Rehan Mahmud

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Animal studies have suggested that spontaneous or programmed ventricular beats that occur simultaneously with atrial activation may facilitate atrioventricular (AV) nodal conduction during subsequent atrial impulses. However, this possibility has not been systematically studied in the human heart. In the present study the AV nodal conduction during a(More)
The effect of abrupt short-to-long changes in cycle length (CL) on the postulated reentrant circuit of ventricular tachycardia (VT) was evaluated. This was performed using single and double ventricular extrastimuli in a group of 21 patients clinically suspected of having VT in whom VT could not be induced at comparable or shorter constant CLs. A second(More)
The term "linking" has been used specifically to describe the mechanism for perpetuation of functional anterograde bundle branch block: namely, repetitive transseptal retrograde concealed penetration by impulses propagating along the contralateral bundle. We present selected examples that demonstrate tht linking-type phenomena actually have a wide spectrum(More)
Misdiagnosis occurs upon initial presentation to medical attention in a considerable number of patients referred for evaluation of wide QRS tachycardia. In order to improve diagnostic accuracy (ventricular versus supraventricular tachycardia), the answers to two key bedside questions were prospectively evaluated: (1) Had the patient experienced a prior(More)
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,(More)
Orthodromic tachycardia is the most common arrhythmia in patients with Wolff-Parkinson-White syndrome. It is often initiated during incremental ventricular pacing that requires the onset of retrograde block along the normal pathway (that is, atrioventricular [AV] node-His-Purkinje system) with concomitant retrograde atrial activation by way of the accessory(More)
We have recently described the ability of abrupt short-to-long changes in atrial cycle length (CL) to prolong refractoriness of the His-Purkinje system (HPS) and increase the likelihood of aberrant ventricular conduction. We have also shown similar functional behavior in retrograde refractoriness of the HPS during changes in ventricular CL. To further(More)
The relation between the morphologic configuration of QRS complexes during wide QRS tachycardia induced during electrophysiologic studies and sinus rhythm was examined in 18 patients who had preexisting left or right bundle branch block. Representative QRS complexes during sinus rhythm and during tachycardia were isolated from each patient and juxtaposed(More)
The electrophysiology of antidromic reentry, a less common phenomenon than orthodromic reentry, remains a poorly understood aspect of the Wolff-Parkinson-White (WPW) syndrome. We used a pacing model of ventricular preexcitation in patients without WPW, so that electrophysiological events in the normal pathway during atrial extrastimulation (A1-A2 technique)(More)
Patients with DDD pacemakers who have intact retrograde conduction are known to be at risk of developing ventricular and "endless loop" tachycardia. To address this problem, a pacing protocol was designed in which V2A2 conduction was assessed in 16 patients during ventricular pacing alone (standard method) and during paced atrioventricular (AV) sequential(More)