surface ECG during premature beats and supraventricular arrhythmias frequently is obscured by the superimposed QRST complex of the previous cardiac cycle. This study examines the performance of a newly developed automatic QRST subtraction algorithm to isolate ectopic P waves from the preceding T-U wave. METHODS AND RESULTS: The 62-lead ECG recordings were obtained during (1) sinus rhythm and programmed right atrial stimulation in 12 patients (group A); and (2) sinus rhythm and atrial premature beats, atrial tachycardia, or paroxysmal atrial fibrillation in 5 patients (group B). Pacing in group A patients was conducted at a slow drive cycle length to generate an ectopic P wave not obscured by the previous QRST complex and by delivering single premature extrastimuli at progressively shorter coupling intervals to produce an ectopic P wave obscured by the upsloping (early T-U wave), peak (middle T-U wave), and downsloping component of the T-U wave (late T-U wave). All ectopic P waves in group B patients were concealed by the preceding T-U wave. Automatic QRST subtraction was attained using an adaptive template constructed from averaged QRST complexes (mean 83 +/- 25 complexes) obtained during sinus rhythm (groups A and B) or atrial overdrive pacing (group A). P wave integral maps subsequently were computed, visually compared, and mathematically correlated. A high correspondence in spatial map pattern was observed between integral maps of "nonobscured" and previously "obscured" paced P waves obtained in group A patients (mean r = 0.88 +/- 0.07) as well as between integral maps of two to three previously obscured P waves with the same atrial arrhythmia morphology obtained in group B patients (mean r = 0.94 +/- 0.05). Improved morphologic P wave replication in group A patients was acquired when concealment occurred in the early (mean r = 0.90 +/- 0.08) or late part of the T-U wave (mean r = 0.90 +/- 0.06) as opposed to the middle T-U wave (mean r = 0.85 +/- 0.07) (P = NS and P < 0.05 for early vs middle and late vs middle T-U wave, respectively). CONCLUSION: This novel automatic 62-lead QRST subtraction algorithm enables discrete isolation of T-U wave obscured ectopic atrial activity on the surface ECG while retaining the intricate spatial detail in P wave morphology. Future clinical application of the algorithm may enable improved ECG localization of focal triggers of paroxysmal atrial fibrillation, atrial tachycardia, and the atrial insertion of accessory pathways.     

Significance of Abnormal Q Waves in the Electrocardiograms of Adults Less than 40 Years Old

Background: Abnormal Q waves (AQW) in the electrocardiogram are commonly ascribed to underlying myocardial infarction (MI). As an imperfectly specific sign of MI, the usefulness of AQW in identifying MI depends on its incidence in the population studied. Methods: Eighty‐two subjects under 40 years of age with AQW were compared with 82 subjects from the same institution aged ≥40 years with similar AQW to determine the presence or absence of cardiac disease or MI. Results: Cardiac disease was present in 90.2% and 92.7% of the younger and older subjects, respectively, whereas MI was present in only 15.9% of younger subjects and in 68.3% of older subjects. Etiologies of cardiac disease differed between younger and older subjects. Some types of AQW were more useful than others in ruling MI in or out. Conclusions: AQW were a strong indicator of organic heart disease in both adult age groups, but their utility to indicate MI was age‐dependent. In the population studied, MI was present in only a small minority of subjects under 40 years of age with AQW, but was usually present in older subjects with similar AQW.     

老年原发性高血压患者伴阵发性心房颤动启动机制的研究

目的探讨老年原发性高血压患者阵发性心房颤动(PAf)的心电启动机制。方法选择老年原发性高血压伴PAf患者63例(高血压组),进行动态心电图人工回放,分析PAf心电触发因素、PAf发作前120、60和30 s房性期前收缩(APB)发作频率及其起源部位,另选老年非高血压PAf患者44例(非高血压组)进行比较。结果高血压组心电触发因素主要为APB(66.2%),触发PAf的APB主要来源于左心房上部(61.7%)。高血压组PAf前120、60和30 s APB发作频率明显高于非高血压组(P<0.01)。高血压组触发性APB联律间期和期前收缩指数均明显低于非高血压组,而期前收缩前心动周期明显高于非高血压组(P<0.01)。结论与老年非高血压PAf患者相似,APB特别是起源于左心房上部是老年原发性高血压患者PAf最主要的触发因素。     

