Anterograde Conduction Research Articles

Rapports entre l’âge et l’incidence d’une voie accessoire atrioventriculaire de localisation antéroseptale dans le syndrome Wolff-Parkinson-White

Background Radiofrequency ablation of atrioventricular accessory pathway (AP) which is currently used, remains associated with a risk of complete AV block in the case of anteroseptal (AS) location and its indication remains debatable. The purpose of the study was to evaluate the frequency of AS location in Wolff-Parkinson-White syndrome (WPW) and the clinical and electrophysiological data of these patients. Methods Electrophysiologic study (EPS) was performed in 503 pts aged from six to 85 years (35 ± 17), 297 men, 206 women, recruited for a patent WPW syndrome. The location of AP was determined on a 12 lead ECG during atrial pacing at maximal preexcitation according to classical criteria. The location was confirmed at EPS. Eleven pts were excluded because the location remained not clearly defined. EPS was indicated for suspected or documented tachycardias ( n = 264), syncope ( n = 68) or was systematic in asymptomatic patients ( n = 171). Results AS AP location was identified in 34 patients aged eight to 48 years (7%). Their mean age was younger than the age of remaining population (25 ± 13 versus 36 ± 17, p < 0.001). According to the age, the prevalence of AS location was significantly higher in children and adolescents (14%) than after 40 years (3%) ( p < 0.01). There was no AS location among 108 patients aged more than 50 years. The maximal rate conducted over AP was lower in patients with AS location than in other locations either in control state (174 ± 60 per minute versus 197 ± 63 per minute) ( p < 0.01) or after isoproterenol (206 ± 71 versus 248 ± 69) ( p < 0.01). The number of induced reciprocating tachycardia (47% versus 57.5%), atrial fibrillation (15% versus 21%) and malign forms (12% versus 17%) did not differ significantly in patients with AS location and in other patients. Anterograde conduction disappeared spontaneously in three of six patients followed 8 ± 1.5 years, and significantly increased in two other patients. Conclusions AS AP location in WPW syndrome was more frequent in children than in adults. The maximal rate conducted over the AP was lower than in other locations. The incidence decreased after 40 years. AS AP location was never noted after 50 years in our population. This disappearance with age should be taken into account for the indications of AS AP ablation.

Radiofrequency ablation of accessory pathways in pre-excitation syndrome

Various parameters relating to the radio-frequency ablation of accessory pathways were studied in 53 patients (27 males, 26 females: mean age 38.5 [14-64] years) with a history of paroxysmal tachycardia (over 1 month to 50 years), shown to be caused by an accessory pathway (Wolff-Parkinson-White syndrome). In all patients the following values were obtained: (1) number of procedures necessary to achieve permanent blockage of the accessory pathway (1-4); (2) duration of each procedure (45-420 min); (3) duration of fluoroscopy (5-102 min); (4) number of necessary radio-frequency applications (1-48); and (5) cumulative energy per procedure. To ablate left-lateral pathways (n = 10) required fewer procedures, shorter duration per procedure, shorter fluoroscopy time, fewer current applications and less total energy than coagulation of right-sided pathways (n = 10). Those various parameters were greatest for ablation of septal and para-septal pathways (n = 9). Pathways which conducted only retrogradely (n = 15) were more difficult to ablate than those with anterograde conduction (n = 38). There were two complications. In one case a tension pneumothorax occurred after faulty puncture of the subclavian vein; in the other, the left ventricle was perforated causing an acute tamponade which required pericardiocentesis with subsequent suture closure of the perforation. It is concluded that, in principle, all accessory pathways, regardless of their conduction potential and site, can be ablated by a radio-frequency current.

