Observations on the antidromic type of circus movement tachycardia in the Wolff-Parkinson-White syndrome

In the differential diagnosis of tachycardias showing a wide QRS complex and having a 1 to 1 relation between ventricular and atrial events, a supraventricular tachycardia with anterograde conduction over an accessory pathway and retrograde conduction by way of the specific conduction system must be considered. Five patients showing this type of circus movement tachycardia were studied by programmed electrical stimulation of the heart. Sudden changes in the tachycardia cycle length were observed in these patients that were based on changes in the VH interval. This finding suggested a change in the reentrant circuit with anterograde conduction over the accessory pathway but retrograde conduction sometimes occurring over the right bundle branch and at other times over one of the two divisions of the left bundle branch system. Characteristically, the tachycardia cycle length changed suddenly depending on the bundle branch used in retrograde direction. In one patient, an important difference was also observed between the anterograde effective refractory period of the accessory bypass (280 ms) and the shortest RR interval between preexcited QRS complexes during atrial fibrillation (measuring 190 ms). It is postulated that the short RR intervals during atrial fibrillation in the Wolff-Parkinson-White syndrome could result from bundle branch reentry after activation of the ventricles over the accessory pathway.     

Surface electrocardiographic clues suggesting presence of a nodofascicular Mahaim fiber

Standard electrocardiograms from 87 consecutive patients with tachycardia of left bundle branch block configuration were analyzed retrospectively for features that might be characteristic of tachycardia utilizing a nodofascicular Mahaim fiber. The study group consisted of 13 patients with nodofascicular tachycardia, 34 with supraventricular tachycardia and aberrant conduction over the His-Purkinje system, 22 with ventricular tachycardia and 18 with antidromic tachycardia utilizing a right-sided accessory atrioventricular pathway. Six variables present during tachycardia of left bundle branch block configuration were predictive of a nodofascicular fiber: cycle length between 220 and 450 ms, QRS axis of 0 to -75 degrees, QRS duration 0.15 second or less, R wave in lead I, rS wave in precordial lead V1 and a precordial transition from a negative to a positive QRS complex after lead V4. All six criteria were present in 16 of the 87 patients. No patient with ventricular tachycardia satisfied these criteria, whereas 3 of 34 with supraventricular tachycardia, 1 of 18 with antidromic tachycardia and 12 of 13 with tachycardia using a nodofascicular fiber did. It is concluded that analysis of the surface electrocardiogram during tachycardia may suggest the presence of a nodofascicular fiber.     

One to one atrioventricular conduction during atrial pacing at rates of 300/minute in absence of wolff-parkinson-white syndrome

One to one atrioventricular (A-V) or atrio-His bundle (A-H) conduction occurred during right atrial pacing at rates of 300/min in two patients with short P-R (and A-H) intervals, narrow QRS complexes and recurrent supraventricular tachyarrhythmias. Patient 1 had episodes of reciprocating A-V tachycardia and of atrial fibrillation with very fast rates (270 to 290/min) that were slowed to 100 to 135/min after administration of intravenous verapamil. Enhanced A-V (A-H) conduction was exposed only during stimulation from the high right atrium, but not from the low lateral right atrium or coronary sinus. Patient 2 had episodes of atrial flutter with 1:1 A-V conduction and rates of 290/min. The H-V interval was short (25 ms) during sinus rhythm and atrial pacing presumably because conduction occurred through an atrio-“distal” His bundle (atriofascicular) tract. In contrast, the H-V interval was normal (40 ms) in echo beats or when the “proximal” His bundle was stimulated.In these two patients, having as “common denominators” short P-R (and A-H) intervals, narrow QRS complexes and recurrent supraventricular tachyarrhythmias, enhanced A-V (A-H) conduction was (1) possibly due to different electrogenetic mechanisms; (2) pacing-site dependent; (3) manifested, during atrial fibrillation and atrial flutter, by extremely fast ventricular rates; and (4) unrelated to the rate of reciprocating A-V tachycardias because the latter was predominantly a function of anterograde conduction through the “slow” nodal pathway.     

His bundle electrocardiography in manifest and concealed right bundle branch extrasystoles.

