Electrocardiographic artifacts during electroconvulsive therapy

Electrocardiographic (ECG) artifacts occur with the use of internal or external monitoring and therapeutic devices. Other common cause of ECG artifact is patient's motion. Electrocardiographic artifact during electroconvulsive therapy is not reported in the literature. We report ECG artifacts due to 2 different mechanisms in the same patient.     

Diabetic microvascular complications associated with myocardial repolarization heterogeneity evaluated by Tp-e interval and Tp-e/QTc ratio

IntroductionThe heterogeneity in myocardial repolarization increases the risk of ventricular arrhythmias and sudden death in patients with diabetes mellitus (DM). The Tp-e interval and Tp-e/QTc ratio are found to be useful in the prediction of ventricular arrhythmias. In this study, we aimed to investigate the Tp-e interval and Tp-e/QTc ratio in diabetic patients with and without microvascular complications.Materials and methodsThis cross-sectional observational study included patients with type 2 DM who presented to the endocrinology outpatient clinic. Diabetic microvascular complications were evaluated. The Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio were also calculated.ResultsA total of 240 patients with type 2 DM (148 patients had microvascular complications) were included in the study. Diabetic neuropathy rate was 30.4%, diabetic nephropathy rate was 38.4%, and diabetic retinopathy rate was 21.7%. Upon comparing patients according to Tp-e/QTc ratio, the median Tp-e/QTc interval of the group of patients with complications was 0.21 (0.19–0.23) and the median Tp-e/QTc ratio of the group of patients without complications was 0.19 (0.18–0.20) (p < 0.001). When patients were grouped according to the presence and severity of retinopathy, the Tp-e/QTc ratio was more prolonged in the proliferative retinopathy group [0.27 (0.23–0.30)] than the non-proliferative retinopathy group [0.20 (0.19–0.22), p < 0.001]. When patients were grouped according to the presence and severity of nephropathy, the Tp-e/QTc ratio was more prolonged in the macroalbuminuria and microalbuminuria group than the normoalbuminuric group [0.25 (0.21–0.30), 0.23 (0.19–0.24), and 0.19 (0.20–0.22), respectively, p = 0.002].ConclusionsOur study is the first to demonstrate the association of the Tp-e interval and Tp-e/QTc ratio with the presence and severity of microvascular complications in patients with type 2 DM.     

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.     

Cardiac repolarization instability during psychological stress in patients with ventricular arrhythmias

Introduction

Changes in the autonomic nervous system activity are a major trigger of life-threatening ventricular tachyarrhythmias (VTAs). Mental arithmetic, a condition administered in a laboratory setting, can provide insight into the autonomic nervous system activity effects on cardiac physiology. We examined the responses of cardiac repolarization to laboratory-induced psychological stressors in patients with implantable cardioverter-defibrillators (ICDs) with the objective of identifying the indices that differentiate patients with and without subsequent VTA in follow-up.

Methods

Continuous electrocardiographic signals were recorded using 3 standard bipolar (Holter) leads in 56 patients (age, 63.6 ± 11.9; female, 12%; left ventricular ejection fraction, 32.3 ± 11) with ICDs during mental arithmetic. The patients were separated into those with subsequent VTA during 3 to 4 years of follow-up (group 1: n = 9) and those without VTA (group 2: n = 47). Changes in repolarization (QT interval, mean T wave amplitude [Tamp], and T wave area) were analyzed during 5 minutes at baseline, stress, and recovery. The temporal instability of Tamp and T wave area was examined using the range (Δ) and variance (σ²) of beat-to-beat variations of the corresponding parameters.

Results

There were no significant differences in heart rate between the 2 groups at baseline (61 vs 63 beats per minute, P = .97), stress (64 vs 65 beats per minute, P = .40), and recovery (62 vs 61 beats per minute, P = .88). However, during mental stress and poststress recovery, ΔTamp was almost 2-fold greater in group 1 compared with group 2 (111 [57-203] vs 68 [44-94] μV, P = .04, respectively). Changes in QT intervals were also greater in group 1 compared with group 2 (P = .02).

Conclusion

Among patients with ICDs, changes of Tamp after psychological stress were greater in those with subsequent arrhythmic events. This might signal proarrhythmic repolarization response and help identify patients who would benefit the most from ICD implantation and proactive management.     