动态心电图对房性早搏诱发的阵发性心房颤动的诊断价值

目的探讨阵发性心房颤动与房性早搏的关系。方法对26例经动态心电图诊断为阵发性房颤的病人,统计房早个数、房颤的发作阵数,诱发房颤的房早联律间期、房早前周期,未诱发房颤的房早联律间期、房早前周期等。结果26例阵发性房颤患者中,24h平均房早11126±2018个,阵发性房颤248±56阵。其中22例(84.6%)由房早诱发,2例(7.68%)由短阵房速诱发,2例(7.68%)由房扑诱发。能够诱发房颤的房早联律间期及房早前周期分别为361.8±42.9ms和828±101ms,未诱发房颤的房早联律间期及房早前周期分别为426.6±43.5ms和728±107ms,诱发房颤的房早联律间期明显短于未诱发房颤的房早联律间期,呈PonT现象,诱发房颤的房早前周期比未诱发房颤的房早前周期长(p<0.01)。结论阵发性房颤主要由房早始动,其与房早的联律间期及前周期有关。     

First Evaluation of P Dispersion and Tp-e Parameters in Electrocardiograms of Children with Diabetic Ketoacidosis

Objective:Diabetic ketoacidosis (DKA) is an important complication of type 1 diabetes mellitus. We aimed to evaluate the effect of metabolic disorders of DKA on electrocardiography (ECG) parameters in children.Methods:This study was performed between December 2018 and March 2020 and included 39 children with DKA and 40 healthy children. Three ECGs (one before and two after treatment) were obtained from the patient group. P-wave dispersion (Pd), QT dispersion (QTd), QTc dispersion (QTcd), Tp-e intervals, and the ratios of Tp-e/QT and Tp-e/QTc were measured electrocardiographically. ECG parameters from children with DKA and healthy controls were compared statistically.Results:The mean age of the patient group was 10.50±4.12 years. There was no significant difference in terms of age, gender, weight, height and body mass index between patients and controls. In the patient group, a statistically significant increase was found in Pd, QTd and QTcd in the initial ECG compared to the second and third ECGs. Also, when the first and third ECGs were compared, a significant increase in Tp-e and Tp-e/QT was evident in the first ECG. There was a significant difference in the values of Pd, QTd, QTcd, Tp-e and Tp-e/QT in the first ECGs, obtained before DKA treatment, and those values obtained from the control group.Conclusion:This is the first article evaluating Pd and Tp-e parameters in children with DKA. Cardiac arrhythmia risk markers were increased in children with DKA compared to controls. Therefore, clinicians should be aware of the possibility of developing new arrhythmias during DKA treatment.     

Premature beats in healthy subjects 40-79 years of age

In order to determine the prevalence and complexity of prematurebeats (PBs) in an adult population without apparent heart disease,260 healthy subjects 40–79 years of age had a 24 h ambulatoryECG recording performed. A total of 221 subjects (87%) had one or more atrial prematurebeats (APBs) in the 24 h period, which was statistically significantlymore than the number of subjects (179 or 69%) with ventricularpremature beats (VPBs). Only 19 subjects (7%) had no PBs. Morethan 200 VPBs/24 h were seen in only 5% of the subjects, anda similar percentage had more than 200 APBs/24 h. There wasa statistically significant increase in the number of VPBs aswell as APBs with an increase in age. Multiform VPBs, VPB pairs,multiform APBs and atrial tachycardia (AT) were ‘normal’findings(seen in more than 5% of the subjects), whereas > 2 differentVPB configurations, > 2 episodes of VPB pairs, ventricularbigeminy, R-on-T VPBs, ventricular tachycardia, > 2 episodesof AT and AT with more than 10 beats per episode were ‘abnormal’findings (seen in less than 5% of the subjects). The number of VPBs was almost identical in two 24 h ECG recordingsobtained at a mean interval of 22 months in 17 out of 22 subjectsstudied. Only two out of 22 had a significant change in thenumber of VPBs/24 h over the 22 month period. As a ‘normal’ range for the number of APBs as wellas VPBs per 24 h a figure of 200 is proposed, and it is concludedthat most complex types of PBs may occur as incidental findingsin healthy adult subjects, but usually in small numbers.     

Cardiac Arrhythmias in Adult Patients with Asthma

Objective. The pathogenesis of cardiac arrhythmias in asthma patients has not been fully elucidated. Adverse drug effects, particularly those of β2-mimetics, may play a role. The aim of this study was to determine whether asthma is associated with the risk of cardiac arrhythmias and electrocardiographic characteristics of arrhythmogenicity (ECG) and to explore the role of β2-mimetics. Methods. A cross-sectional study was conducted among 158 adult patients with a diagnosis of asthma and 6303 participants without asthma from the cohort of the Utrecht Health Project—an ongoing, longitudinal, primary care-based study. All patients underwent extensive examinations, including resting 12-lead electrocardiogram (ECG) and pulmonary function tests. The primary outcome was “any arrhythmia on the ECG” (including tachycardia, bradycardia, premature ventricular contraction (PVC), and atrial fibrillation or flutter). Secondary outcomes were tachycardia, bradycardia, PVC, atrial fibrillation or flutter, mean heart rate, mean corrected QT (QTc) interval length, and prolonged QTc interval. Results. Tachycardia and PVCs were more prevalent in patients with asthma (3% and 4%, respectively) than those without asthma (0.6%, p < .001; 2%, p = .03, respectively). The prevalence of QTc interval prolongation was similar in participants with (2%) and without asthma (3%, odds ratio [OR]: 0.6 and 95% confidence interval [95% CI]: 0.2–2.0). In 74 asthma patients, who received β2-mimetics, tachycardia and PVCs were more common (OR: 12.4 [95% CI: 4.7–32.8] and 3.7 [95% CI: 1.3–10.5], respectively). Conclusions. The adult patients with asthma more commonly show tachycardia and PVCs on the ECG than those without asthma. The patients with asthma received β2-mimetics; the risk of tachycardia and PVCs is even more pronounced.     