His bundle electrocardiography was helpful in the diagnosis of impulse formation in the right bundle branch. Ten patients with narrow QRS complexes had ectopic beats with an "incomplete" left bundle branch pattern and almost simultaneous activation of His bundle and ventricles. Both QRS morphology and H- - V intervals depended on the more proximal or distal location of the ectopic focus. In four patients with "complete" right bundle branch block the morphology of ectopic ventricular complexes and H- - V intervals also depeneded on the presence or absence of retrograde block and differential degrees of forward and/or retrograde conduction delays. Nine patients with "complete" right bundle branch block and four with "complete" left bundle branch block had premature beats which could have originated in the proximal right bundle branch, proximal left bundle branch, or distal His bundle. In one patient with "complete" left bundle branch block, "concealed" His bundle depolarizations (probably originating in an ectopic focus located in the right bundle branch) produced pseudo Type II (Mobitz) A-V block. Although lidocaine appeared to have been more effective in patients with bundle branch block than in those with narrow QRS complexes, further studies are necessary to corroborate this impression.     

Differenzialdiagnostik und Therapie tachykarder Herzrhythmusstörungen

The 12-channel surface electrocardiogram (ECG) is an important diagnostic tool for diagnosis of arrhythmias and acute coronary syndrome. Supraventricular tachycardia (SVT) is a paroxysmal tachycardia as are sinus tachycardia, atrial tachycardia, atrioventricular (AV) nodal reentry tachycardia and tachycardia due to accessory pathways. All SVTs are characterized by a ventricular heart rate >?100 beats/min and small QRS complexes (QRS width <?0.12 s) during tachycardia. It is important to analyze the relation between p-wave and QRS complex, to look for an electric alternans as a main finding for an accessory pathway. Wide QRS complex tachycardia (QRS width ≥?0.12 s) occurs in SVT with aberrant conduction, SVT with bundle branch block or ventricular tachycardia (VT). In broad complex tachycardia, AV dissociation, negative or positive concordant patterns in V1–V6, a notch in V1 and qR complexes in V6 in tachycardia with left bundle branch block morphology, are findings indicating VT. In addition, an R/S relation <?1 in V6 favors VT when right bundle branch block tachycardia morphologies are present. By analyzing the surface ECG in the correct way with a systematic approach, the specificity and sensitivity of correctly identifying SVT or VT can be raised to >?95?%. Therapy of tachycardia is possible with few antiarrhythmic drugs (concept of the 5As), beta-blocking agents, cardioversion and defibrillation. Using these approaches termination of tachycardia is possible in the majority of cases with high success rates.     

Ventricular Extrasystoles with Interpolation or Postponed Compensatory Pause during Atrial Fibrillation: Fact or Fiction?

A Holter recording obtained from a patient with atrial fibrillation showed ventricular extrasystoles often in bigeminal rhythm. Most extrasystoles were followed by a long return cycle, and only in a few instances the postextrasystolic interval was short. The latter phenomenon was interpreted as a manifestation of poor retrograde concealed penetration of the ventricular impulse into the atrioventricular (A‐V) junction: accordingly, an ensuing relatively early fibrillation impulse reached the ventricular chamber, since it did not find the A‐V node refractory. These events are similar to what happens in interpolated ventricular extrasystoles occurring during sinus rhythm, the absent or minimal concealed retrograde penetration of the ectopic impulse into the A‐V node being necessary to permit anterograde conduction of the ensuing sinus impulse. Analysis of the recording also revealed that a very long (>2 second) interval between two consecutive narrow beats only occurred after an “interpolated” extrasystole. This was interpreted with the same mechanism underlying the “postponed compensatory pause” observed at times after interpolated ventricular extrasystoles during sinus rhythm: the minimal or nil penetration of the ventricular ectopic impulse into the A‐V junction, followed by conduction of an ensuing early atrial impulse, “shifts to the right” the A‐V nodal refractory period, preventing conduction of several further supraventricular impulses and generating a pause. Both interpolated ventricular extrasystoles and the phenomenon of “postponed compensatory pause” are, thus, conceivable during atrial fibrillation, although no definite demonstration is possible.     

