Reciprocating tachycardia using bilateral anomalous pathways: electrophysiologic and clinical implications

Three types of atrioventricular reciprocating tachycardia using bilateral accessory pathways in a patient with Wolff-Parkinson-White syndrome

Electrophysiologic studies were performed on a patient with Wolff-Parkinson-White syndrome and recurrent supraventricular tachycardia. Bilateral accessory pathways capable of antegrade and retrograde conduction and three different types of atrioventricular (AV) reciprocating tachycardia were demonstrated. One type of narrow QRS tachycardia used the normal AV pathway for antegrade conduction and the left-sided accessory pathway for retrograde conduction. Two types of wide QRS tachycardia (one with right bundle branch block and one with left bundle branch block) used both accessory pathways for antegrade and retrograde conduction, respectively, and were independent of the normal AV pathway. The data showed that bilateral accessory pathways have different electrophysiologic properties and participate in three different types of AV reciprocating tachycardia.

The localization of bypass tracts in the Wolff-Parkinson-White syndrome from the surface electrocardiogram

The bypass tracts of the WFW syndrome may be situated anywhere along the AV ring. Accurate localization of such tracts has in the past been largely effected by electrophysiologic studies, particularly epicardial mapping. During recent years, however, criteria for localization of the bypass tracts from the conventional 12-lead ECG have become increasingly apparent. The preceding presentation constitutes a review and state of the art governing these rapidly developing diagnostic principles.

Surgical treatment of accessory atrioventricular pathways and symptomatic tachycardia in children and young adults

Twenty-seven patients aged 21 years or younger (mean 15) with symptomatic tachycardia underwent operation for ablation of an accessory atrioventricular pathway. Six patients had associated Ebstein's malformation of the tricuspid valve. Supraventricular tachycardia had been present for a mean of 5 years. At electrophysiologic study, 4 patients were found to have 2 accessory pathways. Left ventricular free wall pathways were found in 14 patients, right ventricular free wall pathways in 10 and septal pathways in 6. Successful initial ablation of all the pathways was achieved in 26 of the 27 patients. No patient died perioperatively and none had persistent complete heart block. During a mean follow-up of 11 months, no patient had recurrence of an arrhythmia related to the accessory pathway. Thus, the surgical treatment of children and young adults with accessory atrioventricular pathways and symptomatic supraventricular tachycardia is safe and effective. For these patients, unless the tachycardia can be easily controlled with a minimal number of drugs and adverse effects, surgical ablation should be considered early in the clinical course.

Cycle length change during reciprocating tachycardia in patients with Wolff-Parkinson-White syndrome

Cycle Length (CL) changes during reciprocating tachycardia (RT) were examined in 82 consecutive patients with Wolff-Parkinson-White syndrome (WPW) during electrophysiological studies. The significant CL changes (sudden and greater than 30 msec.) were found in 21 of 82 patients (26%). Thirteen patients had a manifest WPW and eight had a concealed WPW. An accessory pathway (AP) was located in the left side in 14 patients, the right side in four patients and the septum in two patients. One patient had multiple AP's. The development of ipsilateral bundle branch block during RT was responsible for CL changes in 11 patients. The sudden shift between fast and slow pathways in atrioventricular node (AVN) during RT was responsible for CL changes in two patients. Alternating CL changes during RT were found in eight patients. In five of them, alternating CL changes could be explained by physiological properties of a single AVN pathway. In the remaining three patients, the onset of 2:1 block in a fast pathway with 1:1 conduction in a slow pathway of the AVN may be responsible for CL changes. In one patient with multiple AP's the shift from one re-entrant circuit to the other was responsible for CL changes.

IN CONCLUSION

1) CL changes during RT are not uncommon in patients with WPW. 2) Several different mechanisms are responsible for CL changes.

Coexistent posteroseptal and right-sided atrioventricular bypass tracts

Twelve patients with a posteroseptal accessory pathway underwent complete electrophysiologic studies, and four were found to have a second atrioventricular (AV) bypass tract that was right anterior, right anteromedial or right anterolateral in location. In two of these four patients, the presence of the right-sided AV bypass tract was confirmed by intraoperative epicardial mapping or after catheter-induced abolition of retrograde conduction through the posteroseptal bypass tract. In three of the four patients with a dual AV bypass tract, the delta wave pattern was clearly atypical of the pattern seen with an isolated posteroseptal accessory pathway. Instead of a transition from an isoelectric or slightly positive delta wave in lead V1 to markedly positive delta waves in leads V2 to V6, the delta waves were negative or only slightly positive in leads V2 to V5. However, in a fourth patient with dual AV bypass tracts, the only atypical electrocardiographic finding was an intermittently positive delta wave in lead II; at times this patient's electrocardiogram was consistent with an isolated posteroseptal bypass tract, with negative delta waves in the inferior leads. There appears to be an association between posteroseptal and right-sided accessory pathways. In patients with a posteroseptal accessory pathway who are candidates for catheter or surgical bypass tract ablation, a complete mapping study of the tricuspid anulus is mandatory, even when the electrocardiogram is typical of an isolated posteroseptal bypass tract.

