Testing of a New T‐Wave Subtraction Algorithm as an Aid to Localizing Ectopic Atrial Beats

Background: Identifying the timing and morphology of an ectopic P wave from the surface electrogram can aid in the diagnosis and localization of atrial arrhythmias. Given the relatively short coupling interval of atrial ectopic beats, the P wave is often obscured by the larger amplitude QRS‐T wave complex. A method to uncover such “buried” P waves using a standard 12‐lead surface ECG would be clinically useful and could potentially be a noninvasive guide to catheter ablation of focal atrial tachycardia. Methods: We developed an automated computerized program (BARD DUO LAB SYSTEM?) designed to subtract the QRS‐T wave complex from the surface electrogram and uncover a previously obscured P wave. The purpose of the present study was to validate this program. The surface ECG from 21 patients undergoing atrial pacing during electrophysiologic study (group I) and 10 patients with atrial tachycardia (group II) were analyzed and the derived P‐wave morphology assessed using correlation waveform analysis (CWA) and visual grading by three reviewers. Results: The algorithm successfully uncovered the P wave in each surface ECG. For the 21 patients in group I, average CWA comparing the derived P wave with the previous paced P wave was 83%. Average CWA for group II was 82%. Visual grading of the match between derived P waves and paced P waves revealed a 21/21 match in group I patients and a 12/12 match in 9/10 of group II patients. Conclusions: An ectopic atrial P wave obscured by a coincident QRS‐T wave complex can be accurately uncovered using this new algorithm. Addition of this technique to existing methods may improve the diagnosis of atrial arrhythmias and aid in the localization and ablation of ectopic atrial foci.     

右室选择性部位起搏

右室心尖部起搏产生异常心室电活动,导致心室不同步收缩、腔内分流和二尖瓣反流,患者生活质量下降,心房颤动、心力衰竭发生率及死亡率增加.目前一些研究提示右室选择性部位起搏有较右室心尖更好的电生理稳定性和心室同步性,同时有较好的临床可行性.但最终结果还有待更大规模的临床研究.     

急性心肌梗死早期QRS波群终末变形对预后判断的价值

为探讨急性心肌梗死早期QRS波群终末变形对判断预后的价值,回顾分析67例发病12h内的急性心肌梗死患者的临床和心电图资料。结果显示:QRS波群终末变形组和不变形组在年龄、性别、糖尿病史、原发性高血压史以及心肌梗死部位等方面差异并无显著意义,但变形组患者心绞痛病史少见(27.5％对52.6％,P<0.05),平均每例ST段抬高的导联数(4.24±1.10对3.11±1.22,P<0.01)、平均每个导联ST段抬高的程度(0.45±0.07对0.36±0.09mV,P<0.01)、肌酸磷酸激酶峰值(1275.86±323.97对1107.05±278.06U/L,P<0.05)和严重并发症(65.5％对36.8％,P<0.05)等方面明显高于不变形组,死亡率也趋于升高。提示QRS波群终末变形对于急性心肌梗死的预后判断有一定的价值。     

Frequency-plane analysis of normal and pathological ECG signals for disease identification

In this paper a frequency plane analysis of both normal and diseased ECG signals is performed specifically for disease identification. Image processing techniques are used to develop an automated data acquisition package of 12 lead ECG signals from paper records. A regeneration domain is also developed to check the captured pattern with the original wave shape. A QRS complex detector with an accuracy level ～98.4% in up to 30% signal to noise level is developed. Discrete Fourier transform (DFT) is performed to obtain the frequency spectrum of every ECG signal. Some interesting amplitude and phase response properties of chest lead V2, V3, V4, V6 and limb lead I, II, III, AVL, AVF are seen. Both amplitude and phase properties are different for normal and diseased subjects and can serve an important role in disease identification. A statistical analysis of amplitude property is carried out to show that this property is significantly different for normal and diseased subjects.     

Implantable defibrillator event rates in patients with unexplained syncope and inducible sustained ventricular tachyarrhythmias: a comparison with patients known to have sustained ventricular tachycardia

OBJECTIVES

To assess the clinical significance of inducible ventricular tachyarrhythmias among patients with unexplained syncope.

BACKGROUND

Induction of sustained ventricular arrhythmias at electrophysiology study in patients with unexplained syncope and structural heart disease is usually assigned diagnostic significance. However, the true frequency of subsequent spontaneous ventricular tachyarrhythmias in the absence of antiarrhythmic medications is unknown.

