A second unidirectional, retrograde accessory atrioventricular pathway was unmasked by adenosine during the intracardiac evaluation of a child with a reentrant long RP' tachycardia. This case is further evidence of the value of adenosine during the evaluation of these types of tachycardias.

An opportunity to study the iiechanisin in pre-excitation was provided by 3 patients with unusual features: coexistence of right bundle-branch block and pre-excitation, occurrence of 2 types of anomalous ventricular complex, and simultaneous occurrence of pre-excitation and varying grades of atrioventricular block (first degree to complete). The conclusion was reached that a functioning structu...

Complete atrioventricular block, second-degree Mobitz type II and first-degree atrioventricular block with right bundle branch block were observed consecutively following successful radiofrequency ablation in close proximity to the sinus node. This resulted in the modification and disappearance of the inappropriate sinus tachycardia that had previously been present. Neither tachycardia nor cond...

We describe a 66-year-old woman who had an alternating bundle branch block consisting of coexisting occurrence of right bundle branch block (RBBB) and left bundle branch block (LBBB) combined with Mobitz type II atrioventricular block (AVB). A prolonged PQ interval was associated with the RBBB pattern whereas it was not apparent in the LBBB pattern. Electrophysiologic study revealed that the LB...

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...

A patient with an atrial septal defect, paroxysmal tachyeardia, and the WolffParkinson-White syndrome (type B) had epicardial exploration to determine the nature of the excitation anomaly. Right bundle-branch block in association with the WPW syndrome (type B) was evidenced by the late activation (0.12 sec) of the epicardium over the outflow tract of the right ventricle. Early activation of the...

An opportunity to study the iiechanisin in pre-excitation was provided by 3 patients with unusual features: coexistence of right bundle-branch block and pre-excitation, occurrence of 2 types of anomalous ventricular complex, and simultaneous occurrence of pre-excitation and varying grades of atrioventricular block (first degree to complete). The conclusion was reached that a functioning structu...

An opportunity to study the iiechanisin in pre-excitation was provided by 3 patients with unusual features: coexistence of right bundle-branch block and pre-excitation, occurrence of 2 types of anomalous ventricular complex, and simultaneous occurrence of pre-excitation and varying grades of atrioventricular block (first degree to complete). The conclusion was reached that a functioning structu...

A patient with an atrial septal defect, paroxysmal tachyeardia, and the WolffParkinson-White syndrome (type B) had epicardial exploration to determine the nature of the excitation anomaly. Right bundle-branch block in association with the WPW syndrome (type B) was evidenced by the late activation (0.12 sec) of the epicardium over the outflow tract of the right ventricle. Early activation of the...

A patient with an atrial septal defect, paroxysmal tachyeardia, and the WolffParkinson-White syndrome (type B) had epicardial exploration to determine the nature of the excitation anomaly. Right bundle-branch block in association with the WPW syndrome (type B) was evidenced by the late activation (0.12 sec) of the epicardium over the outflow tract of the right ventricle. Early activation of the...