The Rhythmia ultrahigh-density mapping system with a specific algorithm
seems to be helpful in identifying the target area to successfully treat multiple
morphologies by catheter ablation in the right ventricular outflow tract RVOT.
Interestingly, the acquisition process seemed to be extremely faster than a standard manual point-by-point premature ventricular contraction (PVC) mapping

Bianchi, V. (Valter)

Garcia-Bolao, I. (Ignacio)

Maddaluno, F. (Francesco)

Panella, A. (Alfonso)

Rocca, V. (Vincenzo) la

Simone, A. (Antonio) de

Stabile, G. (Giuseppe)

English

Dadun, University of Navarra

CASE REPORTHigh-density mapping to guide ablation of a right bundlebranch morphology premature ventricular contraction fromthe right outflow tractAntonio De Simone1, Vincenzo La Rocca1, Alfonso Panella1, Valter Bianchi2, Francesco Maddaluno3,Giuseppe Stabile4 & Ignacio Garcia Bolao51Clinica San Michele, Maddaloni, Italy2Ospedale Monaldi, Naples, Italy3Boston Scientific Italia, Milan, Italy4Clinica Mediterranea, Naples, Italy5Clinica Universidad de Navarra, Pamplona, SpainCorrespondenceGiuseppe Stabile, Laboratorio diElettrofisiologia, Clinica Mediterranea,Via Orazio 2, 80100 Napoli, Italy. Tel:+390817259641; Fax: +390817259777;E-mail: gmrstabile@tin.itFunding InformationNo sources of funding were declared for thisstudy.Received: 5 October 2017; Revised: 6December 2017; Accepted: 10 December2017Clinical Case Reports 2018; 6(6): 1060–1065doi: 10.1002/ccr3.1370Key Clinical MessageThe Rhythmia ultrahigh-density mapping system with a specific algorithmseems to be helpful in identifying the target area to successfully treat multiplemorphologies by catheter ablation in the right ventricular outflow tract RVOT.Interestingly, the acquisition process seemed to be extremely faster than a stan-dard manual point-by-point premature ventricular contraction (PVC) mapping.KeywordsCatheter ablation, high-density mapping, premature ventricular contractions,Rhythmia.IntroductionMost premature ventricular contractions (PVCs) with pre-cordial transition ≥V4 are eliminated ablating in the rightventricular outflow tract RVOT, and those transitioning≤V2 are eliminated with lesions at the left ventricular out-flow tract (LVOT) [1]. The complete abolition of a rightbundle brunch block (RBBB) morphology PVC (precordialtransition ≥V1) from the RVOT has been very rarelydescribed [2]. We report the use of an automated high-den-sity 3D mapping system to map the dominant RBBB mor-phology PVC in a patient presenting with multiple PVCs.Case ReportA 35-year-old woman implanted with a subcutaneousimplantable cardioverter defibrillator for a life-threateningventricular tachycardia (VT) was referred to our institutionfor PVC ablation. Her electrocardiogram (ECG) showedsinus rhythm with frequent ventricular premature depolar-izations. The dominant PVC showed RBBB morphologypattern with high amplitude R wave in DII and DIII andslightly negative complex in DI (Fig. 1A). Other PVCswere also observed, and some of them presented verysubtle changes compared to the dominant one (Fig. 1B)posing additional challenges to the mapping process.The dominant PVC was mapped with the Rhythmiamapping system (Boston Scientific, Inc, Cambridge, MA)using the OrionTM multipolar basket catheter (64 elec-trodes of 0.4 mm2 area; 2.5 mm spacing) (Boston Scien-tific, Inc, Cambridge, MA) The system automaticallycollected chamber geometry and electrograms (EGMs)using the operator-defined beat acceptance criteria as fol-lows: (1) respiration gating, (2) stable catheter location,(3) electrocardiographic (ECG) QRS morphology (ECGmetric), (4) tracking quality.1060 ª 2018 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use anddistribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. 20500904, 2018, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ccr3.1370 by Universidad de Navarra, Wiley Online Library on [25/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License(A)(B)Figure 1. (Panel A) Dominant PVC with RBBB morphology and high amplitude R wave in DII and DIII (1.8  0.3 mV). (Panel B) PVC number 1 wasthe dominant one and was targeted for ablation. PVC number 2 was very similar to the clinical one but was slightly different (note the larger QRSwidth) and so needed to be rejected in the activation map. PVC number 3 and 4 were two additional PVCs that were observed in this patient.