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Arrhythmia Rounds Section Editor: George J. Klein, M.D.
Narrow QRS Tachycardia in a Patient with Spongiform Cardiopathy and Preexcitation: What is the Mechanism? ´ ´ ROBERTO MAT´IA, M.D., ANTONIO HERNANDEZ-MADRID, M.D., INMACULADA SANCHEZ, ´ M.D., GIUSEPPE LUMIA, M.D., EDUARDO FRANCO, M.D., JOSE LUIS ZAMORANO, M.D., and JAVIER MORENO, M.D. From the Arrhythmia Unit, Cardiology Department, Hospital Ram´on y Cajal, Madrid, Spain
AV node reentry, catheter ablation, spongiform cardiomyopathy, WPW syndrome Case Summary A 19-year-old man diagnosed with spongiform cardiomyopathy and ventricular preexcitacion was referred to our hospital for electrophysiological (EP) testing after a syncopal episode. Baseline electrocardiogram (ECG) showed ventricular preexcitation consistent with the presence of a superior paraseptal, anteroseptal, accessory pathway (AP). After triple femoral vein puncture, a decapolar catheter was placed in the coronary sinus, a tetrapolar catheter in the His bundle region (with no clear His deflection recorded through the EP study), and a 4-mm-tip irrigated ablation catheter initially at the RV apex. Programmed atrial extrastimuli from the coronary sinus reproducibly induced nonsustained and sustained episodes of an irregular narrow QRS tachycardia with apparent atrioventricular dissociation in the surface ECG (Fig. 1). Intracardiac recording during ongoing tachycardia are also shown (Figs. 2 and 3). What is the involved mechanism? Commentary Atrial stimulation showed a long antegrade effective refractory period of the AP (410 milliseconds pacing at 500 milliseconds basic drive cycle length). During atrial pacing subtle different changes in the QRS were observed, indicating a variable amount of fusion between the AP and the intrinsic nodal conduction, with the AP not showing antegrade decremental conduction. Ventricular stimulation showed a decremental, single pattern of VA conduction compatible with retrograde nodal conduction, with 40 milliseconds longer VA intervals during superior paraseptal RV stimulation as J Cardiovasc Electrophysiol, Vol. 25, pp. 1408-1410, December 2014. No disclosures. Address for correspondence: Roberto Mat´ıa Franc´es, M.D., Arrhythmia Unit, Cardiology Department, Alcalˆa University Ram´on y Cajal Hospital, Carretera de Colmenar Viejo, Km 9, 100, Madrid 28034, Spain. Fax: +34-91-336-9006; E-mail: [email protected] Manuscript received 26 July 2014; Revised manuscript received 12 August 2014; Accepted for publication 19 August 2014. doi: 10.1111/jce.12538
compared with RV apex. Programmed atrial extrastimuli repeatedly induced nonsustained and sustained runs of an irregular (cycle length 330–366 milliseconds) narrow QRS tachycardia (Fig. 1). Intracardiac recordings showed a narrow QRS tachycardia with more ventricular than atrial activations. Atrial activation was concentric at the coronary sinus and similar to the previous VA conduction. A progressive prolongation of the VA intervals until blockade consistently developed, suggesting a nodal retrograde Wenckebach sequence (Fig. 2). The association between noncompaction cardiomyopathy and the presence of APs has been described.1 In the present case, the presence of retrograde VA block during tachycardia excludes the participation of the AP as the retrograde limb of the tachycardia circuit. The differential diagnosis of narrow complex tachycardia with VA block includes automatic junctional tachycardia (AJT), AVNRT with upper common pathway block and a nodofascicular tachycardia using the His–Purkinje system for antegrade conduction and the pathway for retrograde conduction. In our case, reproducible induction ruled out AJT. The onset of AJT is usually spontaneous with absence of critical AH delay and often requires catecholamines.2 We observed reproducible induction with premature atrial extraestimuli followed by long PR intervals and even with spontaneous atrial ectopic beats, which strongly favors the diagnosis of AV node reentry (Fig. 1). The degree of ventricular irregularity observed in our case would not be expected with JT. Moreover, during periods of more regular tachycardia, reset phenomena by sinus beats were repeatedly observed through the AV-node slow pathway, although due to the irregular nature of the tachycardia, a spontaneous change in cycle length cannot be completely excluded. Figure 3 shows how, during a retrograde Wenckebach sequence, a sinus beat timed only 52 milliseconds before QRS onset advances the next ventricular deflection (through a slow nodal pathway) without advancement of the immediate QRS. Reset of the tachycardia by atrial depolarizations timed to atrioventricular junction refractoriness is diagnostic of AVNRT.3 Although concealed conduction into the AV junction cannot be excluded from this tracing due to the lack of a clear His recording, this finding is also highly suggestive of AVNRT in our case since
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Figure 1. A: Surface electrocardiogram during induction (left) and ongoing tachycardia (right). Left: Preexcitation is observed during sinus rhythm and atrial stimulation. After an atrial extrastimulus (A1A2 450–240 milliseconds), a narrow QRS tachycardia with apparent atrioventricular dissociation is observed. B: Intracardiac recordings during induction. A short VA interval (62 milliseconds) of the first tachycardia beat is shown with progressive prolongation of the local VA interval in the coronary sinus electrograms.
