Search

We present the case of a healthy 12-year-old boy without structural heart disease who was followed for several years for an arrhythmia with diverse and incorrect initial diagnoses, refractory to flecainide, metoprolol and verapamil. Thorough reevaluation of the electrocardiographic recordings led to a presumptive diagnosis of a non-reentrant atrioventricular nodal tachycardia, subsequently confirmed with electrophysiology study. Radiofrequency ablation was performed during the procedure and the arrhythmia resolved. Double conduction through the atrioventricular node often simulates other arrhythmias, leading to misdiagnosis. [ABSTRACT FROM AUTHOR]

An analysis was made in 14 isolated and perfused rabbit hearts of the electrophysiological effects of selective radiofrequency (RF) delivery in the anterior (group I, n = 7) or posterior zone (group II, n = 7) of the Koch triangle, with the aim of modifying atrioventricular nodal (AVN) conduction without suppressing 1:1 transmission. After opening the right atrium, RF was delivered (0.5 W) with a 1-mm diameter unipolar electrode positioned in the selected zone until a prolongation of no less than 15% was obtained in the Wenckebach cycle length (WCL). Before and after (30 min) RF, anterograde and retrograde AVN refractoriness and conduction were evaluated, stimulating from the crista terminalis (CT), the interatrial septum (IAS), and from the RV epicardium. After RF, the following percentage increments were observed in group I: AH(CT) - 36% ± 9%, AH(IAS) = 38% ± 11%, WCL(CT) = 28% ± 8%, WCL(IAS) = 22% ± 6%, functional refractory period (FRP) of the AVN(CT) = 13% ± 11%, FRP-AVN(IAS) = 13% ± 8%, retrograde WCL = 20% ± 19%, and retrograde FRPVA = 13% ± 16%. The increments observed in group II and the significances of the differences with respect to group I were: AH(CT) - 11% ± 14% (P < 0.01), AH(IAS) = 19% ± 32% (NS), WCL(CT) = 42% ± 14% (P < 0.051, WCL(IAS) = 42% ± 16% (P < 0.01), FRP-AVN(CT) = 28% ± 28% (NS). FRP-AVN(IAS) = 21% ± 19% (NS), retrograde WCL = 35% ± 24% (NS), and retrograde FRP = 16% ± 13% (NS). In both groups, the AH interval variations were not correlated with those of the rest of the parameters analyzed. Truncated nodal function curves suggestive of a dual AV nodal pathway were obtained in three experiments, though in only one of them was this observed under basal conditions. In the other two experiments with dual AV nodal physiology only after RF (one from each group), AV nodal reentrant tachycardias were triggered with atrial extrastimulus at coupling intervals equal to or shorter than at those that cause a sudden lengthening of the AH interval. RF delivered in the anterior and posterior zones of the Koch triangle produced effects of different magnitude on the AH interval and Wenckebach cycle length. In the anterior zone the AH interval was prolonged to a greater extent, while in the posterior zone the effects were greater on the Wenckebach cycle length. No correlation existed between the variations in AH interval and Wenckebach cycle length. regardless of where RF was delivered. The evaluation of anterograde AV nodal refractoriness was similar when stimulating from the crista terminalis or from the inter atrial septum. By delivering RF, it was possible to induce dual AV nodal physiology and reentrant tachycardias. [ABSTRACT FROM AUTHOR]

Background: Atrioventricular nodal re-entrant tachycardia (AVNRT) is still the most common presentation to our electrophysiology laboratory for ablation. The aim of this study is to document the confirmative value of cross over manoeuvre in successful AVNRT ablation., Methods: This study was conducted in Hayat Abad Medical complex Peshawar June 2006 to October 2015. In all patient with AVNRT, Dual-nodal pathway physiology confirmed by programmed atrial pacing of eight Tran with an extra beat by 10 millisecond (ms) decrement and at least Atrial HIS (A-H) interval prolongation of 50 ms. The dual pathway was further confirmed by cross over manoeuvre. Slow pathway potential identified and radiofrequency ablation (RFA) energy applied at 60 temperatures and 30 powers in Left Anterior Oblique (LAO) projection. Post ablation absence of cross over documented with and without isoproterenol and patient followed for any complication or recurrence., Results: Total 567 patients studied with mean age 36.56±12.16 and male to female ratio 1:1.4 with presentation of supraventricular tachycardia (SVT). Slow pathway was successfully modified and statistically no significant complication or recurrence documented., Conclusions: Failure to cross over reliably excludes any conduction over the slow pathway and so recurrence of AVNRT.