Detection of Ventricular Tachycardia and Fibrillation Using ECG Processing and Intramyocardial Pressure Gradients

The automatic termination of malignant tachyarrhythmias and of ventricular fibrillation by an implantable device requires a reliable sensing of these episodes of abnormal ECG. Therefore, we induced tachyarrhythmias and fibrillation in eleven dogs and recorded electrograms and intramyocardial pressure. The electrograms were analyzed using the autocorrelation function and the probability density function. Intramyocardial pressure was monitored as a hemodynamic parameter. Results show that in the case of sinus rhythm, all methods are reliable, but in the case of VT and VF, electrogram processing only is insuffcient. It is concluded that combined monitoring of ECG processing and a hemodynamic parameter may increase the sensitivity of an automatic tachycardia-fibrillation detection system.     

Use of the pacing pulmonary arterial catheter to detect endocardial electrical activity during hypothermic cardioplegic arrest

The pacing Swan-Ganz catheter was evaluated for its ability to monitor atrial and ventricular electrical activity during cardioplegic arrest on cardiopulmonary bypass. This endocardial electrical activity was compared with the activity found on the standard electrocardiogram (ECG). The atrial electrodes detected activity that was noted also by visual inspection. The ventricular electrodes detected recurring electrical activity in 7 of 18 patients. Three of these 7 patients did not have simultaneous standard ECG activity, indicating that, in the usual monitoring circumstances, this ventricular electrical activity would not have been treated with repeat cardioplegia. If the pacing Swan-Ganz catheter is used for clinical care, it can be used also to monitor myocardial electrical activity during cardioplegic arrest.     

标准12导联心电图与标准监护Ⅱ导联监测心肌缺血对照研究

目的评价标准12导联心电图与标准监护Ⅱ导联监测心肌缺血的有效性和敏感性。方法以标准12导联心电图作为判断心肌缺血的标准,将50例有ST段改变的心脏病患者设为病例组,45例无ST段改变的心脏病患者设为非病例组,比较标准12导联与标准监护Ⅱ导联心电图心肌缺血检出率。结果50例经标准12导联心电图发现存在心肌缺血的患者,同时经标准监护Ⅱ导联检测仅发现15例患者存在心肌缺血,差异有极显著性（χ^2=53．846,P〈0．01）,且标准监护Ⅱ导联心电图出现心肌缺血改变假阳性率为11．1％。结论标准监护Ⅱ导联心电图并不能有效发现心肌缺血,在l临床监护中需同时描记标准12导联心电图。     

老年人体检异常心电图的分析

[目的]探讨老年人心电图异常的相关因素.[方法]对2009年6月至2011年6月来本院体检中心进行体检的1 862例60岁以上老年人检测出的异常心电图进行分析.[结果]心电图异常检出率85.71%（1596/1862）,其中ST-T改变检出率最高心电异常者的75.00%（1197/1596）（P＜0.01）,其次是心律失常类（15.34%）;心电图异常改变有随年龄增长而增加的趋势;心电图异常与血压、血脂、血糖等因素有关.[结论]老年人应定期进行心电图等方面的检测,以便尽早、及时的发现危险因素,从而早期预防,降低发病率和病死率     

Holter monitoring for 24 hours in patients with thromboembolic stroke and sinus rhythm diagnosed in the emergency department