Mechanisms for the genesis of paroxysmal atrial fibrillation in the Wolff--Parkinson--White syndrome: intrinsic atrial muscle vulnerability vs. electrophysiological properties of the accessory pathway

Paroxysmal atrial fibrillation (PAF) develops in up to one-third of patients with the Wolff Parkinson-White syndrome (WPW). The reason for this high incidence of PAF in the WPW syndrome is not yet clearly understood. When PAF appears in patients with WPW syndrome who have anterograde conduction via the accessory pathway (AP), it may be life-threatening if an extremely rapid ventricular response develops degenerating into ventricular fibrillation. Several mechanisms responsible for the genesis of PAF in WPW patients were hypothesized, namely, spontaneous degeneration of atrioventricular reciprocating tachycardia into atrial fibrillation (AF), electrical properties of the APs, effects of APs on atrial architecture, and intrinsic atrial muscle vulnerability. Focal activity, multiple reentrant wavelets, and macroreentry have all been implicated in AF, perhaps under the further influence of the autonomic nervous system. AF can also be initiated by ectopic beats originating from the pulmonary veins, and elsewhere. Several studies demonstrated a decrease incidence of PAF after successful elimination of the AP, suggesting that the AP itself may play an important role in the initiation of PAF. However, PAF still occurs in some patients with the WPW syndrome even after successful elimination of the AP. There is an important evidence of an underlying atrial disease in patients with the WPW syndrome. Atrial vulnerability has been studied performing an atrial endocardial catheter mapping and analysing abnormal atrial electrograms. Other studies evaluated atrial refractoriness and intraatrial conduction times, suggesting an intrinsic atrial vulnerability as the mechanism of PAF and considering the AP as an innocent bystander. It is our intention to analyse the available data on this particular and interesting topic since AF has a singular prognostic significance in patients with the WPW syndrome, and its incidence is unusually high in the absence of any clinical evidence of cardiac organic disease.

Stability of the fittest: organizing learning through retroaxonal signals

Classically, neurons communicate by anterograde conduction of action potentials. However, information can also pass backward along axons, a process that is essential during the development of the nervous system. Here we propose a role for such 'retroaxonal' signals in adult learning. We hypothesize that strengthening of a neuron's output synapses stabilizes recent changes in the same neuron's inputs. During learning, the input synapses of many neurons undergo transient changes, resulting in altered spiking activity. If this in turn promotes strengthening of output synapses, the recent synaptic changes will be stabilized; otherwise they will decay. A representation of sensory stimuli therefore evolves that is tailored to the demands of behavioral tasks. We describe a candidate molecular mechanism for this process involving the activation of CREB by retrograde neurotrophin signals.

Sequential dual chamber extrastimulation: A novel pacing maneuver to identify the presence of a slowly conducting concealed accessory pathway

Transient VA block can be created in the AV node (AVN) when an atrial extrastimulus is delivered at the AVN effective refractory period (ERP) due to anterograde concealed conduction. We hypothesized that ventricular stimulation during pacing-induced AVN refractoriness could identify concealed accessory pathways (APs) that remain hidden with standard maneuvers. Patients undergoing electrophysiological study for supraventricular tachycardia were screened for presence of an AP using standard pacing maneuvers and/or V pacing during adenosine infusion. The dual-chamber sequential extrastimulation maneuver consisted of an 8-beat drive train of simultaneous AV pacing at 600 msec, followed by an A2 delivered at AVN ERP, followed by a V2 delivered at the drive train cycle length (600 msec). Repeat drives were then performed with decrements of 10 msec for V2 until VA block was seen. Retrograde AVN and AP ERP were recorded with standard (V1, V2) and dual-chamber extrastimulation (A1/V1, A2, V2). Patients with an AP identified with standard pacing, manifest pre-excitation, or A ERP < AVN ERP were excluded. Fourteen patients with and 19 patients without an AP were studied. In all patients with an AP, exclusive VA conduction over the AP, without fusion, was seen with the described pacing maneuver. In patients without an AP, retrograde AV nodal ERP was extended by a mean of 138 +/- 46 msec (range 50 to 210 msec) with the A2. Anterograde concealed conduction into the AP was also seen in some patients who showed AP conduction during standard V1V2 pacing (mean retrograde extension of ERP 12 +/- 8 msec, range 0 to 20 msec). Dual-chamber sequential extrastimulation is a useful maneuver for identifying slowly conducting APs not revealed with standard pacing maneuvers because of an ERP and conduction time similar to the AVN. The maneuver uses anterograde concealed conduction to prolong AVN refractoriness much more than that of a concealed AP, thereby allowing the AP to become manifest with the V2.

