The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform

Masood Akhtar - One of the best experts on this subject based on the ideXlab platform.

  • Retrograde Concealed Conduction in the His-Purkinje System.
    Cardiac Electrophysiology Clinics, 2016
    Co-Authors: Masood Akhtar
    Abstract:

    : An 83-year-old man was seen due to recurrent syncopal episodes. Only the His bundle recording was able to be obtained, which showed the His-Purkinje System as the site of a conduction delay. A permanent dual-chamber pacemaker was implanted with no further syncopal episodes.

  • Human His-Purkinje System: Normal Electrophysiologic Behavior.
    Cardiac Electrophysiology Clinics, 2016
    Co-Authors: Masood Akhtar
    Abstract:

    : The His-Purkinje System (HPS) plays a significant role in human pathophysiology, but knowledge is scattered. This article highlights some of the relevant concepts, phenomena, and mechanisms; clarifies, expands, confirms, or modifies commonly encountered clinical events; and adds new information, which is often available but obscure. Also included are the essentials of HPS anatomy and physiology. It is important to abandon inaccurate concepts that are still taught and occasionally appear in text books.

  • Wenckebach Phenomenon in the His-Purkinje System
    Cardiac Electrophysiology Clinics, 2016
    Co-Authors: Masood Akhtar
    Abstract:

    : The author discusses Wenckebach phenomenon (WP) in the His-Purkinje System (HPS). Subtle PR changes may be interpreted as no change, often seen in the HPS-WP. Changes in the QRS axis help to localize the site of delay and block along fascicles of the left bundle branch. Marked PR changes may occur during HPS-WP. All the QRS complexes that are conducted depict right bundle branch and left anterior superior fascicular block, so the visible changes in the HV interval suggest WP mostly occurring in the left posterior inferior fascicle.

  • Human His-Purkinje System: Abnormalities of Conduction, Rhythm Disorders and Case Studies
    Cardiac Electrophysiology Clinics, 2016
    Co-Authors: Masood Akhtar
    Abstract:

    : This review covers many of the arrhythmias and conduction abnormalities related to His-Purkinje System. These include junctional premature complexes, junctional and fascicular tachycardias, bundle branch reentry (BBR), and the role of apparent conduction in various forms of supraventricular tachycardias (SVT) with or without involvement of accessory pathways (AP).

  • Electrophysiologic mechanisms of orthodromic tachycardia initiation during ventricular pacing in the Wolff-Parkinson-White syndrome.
    Journal of the American College of Cardiology, 2010
    Co-Authors: Masood Akhtar, Rehan Mahmud, Stephen Denker, Michael H. Lehmann, Patrick J. Tchou, Mohammad Jazayeri
    Abstract:

    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 pathway. However, the site of retrograde block, that is, the AV node versus the His-Purkinje System, during incremental ventricular pacing and, hence, the mechanism of orthodromic tachycardia initiation have not been Systematically elucidated. The mechanisms of orthodromic tachycardia induction were studied in 17 patients with Wolff-Parkinson-White syndrome using a specially designed pacing protocol. A beat by beat analysis indicated that the retrograde His-Purkinje System block was the most common initiating mechanism of orthodromic tachycardia in 14 of the 17 cases. In two cases, AV node block preceded the onset of orthodromic tachycardia, whereas the data in the remaining case suggested that both mechanisms were operative but at different pacing cycle lengths. The orthodromic tachycardia induction with His-Purkinje System block occurred within the first two cycles in most cases. When orthodromic tachycardia initiation was delayed beyond the first two cycles of the ventricular train it represented either 1) a 2:1 block in the His-Purkinje System; 2) a linking phenomenon in the His-Purkinje System; or 3) a block in the AV node. These data have methodologie, mechanistic and therapeutic implications for patients with the Wolff-Parkinson-White syndrome.

Mohammad Jazayeri - One of the best experts on this subject based on the ideXlab platform.

  • Electrophysiologic mechanisms of orthodromic tachycardia initiation during ventricular pacing in the Wolff-Parkinson-White syndrome.
    Journal of the American College of Cardiology, 2010
    Co-Authors: Masood Akhtar, Rehan Mahmud, Stephen Denker, Michael H. Lehmann, Patrick J. Tchou, Mohammad Jazayeri
    Abstract:

    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 pathway. However, the site of retrograde block, that is, the AV node versus the His-Purkinje System, during incremental ventricular pacing and, hence, the mechanism of orthodromic tachycardia initiation have not been Systematically elucidated. The mechanisms of orthodromic tachycardia induction were studied in 17 patients with Wolff-Parkinson-White syndrome using a specially designed pacing protocol. A beat by beat analysis indicated that the retrograde His-Purkinje System block was the most common initiating mechanism of orthodromic tachycardia in 14 of the 17 cases. In two cases, AV node block preceded the onset of orthodromic tachycardia, whereas the data in the remaining case suggested that both mechanisms were operative but at different pacing cycle lengths. The orthodromic tachycardia induction with His-Purkinje System block occurred within the first two cycles in most cases. When orthodromic tachycardia initiation was delayed beyond the first two cycles of the ventricular train it represented either 1) a 2:1 block in the His-Purkinje System; 2) a linking phenomenon in the His-Purkinje System; or 3) a block in the AV node. These data have methodologie, mechanistic and therapeutic implications for patients with the Wolff-Parkinson-White syndrome.

