Massive pulmonary embolism with anterolateral ST-segment elevation: electrocardiogram limitations and the role of echocardiogram

Although acute pulmonary embolism (PE) may give rise to certain electrocardiographic (ECG) changes, most of these changes have low sensitivity and specificity and are of limited value alone in the diagnosis. Possible ECG changes with acute PE include S(1)Q(3)T(3) pattern, atrial tachyarrhythmias, incomplete right bundle-branch block, or negative T wave over right and midprecordial leads. Elevation of ST segment is a rare ECG manifestation with PE. We present a case of PE that went unrecognized in the emergency department (ED). The patient presented with anterior chest pain and dyspnea, and ECG showed ST elevation in V3 through V6. The differential diagnosis included acute coronary syndrome and acute pericarditis. Echocardiography revealed dilatation and dysfunction of right ventricle. Emergent computed tomographic pulmonary angiography showed bilateral pulmonary artery thrombosis and confirmed the diagnosis. Thrombolytic therapy with tissue plasminogen activator was initiated, and symptoms subsided dramatically. We proposed that the ST elevation in anterolateral leads might be the reciprocal changes of myocardial strain in the interventricular septum or right ventricle lateral wall. In a patient with such a critical condition and a confusing ECG, echocardiography played an important role in the diagnostic procedure, enabling prompt therapeutic intervention.     

Electrocardiographic findings and myocardial damage in acute myocarditis detected by cardiac magnetic resonance

Delayed-contrast-enhancement (DCE) magnetic resonance imaging (MRI) can identify areas of myocardial damage in patients with acute myocarditis (AM). The aim of this study was to assess the electrocardiographic findings in AM diagnosed by DCE-MRI. Eighty-one patients (72 men, 35 ± 13 years) with AM were prospectively enrolled. All of them underwent MRI and 12-lead-ECG recordings. In the admission electrocardiogram (ECG 1), as well as in that obtained 48 h later (ECG 2), the following parameters were analyzed: rhythm, PR, QRS, and QTc-intervals, intraventricular conduction, abnormal Q waves, ST segment elevation, and T wave inversion. On admission, 77 patients (95%) were in sinus rhythm, while four patients (6%) manifested severe arrhythmias. No difference between ECG 1 and ECG 2 was observed regarding abnormal Q waves, PR, QRS, and QTc-intervals. Electrocardiogram 1 was normal in 26 patients (32%, normal ECG group), and abnormal in 55 patients (68%, abnormal ECG group). ST elevation was found in 46 patients (57%), inverted T wave in seven patients (9%) and left bundle branch block (LBBB) in two patients (3%). Areas of DCE suggesting AM were found in each patient. No relationship concerning the location of the involved region (s) was found between ECG (leads with ST/T abnormalities) and MRI (areas showing DCE). The ECG in AM can either be normal or reflect abnormalities including arrhythmias, LBBB, ST segment elevation, and T wave inversion. The location of myocardial involvement deduced on the basis of ECG leads showing ST/T changes is not in close relationship with the areas of ventricular damage detected by MRI.     

Narrow QRS Complex Tachycardia with Atrioventricular Dissociation

We describe the case of a 22-year-old man who had frequent episodes of narrow QRS complex tachycardia with atrioventricular dissociation. The ECG during sinus rhythm showed normal PR and QRS intervals, but it showed a left bundle branch block configuration during atrial pacing or after injection of verapamil. An electrophysiological study demonstrated that the patient had nodoventricular Mahaim fibers. The narrow QRS complex tachycardia was explained by a circuit involving antegrade conduction via the atrioventricular nodo-His axis and retrograde conduction via the nodoventricular bypass tract.     