索他洛尔对运动时QTc和JTc间期的影响

目的探讨生理运动状态下索他洛尔对心室复极作用的影响。方法以随机、双盲、索他洛尔、普萘洛尔和安慰剂进行自身对照,对30例入选的健康志愿者,进行活动平板运动试验;对体表心电图上校正的QT间期(QTc)和校正的JT间期(JTc)进行分析。结果与服普萘洛尔和安慰剂比较,静息状态时索他洛尔对QTc和JTc的延长作用最显著。运动过程中,服索他洛尔、普萘洛尔和安慰剂的QTc和JTc都缩短,其中服索他洛尔的JTc缩短最显著,其JTc的缩短率(ΔJTc%)大于服普萘洛尔和安慰剂(8.83%±6.09%vs2.70%±6.20%和5.73%±5.83%,P<0.001和P<0.05)。并且运动过程中服索他洛尔的ΔJTc%与运动心率呈显著正相关(r=0.148,P<0.01)。结论索他洛尔显著延缓静息状态下的心室复极,在运动过程中与普萘洛尔和安慰剂比较,索他洛尔延缓心室复极的作用呈现出进行性减弱的现象。     

Repolarization heterogeneity in patients with cardiac resynchronization therapy and its relation to ventricular tachyarrhythmias

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Beat-to-beat interplay of heart rate, ventricular depolarization, and repolarization

To improve malignant arrhythmia risk stratification, the causal and random components of spatiotemporal dynamics of heart rate (RR distances), ventricular depolarization sequence, and repolarization disparity were studied based on body surface potential map records taken for 5 minutes, in resting, supine position on 14 healthy subjects (age range, 20-65 years) and on 6 arrhythmia patients (age range, 59-70 years). Beat-to-beat QRS and QRST integral maps, Karhunen-Loève (KL) coefficients, RR, and nondipolarity index time series were computed. Tight relationship was found between RR and QRS integrals in healthy subjects with less association in arrhythmia patients. Tight KL-domain multiple linear association (r² > 0.72) was found between the QRS and QRST integral dynamics (ie, depolarization sequence and repolarization disparity). Beat-to-beat probability of the generation of significant nondipolarity index spikes was proportional to the QRST KL-component standard deviations (SD_i) and inversely proportional with the mean dipolar KL components (M_i) of the average QRST integral map.     

Effect of premature ventricular beats on manual and automatic repolarization measurements

OBJECTIVE: To compare QT interval and QT dispersion in ventricular ectopic beats with measurements from the preceding and the immediately following sinus beats, and investigate differences between manual and automatic measurements. Patients: Eleven chronic uremic patients. Main outcome measures: ECGs were recorded during hemodialysis treatment and 12-lead sections containing five consecutive beats were extracted, each containing four sinus beats and one centrally-positioned premature ventricular beat. QT measurements were performed both manually and with a computer-automated technique. Results: T wave amplitude was greater in the ectopic beats compared to the sinus beats (0.61 +/- 0.18 vs. 0.23 +/- 0.06 mV, P <.001). The ectopic beats had a greater QT than the sinus beats when measured manually (415 +/- 35 ms vs. 386 +/- 28 ms, P <.001), or automatically (375 +/- 30 vs. 366 +/- 27 ms, P<.01). The sinus beats following the ectopics had a greater QT than the preceding sinus beats (400 +/- 27 vs. 386 +/- 28 ms, P<.001, manual; 382 +/- 24 vs. 366 +/- 27 ms, P<.001, automatic). Differences in QT dispersion were seen only between the ectopic and sinus beats (91 +/- 31 vs. 58 +/- 27 ms, P <.001, manual; 68 +/- 33 vs. 49 +/- 35 ms, P <.001, automatic). Conclusions: Manual measurement resulted in greater QT values than automatic measurement. Both techniques identified differences between sinus and ectopic beats. The ventricular ectopic beats resulted in an increase in the QT of the immediately following sinus beats. These results confirm the need to interpret QT measurements with care in the presence of ectopic beats.     

Cardiac resynchronization therapy and ventricular tachyarrhythmia burden

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室性心律失常与 Tp-e 间期、Tp-e／Q-T比值的相关性研究

目的：探讨室性心律失常与T波峰-末间期（Tp-e间期）、Tp-e/Q-T比值的相关性。方法将199例室性心律失常患者按Lown分级分为Lown 1级组（43例）、2级组（40例）、3级组（35例）、4A级组（39例）和4B级组（42例）,再将所有患者分为无器质性心脏病组（107例）和器质性心脏病组（92例）,另选择健康体检者40例为对照组。采用常规12导联同步心电图及24小时动态心电图检测比较各组的Q-T、Q-Tc、Tp-e和Tp-ec间期及Tp-e/Q-T比值。结果 Q-Tc、Tp-e、Tp-ec、TPe/Q-T各测值随Lown级别的增高而增高,与Lown分级呈正相关（ rs＝0.29-0.62,P＜0.01）。Q-Tc、Tp-e、Tp-ec测值心脏病组与无心脏病组及对照组比较差异有统计学意义（ P＜0.05）,无心脏病组与对照组比较差异也有统计学意义（ P＜0.05）;Q-T测值心脏病组与无心脏病组及对照组比较差异有统计学意义（ P＜0.05）,但无心脏病组与对照组比较差异无统计学意义（ P＞0.05）。Tp-e/Q-T比值心脏病组及无心脏病组与对照组比较差异有统计学意义（ P＜0.05）,但心脏病组与无心脏病组比较差异无统计学意义（ P＞0.05）。结论 Tp-e间期、Tp-e/Q-T比值与室性心律失常的严重程度有关,对预测室性心律失常的发生及评估预后有重要的临床意义。     