Supernormal Conduction in the Anomalous Bundles of the Wolff-Parkinson-White Syndrome: An Overlooked Electrophysiologic Property With Potential Clinical Implications

The anterograde refractory period (RP) of the accessory pathway (AP) is the main determinant factor of ventricular rate during atrial fibrillation in the Wolff-Parkinson-White (WPW) syndrome. We describe 3 examples of anterograde supernormal conduction (SNC) and 1 of retrograde SNC in APs. The paradoxical early recovery of propagation due to SNC, well inside a prolonged anterograde RP in the AP, may play a relevant role to determine the rate of ventricular response during atrial fibrillation, eventually leading to extremely fast ventricular rates, syncope, and even ventricular fibrillation in patients with WPW syndrome supposed a priori to be exposed to a low risk of sudden cardiac death. This may require very precise conditions, including an enhanced adrenergic influence on the heart. Retrograde SNC in APs may also participate in the mechanism of paroxysmal supraventricular tachycardias that are not easily induced by programmed cardiac stimulation.

Automaticity with anterograde conduction of a concealed accessory pathway due to radiofrequency energy application

We report a case of a patient with recurrent episodes of supraventricular tachycardia in which a concealed left-posterior accessory pathway-mediated orthodromic tachycardia was reproducibly induced during the EP study. Two interesting and very unusual electrophysiological phenomenon were observed at the same time during the ablation procedure of the accessory pathway: 1— Automaticity of the regular accessory atrioventricular pathway; 2— Emergence of manifest preexcitation following radiofrequency application exclusively during the automatic accessory pathway-mediated rhythm.

Interventional Electrophysiology in Patients With Congenital Heart Disease

“The treatment of congenital heart disease is unsatisfactory. As a rule, nothing can be done to improve patients symptomatically; in some instances digitalis may be of help.” — —L. Emmett Holt, MD, 1933 On August 26, 1938, Dr Robert Gross performed the first successful surgery for a congenital heart defect by closing a patent ductus arteriosus in a 7-year-old girl. The event marked the beginning of an interventional approach to congenital heart disease (CHD) that forever banished the sort of pessimism expressed by Dr Holt in his classic pediatric textbook only 5 years earlier.1 Subsequent diagnostic and operative innovations ultimately led to surgical solutions for nearly all anatomic heart defects, allowing the vast majority of infants born with CHD in the modern era to survive into adulthood. However, improved hemodynamic longevity has exposed alternate sources of morbidity and mortality for this population, central among which are cardiac rhythm disorders. In some instances, arrhythmias are intrinsic to the CHD lesion itself, but in most cases, they arise as an unintended consequence of prior corrective surgery whenever patches and suture lines function in conjunction with hypertrophy and fibrosis to create the substrate for reentrant tachycardias. It is fortunate that improved understanding of rhythm abnormalities in CHD has coincided with the emergence of interventional electrophysiological techniques. Catheter ablation, arrhythmia surgery, pacemakers, and implantable defibrillators have now become indispensable treatment options for this group. It is the purpose of this article to review the application of these tools to CHD with an emphasis on unique technical challenges. Congenital heart defects occur in roughly 0.8% of live births, and in 30% to 50% of cases, the malformations are severe enough to warrant ≥1 surgical procedures during early childhood.2 Arrhythmia mechanisms vary according to the underlying anatomic defect and method of surgical repair. The …

Tachycardiomyopathy Secondary to Nonreentrant Atrioventricular Nodal Tachycardia: Recovery After Slow Pathway Ablation

Nonreentrant atrioventricular (AV) nodal tachycardia is a rare form of arrhythmia due to simultaneous anterograde conduction in dual AV pathways, one atrial impulse triggering two ventricular complexes. We report the case of a 74-year-old man referred for incessant palpitations resistant to antiarrhythmic medication, and effort dyspnea. A nonreentrant AV nodal tachycardia is diagnosed with electrophysiological study. A dilated cardiomyopathy with left ventricular dysfunction is found with gated blood pool single-photon emission computed tomography. A radiofrequency catheter ablation of the slow pathway is successfully performed. The patient is reassessed 11 months after ablation. He is asymptomatic and left ventricular function has fully recovered.