Prevalence of ECG findings in 18–19 year old Swedish men

2268 consecutive men, 18–19 years of age, were examined at an enlistment centre regarding their health, some anthropometric variables and electrocardiogram. ECG items according to the modified Minnesota code [1] were found in 230 subjects (10%). Most common ECG findings were T wave abnormalities (2.2%). Heart rate was higher in the groups with QRS axis deviation, T wave items, sinus tachycardia and supraventricular ectopic beats. Systolic and/or diastolic blood pressure was increased in the groups with T wave items, sinus tachycardia and ventricular ectopic beats. A dysfunction of the autonomic tone can often be suspected as a cause of the abnormality, especially in the groups with tachycardia, T wave changes, AV block grade I and AV junctional rhythm. An ECG recording during orthostasis was considered to be of value to clarify the nature of the ECG abnormality.     

P wave separation after atrial compartment operation for atrial fibrillation

Surgically induced abnormalities in atrial conduction could result in unusual P wave changes. A 31-year-old woman underwent concomitant mitral valve surgery and atrial compartment operation for mitral stenosis and atrial fibrillation (AF). After operation, the AF was successfully converted to sinus rhythm, whereas an unusual electrocardiogram (ECG) with a discrete negative deflection before the T wave in V1 was noted. Electrophysiological study showed a marked conduction delay from the high right atrium (HRA) to the right atrial appendage (RAA) compartment, which resulted in a separation of P waves. The P wave preceding the QRS complex represented the activation of sinus node and the left atrial compartments, and the P at the vicinity of T wave represented the activation of RAA compartment. The conduction from HRA to RAA was worsened on HRA pacing at a faster rate, and improved after isoproterenol infusion. This report demonstrated that conduction across a surgically created isthmus in the atrium could be severely impaired and result in unusual P wave separation.     

Wide QRS complex tachycardia: ECG differential diagnosis.

Wide QRS complex tachycardias (WCT) present significant diagnostic and therapeutic challenges to the emergency physician. WCT may represent a supraventricular tachycardia with aberrant ventricular conduction; alternatively, such a rhythm presentation may be caused by ventricular tachycardia. Other clinical syndromes may also demonstrate WCT, such as tricyclic antidepressant toxicity and hyperkalemia. Patient age and history may assist in rhythm diagnosis, especially when coupled with electrocardiographic (ECG) evidence. Numerous ECG features have been suggested as potential clues to origin of the WCT, including ventricular rate, frontal axis, QRS complex width, and QRS morphology, as well as the presence of other characteristics such as atrioventricular dissociation and fusion/capture beats. Differentiation between ventricular tachycardia and supraventricular tachycardia with aberrant conduction frequently is difficult despite this clinical and electrocardiographic information, particularly in the early stages of evaluation with an unstable patient. When the rhythm diagnosis is in question, resuscitative therapy should be directed toward ventricular tachycardia.     

Electrocardiographic manifestations of COVID-19

IntroductionCoronavirus disease of 2019 (COVID-19) is a lower respiratory tract infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This disease can impact the cardiovascular system and lead to abnormal electrocardiographic (ECG) findings. Emergency clinicians must be aware of the ECG manifestations of COVID-19.ObjectiveThis narrative review outlines the pathophysiology and electrocardiographic findings associated with COVID-19.DiscussionCOVID-19 is a potentially critical illness associated with a variety of ECG abnormalities, with up to 90% of critically ill patients demonstrating at least one abnormality. The ECG abnormalities in COVID-19 may be due to cytokine storm, hypoxic injury, electrolyte abnormalities, plaque rupture, coronary spasm, microthrombi, or direct endothelial or myocardial injury. While sinus tachycardia is the most common abnormality, others include supraventricular tachycardias such as atrial fibrillation or flutter, ventricular arrhythmias such as ventricular tachycardia or fibrillation, various bradycardias, interval and axis changes, and ST segment and T wave changes. Several ECG presentations are associated with poor outcome, including atrial fibrillation, QT interval prolongation, ST segment and T wave changes, and ventricular tachycardia/fibrillation.ConclusionsThis review summarizes the relevant ECG findings associated with COVID-19. Knowledge of these findings in COVID-19-related electrocardiographic presentations may assist emergency clinicians in the evaluation and management of potentially infected and infected patients.     