Figure 2. Narrow QRS tachycardia with progressive increase in VA intervals until block develops. Progressive increase in local VA intervals in the coronary sinus electrogramas is shown. HIS = His bundle; CS = coronary sinus; ABLA D = distal pole of ablation catheter placed at the right ventricular apex.
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Journal of Cardiovascular Electrophysiology
Vol. 25, No. 12, December 2014
Figure 3. During retrograde Wenckebach sequence, a late atrial depolarization (only 52 milliseconds, before QRS onset) presumably caused by a sinus beat advances the next ventricular deflection without advancement of the immediate ventricle. A subtle change in the activation sequence of the coronary sinus during the sinus beat is observed.
52 milliseconds is in the range of normal HV intervals. Tachycardia mediated by a nodofascicular AP was considered a very unlikely option, as this mechanism is very infrequently documented. During isoproterenol infusion, the present tachycardia turned into a typical slow–fast AVNRT tachycardia, with a regular retrograde 1:1 conduction. The AP antegrade effective refractory period shortened to 260 milliseconds. With the diagnosis of slow–fast AVNRT, ablation of the slow AV nodal pathway with radiofrequency applications in low positions of the Koch triangle was performed, rendering it noninducible. Ablation of the AP was also performed.
References 1. Nihei K, Shinomiya N, Kabayama H, Ikeda C, Hosono T, Aoki T, Matsuo N: Wolff-Parkinson-White (WPW) syndrome in isolated noncompaction of the ventricular myocardium (INVM). Circ J 2004;68: 82-84. 2. Hamdan MH, Kalman JM, Lesh MD, Lee RJ, Saxon LA, Dorostkar P, Scheinman MM: Narrow complex tachycardia with VA block: Diagnostic and therapeutic implications. Pacing Clin Electrophysiol 1998;21:1196-1206. 3. Padanilam BJ, Manfredi JA, Steinberg LA, Olson JA, Fogel RI, Prystowsky EN: Differentiating junctional tachycardia and atrioventricular node re-entry tachycardia based on response to atrial extrastimulus pacing. J Am Coll Cardiol 2008;52:1711-1717.
Arrhythmia Rounds Section Editor: George J. Klein, M.D.
Narrow QRS Tachycardia in a Patient with Spongiform Cardiopathy and Preexcitation: What is the Mechanism? ´ ´ ROBERTO MAT´IA, M.D., ANTONIO HERNANDEZ-MADRID, M.D., INMACULADA SANCHEZ, ´ M.D., GIUSEPPE LUMIA, M.D., EDUARDO FRANCO, M.D., JOSE LUIS ZAMORANO, M.D., and JAVIER MORENO, M.D. From the Arrhythmia Unit, Cardiology Department, Hospital Ram´on y Cajal, Madrid, Spain
AV node reentry, catheter ablation, spongiform cardiomyopathy, WPW syndrome Case Summary A 19-year-old man diagnosed with spongiform cardiomyopathy and ventricular preexcitacion was referred to our hospital for electrophysiological (EP) testing after a syncopal episode. Baseline electrocardiogram (ECG) showed ventricular preexcitation consistent with the presence of a superior paraseptal, anteroseptal, accessory pathway (AP). After triple femoral vein puncture, a decapolar catheter was placed in the coronary sinus, a tetrapolar catheter in the His bundle region (with no clear His deflection recorded through the EP study), and a 4-mm-tip irrigated ablation catheter initially at the RV apex. Programmed atrial extrastimuli from the coronary sinus reproducibly induced nonsustained and sustained episodes of an irregular narrow QRS tachycardia with apparent atrioventricular dissociation in the surface ECG (Fig. 1). Intracardiac recording during ongoing tachycardia are also shown (Figs. 2 and 3). What is the involved mechanism? Commentary Atrial stimulation showed a long antegrade effective refractory period of the AP (410 milliseconds pacing at 500 milliseconds basic drive cycle length). During atrial pacing subtle different changes in the QRS were observed, indicating a variable amount of fusion between the AP and the intrinsic nodal conduction, with the AP not showing antegrade decremental conduction. Ventricular stimulation showed a decremental, single pattern of VA conduction compatible with retrograde nodal conduction, with 40 milliseconds longer VA intervals during superior paraseptal RV stimulation as J Cardiovasc Electrophysiol, Vol. 25, pp. 1408-1410, December 2014. No disclosures. Address for correspondence: Roberto Mat´ıa Franc´es, M.D., Arrhythmia Unit, Cardiology Department, Alcalˆa University Ram´on y Cajal Hospital, Carretera de Colmenar Viejo, Km 9, 100, Madrid 28034, Spain. Fax: +34-91-336-9006; E-mail: [email protected] Manuscript received 26 July 2014; Revised manuscript received 12 August 2014; Accepted for publication 19 August 2014. doi: 10.1111/jce.12538
