The Experts below are selected from a list of 354 Experts worldwide ranked by ideXlab platform
M Ralph D Lazzara - One of the best experts on this subject based on the ideXlab platform.
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electrophysiology of the right anterior approach to the atrioventricular node studies in vivo and in the isolated perfused dog heart
Journal of Cardiovascular Electrophysiology, 1997Co-Authors: Matthias Antz, Benjamin J Scherlag, Eugene Patterson, M Kenichiro D Otomo, M Claudio D Tondo, Jan Pitha, D Mario M D Gonzalez, M Warren M D Jackman, M Ralph D LazzaraAbstract:Electrophysiology of Anterior AVN Input. Introduction: Previous reports have described electrophysiologic properties and rate-dependent responses in the transitional cell zone of the posterior AV nodal input (slow pathway). The purpose of tHis study was to investigate the electrophysiology of the anterior transitional cell zone (fast pathway) in vivo and in a Langendorff preparation perfused with a nonblood solution containing butanedionemonoxime to inhibit contraction. Methods and Results: In five anesthetized dogs, the His-Bundle Electrogram recorded from the aortic root included atrial activity in close proximity to the anterior limbus of the fossa ovalis. During decremental atrial pacing, the atrial potential exhibited amplitude alternans at a pacing cycle length (CL) of 135 ± 14 msec. In ten isolated pertused canine hearts, a bipctlar electrode catheter was positioned with its tip against the right anterior interatrial septum just superior to the tendon of Todaro. The AV Wenckebach CL (WCL) averaged 262 ± 21 msec. During further decreases in pacing CL, the bipolar atrial potential developed a 2:1 amplitude alternans (9/10 dogs) at CL = 168 ± 15 msec and then split into two components with subsequent 2:1 block between these components (10/10 dogs) at CL = 152 ± 19 msec. Radiofrequency ablation at tHis site in six dogs prolonged the stimulus to HB interval from 113 ± 19 to 151 ± 30 msec (P < 0.01) without changing the WCL, consistent with ablation of the fast AV nodal pathway. In six other isolated perfused canine hearts, an octapolar catheter (2-mm spacing) was positioned along the anterior limbus of the fossa ovalLs with the tip electrode located over the anterior portion (apex) of the triangle of Koch. The aforementioned 2:1 amplitude alternans occurred at a longer CL in the distal electrodes located at the tendon of Todaro than in the proximal electrodes at farther distances from the tendon of Todaro (185 ± 25 vs 171 ± 20 msec, P < 0.05), as did the 2:1 block between the two components (161 ± 18 vs 150 ± 18 msec, P < 0.05). Microelectrode recordings obtained adjacent to the catheter demonstrated 2:1 alternans and block patterns in the action potentials of transitional cells but not in atrial cells, which exhibited 1:1 conduction at all CL. Conclusions: The transitional cell zone in the anterior interatrial septum exhibits a specific rate-dependent, spatial gradient of conduction block, which can be recorded in bipolar electro-grams as well as microelectrode recordings. Electrophysiologic changes induced by radiofrequency ablation of tHis anterior atrial/transitional cell zone (corroborated by Histology) provide strong presumptive evidence that tHis area constitutes all or a major part of the fast AV nodal pathway.
Jeffrey Goldberger - One of the best experts on this subject based on the ideXlab platform.
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catheter modification of the atrioventricular junction with radiofrequency energy for control of atrioventricular nodal reentry tachycardia
Circulation, 1991Co-Authors: Fred Morady, Melvin M. Scheinman, A Kadish, David J Schamp, Michael Chin, Jerry C Griffin, Michael D Lesh, David N Pederson, Jeffrey GoldbergerAbstract:BACKGROUNDThe utility of transcatheter application of radiofrequency energy to eliminate atrioventricular nodal reentrant tachycardia (AVNRT) was investigated.METHODS AND RESULTSThirty-nine patients (mean age, 53 +/- 20 years; range 14-86 years) with medically refractory AVNRT underwent perinodal ablation with radiofrequency energy. A custom-designed 6F catheter with a large (3-mm-long) distal electrode and interelectrode pacing of 2 mm was used in the majority of cases. The catheter used for ablation was initially positioned across the tricuspid anulus to obtain the largest His Bundle Electrogram, then withdrawn to obtain the largest atrial:ventricular Electrogram ratio, with a small His Bundle Electrogram (less than or equal to 100 microV). Each application of radiofrequency energy (350-550 kHz, 16.2 +/- 5.2 W) was stopped after 60 seconds or if PR prolongation or an impedance rise was noted. The endpoints of the procedure were persistent modification of atrioventricular nodal conduction (either first-d...
