Robert H. Svenson

Catheter technique for closed-chest ablation of the atrioventricular conduction system.

This report describes a catheter technique for ablating the His bundle and its application in nine patients with recurrent supraventricular tachycardia that was unresponsive to medical management. A tripolar electrode catheter was positioned in the region of the His bundle, and the electrode recording a large unipolar His-bundle potential was identified. In the first patient, two shocks of 25 and 50 J, respectively, were delivered by a standard cardioversion unit to the catheter electrode, resulting in an intra-His-bundle conduction defect. Subsequent delivery of 300 J resulted in complete heart block. In the next eight patients, an initial shock of 200 J was used. The His bundle was ablated by this single shock in six of these patients and by an additional shock of 300 J in one. In the remaining patient, conduction in the atrioventricular node was modified, resulting in alternating first and second-degree atrioventricular block. A stable escape rhythm was preserved in all patients. The procedure was well tolerated, without complications, and all patients have remained free of arrhythmia, without medication, for follow-up periods of two to six months.

Wolff-Parkinson-White syndrome. The problem, evaluation, and surgical correction.

Physiological studies of the type we have described, when performed in patients with the WPW syndrome, can yield diagnostic information regarding the mechanism of arrhythmia, demonstrate functional properties of therapeutic import, facilitate therapeutic decision-making about drug regimens and presumptively localize the site of pre-excitation as a basis for possible surgical intervention. Based on our experience, we feel that in selected patients, surgical correction of the WPW syndrome is entirely feasible, and can be accomplished in the majority of patients in whom free wall A-V connections are present. The continuing challenge of identification and correction of septal accessory pathways directs our present work with the WPW syndrome.

Electrophysiological evaluation of the Wolff-Parkinson-White syndrome: problems in assessing antegrade and retrograde conduction over the accessory pathway.

The effect of atrial pacing and recording site and ventricular pacing site on assessment of conduction over the accessory pathway (AP) was examined in a group of patients with the Wolff-Parkinson-White syndrome. The importance of initial localization of the AP by recording the sequence of retrograde atrial activation during circus movement tachycardia is demonstrated. Inability to record or pace near the AP may lead to significant errors in the assessment of the antegrade and retrograde conduction properties of the AP. During ventricular pacing, retrograde atrial fusion was consistently demonstrated with laterally located APs.

Refractory periods of the accessory pathway in the Wolff-Parkinson-White syndrome.

Antegrade (AERPAP) and retrograde (RERPAP) effective refractory periods of the accessory pathway were measured at multiple cycle lengths in 47 patients with the Wolff-Parkinson-White syndrome. In 20 patients the effect of changing cycle length on AERPAP could be determined. In 12 patients AERPAP decreased by 10-45 msec, in six it increased by 10-35 msec, and in two it was unchanged. In 13 of 15 patients in whom the effect of decreasing cycle length on RERPAP could be assessed, RERPAP decreased by 10-60 msec. In eight patients, the shortest AERPAP correlated well (r = 0.83) with the shortest R-R interval of consecutive pre-excited beats in atrial fibrillation. However, predominantly normal conduction was observed in six of 28 patients with atrial fibrillation, probably because of concealment in the bypass. Therefore, induction of atrial fibrillation during electrophysiological evaluation may provide additional information. The RERPAP at the cycle length of the arrhythmia was shorter than the cycle length of reciprocating tachycardia in all but one of 21 patients. At the same or comparable cycle lengths, AERPAP was usually greater than RERPAP.

Coexistence of functional Kent and Mahaim-type tracts in the pre-excitation syndrome. Demonstration by catheter techniques and epicardial mapping.

An unusual patient with Ebsteins anomaly of the tricuspid valve and the Wolff-Parkinson-White syndrome is presented. Ventricular pre-excitation related to conduction over both a right posterior Kent bundle and Mahaim fibers coursing from the atrioventricular node to the right ventricle. Two types of supraventricular tachycardia were demonstrable. These were due to re-entry involving antegrade conduction over either the normal or Mahaim paths, and retrograde conduction via the Kent bundle. Surgical division of the Kent bundle has abolished the clinically debilitating arrhythmias.

