Provocation of Atrioventricular Reentry Tachycardia: A Paradoxical Effect of Adenosine

Adenosine has been used to diagnose latent preexcitation in patients with the Wolff-Parkinson-White syndrome. A case is reported in which intermittent preexcitation had been previously observed, however only retrograde accessory pathway conduction was documented at the time of invasive eiectrophysiological study, Administration of intravenous adenosine during sinus rhythm resulted in provocation of orthodromic atrioventricular reentry tachycardia.     

Right Atrial Diverticulum Presenting as Wolff-Parkinson-White Syndrome

A 7-year-old male presenting with Wolff-Parkinson-White syndrome and tachycardia was suspected by echocardiographic and magnetic resonance imaging evaluation to have an associated pericardial cyst anterior to the right atrium and ventricle. Electrophysiological evaluation demonstrated short antegrade and retrograde accessory connection refractory periods, with inducible orthodromic atrioventricular reentrant tachycardia. Surgical observation revealed a rare congenital right atrial diverticulum bridging the anterior right atrioventricular groove, with the functional accessory connection lateralized to the medial aspect of this structure. Endocardial and epicardial incisions and cryolesions placed along the anterior right atrioventricular groove initially appeared successful, but preexcitation recurred within 4 weeks postoperatively.     

Diagnosis and Surgical Treatment of Tachycardias in Patients with Nodoventricular Fibers

From May, 1982 to April, 1991 25 patients were examined and 23 had open heart surgery for tachycardia with nodoventricular fibers (NVF) participation. All patients suffered tachycardia for more than 5 years. Most patients had syncope. The patients had: true NVF tachycardia (11), atrioventricular node reentry tachycardia (5), orthodromic atrioventricular tachycardia (AVT) (5), and atrial flutter (1) all with passive propagation through NVF, pseudonodoventricular tachycardia (AVT with slow accessory pathways) two patients. In 18 out of the 23 who had surgery there were no signs of preexcitation or tachycardia events in the follow-up period.     

Intravenous Adenosine Reveals Intermittent Preexcitation by Direct and Indirect Effects on Accessory Pathway Conduction

In some patients with accessory pathways preexcitation occurs intermittently during sinus rhythm. In these patients the antegrade refractory period of the accessory pathway may either exceed the sinus cycle length under some circumstances, or conduction block in the accessory pathway may be variable. The ability of intravenous adenosine to unmask intermittent preexcitation was determined in patients with intermittent preexcitation but absent preexcitalion at the time of study. Six patients undergoing assessment of the Wolff-Parkinson-White syndrome received incremental doses of intravenous adenosine (3, 6, and 12 mg). Adenosine administration was repeated in three patients after intravenous β blockade (propranolol 0.2 mg/kg). Adenosine unmasked preexcitation in all patients. P delta intervals with preexcited beats were substantially shorter Ihan resting PR intervals in all cases (range 40–80 msec shorter). In 4/6 patients preexcitation was seen early, coincident with the onset of atrioventricular nodal block. In 4/6 patients preexcitation was seen late during the secondary sinus tachycardia that follows the direct cardiac effects of adenosine. Two patients exhibited early preexcitation and late preexcitation. Beta blockade failed to prevent early preexcitation (2/2 patients) but abolished preexcitation related to sinus tachycardia (3/3 patients). Early preexcitation, coincident with the onset of AV nodal block, suggests a direct effect of adenosine on accessory pathway conduction. Late preexcitation, occurring during secondary sinus tachycardia, and abolished by β blockade, suggests enhanced accessory pathway conduction due to sympathetic activation.     

