Studies on 3 Cases of Wolff-Parkinson-White Syndrome using the Recording Technique of His Bundle Electrograms

Several mechanisms have been suggested with regard to the genesis of the ventricular pre-excitation syndrome. Numerous electrocardiographic studies point to the fact that the various clinical manifestations of this entity are due to the existence of an accessory atrioventricular connection through which atrial impulses can bypass the normal atrioventricular junction. This theory is further supported by several different clinical reports of surgical interruption of anomalous conduction pathways between the atrium and ventricle resulting in eliminating the episodes of supraventricular tachycardia. In this present communication the etiology of Wolff-Parkinson-White syndrome including type A and type B cases was studied using the catheter technique of His bundle recording. Methods The technique of His bundle recordings used in our laboratory is an extension of the method introduced by Scherlag and his associates. The right saphena magna vein was isolated surgically and two bipolar electrode catheters were inserted through a venotomy. One catheter was then advanced under fluoroscopic control, until the tip lay across the septal leaflet of the tricuspid valve. This catheter was connected to a bio-physiological preamplifier at filter settings of 0.003 sec of time constant and 300Hz. Another electrode was positioned at the junction of the superior vena cava and right atrium, and was used for atrial pacing. The pacing rates were gradually increased approximately up to 500/min. A standard lead II elctrocardiogram was also displayed with the intracardiac electrograms. All tracings were monitored with a multichannel oscilloscopic instrument and simultaneously recorded on a direct writer recorder or electro-magnetic photographic recorder at a paper speed of 100 mm/sec. Report of Cases Case 1: The tracings presented in Fig.1 to 5 were obtained from a 24-year old man who complained of occasional episodes of paroxysmal rapid heart beating. The patient's electrocardiogram showed regular sinus rhythm and W-P-W type A. Paroxysmal tachycardia spontaneously disappeared without any specific medical treatment.