It is well known that patients with ischemic stroke show ST-T abnormalities and various rhythm abnormalities on an electrocardiogram (ECG). The most commonly encountered rhythm abnormality is atrial fibrillation. It was recently shown that paroxysmal atrial fibrillation (PAF) is an important causative factor in patients with stroke. Detection of PAF is important in identifying the cause, prognosis, and treatment in patients with thromboembolic stroke. Investigators in the present study followed patients with thromboembolic stroke who had been admitted to the emergency department in sinus rhythm; 24-h Holter monitoring was used, and patients were assessed at referral and every 6 h for 24 h with ECG, which was used to detect rhythm disturbances, especially PAF. In 26 patients with stroke who came to the emergency department, acute thromboembolic stroke was diagnosed on the basis of magnetic resonance imaging; no rhythm abnormalities were noted on Holter monitoring. Eighteen patients were male and 8 were female (mean age: 66±13 y). Arrhythmia was identified on ECG in 3 patients (11%) and on 24-h Holter monitoring in 24 patients (92%). PAF was diagnosed in 3 patients (11%) on ECG and in 11 patients (42%) on Holter monitoring. In 2 patients, nonsustained ventricular tachycardia was detected only on Holter monitoring, which was found to be significantly superior to ECG for the detection of arrhythmias (P < .001). Investigators found no significant relationship between PAF and variables such as hypertension, diabetes, coronary artery disease, history of myocardial infarction, ST-T changes, and elevations in cardiac markers. However, a significant relationship (P < .01) was seen between nonsustained ventricular tachycardia and a history of myocardial infarction. No relationship was discerned between arrhythmia and stroke localization. Study results suggested that (1) PAF is a commonly diagnosed rhythm abnormality, and (2) Holter monitoring is superior to routine ECG for the detection of arrhythmias such as PAF in patients anticipated to have thromboembolic stroke with sinus rhythm.     

冠心病患者动态心电图监测的研究

目的：研究动态心电图对冠心病患监测的价值。方法：对276例冠心病患进行24—72h的动态心电图监测并与常规心电图结果进行对比分析。结果：动态心电图对冠心病患的心律失常检出率达100％，无症状心肌缺血检出率为26．80％，明显高于常规心电图的检出率(61％及5．80％)。结论：动态心电图能及时发现冠心病患的各种心率失常和无症状心肌缺血，对于预防和防止急性心梗和心源性猝死较常规心电图更可靠。     

Prehospital Electrocardiographic Manifestations of Acute Myocardial Ischemia Independently Predict Adverse Hospital Outcomes

Background

Prehospital electrocardiography (PH ECG) is becoming the standard of care for patients activating Emergency Medical Services for symptoms of acute coronary syndrome (ACS). Little is known about the prognostic value of ischemia found on PH ECG.

Objective

The purpose of this study was to determine whether manifestations of acute myocardial ischemia on PH ECG are predictive of adverse hospital outcomes.

Methods

This study was a retrospective analysis of all PH ECGs recorded in 630 patients who called 911 for symptoms of ACS and were enrolled in a prospective clinical trial. ST-segment monitoring software was added to the PH ECG device with automatic storage and transmission of ECGs to the destination Emergency Department. Patient medical records were reviewed for adverse hospital outcomes.

Results

In 630 patients who called 911 for ACS symptoms, 270 (42.9%) had PH ECG evidence of ischemia. Overall, 37% of patients with PH ECG ischemia had adverse hospital outcomes compared with 27% of patients without PH ECG ischemia (p < 0.05). Those with PH ECG ischemia were 1.55 times more likely to have adverse hospital outcomes than those without PH ECG ischemia (95% CI 1.09–2.21; p < 0.05), after controlling for other predictors of adverse hospital outcomes (i.e., age, sex, and medical history).

Conclusions

Evidence of ischemia on PH ECG is an independent predictor of adverse hospital outcomes. ST-segment monitoring in the prehospital setting can identify high-risk patients with symptoms of ACS and provide important prognostic information at presentation to the Emergency Department.     

CAVIAR: a tool to improve serial analysis of the 12-lead electrocardiogram

Summary. An important part of an electrocardiogram (ECG) interpretation is the comparison between the present ECG and earlier recordings. The purpose of the present study was to evaluate a combination of two computer-based methods, synthesized vectorcardiogram (VCG) and CAVIAR, in this comparison. The methods were applied to a group of 38 normal subjects and to a group of 36 patients treated with anthracyclines. A fraction of these patients are likely to develop cardiac injury during or after the treatment, since anthracyclines are known to cause heart failure and cardiomyopathy. Two ECGs were recorded on each patient, one before and one after the treatment. On each normal subject, two ECGs were recorded with an interval of 8–9 years. A synthesized VCG was calculated from each ECG and the two synthesized VCGs from each subject were analysed with the CAVIAR method. The CAVIAR analysis is a quantitative method and normal limits for four measurements were established using the normal group. Values above these limits were more frequent in the patient group than in the normal group. The conventional ECGs were also analysed visually by an experienced ECG interpreter without knowledge of the result of the CAVIAR analysis. No significant serial changes were found in 10 of the patients with high CAVIAR values. Changes in the ECGs were found in two patients with normal CAVIAR values. In summary, synthesized VCG and CAVIAR could be used to highlight small serial changes that are difficult to find in a visual analysis of ECGs.     