An Improved Operation for the Definitive Treatment of the Wolff-Parkinson-White Syndrome

Abstract As our experience increased with the definitive surgical treatment of patients with Wolff-Parkinson-White syndrome (WPW), an intraatrial method was devised that permits separation of the atria from the ventricles at any point along the annulus fibrosus. This technique depends on separating the atrium from the annulus fibrosus, using the fat about the coronary vessels and epicardial reflections from the aorta to the right atrial wall as the plane of dissection. This method allows easy approach to the septal area on the right. Successful results with 2 patients, one with Type A (left-sided) and the other with Type B (right-sided) WPW are recorded to illustrate the use of this method.

Electrophysiologic effects of propranolol on sinus node function in patients with sinus node dysfunction.

SUMMARY The electrophysiologic effects of intravenously administered propranolol (0.1 mg/kg) on three parameters of sinus node function were examined in ten symptomatic patients with sinus node dysfunction. The patients ranged in age from 26 to 79 years. Symptoms ranged from fatigue to frank syncope. Sinoatrial (SA) block and sinus pauses were observed in one patient; sinus pauses alone were observed in three patients. Five (5/10) patients had intraatrial block; three (3/10) patients had atrioventricular block; four (4/10) patients had an intraventricular conduction disturbance. At the time of electrophysiologic study, two patients had a control spontaneous sinus cycle length that exceeded 1000 msec. Following propranolol, the mean spontaneous cycle length increased by 17.4% (924 to 1085 msec, P < 0.005) and spontaneous second degree SA block reappeared in the one patient. The maximum escape cycle ranged from 116% to 229% of the prepacing spontaneous cycle length and was considered to be prolonged in two of ten patients. Propranolol had no significant effect on the maximum escape cycle/prepacing cycle length × 100 (%). The estimated sinoatrial conduction time (SACT) was determined in seven patients and ranged in value from 120 to 238 msec. Propranolol increased the mean value of the estimated SACT from 179 to 213 msec, P < 0.025. Propranolol may cause marked bradyarrhythmias in some patients with sinus node dysfunction, and should be used with caution in these patients.

An Electrophysiologic Approach to the Surgical Treatment of the Wolff-Parkinson-White Syndrome Report of Two Cases Utilizing Catheter Recording and Epicardial Mapping Techniques

The usefulness and limitations of electrode catheter and epicardial mapping techniques in the evaluation of the Wolff-Parkinson-White syndrome are described. In one case epicardial surface mapping was unsuccessful in localizing the accessory connection. However, a septal location was suggested by catheter recording techniques and confirmed by the point at which the surgical incision interrupted the accessory connection. In the second case catheter techniques could not confirm the role of the accessory connection in a re-entrant rhythm. Epicardial mapping of the atrium during PAT confirmed a return route to the atrium over the accessory connection, opposite the point of ventricular pre-excitation during sinus rhythm. In both cases, following surgery, epicardial maps, 12-lead ECGs and catheter recording techniques revealed no evidence of residual pre-excitation.

Surgical Correction of Anomalous Left Ventricular Pre-excitation: Wolff-Parkinson-White (Type A)

This report describes two patients with the Wolff-Parkinson-White syndrome including episodes of supraventricular tachycardia and atrial fibrillation. Both patients had Type A electrocardiograms. Electrophysiological studies demonstrated pre-excitation and evidence that the site of pre-excitation involved the left ventricle. The effective refractory periods of the accessory pathway during atrioventricular conduction were 240 and 220 msec respectively. Epicardial mapping at the time of surgery showed that anomalous excitation began adjacent to the annulus of the mitral valve near a marginal branch of the left circumflex coronary artery. An incision which separated the atrial muscle from the annulus of the mitral valve at the region of anomalous excitation abolished the delta wave. Epicardial maps after surgery showed normal ventricular activation and follow-up studies have shown normal electrocardiograms and no arrhythmias.

Surgery for WPW Syndrome The authors reply

had no further episodes of tachycardia and has undergone one pulse generator replacement. She continues to conduct through the anomalous pathway with the pacemaker capturing only rarely. We do, however, feel committed to lifelong replacement of the pacemaker power source since the reliability of the accessory pathway as a permanent A-V connection is questionable. Since this first case we have treated 2 other Type A WPW patients in the same manner. One is now 3 years postoperative and another 3 months postoperative. Both are free of their tachycardias. If in future patients an accessory A-V pathway cannot be found and divided, then division of the His bundle with implantation of a permanent demand pacemaker is an acceptable alternate approach to the surgical management of patients with Type A Wolff-Parkinson-White svndrome and reentrant atrial tachycardias. SPENCER B. KING, III, M.D. R. BRUCE LOGUE, M. D. Emory University Clinic Atlanta, Georgia