鉴别宽QRS心动过速心电图指标对原有束支传导阻滞患者的应用价值

目的　探讨鉴别宽 QRS心动过速心电图指标对原有束支传导阻滞患者的应用价值。方法　以非选择性、连续性 42 0例完全性束支传导阻滞窦性心律患者为研究对象 ,分析以往文献报道鉴别宽 QRS心动过速心电图标准中的 QRS形态指标的特异性。结果　 12个分析指标中 4个指标特异性 >90 % :右束支传导阻滞 V1 呈三相型 (Rsr′,r SR′,RSR′) ;右束支传导阻滞 V6呈 QS或 QR型 ;左束支传导阻滞 V6有 q或 Q波 ;V1 ～ V6无 RS波。其它 8个指标特异性在 45 %～ 87%范围内。结论　有利于室性心动过速诊断心电图标准中的 QRS形态指标对鉴别原有束支传导阻滞的室上性心动过速患者存在局限性     

Electrocardiographic changes in patients with haemorrhagic fever with renal syndrome

The purpose of the study was to assess the incidence, type and dynamics of electrocardiography (ECG) alterations in patients with haemorrhagic fever with renal syndrome (HFRS) according to different stages of the disease. 79 patients hospitalized at the University Hospital for Infectious Diseases in Zagreb during the large HFRS outbreak in Croatia in 2002 were retrospectively analysed. HFRS diagnosis was confirmed by enzyme-linked immunosorbent assay. A 12-lead resting ECG was obtained. 30 (38%) patients had abnormal ECG findings, most frequently in the oliguric stage. Increased levels of urea and creatinine were observed in all patients with abnormal ECG, along with abnormal chest X-ray in nearly 50% of cases. Sinus tachycardia was the most frequent ECG disorder in the febrile stage, and bradycardia in the oliguric stage. During the course of disease, some other ECG disorders were recorded: bundle branch conduction defects, non-specific ventricular repolarization disturbances, supraventricular and ventricular extrasystoles, prolonged QT interval, low voltage of the QRS complexes in standard limb leads, atrioventricular block first-degree, and atrial fibrillation. Myocarditis was present in 3 patients. In conclusion, abnormal ECG was found in more than one-third of HFRS patients with the most common findings during the oliguric stage. All ECG changes were transient.     

Atrial Pacing in Ventricular Tachycardia and Supraventricular Tachycardia with Aberrant Intraventricular Conduction: Diagnostic and Therapeutic Implications*

Summary: The diagnostic and potential therapeutic value of rapid right atrial pacing in ventricular tachycardia and supraventricular tachycardia with aberrant intraventricular conduction, was examined. The effect of right atrial pacing at incremental rates beginning 10 bpm above the rate of the tachycardia was studied in five patients with ventricular tachycardia, and in four patients with supraventricular tachycardia with rate-related bundle branch block aberration, the mechanism of tachycardia having been demonstrated at electrophysiology study. Atrial pacing resulted in persistent (four) or occasional (one) normalisation of the QRS complexes to that seen in sinus rhythm in those five patients with ventricular tachycardia. The intraventricular conduction pattern persisted with atrial pacing in those patients with supra-ventricular tachycardia and aberrant intraventricular conduction. This confirms that atrial pacing is a useful and simple diagnostic test in wide QRS tachycardia, which does not require sophisticated electrophysiological facilities. In three of the patients with ventricular tachycardia, atrial pacing terminated the arrhythmia, suggesting potential therapeutic use of rapid atrial pacing in such patients.     

Atrial flutter, supraventricular tachycardia, junctional rhythm and complete right bundle branch block in a patient with the Wolff-Parkinson-White Syndrome (type B)

During an attack of tachycardia in a 55-year-old Chinese woman, continuous electrocardiographic monitoring showed the unique changes of, firstly, atrial flutter with aberrant conduction; secondly, a supraventricular tachycardia and junctional rhythm with QRS complexes showing a complete right bundle branch block pattern; and lastly, sinus rhythm with evidence of the Wolff-Parkinson-White Syndrome (type B) and complete right bundle branch block in the same scalar electrocardiogram.     