Lewis Lead Enhances Atrial Activity Detection in Wide QRS Tachycardia

Background: The differential diagnosis of wide QRS tachycardia is a challenge for the emergency physician. The major tool is the electrocardiogram (ECG), even though the sensitivity and specificity may be variable, depending on presentation. Additional leads could be used to improve the diagnostic accuracy of the ECG. Objective: To document the use of the Lewis lead in improving the diagnostic accuracy of the ECG in wide QRS tachycardia. Case report: A 52-year-old woman with rheumatoid arthritis, in treatment with methotrexate, was admitted with progressive dyspnea that evolved to acute respiratory distress and shock at arrival. Pneumonia was diagnosed as the infection and she received antibiotics, and respiratory and inotropic support. She was also using amiodarone for more than 10 years, but she couldn't state the reason. On cardiac monitoring, wide QRS tachycardia was detected and ventricular tachycardia was considered on the differential diagnosis. The standard 12-lead ECG was complemented with the Lewis lead, obtained with higher speed and amplitude, demonstrating atrioventricular concordance and excluding ventricular tachycardia. The patient was treated for septic shock, and she died 2 days later. Conclusion: The Lewis lead is a simple and easy strategy to enhance atrial activity detection in wide QRS tachycardia.     

Remote Electrocardiographic Monitoring with a Wireless Implantable Loop Recorder: Minimizing the Data Review Burden

Introduction: Currently available implantable loop recorders (ILRs) are hampered by limited memory, sensing artifacts, and need for manual memory download. Remote monitoring techniques that automatically transfer stored recordings for review may enhance ILR utility. However, automatic electrocardiograph (ECG) detection and transmission of an excessive number of tracings directly to physicians may be burdensome. This pilot study assessed the utility of direct ILR transmission to a central ECG monitoring center on the burden of data to be reviewed by the physician. Methods: Patients with unexplained syncope were implanted with a novel ILR with automatic (i.e., independent of patient intervention) wireless telemetry download. Transmitted recordings underwent a two‐step review process: initial algorithmic filtering followed by human overread at a monitoring center using predefined criteria. Results: Forty patients were enrolled and followed for 8.5 ± 5.1 months. A total of 223,226 ECG recordings were transmitted to the monitoring center (on average 660 per patient per month). Algorithmic filtering eliminated 191,305 ECGs as artifact (89%), with monitoring center overread of 31,921 strips. Ultimately, 117 relevant ECGs were selected for further evaluation by the physician (0.0053%). One or more relevant ECGs were identified for 20 patients (50%). Conclusions: Automatic ILR recording and wireless technique is feasible for remote ECG monitoring by ILRs. However, sensitive criteria for recording and transmission may result in an excessive ECG burden. The two‐step screening process in this pilot study minimized physician overread time while providing clinically relevant recordings in a substantial proportion of patients. (PACE 2010; 1347–1352)     

中国心电学标准化的发展历程

心电图作为一项常规临床检查技术,以其简便易行、无创,且可多次重复等特点已广泛应用于临床。但在临床实际应用中,发现仍存在许多细节问题需要有统一的规范和标准。因此,中国心电学及心电图标准化随之逐步发展,主要体现在心电图机、操作方法、名词术语、测量诊断、分析软件等方面。本文对中国心电学标准化的发展历程进行详细介绍。     

Prevalence of electrocardiographic findings suggestive of sudden cardiac death risk in 10,867 apparently healthy young Korean men