心电图在肺栓塞诊断中的研究

目的 通过对肺栓塞及有相似临床表现的几组疾病心电图的对比,试图了解肺栓塞心电图的特点和心电图在肺栓塞诊断及鉴别诊断中的应用及意义.方法 共入选364例肺栓塞病例.其中肺栓塞组197例,对照组共167例.对照组分为:1组冠心病心力衰竭组70例,2组原发性高血压心力衰竭组47例,3组急性肺损伤/急性呼吸窘迫综合征组50例.对364例患者的心电图等临床资料进行分析.结果 肺栓塞组心电图出现电轴右偏、顺钟向转位、右束支传导阻滞、肺型P波、V1导联S波粗顿或挫折等与对照组相比明显增加,差异有统计学意义;S1Q3T3、胸前导联T波倒置出现的比率也是肺栓塞组最高,差异有统计学意义.结论 肺栓塞患者心电图的表现以右心负荷增加和反射性的冠状动脉缺血为主要表现;S1Q3T3可能是电轴右偏的表现;每一个指标的敏感性和特异性都难以承担诊断和鉴别诊断的重任;动态观察心电图对肺栓塞的诊断意义重大.     

前间隔心动过速源于主动脉无冠窦的射频消融

【目的]探讨经主动脉无冠窦途径导管射频消融治愈的前间隔房速、前间隔旁路患者的心电图特点及射频消融治疗情况。【方法】回顾性分析经无冠窦途径导管射频消融治愈的3例前间隔房速和2例前间隔旁路的体表心电图、心内电图以及消融成功时靶点电图等心电生理学特征。【结果】3例局灶性前间隔房速均能被心房刺激反复诱发和终止,其心电图特点：房速时P波间期明显窄于窦律时P波间期,I、aVL导联P渡正向,Ⅱ、Ⅲ和aVF导联P呈负正双向,心房标测提示最早的心房激动在希氏柬区,但主动脉无冠窦内标测的心房激动较希氏束区的心房波提前,解剖定位希氏柬上后方,消融靶点无希氏束电位。2例前间隔旁路心电图示：窦性心律时呈窄ORS波形,未见预激波,心动过速呈窄QRS形,在主动脉无冠窦内记录到最早心房激动点,且无希氏柬电位。5例均在无冠窦消融成功。随访15．2±12．1（2～40）个月,无复发病例。【结论】源于无冠窦的前间隔房速和前间隔旁路具有其相对的心电生理学特征,常规心内膜途径消融困难时应考虑从无冠窭玲径标测消融策略．     

心电图在急性肺动脉栓塞诊断中的价值

目的 评估心电图对急性肺动脉栓塞(肺栓塞)的诊断价值.方法 回顾性分析43例既往无心肺疾病的急性肺栓塞患者住院首次、溶栓后及出院前系列心电图变化.结果 ①入院时首次心电图:心动过速26例(60.47%),右束支传导阻滞10例(23.26%);V1导联和V1～V2导联、V1～V3导联、V1～V4导联、V1～V5导联、V1～v6导联T波倒置分别为34例(79.70%)、20例(46.52%)、12例(27.91%)、9例(20.93%)、7例(16.28%)和2例(4.65%);SⅠ＞0.1 mV、TⅢ倒置、QⅢ和SⅠQⅢTⅢ分别为23例(53.49%)、21例(48.84%)、27例(62.79%)和20例(46.52%).②溶栓后心电图:心动过速消失20例(76.9%),右束支传导阻滞消失4例(40%),胸前导联T波倒置加深4例,SⅠ变浅、QⅢ减小或消失、TⅢ倒置变浅或直立11例.③出院前心电图:心动过速消失;胸前导联T波直立数增加,ST段回基线,QⅢ进一步减小或消失,TⅢ倒置变浅或直立.结论 急性肺栓塞心电图变化多变,需动态观察并密切结合临床加以识别.     