Pseudo–Atrial Fibrillation, Rare Manifestation of Multiple Anterograde Atrioventricular Nodal Pathways

In patients with dual or multiple atrioventricular (AV) nodal pathways manifesting nonreentrant tachycardia or unusual forms of AV nodal reentry, paroxysmal atrial fibrillation is often misdiagnosed and patients may erroneously be considered for pulmonary vein isolation. Multiple anterograde slow AV nodal pathways, identified by >1 discontinuity in the anterograde AV nodal conduction curve, are not rare in patients with slow-fast AV nodal reentrant tachycardia (AVNRT). However, only 1 slow AV nodal pathway is usually involved in anterograde conduction during tachycardia. It was reported that patients with multiple anterograde slow AV nodal pathways presented with different tachycardia cycle lengths. For the first time, 2 patients with AVNRT in which maintenance of tachycardia was strictly dependent on participation of 3 different anterograde slow AV nodal pathways in an uniquely alternating sequence are reported. In both patients, a single application of radiofrequency energy in the posterior aspect of Koch's triangle eliminated simultaneously all evidence of anterograde slow pathway conduction. These findings implied that functional differences in a determined circuit based on nonuniform anisotropy rather than anatomically distinct pathways form the electrophysiologic basis for this rare variant of AVNRT. In conclusion, particularly in patients with lone atrial fibrillation who are potential candidates for pulmonary vein isolation, careful analysis of the surface electrocardiogram during irregular supraventricular tachycardia and invasive electrophysiologic examination helps identify rare arrhythmia mechanisms that can be cured by slow pathway ablation alone.

A NavX™ -guided ablation of a nodo-fascicular fibre

The NavX system was used to guide mapping and successful ablation of a reciprocating antidromic tachycardia involving anterograde conduction over a nodo-fascicular fibre and retrograde conduction over the His bundle and AV node. This novel mapping system allowed visualization of the lower insertion site of the nodo-fascicular accessory pathway approximately 1.5-2 cm away from the tricuspid annulus in a three-dimensional reconstruction of the right atrium and right ventricle.

Noninvasive Classification of Ventricular Preexcitation with Unshielded Magnetocardiography and Transesophageal Atrial Pacing and Follow‐Up

Ventricular preexcitation (VPx) is usually localized noninvasively by means of electrocardiogram (ECG) algorithms, which vary in their concordance levels. Contactless magnetocardiography (MCG) has been used as an alternate 3-dimensional (3D) method of accessory pathways (AP) localization. The sensitivity of MCG can be increased for preoperative evaluations and planning of ablation procedures by combining it with transesophageal pacing (TEP) and electrophysiological (EP) studies. This study compared the accuracy of VPx localization with MCG with ECG algorithms, and examined the increment in diagnostic accuracy achievable with TEP. Multisite mapping from the anterior chest wall was performed with a 36-channel MCG system. TEP allowed the evaluation of anterograde conduction properties and inducibility of arrhythmias. The reproducibility of the test and follow-up was examined in 88 patients with Wolff-Parkinson-White (WPW) syndrome. The accuracy of MCG localization was reevaluated during pacing-induced maximal VPx in 36 patients in whom, during MCG, the degree of VPx was highest during TEP. The gold standard for validation was effective ablation of the AP. The MCG classification of VPx was accurate in 94% of AP, versus 64% and 67% with ECG, during sinus rhythm and during pacing-induced maximal VPx, respectively. In 4.5% of cases with unclear ECG localization, MCG suggested a complex septal VPx. In all patients with successful ablations, the 3D MCG localization of the AP corresponded to the ablation site. MCG was more accurate than ECG for the classification of VPx and provided additional information in the non-invasive EP assessment of patients with WPW syndrome.