Background: The objective of this study was to determine the prevalence of electrocardiographic (ECG) findings suggestive of sudden cardiac death risk in apparently healthy young Korean men. Methods: We administered questionnaires that elicited personal and family histories and performed ECGs on 10,867 male subjects (mean age, 20.9 years). The subjects with abnormal ECG findings underwent echocardiography, a treadmill test, Holter monitoring, a flecainide provocation test, or an electrophysiologic study (EPS) according to the ECG findings and histories. Results: Of the subjects, 5.95% had left ventricular hypertrophy on ECG, but no subjects had hypertrophic cardiomyopathy by echocardiography. The percentage of subjects with a Brugada ECG pattern was 0.90%. We identified one subject with a positive result on the flecainide provocation test. The percentage of subjects with a preexcitation ECG was 0.17%. In two of the subjects, supraventricular tachycardia was induced in the EPS. Of the subjects, 0.05% had epsilon waves, but there were no subjects with arrhythmogenic right ventricular dysplasia/cardiomyopathy by echocardiography. The percentage of subjects with long QT intervals was 0.02%, but there were no arrhythmias on the treadmill test or Holter monitoring. Conclusions: The prevalence of a Brugada ECG pattern in apparently healthy young men is higher in Korea than other countries. (PACE 2011; 717–723)     

Electrocardiographic ambulatory monitoring with a real-time analysis system

The analysis of records collected during long-term ambulatory electrocardiographic monitoring has traditionally involved the review of massive data, either manually or with the aid of interactive scanning computers. Many factors complicate this analysis, including the use of analog tape for storage of electrocardiographic waveforms, the need to analyze 100,000 waveforms from an average 24-hour study, and the need to deal with an interface that compresses 24 hours of data into as little as 6 minutes on a screen. Today, the computer incorporated in the monitor can scrutinize each cardiac cycle in real time. The system produces a statistical report based on every heart beat and also performs data reduction and storage of electrocardiograph samples. To assess real-time analysis we examined data collected from the Circadian CircaMed ambulatory electrocardiography system. We found that it could detect and quantify simple or complex ventricular ectopic beats, brady- or tachyarrhythmic events, and ST-segment deviation. One hundred fifty patients 21 to 85 years old with symptoms or clinical findings suggestive of ischemia, cardiac arrhythmia, or conductive defects were referred to our electrocardiography laboratory for ambulatory monitoring. The results demonstrate that this system can detect the full range of cardiac disease found with the traditional method. Of the 150 patients, ambulatory electrocardiographic tests were positive in 93 (62%). In addition, we developed a methodology for lead placement when using two bipolar leads, as is typical for ambulatory electrocardiography. We present a procedure for determining the optimum lead placement that is based on the patient’s history and a 12-lead electrocardiogram.     

心电图智能分析-助力精准医疗新时代

心电图是临床上最为常见的检查方法,它无创、简便、快速且价格低廉,在临床应用广泛。然而,传统心电图报告方式为心电医师和技师依靠手工测量、分析心电图,出具报告,速度慢、工作效率低,测量数据偏差较大,影响了心电图报告的可靠性和准确性。随着人工智能的逐渐普及,心电图智能分析的重要性亦逐渐凸显。心电图智能分析利用计算机分析心电图, 测量必要的参数, 再根据临床标准作出正确的诊断或评价,减少了医生的工作量,提高了临床指标分析的精度。本文就心电图智能分析的发展背景、现状及展望进行综述。     

心电图、高频心电图和运动平板试验对冠心病诊断价值的对比研究

【目的】比较心电图、高频心电图和运动平板试验在冠心病诊断中的意义。【方法】对100例心内科住院病人作选择性冠状动脉造影并造影前后2周内分别进行心电图、高频心电图、运动平板试验检查,以至少一支冠脉直径狭窄≥50％作为诊断冠心病的标准,比较冠心病组（60例）与非冠心病组（对照组,40例）的检测结果。【结果】冠心病组心电图、高频心电图和运动平板试验的阳性检出率均显著高于对照组（P〈0．01）;在三种检查方法中,冠心病组高频心电图与运动平板试验的阳性检出率无显著性差异（P〉0．05）,但均显著高于心电图（P〈0．01）;对照组中,心电图、高频心电图的阳性检出率无显著性差异（P〉0．05）,但均显著高于运动平板试验（P〈0．01）。【结论】运动平板试验能够对大多数的冠心病患者进行筛查,且对无冠心病者误诊率相对较低,应根据患者实际情况,正确选择或联合应用以上检查方法。     