Bundle branch block. Demonstration of the incomplete nature of some "complete" bundle branch and fascicular blocks by the extrastimulus technique

The incomplete nature of some electrocardiographic “complete” bundle branch and fasclcular blocks is demonstrated using the atrial extrastimulus technique. Patient 1, with a QRS pattern of “complete” left bundle branch block, manifested a QRS pattern of right bundle branch block at a shorter coupling interval, indicating that the left bundle could conduct. Patient 2, with a QRS pattern of right bundle branch block and “complete” left anterior hemiblock, manifested a pattern of left posterior hemiblock at a shorter coupling interval, indicating that the left anterior fascicle could conduct. Patient 3, with a normal QRS complex, showed left bundle branch block at shorter coupling intervals and then a pattern of right bundle branch block as the coupling interval was further decreased, indicating that functional left bundle branch block was incomplete. This demonstration of partial bundle branch block depends on a discordance of conduction time and refractory period, the bundle or fascicle with depressed conduction (incomplete block) having a shorter refractory period than the more normally conducting bundle or fascicle. This discordance may be related to the development of trifascicular block in patients with bifascicular block and a normal H-V interval. It is a predisposing factor in the complex patterns of aberrant conduction seen during supraventricular tachyarrhythmias with varying cycle lengths.     

Pure anterior conduction delay: A variant “fascicular” defect

Based upon electrocardiographic studies of conduction disturbances, the human intraventricular conduction system has been considered trifascicular: a right bundle and a bidivisional left bundle. Right bundle branch block, left anterior hemiblock, and left posterior hemiblock have been described. Microscopic and endocardial mapping studies, however, do not demonstrate a corresponding anatomical basis of this useful functional concept. Atrial premature beats in our two cases resulted in ventricular aberrancy which strongly suggests an additional form of a functional conduction delay. Such delay is manifest as a narrow QRS with anterior displacement in the horizontal plane but no axis shift in the frontal plane. This aberrancy is important to recognize because it can mimic the ECG findings of true posterior myocardial infarction. We do not postulate, however, a specific fascicle of the left bundle as the anatomic substrate for this recently recognized defect.     

Ventricular tachycardia masquerading as supraventricular tachycardia: A wolf in sheep''s clothing

It is generally assumed that if a wide QRS complex tachycardia has the same morphology on the 12-lead electrocardiogram as during sinus rhythm, the tachycardia is supraventricular. The author presents unique electrocardiographic data on four patients with QRS complex morphologies that are nearly identical during ventricular tachycardia and during sinus rhythm. The QRS complex duration during sinus rhythm was 140-180 msec and was the same as that of the tachycardia. The QRS complex morphology on the electrocardiogram was a right bundle branch block, left axis in three patients and right bundle branch block, normal axis in one patient. The mean ventricular tachycardia cycle length was 345 msec. The diagnosis of ventricular tachycardia was established by electrophysiologic testing in two patients and by atrial electrograms demonstrating AV dissociation in two patients. Thus, if the 12-lead electrocardiogram morphology of a wide QRS complex tachycardia is similar to that during sinus rhythm, it does not necessarily imply that the tachycardia is supraventricular. Ventricular tachycardia can occur with the same QRS complex morphology as occurs during sinus rhythm.     

QRS aberration during atrial fibrillation at rest and during exercise. Effect of a selective potassium channel blocking agent

This study assesses the occurrence of and identifies clinical characteristics associated with the development of aberrant conduction during infusion of the I(kr)-blocker almokalant. Class III drugs may induce aberrant conduction by prolongation of cardiac repolarization, especially during atrial fibrillation (AF). Ninety-two patients with AF received a 6-hour almokalant infusion, aiming at conversion to sinus rhythm (SR). Fiftyfive of the patients received an identical infusion during SR. During almokalant infusion, the number of patients with intermittent QRS aberration during AF increased, from 21% to 80% at rest, and was further increased to 89% during exercise, with predominantly left, and sequential bilateral, bundle branch aberrancy. Patients with aberrant conduction showed signs of more advanced myocardial disease. Predictors of the development of QRS aberration were female gender, arrhythmia duration, and decreased left ventricular ejection fraction, while use of calcium antagonists decreased the probability. No patient showed aberration during regular SR. Twenty-one patients experienced aberrantly conducted supraventricular premature beats. In conclusion, aberrant conduction is common during infusion of the I(kr)-blocker almokalant during AF, and seems to be more frequent in females and in patients with more advanced myocardial disease.     

