bundle branch reentrant ventricular tachycardia in a patient with the brugada electrocardiographic...
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Bundle Branch Reentrant VentricularTachycardia in a Patient with the BrugadaElectrocardiographic Pattern
Alexander Mazur, M.D., Zaza Iakobishvili, M.D., Jairo Kusniec, M.D.,and Boris Strasberg, M.D.From the Cardiology Department, Rabin Medical Center, Beilinson Campus, Petah-Tikvaand Sackler School of Medicine, Tel Aviv University, Israel
A 55-year-old, previously healthy man presented with an episode of wide QRS tachycardia that hadleft bundle branch morphology and left superior axis. His electrocardiogram in sinus rhythm showedcharacteristic Brugada pattern with coved type ST-segment (J-point) elevation in leads V1V2, mildQRS widening of 110 ms, and left axis deviation. The mechanism of the tachycardia was shownto be bundle branch reentry. Baseline H-V interval of 68 ms additionally lengthened to 119 msafter intravenous procainamide administration indicating significant conduction system disease. Thetachycardia was no longer inducible after successful ablation of the right bundle branch.
Brugada syndrome; conduction system disease; bundle branch reentrant ventricular tachycardia
The Brugada syndrome is a genetically transmittedprimary arrhythmogenic disorder with a high riskof sudden death. The syndrome is characterized bya right bundle branch block pattern and ST-segment(J-point) elevation in the right precordial leads ofthe electrocardiogram (ECG).1 Sudden death in thissyndrome is typically caused by fast polymorphicventricular tachycardia (VT) or ventricular fibrilla-tion (VF).2 The present report describes a patientwith characteristic Brugada ECG pattern who pre-sented with bundle branch reentrant (BBR) VT.
A 55-year-old, previously healthy man, pre-sented to the hospital with an episode of fast (200beats/min) wide QRS tachycardia treated by car-dioversion (Fig. 1(A)). His past medical historywas unremarkable. He had no family history ofsudden death or cardiac arrhythmia. Serial ECGsrecorded in sinus rhythm showed dynamic J-point
Address for reprints: Alexander Mazur, M.D., Cardiology Department, Rabin Medical Center, Beilinson Campus, Petah-Tikva 49100,Israel. Fax: 972-3-9249850; E-mail: firstname.lastname@example.org
and coved type ST-segment elevation in leads V1V2 compatible with the Brugada pattern, mild QRSwidening of 110 ms, left axis deviation, and PR-interval of 200 ms (Fig. 2). Physical and neuro-logical examination, laboratory tests, echocardio-gram, and coronary angiogram were normal. Elec-trophysiological study was remarkable for mildHis-ventricular (H-V) interval prolongation of 68 msand reproducibly inducible sustained monomorh-pic VT with surface ECG morphology identical tothe clinical arrhythmia. The tachycardia mecha-nism was consistent with BBR VT based on the fol-lowing criteria: (1) left bundle branch block (LBBB)morphology and left superior axis (Figs. 1(A)(C)),(2) AV dissociation (Fig. 1(C)), (3) H precedingevery V with the H-V interval (112 ms) greaterthan that recorded during sinus rhythm (Figs. 1(B)and (C)), (4) H before the right bundle deflection(Fig. 1(B)), (5) spontaneous changes in the HH in-tervals preceded similar changes in the VV intervals(Fig. 1(C)), and (6) reproducible spontaneous
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Figure1. Twelve-lead ECG during the spontaneous episode of tachycardia (A). Surface ECG leads I, II, III, V1, V2, V6(B) or II, III, V1 (C) and intracardiac recordings from the His bundle (His) and right ventricular apex (RVA) obtainedduring induced tachycardia of the same ECG morphology. The recordings are consistent with bundle branch reentrantventricular tachycardia. See text for discussion. A, H, RB, and V denote atrial, His bundle, right bundle, and ventricularelectrograms, respectively.
termination of the VT with retrograde conductionblock to H (V with no H) (Fig. 1(C)). PolymorphicVT/VF was not inducible at baseline. Administra-tion of intravenous procainamide (10 mg/kg over a30-minute period) resulted in marked ST-segment(J-point) elevation in leads V1V2 additionallysupporting the relation of the ECG findings to theBrugada phenotype. The H-V interval lengthenedto119 ms indicating significant conduction systemdisease. Sustained polymorphic VT was inducedwith triple ventricular extrastimuli. Right bundlebranch was subsequently ablated. The BBR VT wasno longer inducible. The patient underwent im-plantable cardioverter-defibrillator placement. Heremained free from arrhythmia over a follow-up of9 months.
It is well recognized that fast polymorphic VT/VFis the underlying cause of sudden death and syn-cope in patients with the Brugada syndrome.2 Theproposed mechanism of the arrhythmia is func-tional reentry (phase 2 reentry) caused by markedtransmural dispersion of ventricular repolarizationdue to heterogeneous loss of the action potentialdome.3 Occurrence of monomorphic VT in pa-tients with the Brugada syndrome has been pre-viously reported,4,5 although BBR VT has neverbeen described as a part of arrhythmia spectrumassociated with this syndrome. Boersma et al. re-cently described a patient with the Brugada syn-drome who presented with monomorphic VT that
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Figure2. Twelve-lead ECG demonstrating dynamic pattern of right bundle branch block and coved type of ST seg-ment (J-point) elevation in leads V1-V2 compatible with Brugada phenotype (A). Disappearance of the Brugada ECGmanifestations on the third day of hospitalization (B).
had LBBB morphology and superior axis.5 Similarto our case, their patient showed baseline intra-ventricular conduction abnormalities manifestedby QRS duration of 160 ms, left anterior fascic-ular block, and prolonged H-V interval of 70 ms.The VT was inducible with programmed stimula-tion. However, the authors do not report if BBRmechanism was sought during electrophysiologicalstudy.
Whether BBR VT and Brugada ECG pattern ob-served in our patient are related phenomena isunknown. BBR is a well-known mechanism ofVT in patients with abnormal His-Purkinje con-duction. Significant conduction delay within theHis-Purkinje system is required to sustain BBR.6
His-Purkinje abnormalities manifested through in-traventricular conduction defects and H-V intervalprolongation are commonly found in patients withthe Brugada syndrome.2 Mutations in the SCN5Agene encoding voltage-gated Na+ channel subunithave been associated with both the Brugada syn-drome and isolated progressive cardiac conduction
defect (Lenegre-Lev disease) phenotypes.7,8 More-over, it has recently been shown that a single genemutation may produce both these phenotypes.9 Itis plausible, therefore, that the electrophysiologicalsubstrates for BBR VT and the Brugada syndromemay share a common genotype and that BBR VTmay be a potential mechanism of arrhythmia inpatients with this syndrome.
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