The genesis of complex ventricular rhythms during atrial tachyarrhythmias in humans is not fully understood. To clarify the dynamics of atrioventricular (AV) conduction in response to a regular high-rate atrial activation, 29 episodes of spontaneous or pacing-induced atrial flutter (AFL), covering a wide range of atrial rates (cycle lengths from 145 to 270 ms), were analyzed in 10 patients. AV ...

SINCE their introduction by Lopez and coworkers,' paired electrical stimulation and coupled pacing of the heart have been investigated intensively and have been shown to be useful in slowing the effective mechanical rate of the heart or in causing sustained potentiation of cardiac contraction or for both. A recent symposium on this subject provides an excellent review.2 The techniques, in essen...

BACKGROUND Patients with manifest atrioventricular accessory pathways (mAPs) have a greater tendency to develop atrial fibrillation (AF) compared with patients with concealed atrioventricular accessory pathways (cAPs). However, the risk factors of developing AF in patients with various atrioventricular accessory pathways (APs) are not clear. METHODS This retrospective study included 460 sympt...

Three cases in which left anterior hemiblock (LAH) obscured the diagnosis of right bundle branch block (RBBB) are reported. The RBBB was incomplete in one case and complete or of high degree in the other two. The LAH was intermittent in two cases. In the three cases, the LAH abolished not only the S waves in leads I and aVL, but also the terminal R wave in Vl. The possibility that RBBB, complet...

Transient entrainment of circus-movement tachycardia utilizing an atrioventricular (AV) bypass pathway was studied in 13 patients (nine with the orthodromic form, two with the antidromic form, and two with both the orthodromic and antidromic forms). All patients had a left-sided AV bypass pathway. Pacing at selected rates faster than the spontaneous rate was performed during the tachycardia at ...

In case of the first possibility (AVRT), an accessory pathway is responsible for the retrograde limb of the tachycardia circuit (there is no evidence for anterograde conduction over the accessory pathway on the ECG in sinus rhythm, as show in Fig. 1b of the question). Therefore a ‘concealed’ accessory pathwaymust be present. Anterograde conduction occurs over a dual AV nodal pathway (Fig. 2, up...

The mechanisms of aberrant conduction at the onset of induced orthodromic tachycardia in the Wolff-Parkinson-White syndrome were analyzed in 20 consecutive patients in whom this tachycardia was initiated by the atrial (A2) and/or right ventricular (V2) extrastimulus techniques. Of 13 patients in whom orthodromic tachycardia was induced by the A2 method, functional right bundle branch block occu...