Spectrum of regular tachycardias with wide QRS complexes in patients with accessory atrioventricular pathways

Reciprocating tachycardia and atrial flutter or fibrillation are the rhythm disorders most frequently documented in patients with accessory atrioventricular (A-V) pathways. Reciprocating tachycardia typically results in a regular tachycardia (140 to 250/min) with a normal QRS pattern, although on occasion bundle branch block aberration occurs. Atrial flutter or fibrillation may result in an irregular ventricular response, with the QRS configuration being normal or exhibiting bundle branch block or various degrees of ventricular preexcitation, or both. Although much less common than either reciprocating tachycardia or atrial flutter/fibrillation, regular tachycardias with a wide QRS complex suggestive of ventricular preexcitation are observed in patients with accessory pathways. Excluding functional or preexisting bundle branch block, several arrhythmias may cause these electrocardiographic findings which may mimic those of ventricular tachycardia.In the present study a variety of arrhythmias that resulted in tachycardias with a wide QRS complex were examined in 163 patients with accessory pathways who underwent clinical electrophysiologic study for evaluation of recurrent tachyarrhythmias. Twenty-six patients (15 percent) manifested a regular tachycardia with a wide QRS complex suggesting ventricular preexcitation. Atrial flutter with 1:1 anterograde conduction over an accessory pathway (15 of 26 patients, 58 percent) was the most frequent arrhythmia and was usually associated with a heart rate of 240/min or greater (12 of 15 patients). Reciprocating tachycardia with conduction in the anterograde direction over an accessory pathway (antidromic reciprocating tachycardia) occurred in 7 of 26 patients (27 percent), and resulted in a slower ventricular rate than atrial flutter (217 ± 22 versus 262 ± 42, P < 0.01). Other arrhythmias included reciprocating tachycardia with reentry utilizing a fasciculoventricular or nodoventricular connection (two patients, 8 percent), reciprocating tachycardia with reentry in the atrium or A-V node and anterograde accessory pathway conduction (one patient, 4 percent) and ventricular tachycardia (one patient, 4 percent).In this study the clinical electrophysiologic diagnostic features of several arrhythmias which cause tachycardias with a wide QRS compex suggesting ventricular preexcitation are outlined. It is apparent that definitive arrhythmia diagnosis during these tachycardias is often complex and usually requires careful study using intracardiac electrode catheter techniques.     

Bundle branch block in alternate beats during 2:1 atrial flutter

This presentation deals with a case of atrial flutter. During 2:1 A/V conduction, the QRS complexes showed a regular alternation of narrow beats and wide beats with a typical configuration of left bundle branch block. In contrast, pauses resulting from 4:1 A/V conduction ratio always resulted in narrow beats. Disappearance of left bundle branch block with long R-R intervals demonstrated that the block was tachycardia-dependent or phase 3. Analysis of the tracing suggested that narrowing of QRS complexes in alternate beats was due to supernormal left bundle branch conduction associated with retrograde concealed conduction into the anterogradely blocked bundle branch.     