阵发性心房颤动的动态心电图分析

目的探讨动态心电图对阵发性心房颤动诊断和疗效判断的意义。方法分析78例阵发性心房颤动患者和80例对照组的24h动态心电图。统计单个期前收缩总数、心房颤动的频率和持续时间、心房颤动相关的偶联间期、非心房颤动患者房性期前收缩的偶联间期及24h房性期前收缩总数。结果心房颤动组:共发作33314阵心房颤动,其中36例11173阵发生在8∶00至22∶00,74例22141阵发生在22∶00至8∶00。平均24h房性期前收缩8242±1245个,心房颤动456±122阵。诱发心房颤动的,17例为单一房性期前收缩的偶联间期,33例为两种房性期前收缩的偶联间期,28例为两种以上房性期前收缩的偶联间期。发作前与发作相关的房性期前收缩偶联间期为0.429±0.089s,54例房性期前收缩伴心室内差异性传导,平均心率175±41次/min,64例6284阵心房颤动时伴有心悸、胸闷等症状,而69例27026阵发作时前无明显症状。对照组无心房颤动发生,35例有短阵房性心动过速,24例有频发房性期前收缩,56例有偶发房性期前收缩,房性期前收缩偶联间期0.633±0.014s,明显长于心房颤动组发作前与心房颤动相关的房性期前收缩及未下传的房性期前收缩偶联间期(P<0.01)。结论动态心电图监测是阵发性心房颤动诊断和疗效评价方面可靠、高效、重复性好的检查手段。     

Effects of Acute Volume Changes on P Wave Characteristics:

Effects of Acute Volume Changes on P Wave. Introduction: This study was performed to determine the effect on the P wave of different hemodynamic loads to the heart.
Methods and Results: Signal–averaged P wave ECC and atrial echocardiographic measurements were obtained from eight healthy male volunteers at rest and after infusion of 1000 mL of plasma expander (Haemaccel®) over 15 minutes. These measurements were repeated 24 hours later at rest and after 0.8 mg of nitroglycerin given sublingually. The effect of positional changes was also studied. At rest the amplitude of the P wave and the time of the maximal the P wave amplitude were reproducible. Sitting increased heart rate variability; no significant changes of the P wave were found. Volume overload decreased the heart rate and increased the atrial size on echocardiography with changes in lead V, (earlier appearance of the first positive deflection). Nitro–glycerin administration increased heart rate and decreased the echocardiographic size of the atria, the latter not reaching statistical significance. Administration of nitroglycerin induced P wave amplitude rise in leads 1 and II. The maximal power in fast Fourier transformation for calculated orthogonal leads X and Y increased as well.
Conclusions: Amplitude behavior in leads I, II, and V, appears to correlate with load conditions, particularly with volume redistribution. In healthy men subtle changes in the P wave morphology after volume changes can be detected by the signal–averaged ECU. Application of these findings in patients following acute changes in circulation needs further investigation.     

Implementation of an intravenous sotalol initiation protocol: Implications for feasibility,safety, and length of stay

Introduction

Oral sotalol initiation requires a multiple-day, inpatient admission to monitor for QT prolongation during loading. A 1-day intravenous (IV) sotalol loading protocol was approved by the United States Food and Drug Administration in March 2020, but limited data on clinical use and administration currently exists. This study describes implementation of an IV sotalol protocol within an integrated health system, provides initial efficacy and safety outcomes, and examines length of stay (LOS) compared with oral sotalol initiation.

Methods

IV sotalol was administered according to a prespecified initiation protocol to adult patients with refractory atrial or ventricular arrhythmias. Baseline characteristics, safety and feasibility outcomes, and LOS were compared with patients receiving oral sotalol over a similar time period.