METHODS

In a retrospective case-control study, the incidence of implantable cardiac defibrillator (ICD) therapies for sustained ventricular arrhythmias among patients with unexplained syncope or near syncope (syncope group, n = 22) was compared with that of a control group of patients (n = 32) with clinically documented sustained ventricular tachycardia (VT). Sustained ventricular arrhythmias were inducible in both groups and neither group received antiarrhythmic medications. All ICDs had stored electrograms or RR intervals. Clinical variables were similar between groups except that congestive cardiac failure was more common in the syncope group.

RESULTS

Kaplan-Meier analysis of the time to first appropriate ICD therapy for syncope and control groups produced overlapping curves (p = 0.9), with 57 ± 11% and 50 ± 9%, respectively, receiving ICD therapy by one year. In both groups, the induced arrhythmia was significantly faster than spontaneous arrhythmias, but the cycle lengths of induced and spontaneous arrhythmias were positively correlated (R = 0.6, p < 0.0001). During follow-up, three cardiac transplantations and seven deaths occurred in the syncope group, and two transplantations and five deaths occurred in the control group (36-month survival without transplant 52 ± 11% and 83 ± 7%, respectively, p = 0.03).

CONCLUSIONS

In patients with unexplained syncope, structural heart disease and inducible sustained ventricular arrhythmias, spontaneous sustained ventricular arrhythmias occur commonly and at a similar rate to patients with documented sustained VT. Thus, electrophysiologic testing in unexplained syncope can identify those at risk of potentially life-threatening tachyarrhythmias, and aggressive treatment of these patients is warranted.     

Fragmented QRS complex in patients with implantable cardioverter defibrillator—Prevalence and predisposing factors

Background

Incidence of fragmented (fQRS) and predisposing factors in patients with implantable cardioverter-defibrillator (ICD) have not yet been established.AimTo examine incidence of fQRS, associated factors as well as predictive value in identifying site of coronary artery disease (CAD).

QRS时限与缺血性心肌病预后关系

目的观察缺血性心肌病患者QRS时限与远期预后相关性方法入选2006年1月至2009年12月于我院导管室进行冠状动脉造影,经左室造影证实LVEF≤35%,出院诊断明确的缺血性心肌病患者。按照患者的心电图记录的QRS波时限将所有患者分为2组,分别为QRS时限120ms组,QRS时限≥120ms组。比较两组患者的基线临床特征,远期预后。影响全因死亡、心脏移植、室性心律失常事件、心衰再入院的危险因素。结果缺血性心肌病患者921例,5例患者失访,916例患者完成研究。入选患者中QRS时限120ms患者835例(91.2%),QRS时限≥120ms患者81例(8.8%)。与QRS时限120ms组比较,QRS时限≥120ms患者,左室舒张末期内径明显增加;心功能分级有所减低;房颤病史更为常见。916例患者随访9-58月,49例(5.3%)患者发生全因死亡;发生全因死亡、新发生的血流动力学改变的室性心律失常、心衰再入院,心脏移植事件总计96例(10.5%)。Cox回归分析显示:超声心动图射血分数≤35%,QRS时限≥120ms,完全性左束支传导阻滞是缺血性心肌病发生全因死亡、心衰再入院、室性心律失常、心脏移植复合终点事件的危险因素。结论冠状动脉造影证实的LVEF≤35%缺血性心肌病患者,QRS时限≥120ms是影响患者全因死亡、心衰再入院、室性心律失常、进行心脏移植事件的高危因素。     

碎裂QRS波对冠心病心肌缺血的预测价值

目的探讨心电图中的碎裂QRS波(Fragmented QRS,fQRS)对冠心病心肌缺血的预测价值。方法回顾性分析2012年1月~2013年12月在包头市中心医院心内科住院的临床上考虑冠心病并进行过选择性冠状动脉造影(CAG)检查的患者病例492份。根据患者入院以后前三日内心电图中有无碎裂QRS(fQRS)波分为两组,其中A组(有fQRS波)271例,B组(无fQRS波)221例。首先比较两组患者的一般临床资料(包括年龄、性别,合并症有无高血压、糖尿病、高脂血症),然后比较两组患者的血管狭窄程度有无差异。结果 (1)AB两组患者的一般临床资料差异均无统计学意义(P≥0.05)。(2)AB两组患者的冠脉血管狭窄程度不同,差异具有统计学意义(P0.05),A组的冠心病心肌缺血患病率高于B组,差异具有统计学意义(P0.05)。结论碎裂QRS波对冠心病心肌缺血的发生有较高的预测价值。