体表心电图V1和aVL/aVR导联对房室结折返性心动过速的诊断价值

目的探讨体表心电图V1联合aVL或aVR导联对房室结折返性心动过速(AVNRT)的诊断价值。方法143例窄QRS心动过速患者的体表心电图,含窦性心律和心动过速心电图。由两位未知心动过速类型的心电生理医师进行诊断,记录包括V1导联假r′波、aVL导联末端切迹、心动过速RP′间期≥100 ms等指标,心动过速类型由心内电生理检查确定。结果AVNRT患者年龄较大(P<0.01),女性较多(72.4% vs 50.0%,P<0.01)。aVL导联末端切迹对于诊断AVNRT具有较高敏感度（60.9%）和特异度（89.3%）,高于传统V1导联假r′和下壁导联假s波（P均小于0.05）;联合V1导联假r′和aVL导联末端切迹或aVR导联假r′波明显提高AVNRT诊断敏感度至78.2%和74.7%,而阳性预测值无明显降低。RP′间期≥100 ms诊断顺向型房室折返性心动过速(AVRT)具有较高敏感度和特异度(敏感度69.6%, 特异度87.4%),联合aVR导联ST段J点后80 ms下斜型抬高超过1.5 mV指标,明显提高AVRT诊断敏感度（89.2%）。结论体表心电图V1和aVL或aVR导联可提高AVNRT诊断价值。     

The resting electrocardiogram in the management of patients with congestive heart failure: established applications and new insights

The resting electrocardiogram (ECG) furnishes essential information for the diagnosis, management, and prognostic evaluation of patients with congestive heart failure (CHF). Almost any ECG diagnostic entity may turn out to be useful in the care of patients with CHF, revealing the non-specificity of the ECG in CHF. Nevertheless a number of CHF/ECG correlates have been proposed and found to be indispensable in clinical practice; they include, among others, the ECG diagnoses of myocardial ischemia and infarction, atrial fibrillation, left ventricular hypertrophy/dilatation, left bundle branch block and intraventricular conduction delays, left atrial abnormality, and QT-interval prolongation. In addition to the above well-known applications of the ECG for patients with CHF, a recently described association of peripheral edema (PERED), sometimes even imperceptible by physical examination, with attenuated ECG potentials, could extend further the diagnostic range of the clinician. These ECG voltage attenuations are of extracardiac mechanism, and impact the amplitude of QRS complexes, P-waves, and T-waves, occasionally resulting also in shortening of the QRS complex and QT interval duration. PERED alleviation, in response to therapy of CHF, reverses all above alterations. These fresh diagnostic insights have potential application in the follow-up of patients with CHF, and in their selection for implantation of cardioverter/defibrillator and/or cardiac resynchronization systems. If sought, PERED-induced ECG changes are abundantly present in the hospital and clinic environments; if their detection and monitoring are incorporated in the clinician's "routine," considerable improvements in the care of patients with CHF may be realized.     

Automatic detection of ECG electrode misplacement: a tale of two algorithms

Artifacts in an electrocardiogram (ECG) due to electrode misplacement can lead to wrong diagnoses. Various computer methods have been developed for automatic detection of electrode misplacement. Here we reviewed and compared the performance of two algorithms with the highest accuracies on several databases from PhysioNet. These algorithms were implemented into four models. For clean ECG records with clearly distinguishable waves, the best model produced excellent accuracies (> = 98.4%) for all misplacements except the LA/LL interchange (87.4%). However, the accuracies were significantly lower for records with noise and arrhythmias. Moreover, when the algorithms were tested on a database that was independent from the training database, the accuracies may be poor. For the worst scenario, the best accuracies for different types of misplacements ranged from 36.1% to 78.4%. A large number of ECGs of various qualities and pathological conditions are collected every day. To improve the quality of health care, the results of this paper call for more robust and accurate algorithms for automatic detection of electrode misplacement, which should be developed and tested using a database of extensive ECG records.     

A QRS detection algorithm

In this article we present the choices that the designers of any QRS detector must make and explain the constraints we adopted. We outline the signal processing that precedes and the beat analysis that follows QRS detection in our single-channel, arrhythmia-monitoring algorithm and then expound the QRS detection algorithm in detail. Finally, we present the results of a QRS detector performance evaluation and comment on their importance. This article can be read to three depths: the text affords an overview of QRS detection for on-patient, ambulatory arrhythmia analysis; the commented pseudocode documents the logic of our QRS detector; and the pseudocode footnotes supply technical detail.