Results

From January 2021 to June 2022, a total of 29 patients (average age 66.0 ± 8.6 years, 27.6% women) underwent IV sotalol load and 20 patients (average age 60.4 ± 13.9 years, 65.0% women) underwent oral sotalol load. The load was successfully completed in 22/29 (75.9%) patients receiving IV sotalol and 20/20 (100%) of patients receiving oral sotalol, although 7/20 of the oral sotalol patients (35.0%) required dose reduction. Adverse events interrupting IV sotalol infusion included bradycardia (seven patients, 24.1%) and QT prolongation (three patients, 10.3%). No patients receiving IV or oral sotalol developed sustained ventricular arrhythmias before discharge. LOS for patients completing IV load was 2.6 days shorter (mean 1.0 vs. 3.6, p < .001) compared with LOS with oral load.

Conclusion

IV sotalol loading has a safety profile that is similar to oral sotalol. It significantly shortens hospital LOS, potentially leading to large cost savings.     

P Wave Signal-Averaged Electrocardiography Techniques

Background: P wave signal-averaged electrocardiography (PW-SAECG) is a new method that is proving to be an accurate and independent noninvasive marker for the risk of developing atrial fibrillation. This article presents current data acquisition and analysis techniques for PW-SAECG. It also discusses in detail the interplay of inherent challenges present in the morphological attributes of the P wave, and how correct technique can play a large role in surmounting these challenges, thereby producing good results. Methods: Proper patient preparation and correct configuration of instrument settings ensure accurate P wave detection and alignment during the signal-averaging process. This in turn preserves waveform integrity of the resulting signal-averaged P wave data. Subsequent application of appropriate filtering schemes and signal processing methods permit the calculation and analysis of key PW-SAECG time-domain parameters. Conclusions: Judicious modification of established data acquisition protocols from R wave signal averaging, coupled with appropriate postprocessing and analysis techniques, are necessary precursors for arriving at acceptable time-domain PW-SAECG results.     

射频消融术对不同起源频发室性期前收缩患者左心房功能、结构及血浆脑钠肽浓度的影响

目的 分析射频消融术(radiofrequency catheter ablation,RFCA)对不同起源频发室性期前收缩患者左心房功能、结构及血浆脑钠肽(brain natriuretic peptide,BNP)浓度的影响.方法 收集2016年1月至2019年12月宣城市中心医院与南京市第一医院93例行RFCA治...     

Global P wave duration on the 65-lead ECG: single-site and dual-site pacing in the structurally normal human atrium

INTRODUCTION: Pacing is believed to prevent atrial fibrillation by reducing atrial activation time. Exact correlation between P wave duration (PWD) on surface ECG and endocardial atrial activation time is still unexplored. METHODS AND RESULTS: In 15 patients without structural heart disease (9 women, age 45 +/- 14 years), single site [high right atrium (HRA), coronary sinus ostium (CSos), distal CS (CSd), high RA septum (Bachmann's bundle, BB)] and dual-site pacing (various combinations) was performed after ablation of supraventricular tachycardia. A 65-lead surface ECG was recorded simultaneously. Endocardial atrial activation time was measured off-line (stimulus - last bipolar recording), and the respective PWD was assessed using the root mean square and 65-channel summary plots. PWD during pacing from BB was significantly shorter (96 +/- 12 msec) than during HRA (121 +/- 15 msec), CSos (108 +/- 9 msec), and CSd pacing (126 +/- 14 msec; P < 0,01, respectively). PWD during dual-site pacing (HRA+BB, 91 +/- 14 msec; HRA+CSos, 96 +/- 7 msec; HRA+CSd, 90 +/- 7 msec; BB+CSd, 96 +/- 12 msec) was not significantly shorter than during pacing from BB. Correlation between endocardial atrial activation time and PWD was 0.83. CONCLUSION: PWD during single-site and dual-site atrial pacing represents endocardial atrial activation time and can be measured precisely using the 65-lead surface ECG. The fact that high septal pacing results in the shortest PWD may have implications for preventive pacing in patients with atrial fibrillation.     

应用12导联动态心电图分析P on T房性早搏

目的分析在12导联动态心电图中频发性P on T房性早搏的形态、联律间期、前周期间期、时间分布,探讨其机制及临床意义。方法选自2013年1月至2013年12月在我院行12导联动态心电图检查诊断P on T房性早搏33例,分析其形态、联律间期、前周期间期、时间分布。并随访8~22个月,期间每3个月或患者有心前区不适来行动态心电图检查,或者以发现阵发性心房颤动/行射频消融术为终点。结果 33例中29例(87.9%)发生阵发性心房颤动;根据P on T房性早搏极性诊断起源部位,双上肺静脉占27例(81.8%),在28例行心内标测中25例(89.2%)符合;P on T房性早搏的联律间期364±46ms,时间分布:白天42.6%±14.3%,夜间54.3%±15.5%,p0.05。结论频发性P on T房性早搏易引发阵发性心房颤动,并对确定其心电触发因素及部位和临床选择治疗方式、观察疗效都有重要的参考价值。