ª 2018 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd. 1061A. De Simone et al. High density mapping ablation of PVCs 20500904, 2018, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ccr3.1370 by Universidad de Navarra, Wiley Online Library on [25/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License(A)(B)Figure 2. (Panel A) Activation map of the LVOT in the anteroposterior projection. A representative EGM of the broad orange area that hadearliest activation time was shown in the lower left corner. (Panel B) Activation map of the RVOT in the left lateral projection. The EGM found atthe earliest point in the most leftward aspect of the septal RVOT was shown in the left lower corner.1062 ª 2018 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd.High density mapping ablation of PVCs A. De Simone et al. 20500904, 2018, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ccr3.1370 by Universidad de Navarra, Wiley Online Library on [25/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons LicenseFor annotation of the local activation time of eachacquired bipolar EGM, the system combines unipolar(maximum negative dV/dt) and bipolar (maximumamplitude) EGMs. For multiple potentials and fraction-ated EGMs, the system annotates timing using a propri-etary algorithm which considers the timing ofsurrounding EGMs. The mapping window can beadjusted (to focus on clinically relevant parts of the tachy-cardia cycle) at any time without loss of information, andall points are re-annotated near instantaneously. Scar set-ting may be finely tuned with the confidence mask tool(points in the immediate surrounding area with EGMbipolar amplitude below the confidence mask have nocolor code and are displayed in gray color).The LVOT was mapped first using both a trans-septaland a retrograde approach. In particular, the aortic cusps,the mitral annulus, and the endocardial LVOT weremapped. The earliest activating area we found was abroad anteroseptal region whose activation was neverbefore the QRS complex (Fig. 2A). Considering the RBBBmorphology and the lack of any early ventricular EGM inthe left ventricle, we suspected an epicardial origin of thePVC. For this reason, we tried to advance the coronarysinus (CS) diagnostic 6F catheter (Dynamic XT; BostonScientific, Inc, Cambridge, MA) in the great cardiac vein(GCV) and then into the anterior interventricular vein(AIV). Because of difficult CS anatomy, we could onlymap the proximal part of the GCV where the ventricularEGM was slightly in advance with respect to the QRSonset during the clinical PVC. So, we decided to map theright ventricle. In the most leftward aspect of the septalRVOT, just beneath the pulmonary valve, we found avery early activation (30 msec before QRS onset)(Fig. 2B) where we delivered radiofrequency ablation(40 Watts for 3 min) by means of an irrigated 4-mm tipcatheter (Intella NAV OI; Boston Scientific, Inc, Cam-bridge, MA) and observed suppression of all PVCs. Thepacemapping performed at high current from the site ofsuccessful ablation is shown in Figure 3. A 24-h ECGHolter monitoring, performed after 3 months, showedonly 22 PVCs.DiscussionThe ECG is the basic tool to predict the site of origin ofa PVC and plan the ablation strategy. Then, activationmapping is used to precisely and accurately localize theearliest site of activation where radiofrequency ablation isdelivered. In our case, the patient presented with differentPVC morphologies, but the RBBB morphology pattern ofFigure 3. The pacemapping performed at high current from the site of successful ablation shows a very similar ECG morphology to thedominant PVC.ª 2018 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd. 1063A. De Simone et al. High density mapping ablation of PVCs 20500904, 2018, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ccr3.1370 by Universidad de Navarra, Wiley Online Library on [25/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons Licensethe dominant one, was strongly suggestive of a left origin[1]. Nonetheless, endocardial mapping found the earliestsite of activation on the septal RVOT.The findings of this case can be explained by an epicar-dial focus anatomically close to the most leftward aspectof the septal RVOT with different exit sites that gave riseto multiple PVC morphologies. The deep penetration ofthe radiofrequency energy from the earliest ventricularactivation site, in the septal RVOT to the epicardial focus,led to the abolition of all PVCs.The most leftward aspect of the septal RVOT is in closeanatomical relationship with an epicardial region of theleft ventricle named left ventricular summit (LVS) thathas been reported to be a major source of origin of idio-pathic ventricular arrhythmias. The LVS is a triangularportion of the epicardial LVOT bounded by the bifurca-tion between the left anterior descending and the left cir-cumflex coronary arteries and transected laterally by theGCV at its junction with the AIV [3]. The most leftwardseptal RVOT is in close proximity to the AIV and the leftanterior descending artery and can extend more anteriorlyand leftward to the sinuses of Valsalva.Some authors have reported that VTs originating fromone focus in the LVS can present with multiple mor-phologies due to different exit sites [4–6]. PVCs from thisarea are often targeted from the CS system (AIV/GCV)but can also be accessed directly via pericardial puncture.Both approaches can be limited by inability to advancethe catheter to the site of interest, inadequate powerdelivery, and proximity to coronary arteries. For thesereasons, ablation from the endocardium can be preferredand some authors reported successful abolition of LVSPVCs from adjacent endocardial structures including theseptal RVOT [7].Our case is in line with the findings of these