Bronchial electrocardiography to determine left or right main bronchial placement of an endotracheal suction catheter tip

Objective To assess the utility of a blue lined angle tiped and electrode tipped catheter, to guide left and right main bronchus cannulation.Design A prospective studySetting An 11-bed general intensive care unit in a 900-bed teaching hospital.Patients 50 intubated intensive care patients, in sinus rhythm with normal P and QRS mean frontal axis, who required endobronchial suctioning for routine respiratory management.Interventions Endobronchial electrocardiography was used to position a blue lined angle tiped and electrode tiped suction catheter into the right and left main bronchi.Results Selective cannulation of the left main bronchi was determined by observing a biphasic or inverted P wave in 42 patients, or biphasic or inverted QRS complex in 31 patients. In 8 patients in whom no changes in the ECG were found, bronchoscopic placement of an ECG electrode into the left main bronchus demonstrated a biphasic or inverted P wave in 8 patients and a biphasic QRS complex in 3 patients, confirming the failure to cannulate the left main bronchus in these 8 patients.Conclusions Using a blue lined, angle tipped and electrode tipped catheter for endotracheal suctioning, endobronchial electrocardiography may be a simple method to signal left or right main bronchus cannulation.     

Pre-excited atrial fibrillation triggered by intravenous adenosine: a commonly used drug with potentially life-threatening adverse effects

Although serious adverse events following adenosine administration are rare, it should only be administered in an environment where continuous ECG monitoring and emergency resuscitation equipment are available. The case report describes the development of pre-excited atrial fibrillation in a 31-year-old woman with Wolff-Parkinson-White syndrome following the administration of adenosine. She had previously been fit and well and was admitted to the coronary care unit with a 2 h history of regular palpitations. A 12-lead ECG showed a narrow QRS complex tachycardia. Carotid sinus massage was unsuccessful in terminating the tachycardia and the patient subsequently received rapid boluses of intravenous adenosine. The cardiac rhythm degenerated into atrial fibrillation with ventricular pre-excitation following 12 mg adenosine.     

A New Orthogonal Lead for P Synchronous Pacing

P synchronous pacing has long been identified as advantageous for patients with atrioveniricular conduction defects and intact sinus node function. Prior endocavitury systems have been infrequently employed, because of unreliable P wave sensing from standard ring electrodes in the atrium or the requirement for a second atriaJ sensing lead. A single endocardial lead employing a unipolar ventricular stimulating electrode and an orthogonal P wave sensing design was developed and tested in 22 patients undergoing electrophysiologic study or pacemaker implantation. Thirteen centimeters from the stimulating tip of a standard permanent pacing lead, three or four electrodes with a surface area of one millimeter squared, equidistant from the tip, were placed circumferentially about the catheter. With the catheter tip normally placed in the right ventricular apex, atrial sensing eJectrodes were positioned in the mid-high lateral right atrium, adjacent to, but not affixed to, the right atrial wall. Bipolar orthogonal leads X and Y were obtained. In 22 patients, during sinus rhythm, atrial electrogram voltages in the X axis of 2.47 plus or minus 1.6 millivolts and 2.32 plus or minus 1.6 millivolts in the Y axis were recorded. QRS voltages of 0.078 millivolts and 0.073 millivolts, respectively, allowed dramatic ability to discriminate P from QRS complexes (P/QRS equals 32/1). There was no change in QRS voltages recorded during spontaneous premature ventricular contractions, bipolar or unipolar ventricular pacing. A single catheter designed for P synchronous pacing empJoying circumferentially placed atrial sensing electrodes has demonstrated unique atrial sensing voltages with excellent QRS signal rejection. (PACE, Vol. 4, November-December, 1981)     