心脏病室性心律失常患者Tp-e间期、Tp-e/Q-T比值的研究

目的探讨器质性心脏病患者Tp-e间期、Tp-e/Q-T比值与室性心律失常的关系。方法选择器质性心脏病患者85例,分为两组,器质性心脏病室性心律失常组(A组)43例,并进一步按LOWN分级分为两个亚组,A1组(LOWN2-3级)20例,A2组(LOWN3级以上)23例;器质性心脏病无室性心律失常组(B组)42例。另选择健康体检者40例为正常对照组(C组)。采用常规12导联同步心电图及24小时动态心电图分析比较各组的Q-T间期、Q-Tc间期、Tp-e间期、Tp-ec间期和Tp-e/Q-T测值。结果 A组Q-T间期、Q-Tc间期、Tp-e间期、Tp-ec间期、Tp-e/Q-T测值比C组显著升高,差异有统计学意义(P<0.05),而Q-Tc间期、Tp-e间期、Tp-ec间期、Tp-e/Q-T比B组显著升高,差异有统计学意义(P<0.05)。上述各测值A2组比A1组显著升高,差异有统计学意义(P<0.05或P<0.01)。结论 Tp-e间期、Tp-e/Q-T等心电学指标与室性心律失常的发生有关,对室性心律失常的发生具有预测意义。     

Spatiotemporal electrocardiographic characterization of ventricular depolarization and repolarization abnormalities in long QT syndrome

Background and Purpose

If only a standard electrocardiogram (ECG) is available, at least 25% of patients with long QT syndrome (LQTS) may be missed. Our goal is to quantify abnormal electrical activity and to develop an ECG decision rule for the patients with LQTS.

Methods

One hundred forty-one subjects were included in this study (71 patients with LQTS and 70 healthy subjects). A 12-lead digital ECG was recorded for each subject and analyzed using the CAVIAR (comparative analysis of ECG-VCG and their interpretation with auto-reference to the patient) method.

Results

A decision tree involving criteria based on 3 spatiotemporal ECG measurements—the QT interval and the maximum amplitude of the T wave, both corrected from heart rate, and the loss of planarity of the end of QRS—identified patients with LQTS from healthy subjects with a sensitivity of 89%, a specificity of 96%, and a total accuracy of 92%.

Conclusions

This study suggests that 3-dimensional ECG analysis may improve the detection of patients with LQTS.     

急性心肌梗死时QTc,JTc及QT离散度增加,与室性心律失常和猝死的关系

本文测定了１２３例急性心肌梗死（ＡＭＩ）患者首次心电图的ＱＴｃ间期，ＪＴｃ间期及ＱＴ离散度（ＱＴｄ），并与ＡＭＩ患者的室性心律失常和心性猝死的关系进行了探讨。结果为ＡＭＩ时早期原发性室额患者ＱＴｃ显著高于无室颤者（ＱＴｃ４８８．６３±３９．３６ｍｓ与４０５．８８±２２．３１ｍｓ，Ｐ＜０．０１）；ＪＴｃ异常组与ＱＴｄ＞６０ｍｓ组室速、室颤及猝死的发生率均较对照组高（Ｐ＜０．０１），表明ＱＴｃ，ＪＴｃ延长及ＱＴｄ增加者室颤发生的可能性增大。     

心脏再同步治疗术中不同起搏模式对室性心律失常诱发的影响

目的 评价心脏再同步治疗(CRT)植入术中不同起搏模式对室性心律失常诱发情况的影响.方法 连续入选植入心脏再同步治疗除颤器(CRT-D)的患者,术中采用3种起搏模式:右心室起搏、双心室同步起搏和双心室顺序起搏(左心室优先50 ms和80 ms,右心室优先50 ms和80 ms).然后分别从左心室或右心室导线引入最多2个期前刺激,评估室性心律失常的诱发情况.结果 共有15例成功植入CRT-D的患者入选,男11例,年龄49 ～72(61±7)岁.缺血性心肌病7例,扩张型心肌病8例.左心室射血分数0.30±0.07.9例患者发生终点事件:5例诱发持续性室性心动过速(VT)/心室颤动(VF),4例诱发非持续性VT.双心室同步起搏时未诱发持续性VT/VF事件,双心室顺序起搏时有5例诱发VT/VF( P＜0.01).结论 双心室顺序起搏模式可能具有潜在致心律失常作用.双心室顺序起搏模式下心脏电生理刺激或自发的室性期前收缩对衰竭心脏电生理稳定性的影响需长期临床研究进一步证实.