authorsand confirms the usefulness of mapping the septal RVOTin patients presenting with dominant RBBB morphologyPVCs and no early activations in the LVOT.The use of an automated high-density mapping systemwas extremely useful in this complex case both for auto-matically rejecting nonclinical PVC morphologies and forspeeding up the acquisition of multiple activation maps.When mapping premature ventricular depolarization,extreme care is needed to ensure that only the relevantPVC morphology is being mapped and to exclude fusedbeats, different morphology, or catheter ectopy in orderto avoid “multiple” early points in the activation map.Using the Rhythmia system, this is automatically accom-plished by a correlation-based criteria (the ECG metric),aimed at computing the similarity between the 12-leadECG from a given beat and a user-defined “favorite beat.”In our case, the favorite beat was strictly adjusted to tar-get the clinical PVC and was the only tool we used to ruleout the other PVCs from the activation map. In this case,the application of this automatic tool accurately rejectednonclinical PVCs, even if they presented with very subtlechanges compared to the dominant PVC.In addition to that, the high-density of points acquiredfor each accepted clinical PVC morphology beat led to avery fast acquisition of the activation maps despite therejection of multiple beats (nonclinical PVCs and sinusbeats). The acquisition process seemed to be extremely fas-ter than a standard manual point-by-point PVC mapping.ConclusionThis case report suggested that RBBB morphology PVCin patients presenting with multiple morphologies can besuccessfully treated by catheter ablation in the RVOT. Ahigh-density mapping with a specific algorithm seems tobe helpful in identifying the target area of RF ablation.Conflict of InterestF. Maddaluno is a Boston Scientific employee, no otherconflicts of interest exist.AuthorshipAD: performed the procedure, interpreted the data, anddrafted the manuscript. AP: performed the procedure,assisted in signals acquisition and interpretation, andhelped to draft the manuscript. VL and VB: planned theprocedure, assisted in signals acquisition and interpreta-tion, and helped to draft the manuscript. FM: providedtechnical support during the procedure, reviewed the lit-erature, and critically reviewed the manuscript. GS andGB: reviewed the literature, provided additional supervi-sion, and critically reviewed the manuscript.References1. Hutchinson, M. D., and F. C. Garcia. 2013. An organizedapproach to the localization, mapping, and ablation ofoutflow tract ventricular arrhythmias. J. Cardiovasc.Electrophysiol. 24:1189–1197.2. Frankel, D. S., S. E. Mountantonakis, M. I. Dahu, and F. E.Marchlinski. 2014. Elimination of ventricular arrhythmiasoriginating from the anterior interventricular vein withablation in the right ventricular outflow tract. Circ.Arrhythm. Electrophysiol. 7:984–985.3. Santangeli, P., F. E. Marchlinski, E. S. Zado, D. Benhayon,M. D. Hutchinson, D. Lin, et al. 2015. Percutaneousepicardial ablation of ventricular arrhythmias arising fromthe left ventricular summit: outcomes andelectrocardiogram correlates of success. Circ. Arrhythm.Electrophysiol. 8:337–343.1064 ª 2018 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd.High density mapping ablation of PVCs A. De Simone et al. 20500904, 2018, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ccr3.1370 by Universidad de Navarra, Wiley Online Library on [25/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License4. Wang, Y. B., J. Ma, J. Z. Dong, R. Bai, J. Wang, S. N. Li,et al. 2015. Catheter ablation of premature ventricularcontractions originating from the aortic cusps or greatcardiac vein: two QRS morphologies with one origin.Pacing Clin. Electrophysiol. 38:1029–1038.5. Ma, J., K. X. Wu, Y. B. Wang, C. S. Ma, and J. M. Chu.2016. Premature ventricular contractions with two QRSmorphologies originate from one focus in great cardiacvein. Heart Rhythm Case Rep. 2:204–207.6. Dan Do, V. B., S. L. Chang, Y. J. Lin, and S. A. Chen. 2015.Shift of exit site during ablation of ventricular tachycardiaoriginating from the vicinity of left ventricular summit. J.Cardiovasc. Electrophysiol. 26:90–92.7. Enriquez, A., F. Malavassi, L. C. Saenz, G. Supple, P.Santangeli, F. E. Marchlinski, et al. 2017. How to map andablate left ventricular summit arrhythmias. Heart Rhythm14:141–148.ª 2018 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd. 1065A. De Simone et al. High density mapping ablation of PVCs 20500904, 2018, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ccr3.1370 by Universidad de Navarra, Wiley Online Library on [25/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

High-density mapping to guide ablation of a right bundle branch morphology premature ventricular contraction from the right outflow tract

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High-density mapping to guide ablation of a right bundle branch morphology premature ventricular contraction from the right outflow tract

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