Influence of Reciprocating Tachycardia on the Development of Atrial Fibrillation in Patients with Preexcitation Syndrome

We sought to evaluate the influence of atrio-ventricular reentrant tachycardia (AVRT) on atrial pressures during tachycardia and the presence of atrial fibrillation (AF) in patients with preexcitation syndrome. The study population consisted of 88 patients (37 females, mean age 37.3 years) with left-sided accessory pathway and AVRT induced during electrophysiologic study. The AF-inducible group consisted of 32 patients with sustained episodes of AF provoked during electrophysiologic study, whereas the noninducible group comprised 56 patients without AF. We found significantly higher values of maximal and mean left (LAP) and right (RAP) atrial pressures in the AF group compared with noninducible group: LAP max 32.0 versus 20.8, LAP mean 21.6 versus 13.2, RAP max 15.2 versus 11.5, RAP mean 8.2 versus 6.2 respectively (P < 0.001). When analyzing the effect of AVRT on atrial pressures, we found a significant (P < 0.001) negative correlation between anterograde conduction times during tachycardia and LAP max and LAP mean in the whole population, but a significant positive correlation between retrograde conduction time and left atrial pressures. Similar effects of AVRT on the right atrial pressures were found. Atrial pressures during AVRT, which depend on the electrophysiological features of tachycardia, play an important role in the genesis of atrial fibrillation in patients with preexcitation syndrome.

FBI (Fast Broad Irregular)

HomeCirculationVol. 114, No. 24FBI (Fast Broad Irregular) Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessReview ArticlePDF/EPUBFBI (Fast Broad Irregular)A Case for the Secret Service? Sergio Richter, MD and Pedro Brugada, MD, PhD Sergio RichterSergio Richter From the Heart Rhythm Management Institute, Department of Cardiology, Free University of Brussels, Brussels, Belgium. Search for more papers by this author and Pedro BrugadaPedro Brugada From the Heart Rhythm Management Institute, Department of Cardiology, Free University of Brussels, Brussels, Belgium. Search for more papers by this author Originally published12 Dec 2006https://doi.org/10.1161/CIRCULATIONAHA.106.641746Circulation. 2006;114:e638–e639A 34-year-old man without a medical history of cardiac disease presented to our emergency room with fast and irregular palpitations. An instantaneously recorded surface ECG revealed the diagnosis (Figure). The tracing showed an irregular, wide QRS-complex tachycardia with right bundle-branch block, right superior axis deviation, and short RR intervals varying from 160 to 340 ms. The widths of the right bundle-branch block–shaped QRS complexes varied in response to changes in ventricular cycle length. A narrow QRS complex with normal axis was observed (Figure, asterisk), indicating a normally conducted capture beat. Download figureDownload PowerPointTwelve-lead ECG during fast, broad, and irregular (FBI) tachycardia. Preexcited atrial fibrillation with rapid anterograde conduction over a left posterolateral bypass tract is present. Note the normal, narrow QRS complex (asterisk) among the irregularly irregular preexcited ventricular complexes and the varying degrees of preexcitation depending on variation in ventricular cycle length (the concertina phenomenon). The shortest RR interval is 160 ms.This grossly irregular, rapid right bundle-branch block tachycardia represented preexcited atrial fibrillation (AF) with anterograde conduction over a left posterolateral accessory pathway, leading to irregularly irregular preexcited ventricular complexes with varying degrees of preexcitation. The shortest RR interval during preexcited AF was 160 ms, indicating a short anterograde refractory period of the accessory pathway and an increased risk for the development of ventricular fibrillation and sudden death.The differential diagnosis of preexcited AF includes ventricular tachycardia and atrial fibrillation with aberrancy. The presence of an apparent fusion and capture beat could lead one to the diagnosis of ventricular tachycardia, because these findings are considered diagnostic for ventricular tachycardia. Morphologically speaking, the tachycardia is ventricular in origin. Nevertheless, the marked cycle-length variation of more than 100% strongly argues against ventricular tachycardia and instead favors preexcited AF as the underlying arrhythmia mechanism. The right superior axis deviation and the fact that longer RR intervals lead to more fully preexcited QRS complexes compared with shorter RR cycles (the concertina phenomenon) virtually exclude AF with solely aberrant conduction.Preexcited atrial fibrillation with rapid ventricular response reveals a typical electrocardiographic pattern that is often diagnostic at first glance. Because of its characteristic ECG features (fast, broad, and irregular), this tachyarrhythmia has been named FBI tachycardia. This potentially life-threatening clinical condition is obviously a case for the emergency rather than the secret service.DisclosuresNone.FootnotesCorrespondence to Sergio Richter, MD, Heart Rhythm Management Institute, Department of Cardiology, Free University of Brussels, Laarbeeklaan 101, 1090 Brussels, Belgium. E-mail [email protected] Previous Back to top Next FiguresReferencesRelatedDetailsCited By Littmann L, Olson E and Gibbs M (2019) Initial evaluation and management of wide-complex tachycardia: A simplified and practical approach, The American Journal of Emergency Medicine, 10.1016/j.ajem.2019.04.027, Online publication date: 1-Apr-2019. December 12, 2006Vol 114, Issue 24 Advertisement Article InformationMetrics https://doi.org/10.1161/CIRCULATIONAHA.106.641746PMID: 17159067 Originally publishedDecember 12, 2006 PDF download Advertisement SubjectsArrhythmiasElectrophysiology