Atypical Form of the Fourth Criterion for Transient Entrainment

The typical fourth criterion for transient entrainment is defined when both a sudden shortening in conduction interval to and a distinct change in electrogram morphology at a bipolar recording site are demonstrated while performing overdrive pacing of a reentrant tachycardia from a single pacing site at two different constant rates. The purpose of this article was to test the hypothesis that if an intracardiac recording site showing both orthodromic and antidromic capture with entrainment pacing is located suitably distant from the circuit, sudden shortening in conduction interval to that site may occur without any significant change in the bipolar electrogram morphology (i.e., atypical form of the fourth criterion). Atrial overdrive pacing of orthodromic tachycardia was performed in 20 patients with either left anterior (12 patients) or left posterior (8 patients) accessory pathways. We investigated the effects of overdrive pacing from the proximal or distal coronary sinus, specifically effects on the electrogram interval and the electrogram morphology at the right atrial appendage. Overdrive pacing of orthodromic tachycardia from the proximal coronary sinus was performed in 10 of the 12 patients with left anterior accessory pathways; those 10 patients demonstrated the first entrainment criterion at the right atrial appendage site. Overdrive pacing of orthodromic tachycardia at still shorter cycle lengths demonstrated a sudden shortening in conduction interval to the right atrial appendage site. Despite shortening in conduction interval the morphology of the right atrial appendage electrogram was completely or almost identical to that during orthodromic tachycardia, indicating an atypical form of the fourth criterion. This criterion was not demonstrated in patients with left posterior accessory pathways. Thus, atypical fourth entrainment criterion was demonstrated during overdrive pacing of orthodromic tachycardia from the proximal coronary sinus only in patients with left anterior accessory path ways. Demonstration of atypical fourth criterion seems largely dependent on the location of the accessory pathway, the pacing, and the recording sites.     

Radiofrequency Ablation of Anteroseptal, Para-Hisian, and Mid-Septal Accessory Pathways Using a Simplified Femoral Approach

Feasibility of RF ablation using a simplified two-catheter technique from a femoral approach was studied in 97 consecutive patients with a manifest or concealed accessory pathway located at the anteroseptal, mid-septal, and para-Hisian areas. BF was applied at the site with the shortest V-delta interval or the earliest retrograde atrial activation during orthodromic tachycardia or right ventricular pacing. Ablation was initially successful in 88 of'97 patients (91 %). Success rate was 94% (16/17) for anteroseptal. 94% (39/43] for para-Hisian, and 89% (33/37) for mid-septal accessory pathways, without differences between manifest and concealed pathways for any of the locations. Mean number of BF pulses was 8 ± 5 for anteroseptal, 6 ± 6 for mid-septal, and 12 ± 13 for para-Hisian accessory pathways. Two patients (2%) required implantation of a permanent pacemaker for complete A V block. At a mean follow-up of 27 ± 14 months, four patients with previous manifest preexcitation experienced resumption of intermittent preexcitation, but only one required a second successful procedure for recurrence of palpitations. RF ablation can be used effectively and without impairment of normal AV conduction in the majority of patients with anteroseptal, para-Hisian, and mid-septal accessory pathways using a simplified two-catheter technique from a femoral approach.     

Radiofrequency Catheter Ablation of Accessory Pathways During Entrainment of AV Reentrant Tachycardia

Radiofrequency ablation of accessory pathways must sometimes be done during orthodromic atrioventricular reentrant tachycardia when manifest anterograde accessory pathway conduction is absent or retrograde fusion obscures accessory pathway location during ventricular pacing. Unfortunately, abrupt heart rate slowing upon radiofrequency induced termination of atrioventricular reentrant tachycardia often causes catheter dislodgment. We report our experience in circumventing this problem during radiofrequency ablation by using entrainment of atrioventricular reentrant tachycardia. The latter maintains retrograde activation pattern over the accessory pathway while preventing abrupt ventricular rate change. Eight patients (4 men and 4 women, mean age 37.3 ± 17.9) with eleven left-sided accessory pathways were included. Ablation during entrainment was used as the first approach in three patients with concealed accessory pathways and one patient with a bidirectional accessory pathway. In another four patients, ablation during entrainment was used after technical difficulties in ablating during tachycardia. Only 1–3 radiofrequency applications were required to eliminate the accessory pathway using the entrainment technique. The catheter remained stable when accessory pathway conduction was interrupted by radiofrequency current. In conclusion, entrainment of atrioventricular reentrant tachycardia during radiofrequency application is useful for maintaining catheter position for accessory pathway ablation during atrioventricular reentrant tachycardia.     

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.     

