Mahaim fibres are cardiac accessory bundles which can cause dangerous tachyarrhythmias. Despite their first description being many years ago, their recognition and diagnosis still proves difficult. The electrocardiographic features of Mahaim pathways are subtle and shared with other accessory pathways; as such, an electrophysiology study must be used to diagnose this pathway. Even then, it is o...

We describe a technique for interruption/modification of atrioventricular conduction using a direct current shock delivered from a defibrillator to the atrioventricular junctional tissue by means of a conventional electrode wire. The method was used in three patients with refractory supraventricular tachycardia. After the procedure two patients received an atrioventricular sequential pacemaker....

Atrial pacing in a patient with a Wolff-Parkinson-White syndrome pattern showed unusual variability in AV nodal conduction time. Changes in the AV nodal conduction time occurred predominantly at paced rates in excess of 100/min and consisted of abrupt or gradual decreases in the AH interval. Such decreases resulted in unexpected normalization of the QRS pattern. In addition, pacing also reveale...

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 fo...

Three patients with the Wolff-Parkinson-White (WPW) syndrome were studied using His bundle recordings and programmed atrial stimulation. In two of them conduction of premature atrial depolarizations via the accessory pathway was possible when the His-Purkinje system was still refractory. The consequent conduction delay in the His-Purkinje system resulted in re-entry phenomena at the ventricular...

BACKGROUND Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of supraventricular tachycardia. In contrast, Wolff-Parkinson-White (WPW) pattern consists of an accessory pathway, which may result in the development of ventricular arrhythmias. Frequent tachycardia caused by AVNRT and accessory pathways may play a role in left ventricular systolic dysfunction. CASE REPO...

The incidence, mechanisms and sites of block of spontaneous termination of circus movement tachycardia (CMT) using an atrioventricular accessory pathway (AP) were analyzed in 24 consecutive patients (17 with Wolff-Parkinson-White syndrome and seven with a concealed AP) who were not ieceiving antiarrhythmic drugs. Spontaneous termination of tachycardia occurred in 10 patients (105 episodes). A r...

To study the pathway of tachycardia in patients with the Wolff-Parkinson-White (WPW) syndrome and reciprocal tachycardias, results from intracavitary recordings and atrial and ventricular stimulation were reviewed in 71 patients with the WPW syndrome and 54 patients without pre-excitation. In all patients a reproducible tachycardia could be initated and terminated by appropriately timed electri...

Identical 10-year-old twins, both with electrocardiograms showing a short PR interval and a normal QRS complex but with dramatically different electrophysiological characteristics, are described. One twin experienced episodes of rapid palpitation and on one occasion was resuscitated from ventricular fibrillation. An intracardiac electrophysiological study confirmed the presence of an atrioventr...

At electrophysiologic study in a patient with the Wolff-Parkinson-White syndrome, intracardiac catheter recordings demonstrated a deflection that occurred 30 ms before ventricular activation. The rapid deflection was present during ventricular preexcitation but not during normal atrioventricular conduction. All QRS complexes were preexcited to varying degrees during atrial fibrillation, yet the...