正常人标准胸导联和Mason-Likar胸导联心电图波段定量比较

目的：对我国正常人群标准12导联（标准导联）和Mason-Likar导联系统所记录胸导联心电图的波段进行定量比较。方法：选择84例冠状动脉造影和心脏超声检杏结果均正常者作为研究对象，其均接受标准导联加Mason-Likar导联心电网记录检查，观察2种导联系统胸导联心电图中以下测定值的相关性及差异，包括R波振幅、QRS波振幅、ST段值[J点（ST on）、J点后0．08s（ST80 ms）和终点（ST end）]、ST段斜率及T波振幅。结果：标准导联与Mason-Likar导联系统所记录的胸导联心电图存在良好相关性，但也存在统计学差异（P〈0．001）与标准胸导联相比，Mason-Likar胸导联心电网差异包括部分导联QRS波振幅明显降低、ST段显著下移伴V1～V0导联T波振幅下降，V1导联中各波段降低均较显著（P均〈0．001）；Mason-Likar各胸导联中ST段的降低幅度均超过同一导联QRS波和T波的幅度改变,以V6导联变化最显著。平均体重指数（BMI）与V1、V3导联QRS波振幅的改变呈负相关：V1、V2导联ST80ms与T波振幅、QRS波振幅的改变呈正相关。结论：标准导联与Mason-Likar导联系统所记录心电图波段有一定差异。     

Activation of the Right Ventricular Apical Electrogram during Ventricular Tachycardia: Suitahility for Synchronizing Intracavitary Cardioversion

An intravascular catheter positioned in the right ventricular apex has been used for intracavitary cardioversion in patients with recurrent ventricular tachycardia. We examined the timing of the right ventricular apical electrogram during sinus rhythm and ventricular tachycardia (VT) in order to determine if this signal could be used to synchronize the delivery of a countershock. Sixty-three distinct morphologies of VT were observed in 33 patients undergoing electrophysiologic testing with programmed stimulation. Regardless of VT morphology or site of origin, the bipolar right ventricular electrogram always occurred within the peripheral QRS complex during ventricular tachycardia. Relative timing occurred within the QRS ranging from the initial 13% of the QRS to the last 12%. When all episodes of VT were examined, the timing of the right ventricular electrogram did not correlate linearly with the peak of the ECG, but the right ventricular electrogram occurred within 60 ms of the peak ECG in 83% of episodes of ventricular tachycardia. In one case of arrhythmogenic right ventricular dysplasia, the right ventricular electrogram occurred 160 ms after the peak ECG in ventricular tachycardia, a time when delivery of a countershock may have precipitated ventricular fibrillation. Six of these patients underwent cardioversion utilizing an intracavitary catheter and external generator. Acceleration of VT, or conversion to ventricular fibrillation, occurred following two of 27 shocks (7.4%). The right ventricular electrogram occurred the latest within the QRS complex in the two patients who developed acceleration of the tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ebstein anomaly in an adult presenting with wide QRS tachycardia: diagnostic and therapeutic dilemmas

A 51-year-old man presented to the emergency department with sustained hemodynamically unstable wide QRS tachycardia and was revived successfully by immediate direct current (DC) cardioversion. There was evidence of previous open heart surgery, possibly atrial septal defect closure. Transthoracic echocardiography showed severe Ebstein anomaly with severe tricuspid regurgitation, no residual atrial septal defect, but with severe right ventricular dysfunction. Subsequent electrocardiograms showed transient atrial fibrillation with no manifest Wolff-Parkinson-White (WPW) accessory pathway during sinus rhythm. The cause of wide QRS tachycardia in this patient may be WPW related or ventricular tachycardia. This case illustrates the diagnostic and therapeutic dilemmas in patients with wide QRS tachycardia and suspected WPW syndrome. In addition, this case demonstrates that unoperated Ebstein anomaly can present in late adult life with tachyarrhythmias.     