Wide QRS Tachycardia Due to AV Nodal Reentry and a "Bystander" Bypass Tract with Slow Conduction Properties

An unusual mechanism for recurrent, wide QRS complex supraventricular tachycardia is described in this report. A 25-year-old man with normal PR and QRS intervals during sinus rhythm was shown to have preexcitation with a left bundle branch block pattern during tachycardia and during atrial pacing. Electrophysiologic studies demonstrated slow and decremental conduction properties in an accessory "bystander" AV pathway utilized for antegrade conduction during AV nodal reciprocating tachycardia. The differential diagnosis of this tachycardia is discussed in detail.     

Intermittent Preexcitation: Marked Enhancement of Anterograde Conduction in the Atrioventricular Accessory Pathway with Isoproterenol

A 29-year-old man presented with intermittent preexcitation and exertional syncope. Electrophysiological evaluation in the control state demonstrated a single, left posterior free-wall atrioventricular accessory pathway. The anterograde and retrograde effective refractory periods and block cycle lengths were long in the control state. No tachycardias were induced during programmed electrical stimulation. After intravenous administration of isoproterenol, anterograde conduction of the accessory pathway was markedly enhanced (block cycle length shortened 45% to less than 240 ms) and rapid antidromic reciprocating tachycardia (CL = 250 ms) associated with syncope was observed. Following successful surgical dissection of the accessory pathway the patient has been without tachycardia or exertional symptoms. We conclude that, under the influence of exercise or emotion, patients with intermittent preexcitation may be at risk for serious arrhythmias.     

Correlations Between the Localization of Accessory Atrioventricular Pathway and Doppler Indices of Left Ventricular Output and Function in Patients With Wolff-Parkinson-White Syndrome

Left ventricular (LV) output and function was investigated, using pulsed Doppler echocardiography in 52 patients with various localizations of accessory AV pathway (AP) in sinus rhythm and during paroxysm of AV reentrant tachycardia. In patients with sinus rhythm and ventricular preexcitation the most marked decrease in LV output and function (reduced aortic flow peak velocity [PV], mean acceleration [MA], stroke distance [SD], minute distance [MD], and lengthened time to peak velocity [TTP]) was noted in the presence of right parietal AP and less marked changes (decreased MA, lengthened TTP)--in the presence of posteroseptal AP, in comparison with the controls (P less than 0.005). During antidromic tachycardia the pronounced decrease in PV, MA, SD, and MD was noted, especially in patients with left parietal and posteroseptal AP, while in the case of right parietal AP changes in MA and MD were insignificant. During orthodromic tachycardia the decrease in LV function was less marked and no significant differences in the magnitude of LV output and function changes were found in various localizations of AP, except MA, which was more severely decreased in patients with posteroseptal AP. We conclude, that the alterations in Doppler indices of LV output and function are related to the localization of AP during AV reentrant tachycardia and regular sinus rhythm.     

Electrophysiologic Demonstration of an Atriofascicular Accessory Pathway

Evidence of an atriofascicular accessory pathway has not been reported previously. In the patient presented in this case report, an electrophysiology study demonstrated a constant left bundle branch block QRS configuration despite varying degrees of ventricular preexcitation, in association with a constant artrioventricular interval during incremental atrial pacing and programmed atrial stimulation. The presence of an atrioventricular, nodoventricular, nodofascicular, and atrial-His accessory pathway was ruled out. The findings are best explained by the presence of an underlying left bundle branch block and an atriofascicular accessory pathway connecting the atrium and right bundle. The atriofascicular accessory pathway was a passive bystander during an atrial tachycardia and was not directly involved in the generation of the tachycardia. To our knowledge, this is the first report of an atriofascicular accessory pathway.     