Electrocardiographic Follow‐Up of Biventricular Pacemakers

Multisite pacing for the treatment of heart failure has added a new dimension to the electrocardiographic evaluation of device function. During left ventricular (LV) pacing from the appropriate site in the coronary venous system, a correctly positioned lead V1 registers a right bundle branch block pattern with few exceptions. During biventricular stimulation associated with right ventricular (RV) apical pacing, the QRS is often positive in lead V1. The frontal plane QRS axis is usually in the right superior quadrant and occasionally in the left superior quadrant. Barring incorrect placement of lead V1 (too high on the chest), lack of LV capture, LV lead displacement or marked latency (exit block or delay from the stimulation site), ventricular fusion with the spontaneous QRS complex, a negative QRS complex in lead V1 during biventricular pacing involving the RV apex probably reflects different activation of an heterogeneous biventricular substrate (ischemia, scar, His‐Purkinje participation in view of the varying patterns of LV activation in spontaneous left bundle branch block) and does not necessarily indicate a poor (electrical or mechanical) contribution from LV stimulation. In this situation, it is imperative to rule out the presence of coronary venous pacing via the middle cardiac vein or even unintended placement of two leads in the RV. During biventricular pacing with the RV lead in the outflow tract, the paced QRS in lead V1 is often negative and the frontal plane paced QRS axis is often directed to the right inferior quadrant (right axis deviation). In patients with sinus rhythm and a relatively short PR interval, ventricular fusion with competing native conduction during biventricular pacing may cause misinterpretation of the ECG because narrowing of the paced QRS complex simulates appropriate biventricular capture. This represents a common pitfall in device follow‐up. Elimination of ventricular fusion by shortening the AV delay, is often associated with clinical improvement. Anodal stimulation may complicate threshold testing and should not be misinterpreted as pacemaker malfunction. One must be cognizant of the various disturbances that can disrupt 1:1 atrial tracking and cause loss of ventricular resynchronization. (1) Upper rate response. The upper rate response of biventricular pacemakers differs from the traditional Wenckebach upper rate response of conventional antibradycardia pacemakers because heart failure patients generally do not have sinus bradycardia or AV junctional conduction delay. The programmed upper rate should be sufficiently fast to avoid loss of resynchronization in situations associated with sinus tachycardia. (2) Below the programmed upper rate. This may be caused by a variety of events (especially ventricular premature complexes and favored by the presence of first‐degree AV block) that alter the timing of sensed and paced events. In such cases, atrial events become trapped into the postventricular atrial refractory period at atrial rates below the programmed upper rate in the presence of spontaneous AV conduction. Algorithms are available to restore resynchronization by automatic temporary abbreviation of the postventricular atrial refractory period.     

The Electrocardiographic Manifestations of Arrhythmogenic Right Ventricular Dysplasia

The ECG is abnormal in most patients with arrhythmogenic right ventricular dysplasia (ARVD). Right ventricular parietal block, reduced QRS amplitude, epsilon wave, T wave inversion in V1-3 and ventricular tachycardia in the morphology of left bundle branch block are the characteristic changes that reflect the underlying genetic predetermined pathology and pathoelectrophysiology. Recognizing the characteristic ECG changes in ARVD will be of help in making a correct diagnosis of this rare disease.     

Acute myocardial infarction and left bundle branch block with changing axis deviation

Changing axis deviation has been reported also during atrial fibrillation or atrial flutter. Changing axis deviation has been also reported during acute myocardial infarction associated with atrial fibrillation too or at the end of atrial fibrillation during acute myocardial infarction. Left bundle branch block is usually associated with normal or left axis deviation. Rarely the ECG shows a LBBB with changing QRS morphology and changing axis deviation. There are several possible explanations for the intermittent shift in the QRS axis in the presence of complete left bundle branch block. The most plausible explanation is the coexistence of left posterior hemiblock and predivisional left bundle branch block. We present a case of a left bundle branch block with changing axis deviation in a 93-year-old Italian woman admitted to the Cardiology Unit with an acute myocardial infarction.     

Wide complex tachycardia with atrioventricular dissociation and QRS morphology identical to that of sinus rhythm: a manifestation of bundle branch reentry.

OBJECTIVE: To determine the features that distinguish bundle branch reentry (BBR) ventricular tachycardia from a supraventricular tachycardia with aberration on the 12 lead electrocardiogram (ECG). PATIENTS: Three patients in whom premature beats (2 cases) or sustained tachycardia (2 cases) showed a QRS configuration identical to that observed during sinus rhythm. INTERVENTIONS: Programmed electrical stimulation. RESULTS: These arrhythmias were ventricular in origin and caused by a BBR mechanism, as suggested by the following data obtained during electrophysiological study: (a) an H-V interval shorter during tachycardia than during sinus rhythm; (b) A-V dissociation; (c) activation of the right bundle branch before activation of the bundle of His. The ECG of all 3 patients showed right bundle branch block with very prolonged QRS duration (0.16 to 0.20 s). Characteristically, all 3 had prolonged H-V interval during sinus rhythm. All patients had had a previous myocardial infarction and had a dilated left ventricle. CONCLUSION: The presence of (a) wide complex extrasystoles or tachycardia with a QRS morphology identical to that of sinus rhythm; (b) A-V dissociation; and (c) a very prolonged QRS duration (0.16 s or more) is suggestive of ventricular tachycardia caused by bundle branch reentry.