R. Bahra - One of the best experts on this subject based on the ideXlab platform.

  • Clinical trial of the non-invasive recording of His-Purkinje System signals
    Computers in Cardiology 1996, 1996
    Co-Authors: S. Minelly, S. W. Kelly, R. Bahra
    Abstract:

    A clinical System has been developed to detect His-Purkinje System (HPS) signals using surface recording technology and ensemble averaging. The reproducibility of this non-invasive methodology for recording His-bundle signals in normal human volunteers has been tested in a controlled clinical environment. The study recorded HPS signals from eight healthy volunteers, undosed, on placebo and following a single dose of /spl beta/-blocker (atenolol). This allowed the effects of the atenolol on the His-bundle intervals to be observed in a controlled fashion. A late notch (H) is recorded about 15 ms before ventricular activation for most subjects in both dosed and un-dosed conditions. However in some subjects there is a distinct increase in the A-H interval with atenolol. This indicates that the H-notch originates from the conduction System.

Rehan Mahmud - One of the best experts on this subject based on the ideXlab platform.

  • Voltage dependent conduction abnormalities in His bundle pacing in patients without His Purkinje System disease.
    Journal of Electrocardiology, 2019
    Co-Authors: Rehan Mahmud, Shakeel Jamal, Mohamed Musheinesh
    Abstract:

    Abstract Background During His bundle (HB) pacing, the active fixation of HB lead may cause disruption of the enclosed conduction fibers and cause conduction delay. His Purkinje conduction delays have been shown to revert to normal with higher voltage pacing. Objective To determine if conduction delays seen with penetrative HB pacing are voltage dependent and can resolve with higher stimulus voltage. Methods In 17 patients undergoing HBP, the effect of voltage on a composite His Purkinje System-ventricular activation time (hVAT) as well as electrocardiographic (ECG) evidence of conduction delay, was Systematically evaluated. Results There was highly significant prolongation of hVAT indicative of conduction delay in 13/17 patients. ECG changes of rightward delay were also seen in 9/13 patients. Both types of delays we manifest at lower voltages and we uniquely resolved by higher stimulation voltage. A pre-excitation like abnormality was also seen in 15/17 patients. This conduction abnormality was manifest at higher voltage without prolongation of hVAT. In 6/15 patients the pre-excitation like abnormality ceased at lower voltage. Conclusion HB pacing is associated with evidence of significant conduction delay noted at low voltage, which resolves with higher stimulation voltage. The more common pre-excitation like abnormality appears to occur at high voltage and, in of itself, does not appear to prolong hVAT.

  • Electrophysiologic mechanisms of orthodromic tachycardia initiation during ventricular pacing in the Wolff-Parkinson-White syndrome.
    Journal of the American College of Cardiology, 2010
    Co-Authors: Masood Akhtar, Rehan Mahmud, Stephen Denker, Michael H. Lehmann, Patrick J. Tchou, Mohammad Jazayeri
    Abstract:

    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 pathway. However, the site of retrograde block, that is, the AV node versus the His-Purkinje System, during incremental ventricular pacing and, hence, the mechanism of orthodromic tachycardia initiation have not been Systematically elucidated. The mechanisms of orthodromic tachycardia induction were studied in 17 patients with Wolff-Parkinson-White syndrome using a specially designed pacing protocol. A beat by beat analysis indicated that the retrograde His-Purkinje System block was the most common initiating mechanism of orthodromic tachycardia in 14 of the 17 cases. In two cases, AV node block preceded the onset of orthodromic tachycardia, whereas the data in the remaining case suggested that both mechanisms were operative but at different pacing cycle lengths. The orthodromic tachycardia induction with His-Purkinje System block occurred within the first two cycles in most cases. When orthodromic tachycardia initiation was delayed beyond the first two cycles of the ventricular train it represented either 1) a 2:1 block in the His-Purkinje System; 2) a linking phenomenon in the His-Purkinje System; or 3) a block in the AV node. These data have methodologie, mechanistic and therapeutic implications for patients with the Wolff-Parkinson-White syndrome.

S. Minelly - One of the best experts on this subject based on the ideXlab platform.

  • Clinical trial of the non-invasive recording of His-Purkinje System signals
    Computers in Cardiology 1996, 1996
    Co-Authors: S. Minelly, S. W. Kelly, R. Bahra
    Abstract:

    A clinical System has been developed to detect His-Purkinje System (HPS) signals using surface recording technology and ensemble averaging. The reproducibility of this non-invasive methodology for recording His-bundle signals in normal human volunteers has been tested in a controlled clinical environment. The study recorded HPS signals from eight healthy volunteers, undosed, on placebo and following a single dose of /spl beta/-blocker (atenolol). This allowed the effects of the atenolol on the His-bundle intervals to be observed in a controlled fashion. A late notch (H) is recorded about 15 ms before ventricular activation for most subjects in both dosed and un-dosed conditions. However in some subjects there is a distinct increase in the A-H interval with atenolol. This indicates that the H-notch originates from the conduction System.