Latent Atriofascicular Pathway Participating in a Wide Complex Tachycardia: Differentiation from Ventricular Tachycardia

Accessory pathways with anterograde decremental conduction properties usually are characterized by presence of antegrade preexcitation during atrial pacing. We report a 38-year-old man with frequent episodes of palpitation. No evidence of ventricular preexcitation was seen during sinus rhythm or atrial pacing. All electrophysiologic maneuvers were compatible with an antidromic tachycardia using atriofascicular pathway as the antegrade limb and the atrioventricular nodal pathway as retrograde limb. Radiofrequency ablation at recording site of accessory pathway potential resulted in cure of tachycardia with no recurrence during 3-month follow-up. This report indicated that atriofascicular pathway-mediated tachycardia should be considered in differential diagnosis of all cases of wide complex tachycardia with left bundle branch morphology and left axis.

Twin atrioventricular node associated with interruption of the inferior vena cava and atrioventricular nodal reentrant tachycardia

We report the case of a patient exhibiting symptomatic junctional bigeminy associated with twin atrioventricular (AV) node and an anomaly in the inferior vena cava. The patient evidenced twin AV node and complete interruption of the inferior vena cava, with azygos continuation. The catheters for mapping of the AV junctional area and ablation were accessed via jugular and subclavian venous approaches, and azygos venous approach via the femoral vein. Twin AV node was diagnosed by (1) the existence of 2 discrete non-preexcited QRS morphologies of junctional bigeminy, (2) decremental anterograde and retrograde conduction, and (3) inducible AV nodal reentrant tachycardia. Atrioventricular nodal reentrant tachycardia and bigeminal rhythm were eliminated by ablation of the retrograde pathway. The postablation rhythm was a regular junctional rhythm, without tachycardia.

(Artigo 10 publicado v.28 n.2) O efeito da morfina na inibição vagal do coração: demonstração da dupla via do nodo atrioventricular

That electrical stimulation of the vagus decreased heart rate and increased the PQ interval in electrocardiogram, consistent with anterograde dual atriventricular conduction. The present experiments were investigating the interaction of the morphine with cardiac parasympathetic nervous control in dual atrioventricular node. Electrical stimulation of the vagus nerve induced significant bradycardia and of third degree atrioventricular block and the P wave appearance was negative in leads II. Because background anesthesia modulates the heart, administered morphine injection the P waves appearance was positive through one inhibitory action on atrioventricular nodal reentry. All suggest the presence of two functionally and anatomically distinct atrioventricular pathways