Near Doubling of Heart Rate After Intravenous Verapamil for Treatment of Atrial Fibrillation Without Preexcitation

Initial treatment of atrial fibrillation often involves pharmacological therapy to control ventricular response. While verapamil is usually safe and effective when used for this purpose, we report a proarrhythmic response. In this report a 30-year-old female presented with paipitations associated with atrial fibrillation and a ventricular response of 145 beats/min. Soon after she was given 5 mg of intravenous verapamil her ECG documented a regular wide QRS tachycardia at 290 beats/min. After 7 seconds the rhythm returned to an irregularly irregular narrow QRS tachycardia at 125–150 beats/min. At a later electropliysiology study there was neither evidence of preexcitation norinducible supraventricular or ventricular tachycardia. These data suggest that verapamil may have been associated with acceleration of the heart rate. The mechanism of proarrhythmia may be reiated to an aiteration in the atrial rhythm from atriaL fibrillation to atrial flutter, with additional factors as well.     

aVR导联ST段抬高对窄QRS波心动过速的鉴别及旁道定位作用

目的:观察aVR导联ST段抬高对窄QRS波心动过速的鉴别及旁道定位作用。方法:120例窄QRS波心动过速均经心内电生理和射频消融证实,分析其心动过速发作时体表12导联心电图aVR导联ST段抬高程度及持续时间。结果:120例窄QRS波心动过速中有58例房室折返性心动过速(AVRT),62例房室结折返性心动过速(AVNRT)。aVR导联ST段抬高在AVRT发生率为67.2%,AVNRT为16.1%(P<0.05),诊断AVRT的敏感性、特异性和准确性分别是67.2%、83.9%和75.8%。在39例aVR导联ST段抬高的AVRT中,有28例位于左旁道,7例位于右旁道,3例位于后间隔,1例位于前间隔。aVR导联ST段抬高定位左侧旁道的敏感性、特异性、阳性预测值和准确性分别是77.8%、50.0%、71.8%和76.5%。结论:aVR导联ST段抬高有助于鉴别窄QRS波心动过速及旁道定位。     

A modified electrocardiographic algorithm for differentiating typical atrioventricular node re-entrant tachycardia from atrioventricular reciprocating tachycardia mediated by concealed accessory pathway

Non-invasive prediction of tachycardia mechanism is becoming clinically important in the era of catheter ablation for curing supraventricular tachycardia. Twelve-lead electrocardiograms (ECGs) during sinus rhythm and atrioventricular node re-entrant tachycardia (AVNRT) or atrioventricular reciprocating tachycardia (AVRT) with a narrow QRS complex were obtained from 154 consecutive adult patients who had received successful radiofrequency catheter ablation. The ECGs of initial 104 patients were analysed by three observers without knowledge of the electrophysiological diagnosis. The two arrhythmias were accurately diagnosed in 68% of cases. Three criteria were found to be discriminators of tachycardia mechanism by univariable analysis. Pseudo r/Q/S waves predicated AVNRT in 92% of cases (sensitivity 71%; specificity 95%). Retrograde P wave predicated AVRT in 86% of cases (sensitivity 75%; specificity 85%), RP interval > or =100 ms in 93% (sensitivity 71%; specificity 94%) and ST-segment elevation in lead aVR in 83% (sensitivity 71%; specficity 83%). According to the initial results, we proposed a modified stepwise ECG algorithm which used pseudo r/S/Q waves, RP interval and ST-segment elevation in lead aVR during tachycardia. Two observers assessed the modified algorithm in the remaining 50 patients. The algorithm was able to correctly diagnose the tachycardia mechanism in 84% and 87%, respectively. Using the modified algorithm can improve the accuracy and simplify the differential diagnosis between typical AVNRT and AVRT via concealed accessory pathway in adult patients.     

Right pneumothorax with the S1Q3T3 electrocardiogram pattern usually associated with pulmonary embolus

An 18-year-old man presented with a spontaneous right pneumothorax. An initial electrocardiogram (ECG) showed an S wave in lead I, a Q wave in lead III, and an inverted T wave in lead III. This ECG pattern, S1Q3T3, has been most often associated with pulmonary embolus. These changes resolved with partial reexpansion of the lung. Both right and left pneumothorax have been associated with ECG changes, including changes that mimic myocardial ischemia. Because the clinical presentation of pneumothorax may be similar to angina or pulmonary embolus, ECG changes with pneumothorax may lead to confusion in the diagnosis.