Fulguration of Accessory Pathways in any Location: Report of Seventy Cases

Ablation of accessory pathways (AP) in any location was performed in 70 consecutive patients using either a right or a left approach. Left free wall pathways were approached via a patent foramen ovale (eight patients) or by transseptal catheter (eight patients). The best ablation site was localized by recording a potential most likely due to Kent bundle activation (33/70 patients), the earliest site of retrograde atrial activation during orthodromic reciprocating tachycardia, earliest ventricular potentials recorded before or synchronous with the delta wave in standard ECG leads, disappearance of preexcitation due to pressure of the catheter on the AP (eight patients), good degree of pacemap concordance with ventricular preexcitation. Two 160 joules cathodal shocks in close succession were delivered and the sequence reeated depending on the results. Preexcitation disappeared in 63 patients and there was no recurrence of arrhythmia in 68 patients without any antiarrhythmic therapy over a follow-up ranging from 1 to 42 months. No serious side effects were observed except for two patients who developed permanent complete AV block. However, one of them occurred after an unsuccessful surgical attempt which had damaged the AV function. Fulguration is effective for APs in diverse locations. These results indicate that appropriate treatment of patient with the Wolff-Parkinson-White syndrome should be reassessed. At present, the therapy of arrhythmias related to the Wolff-Parkinson-White syndrome is no longer a question of either antiarrhythmic drugs or surgery. Fulguration, in our experience, is effective for abolishing accessory pathways in any location.     

Electrophysiologic mechanisms of functional bundle branch block at onset of induced orthodromic tachycardia in the Wolff-Parkinson-White syndrome. Role of stimulation method.

The mechanisms of aberrant conduction at the onset of induced orthodromic tachycardia in the Wolff-Parkinson-White syndrome were analyzed in 20 consecutive patients in whom this tachycardia was initiated by the atrial (A2) and/or right ventricular (V2) extrastimulus techniques. Of 13 patients in whom orthodromic tachycardia was induced by the A2 method, functional right bundle branch block occurred at tachycardia onset in four (31%) and left bundle aberrancy in two (15%), one of whom also manifested right bundle aberrancy. The occurrence of bundle branch block at the onset of tachycardia was linked to aberrant conduction of the initiating A2 impulse which, in turn, was associated with attainment of relatively short His1His2 intervals within the tachycardia initiation zone. Aberrant conduction of A2 was also more common in patients without manifest preexcitation. In contrast, of 14 patients in whom orthodromic tachycardia was induced by the V2 method, left bundle aberrancy occurred at the onset of tachycardia in 11 (79%), one of whom manifested right bundle branch block as well. Left bundle aberrancy was more likely to occur when the interval from the initiating V2 (or macro-reentrant V3) impulse to the first anterograde His deflection was less than 300 ms. This suggests that left bundle aberrancy at the onset of orthodromic tachycardia induced by the V2 method results from concealed retrograde penetration of the His-Purkinje system, with the left bundle being last to recover. Our findings provide the conceptual basis for a physiologic approach to the deliberate induction of specific types of aberrant conduction at onset of orthodromic tachycardia in patients with Wolff-Parkinson-White syndrome.     

Radiofrequency ablation of an accessory pathway in a surgically created atrioventricular Fontan anastomosis: case report and review of previous published cases

Supraventricular tachyarrhythmias following the Fontan procedure can be life-threatening. Though most are commonly due to intraatrial reentry, orthodromic reentrant tachycardia may also be present. Atrioventricular accessory pathways may develop across suture lines following right atrial to right ventricular anastomosis in patients with tricuspid atresia. We report a case of a patient who underwent this type of Fontan who developed orthodromic reentrant tachycardia and heart failure. An electrophysiological study revealed the presence of an atrioventricular accessory pathway traversing the Fontan anastomosis suture line. Successful radiofrequency ablation of the accessory pathway led to control of the tachyarrhythmia and improvement of heart failure.     

Atrial Flutter with 1:1 Conduction in Undiagnosed Wolff-Parkinson-White Syndrome

Background

Atrial flutter with 1:1 atrioventricular conduction via an accessory pathway is an uncommon presentation of Wolff-Parkinson-White syndrome not previously reported in the emergency medicine literature. Wolff-Parkinson-White syndrome, a form of ventricular preexcitation sometimes initially seen and diagnosed in the emergency department (ED), can present with varied tachydysrhythmias for which certain treatments are contraindicated. For instance, atrial fibrillation with preexcited conduction needs specific consideration of medication choice to avoid potential degeneration into ventricular fibrillation.