Frank Cecchin - One of the best experts on this subject based on the ideXlab platform.
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ablation of atrioventricular nodal reentrant tachycardia in tricuspid atresia
Journal of Cardiovascular Electrophysiology, 2004Co-Authors: P Khairy, Stephen P Seslar, John K Triedman, Frank CecchinAbstract:A 31-year-old woman with tricuspid atresia and a palliative Waterston shunt presented with intractable poorly tolerated supraventricular tachycardia. Electrophysiologic evaluation was consistent with AV nodal reentrant tachycardia. The fast pathway region was mapped electroanatomically during tachycardia and with constant rate ventricular pacing. Successful radiofrequency ablation was achieved by placement of lesions in an area adjacent and inferior to the His-Bundle Electrogram on the left side of the septum.
Darryl R Davis - One of the best experts on this subject based on the ideXlab platform.
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posterior His Bundle Electrogram location in a patient with atrioventricular nodal reentrant tachycardia and structurally normal heart
Canadian Journal of Cardiology, 2011Co-Authors: Yahya Al Hebaishi, Malek Kass, Martin S Green, Darryl R DavisAbstract:Atrioventricular (AV) nodal reentrant tachycardia is the most common form of paroxysmal supraventricular tachycardia in adults, and slow AV nodal pathway ablation has evolved into first-line therapy. Variations in conduction system anatomy are occasionally found at electrophysiological study and may make tHis ablation procedure very challenging. Here, we present the case of a 69-year-old man with a structurally normal heart and posterior displaced His Bundle who underwent successful slow pathway ablation. Demonstration of the characteristic slow pathway recording and His Bundle Electrogram is strongly recommended prior to radiofrequency energy application in the posterior septal region.
Dan Dan - One of the best experts on this subject based on the ideXlab platform.
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identification of preferential sites of parasympathetic input to the atrioventricular node in man
Heart Rhythm, 2004Co-Authors: Paresh Shah, Kenneth A Ellenbogen, Mark A Wood, David M Gilligan, Dan DanAbstract:Abstract Objectives The effects of subthreshold stimulation performed at various sites in the perinodal and posteroseptal space on atrioventricular (AV) nodal conduction were investigated. Background The identification of specific or preferential sites of parasympathetic innervation to the AV node is suggested by observations made in both the animal and clinical laboratories. Pathologic studies of the parasympathetic innervation to the AV node show it is made up of serpiginous fibers traveling at highly specific sites within the myocardium endocardially towards the compact AV node. Methods We utilized endocardial subthreshold stimulation to selectively identify and characterize AV nodal inputs. Fourteen patients (age: 56 ± 4 years) undergoing electrophysiologic testing with or without radiofrequency ablation for supraventricular tachycardia were studied. A steerable quadripolar catheter was positioned in 3 to 9 locations in the region between the site recording the His Bundle Electrogram and the coronary sinus (CS) os under flouroscopic and electroanatomic guidance. We mapped anterosuperior sites at or near sites with His potential recordings, and up to 2 mm inferior to the His Bundle recording, posteroseptal sites included the CS os and sites along the posterior, superior, and inferior border of the CS. Atrial pacing was performed at a cycle length 50 ms longer than Wenckebach cycle length. Subthreshold stimulation was applied at a frequency of 10 Hz and 20 Hz delivered to the distal electrode pair. AH and HV intervals were recorded before and during subthreshold stimulation. AH prolongation was defined as a reproducible increase in AH interval by >10 ms from a stable baseline AH interval. Results Eight of 14 patients demonstrated prolongation of AV conduction at a mean of 1.75 ± 0.2 sites. Mean AH prolongation was 56.4 ± 13.0 ms (p = 0.02) from baseline. AH prolongation was achieved 15.4 ± 1.8 mm below the His Bundle recording in 7 patients, at the site of the His Bundle recording in 3 patients, and along the posterior CS os border in 3 patients. Conclusion Subthreshold stimulation prolongs AV nodal conduction only at specific sites within the triangle of Koch, suggesting discrete parasympathetic endocardial inputs into the AV nodal region.