3D Non-Fluoroscopic Cryoablation of Right-Sided Accessory Pathways in Children:Monocentric Study and Literature Review

Background:Cryoablation of accessory pathways(APs)is effective and very safe in children,as previously reported by our group.The aim of this retrospective study was to evaluate the current efficacy of 3D non-fluoroscopic cryoablation of right sided APs in children,comparing results obtained with the Ensite VelocityTM and the more recent Ensite PrecisionTM 3D mapping systems.Methods and Results:From January 2016 to December 2019,102 pediatric patients[mean age 12.5±2.8,62 males(61%of total cohort)]with right APs underwent 3D non-fluoroscopic transcatheter cryoablation at our Institution.Fifteen(14.7%)patients had previously undergone catheter ablation.Acute procedural success rate was 95.1%(n=97).No significant differences were detected in acute success rates achieved with Ensite Velocity^(TM)or Ensite PrecisionTM systems nor between manifest(94%)and concealed APs(100%).No permanent complications occurred.During follow-up(428±286 days,median 396 days[interquartile range 179-713]),19 patients(19.6%)had recurrences.Recurrences were more frequent for parahissian/anterior APs compared to midseptal/posterior and lateral APs(p=0.043).Recurrences were not related to the Ensite system used.A redo ablation procedure was attempted in 13 cases,11 cryoablation and 2 radiofrequency ablations:the former was successful in 10 cases out of 11(90.9%).Conclusion:3D cryoablation of right-sided APs is associated with a very high acute success rate with limited use of fluoroscopy,resulting in great benefit to the children.Recurrence rates are not high and patients can be retreated with cryo-energy with higher success rates.

Transseptal approach for catheter ablation of left-sided accessory pathways in children with Marfan syndrome:A case report

BACKGROUND Left-sided accessory pathways(APs)can be accessed with either a transaortic(TA)or transseptal approach(TS).For children with Marfan syndrome(MFS)who have aortic disease,the use of TA can aggravate the disease,making TS the best choice for these patients.CASE SUMMARY A 10-year-old girl was hospitalized because of intermittent heart palpitations and chest tightness.She was diagnosed with MFS,supraventricular tachycardia,Wolff-Parkinson-White syndrome,and left-sided AP was detected by cardiac electrophysiological.Catheter ablation was successfully performed via TS under the guidance of the Ensite system.During the follow-up,no recurrence or complications occurred.CONCLUSION The TS for catheter ablation of left-sided APs can be considered in children with MFS.Adequate evaluation and selection of the appropriate puncture site are particularly important.

Successful left-sided accessory pathway ablation without reference catheter in patient with atresia of coronary sinus and thin persistent left superior vena cava

We report a case of atrioventricular reentrant tachycardia (AVRT) with ostial atresia of the coronary sinus (CS). Without the anatomic angiography, radiofrequency (RF) energy was applied at the mitral valve annulus and the bypass tract was eliminated. After the therapy procedure, by CS angiography, we knew the persistent left superior vena cava (PLSVC), and the coronary sinus was connected with vena cava superior, very thin in a diameter. The therapy procedure was successful. The patient has remained completely symptom free.

Electrophysiologic behaviour of a left sided accessory pathway with decremental (Mahaim-like) properties

The observation of a left sided accessory pathway with decremental properties is rare. We describe the behaviour of one of these pathways which was characterized by the presence of retrograde conduction (not previously reported) and thus inducibility of atrio-ventricular orthodromic reentrant tachycardia.

Effect of Accessory Pathway Conduction on PJ Interval in Wolff-Parkinson-White Syndrome

Objective To observe the effect of accessory pathway (AP) conduction on PJ interval in patients with Wolff-Parkinson-White syndrome. Methods 129 patients with a single manifestation of AP who underwent successful radiofrequency ablation (RFCA) were included. Patients were divided into 10 groups according to AP location. The PR intervals, QRS durations and the PJ intervals were measured using simultaneous 12-lead ECG before and after ablation. The PJ intervals before ablation were compared with that after ablation. The atrioventricular (AV) conduction time via atrioventricular node-His conduction system before ablation were compared with the PR intervals after ablation. The ventricular depolarization time via atrioventricular node-His conduction system before ablation were compared with the QRS durations after ablation. Delta waves were compared between each two groups. Results (1) The PJ intervals of right posterior (RP) group and right posteroseptal (RPS) group before ablation were shorter than that after ablation (RP group 226±18 ms vs 236±19 ms, P<0.01, RPS group 221±18 ms vs 238±31 ms, P<0.05, respectively). (2) There were no significant differences between the atrioventricular (AV) conduction time via atrioventricular node-His conduction system before ablation and the PR intervals after ablation. (3)The ventricular depolarization time via atrioventricular node-His conduction system of RP group and RPS group before ablation were shorter than the PR intervals after ablation(RP group 79±12 ms vs 87±9 ms, P=0.01; RPS group 70±13 ms vs 86±9 ms, P<0.05, respectively). (4)The delta waves of RP group and RPS group were longer than that of left posterior group and left posteroseptal group(P<0.05). Conclusion PJ interval is shortened by AP conduction which pre-excites the general last excited part of left ventricle. It is determined by AP location and the extent of preexcitation.