Successful Elimination of Concealed Accessory Pathway‐Mediated Tachycardia by Ablation of AV Nodal Slow Pathway

We report a case of atrioventricular reentrant tachycardia (AVRT) using a concealed para-Hisian accessory pathway for retrograde conduction, which also required anterograde conduction over the AV nodal slow pathway to maintain the tachycardia. The shortest VA interval during AVRT (70 ms) was noted at a site with His bundle electrogram amplitude of 0.25 mV. The AVRT was cured by radiofrequency ablation of the AV nodal slow pathway without affecting accessory pathway conduction. The patient has not reported any sustained palpitations at 2 years after ablation while receiving no medications. The case presented in this report illustrates a para-Hisian AVRT that was successfully eliminated by an unconventional approach of ablation of the atrial inputs to the AV nodal slow pathway.

Effects of Right Bundle Branch Block on the Antidromic Circus Movement Tachycardia in Patients with Presumed Atriofascicular Pathways

The typical and most common tachycardia in patients with atriofascicular pathways is a macro reentrant tachycardia, with anterograde conduction over the decrementally conducting bypass tract and retrograde conduction over the right bundle branch-His-AV node axis resulting in a short V-right bundle branch and short V-H interval. To report on changes in rate and QRS configuration when right bundle branch block (RBBB) develops spontaneously during antidromic tachycardia using an atriofascicular fiber. Three of 25 patients with an antidromic circus movement tachycardia using a right-sided atriofascicular pathway showed episodes of right bundle branch block (RBBB) during ventriculo-atrial conduction. Effect of retrograde RBBB on tachycardia rate and QRS configuration was studied using intracardiac and extracardiac recordings. All 3 patients showed prolongation of their V-A interval when retrograde RBBB occurred during tachycardia, resulting in a longer tachycardia cycle length. The VA time increase ranged from 85 to 100 msec, with a mean 346 +/- 5 msec. Two of the 3 patients also showed a change in QRS configuration due to a more leftward shift of the frontal plane QRS axis. Rate changes in antidromic tachycardia in patients with atriofascicular fibers can be based on a shift in VA conduction from one bundle branch to the other. This may be accompanied by changes in the frontal plane QRS axis because of a change in ventricular activation sequence.

When to Perform Catheter Ablation in Asymptomatic Patients With a Wolff-Parkinson-White Electrocardiogram

What to do when a person without any cardiac complaint shows a Wolff-Parkinson-White (WPW) pattern on the ECG has been an important question for more than 2 decades. Recent articles by Pappone et al1–3 make it necessary to revisit that question. Epidemiological data indicate that 0.1% to 0.3% of the general population have ECG findings suggesting that during sinus rhythm, in addition to AV conduction over the AV node His pathway, there is also AV conduction over an accessory AV pathway (AP).4 This means that each year ≈4 new cases are found in a population of 100 000. It is also known that there is a 4-fold increase of this finding in family members of WPW patients.5 The WPW patient is often symptomatic because of cardiac arrhythmias. When arrhythmias are present, the disorder is called the WPW syndrome. The 2 most common types of arrhythmia in the WPW syndrome are (1) a circus movement tachycardia (CMT), also called an AV reentrant tachycardia, in which AV conduction goes by way of the normal AV conduction system and VA conduction over the AP and (2) atrial fibrillation (AF).6 AF can be a life-threatening arrhythmia in the WPW syndrome if the AV AP has a short anterograde refractory period (RP), allowing many atrial impulses to be conducted to the ventricle. That will result in very high ventricular rates with possible deterioration into ventricular fibrillation (VF) and sudden death.7,8 A CMT that in general is well tolerated by the patient when additional heart disease is absent may deteriorate into AF, and the ventricular rate and risk for VF will depend on the anterograde RP of the AP. Therefore, the most important question in the asymptomatic WPW patient in whom the typical ECG accidentally is recorded is whether he or …