Case Report

We describe an adult female presenting with a very rapid, regular wide complex tachycardia successfully cardioverted in the ED followed by a normal electrocardiogram (ECG). Electrophysiology study confirmed atrial flutter with 1:1 conduction and revealed an accessory pathway consistent with Wolff-Parkinson-White syndrome, despite lack of ECG findings of preexcitation during sinus rhythm.Why should an emergency physician be aware of this? Ventricular tachycardia must be the first consideration in patients with regular wide complex tachycardia. However, clinicians should consider atrial flutter with 1:1 conduction related to an accessory pathway when treating patients with the triad of very rapid rate (>250 beats/min), wide QRS complex, and regular rhythm, especially when considering pharmacologic treatment. Emergency physicians also should be aware of electrocardiographically concealed accessory pathways, and that lack of delta waves does not rule out preexcitation syndromes such as Wolff-Parkinson-White syndrome.     

Mechanical Ablation of Concealed Left Lateral Bypass Tract

A 50-yaer-old man with hypertension had been treated for supraventricular tachycardia with several medications for nine years. In 1990, he was started on amiodarone but a year later he developed side effects causing discontinuation of amiodarone. Because of his recurrent episodes of palpitations associated with near syncope, chest pain and shortness of breath, he underwent an electrophysiology study in 1992 that showed orthodromic AVRT with the presence of a concealed left-sided accessory bypass tract. Scheduled for radiofrequency ablation the following day, after catheters were placed and during mapping of the lateralmitral annulus, his tachycardia stopped abruptly without further inducability. Isoproterenol infusion during atrial and ventricular stimulation also failed to induce his original tachycardia. A year later, the patient presented with palpitations that felt different than his previous experiences. Work-up at that point only revealed a parasystolic focus on a 24-hour ECG monitoring without any form of supraventricular tachycardia. This represents a very unusual case by which the left lateral accessory pathway was mechanically ablated with catheter manipulation. This led to the disappearance of the orthodromic tachycardia that was easily induced before due to the activity of his parasytolic focus. The latter continued for the following four years but the patient has had no recurrences of his tachycardia.     

Significance of Ventricular Pacing Site in Manifest Entrainment During Orthodromic Atrioventricular Reentrant Tachycardia with Left-Sided Accessory Pathway

We examined entrainment by ventricular pacing in six patients during orthodromic atrioventricular reentrant tachycardia (AVRT) utilizing a left-sided lateral accessory pathway. Constant fusion and progressive fusion were demonstrated in all patients by left ventricular pacing during tachycardia, but in none of the patients by right ventricular pacing. When left ventricular pacing was performed during AVRT, the antidromic wave front from the pacing impulse (n) collided with the orthodromic wave front of the previous pacing beat (n - 1) within the ventricle, therefore, constant fusion and progressive fusion were demonstrated in the surface electrocardiographic QRS complexes. On the other hand, when right ventricular pacing was performed during orthodromic AVRT, the antidromic wave front from the pacing impulse (n) collided with the orthodromic wave front of the previous paced beat (n - 1) within the normal atrioventricular pathway, and constant fusion and progressive fusion were therefore not demonstrated. These phenomena were explained by the relationship of the ventricular pacing site and the reentrant circuit. This study demonstrates the importance of the pacing site in manifest entrainment of orthodromic AVRT during ventricular pacing.     

Successful Radiofrequency Ablation of an Accessory Pathway During Pregnancy

The preexcitation syndrome is a rare entity during pregnancy. We present a 20-week pregnant patient with Wolff-Parkinson-White syndrome and recurrent episodes of tachycardia with hemodynamic compromise refractory to medical treatment that required electrical cardioversion several times. Due to the poor evolution we performed a successful radiofrequency ablation of a right posteroseptal accessory pathway using 70 seconds of total fluoroscopy time without complications. We consider this is an alternative and safer treatment in those cases in which the tachyarrhythmias compromise the hemodynamic state during pregnancy.     

Interaction Between Accessory Pathways Resulting in Inability to Induce Reciprocating Tachycardia

A 44-year old male with Wolff-Parkinson-White syndrome presented with atrial fibrillation. The patient was found at the electrophysioiogical study to have two accessory pathways, one concealed and the other conducting exclusively in the anterograde direction. After radiofrequency catheter ablation of the anterograde conducting pathway, orthodromic reciprocating tachycardia, which previously could not be induced despite an aggressive protocol, was easily induced. Ablation of the concealed pathway resulted in termination of the tachycardia and suppression of inducibility. We propose that interaction between the two accessory pathways resulted in an inability to induce reciprocating tachycardia.