The Experience of Radiofrequency Ablation for Treatment of Multiple Accessory Pathways

Objective To analyse retrospectively the experience of radiofrequency ablation for successful treatment of multiple accessory pathways (APS). Methods 150 patients with supraventricu-lar tachycardia related to APS have undergone radiofrequency ablation since 1994; the data was analysed. Results 8 patients with multiple APS were cured, 4 patients could be diagnosed to have multiple APS during electrophysiologic study (EPS) before ablation, and in the remaining 4 patients the multiple APS could only be diagnosed after successful ablation of one AP. Conclusion right - sided multiple APS are sometimes very difficult to treat by ablation, because there are no standard reference electrograms for bracketing the earliest site. Mapping area should be broader rather than limited by preestablished idea.

Localization and radiofrequency ablation of slow conducting pathway in left free wall

Objectives To study the Electrophysiologic characteristics and method of radiofrequency ablation in patients with slow conduction in left free wall. Methods When 5 cases induced tachycardia, using VS_2 program stimulation terminated the tachycardia to establish that ventricle is the part of reentry circle. Results No retrograde A waves in 4 cases but only 1 case present A wave in terminating tachycardia. The accessory pathways have decreasing conduction in One case. Successful ablation were located in ventricle sides. Conclusions Ventricular sense and S_2 program stimulation to terminate tachycardia is a reliable method to different atrial tachycardia . A wave of successful targets ahead of A wave of any coronary sinus leads is 8～22 ms.

Manifold benefits of choosing a minimally fluoroscopic catheter ablation approach

We report the case of a 14-year-old boy with ventricular preexcitation. A standard, fluoroscopy guided, ablation procedure was successfully performed in a postero-midseptal region with a total fluoroscopy time of about 45 min (2430 cGy.cm2). A few hours after the procedure, preexcitation reappeared. A second ablation procedure was scheduled using the EnSite NavXTM mapping system. During mapping along the tricuspid groove, preexcitation suddenly disappeared due to mechanical "bumping" of the accessory pathway and it did not recover over the next 30 min. As per our routine practice, the phase of geometry reconstruction has been continuously recorded by the system; thus, an off-line analysis allowed to pinpoint the site of earliest activation and the site of mechanical bumping, where radiofrequency obtained the accessory pathway ablation. The second procedure was performed without using fluoroscopy at all. Thanks to the geometry reconstruction, the procedure was completely successful thus avoiding a further rehospitalization.

Dyssynchrony Induced by Ventricular Preexcitation: A Risk Factor for the Development of Dilated Cardiomyopathy

Background:Signifi cant left ventricular dysfunction may arise in right-sided accessory pathways with ventricular preexcitation in the absence of recurrent or incessant tachycardia.This has just been realized and not enough attention has been paid to it.Methods:In the last 7 years,we identifi ed 12 consecutive children with a diagnosis of ventricular preexcitation–induced dilated cardiomyopathy.This report describes the clinical and echocardiographic characteristics of the patients before and after ablation.Results:Dyssynchronous ventricular contraction was observed by M-mode echocardiography and two-dimensional strain analysis in all patients.The basal and middle segments of the interventricular septum became thin and moved similarly to an aneurysm,with typical bulging during the end of systole.The locations of the accessory pathways were the right-sided septum(n=5)and the free wall(n=7).Left ventricular synchrony was obtained shortly after ablation.The left ventricular function recovered to normal and the left ventricular end-diastolic diameter decreased gradually during follow-up.Conclusions:A causal relationship between ventricular preexcitation and the development of dilated cardiomyopathy is supported by the complete recovery of left ventricular function and reversed left ventricular remodeling after the loss of ventricular preexcitation.Preexcitation-related dyssynchrony was thought to be the crucial mechanism.Ventricular preexcitation–induced dilated cardiomyopathy is an indication for ablation with a good prognosis.

Orthodromic Atrioventricular Reciprocating Tachycardia in a Dalmatian

Supraventricular tachyarrhythmias may be caused by macroreentry circuits involving the AV node and accessory pathways. This paper reports a case of suspected orthodromic atrioventricular reciprocating tachycardia in an 18-month-old Dalmatian admitted with dyspnea and a lifelong history of fatigue. Cardiac auscultation documented a regular fast pace with no heart murmurs. The electrocardiogram characteristics were consistent with supraventricular tachycardia, with very regular RR interval and narrow QRS complexes. At lead II, we identified negative P waves buried within the ST segment, which resulted in a RP-to-PR ratio of 0.60, but in aVR these P waves were positive, suggesting a retrograde conduction of electrical impulses throughout the atrial myocardium. The echocardiographic study showed volume overload, and a decreased fractional shortening was calculated when SVT was sustained, highlighting its impact on systolic function. This is likely the first description of an orthodromic atrioventricular reciprocating tachycardia in a Dalmatian, and although cardiac mapping was not available to confirm this suspicion, all electrocardiograpic features were supportive of such arrhythmia.