Electrophysiologic effects of unilateral right and left stellate ganglion block on the human heart

To determine the electrophysiologic effects of stellate ganglion (SG) block on the human heart, the two SGs were anesthetized separately, with a 24-hour interval between the two procedures, in 13 patients with episodes of supraventricular tachycardia (six had Kent bundles). Left SG block caused: (1) a lengthening of the AH interval, measured at fixed atrial rates of 10 +/- 12 msec (p less than 0.01); (2) a marked depression of the VA conduction in six of the seven patients with measurable VA interval (in two patients it produced complete VA block); (3) a slowing of 20 to 40 msec of the cycle of an electrically induced reciprocating tachycardia; and (4) failure to modify the QT interval duration. In contrast, right SG block produced asymmetric or opposite changes and prolonged the QT interval (7.6 +/- 8.8 msec, p less than 0.05). Atrial and ventricular refractoriness was not significantly altered by SG block. Retrograde effective refractory period of the Kent bundle changed 20 to 60 msec after unilateral SG blockade. Thus, this study suggests that the human conduction system and the Kent bundles receive an appreciable sympathetic influence from the SG. Like experimental studies, we also found an asymmetric response to unilateral SG block and a dominance, in most of our patients, of the left SG. The influence on myocardial refractoriness was less apparent.

Mechanisms of junctional tachycardia showing ventricular pre-excitation

Over a period of five years 12 patients underwent electrophysiological studies for the investigation of recurrent tachycardias which showed ventricular pre-excitation. Nine patients had a type B pattern and two a type A. One patient had episodes of both types. Dual atrioventricular nodal pathways were found in six of seven patients with atrioventricular nodal re-entrant tachycardia mechanisms. Single direct atrioventricular accessory pathways were present in four patients, single nodoventricular pathways in five, and multiple pathways in three. Twenty one tachycardias were induced, of which 13 showed ventricular pre-excitation. Five patients had nodoventricular pathway conduction during atrioventricular nodal tachycardia and one during atrioventricular re-entrant tachycardia. Only three patients had simple antidromic tachycardia and one additional atrioventricular nodal tachycardia with bystander atrioventricular accessory conduction. Three patients had three different tachycardias, three had two types, and six had one type. Thus junctional tachycardias showing ventricular pre-excitation are often associated with multiple mechanisms and complex anatomical and functional substrates. An accessory pathway was an essential component in only six of 13 tachycardias showing ventricular pre-excitation. Determination of the tachycardia mechanism requires detailed study and analysis.

Multiple circus movement tachycardias with multiple accessory pathways

A patient with the Wolff-Parkinson-White syndrome manifesting four types of tachycardia is described. The location and the participation during tachycardia of two different types of accessory atrioventricular pathways were documented during a programmed stimulation study. Unusual modes of initiation of tachycardias were observed, such as the initiation of an orthodromic circus movement tachycardia by an atrial premature beat that conducted in anterograde direction down the accessory pathway.

Shortening of ventriculoatrial conduction in patients with left-sided Kent bundles

In six patients with electrophysiologic evidence of ventriculoatrial conduction through a left Kent bundle, we documented that programmed right ventricular stimuli falling within an interval of 60 to 160 msec from the end of the T wave propagated to the left atrium (distal coronary sinus unipolar lead) 10 to 20 msec earlier than the basic paced beats. This phenomenon could be reproduced 24 hours later in two patients, and it was abolished by procainamide and amiodarone in one instance. During this interval we were unable to induce reciprocating tachycardia. Our observations outline a new pattern in ventriculoatrial conduction in patients with left-sided Kent bundles. The findings suggest in addition, that (1) supernormal conduction may be responsible for the observed shortening in retrograde conduction and (2) this phenomenon does not facilitate induction of reciprocating tachycardia.

Quintuple pathways participating in three distinct types of atrioventricular reciprocating tachycardia in a patient with Wolff-Parkinson-White syndrome

Electrophysiologic studies were performed in a patient with recurrent supraventricular tachyarrhythmias. Sinus and paced atrial beats had QRS complexes characteristic of atrioventricular (A-V) conduction through a manifest left lateral accessory pathway (Wolff-Parkinson-White syndrome, type A). Three distinct types of A-V reciprocating tachycardia and three different modes of retrograde atrial activation were demonstrated. Type 1 tachycardia involved the slow A-V nodal pathway and a second (left lateral or left paraseptal) accessory A-V pathway capable of retrograde conduction only. Type 2 tachycardia was of the slow-fast A-V nodal pathway type. Type 3 tachycardia involved in heretofore undescribed circuit in that retrograde conduction occurred through an accessory A-V pathway with long retrograde conduction times and anterograde conduction through both the manifest left lateral accessory A-V pathway and fast A-V nodal pathway. Premature ventricular beats delivered late in the cycle of this tachycardia advanced (but did not change) the retrograde atrial activity without affecting the timing of the corresponding anterograde H deflection. In summary, this patient had five (three accessory and two intranodal) pathways participating in three different types of A-V reciprocating tachycardia; the recurrence of these were prevented with oral amiodarone therapy.

Surgical division of right and left free wall accessory atrioventricular electrical connections in a child with incessant supraventricular tachycardia

A child with Wolff-Parkinson-White syndrome developed incessant supraventricular tachycardia refractory to medical therapy and countershocks. Supraventricular tachycardias incorporating both right and left free wall accessory atrioventricular electrical connections were demonstrated. The more frequent, broad complex tachycardia utilised both the accessory connections and was independent of the atrioventricular node. The less frequent, narrow complex tachycardia utilised the atrioventricular node for anterograde conduction and the left sided accessory connection for retrograde conduction. Surgical division of the accessory connections restored normal sinus rhythm and eliminated supraventricular tachycardia.