compared with RV apex. Programmed atrial extrastimuli repeatedly induced nonsustained and sustained runs of an irregular (cycle length 330–366 milliseconds) narrow QRS tachycardia (Fig. 1). Intracardiac recordings showed a narrow QRS tachycardia with more ventricular than atrial activations. Atrial activation was concentric at the coronary sinus and similar to the previous VA conduction. A progressive prolongation of the VA intervals until blockade consistently developed, suggesting a nodal retrograde Wenckebach sequence (Fig. 2). The association between noncompaction cardiomyopathy and the presence of APs has been described.1 In the present case, the presence of retrograde VA block during tachycardia excludes the participation of the AP as the retrograde limb of the tachycardia circuit. The differential diagnosis of narrow complex tachycardia with VA block includes automatic junctional tachycardia (AJT), AVNRT with upper common pathway block and a nodofascicular tachycardia using the His–Purkinje system for antegrade conduction and the pathway for retrograde conduction. In our case, reproducible induction ruled out AJT. The onset of AJT is usually spontaneous with absence of critical AH delay and often requires catecholamines.2 We observed reproducible induction with premature atrial extraestimuli followed by long PR intervals and even with spontaneous atrial ectopic beats, which strongly favors the diagnosis of AV node reentry (Fig. 1). The degree of ventricular irregularity observed in our case would not be expected with JT. Moreover, during periods of more regular tachycardia, reset phenomena by sinus beats were repeatedly observed through the AV-node slow pathway, although due to the irregular nature of the tachycardia, a spontaneous change in cycle length cannot be completely excluded. Figure 3 shows how, during a retrograde Wenckebach sequence, a sinus beat timed only 52 milliseconds before QRS onset advances the next ventricular deflection (through a slow nodal pathway) without advancement of the immediate QRS. Reset of the tachycardia by atrial depolarizations timed to atrioventricular junction refractoriness is diagnostic of AVNRT.3 Although concealed conduction into the AV junction cannot be excluded from this tracing due to the lack of a clear His recording, this finding is also highly suggestive of AVNRT in our case since
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Figure 1. A: Surface electrocardiogram during induction (left) and ongoing tachycardia (right). Left: Preexcitation is observed during sinus rhythm and atrial stimulation. After an atrial extrastimulus (A1A2 450–240 milliseconds), a narrow QRS tachycardia with apparent atrioventricular dissociation is observed. B: Intracardiac recordings during induction. A short VA interval (62 milliseconds) of the first tachycardia beat is shown with progressive prolongation of the local VA interval in the coronary sinus electrograms.
Figure 2. Narrow QRS tachycardia with progressive increase in VA intervals until block develops. Progressive increase in local VA intervals in the coronary sinus electrogramas is shown. HIS = His bundle; CS = coronary sinus; ABLA D = distal pole of ablation catheter placed at the right ventricular apex.
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Journal of Cardiovascular Electrophysiology
Vol. 25, No. 12, December 2014
Figure 3. During retrograde Wenckebach sequence, a late atrial depolarization (only 52 milliseconds, before QRS onset) presumably caused by a sinus beat advances the next ventricular deflection without advancement of the immediate ventricle. A subtle change in the activation sequence of the coronary sinus during the sinus beat is observed.
52 milliseconds is in the range of normal HV intervals. Tachycardia mediated by a nodofascicular AP was considered a very unlikely option, as this mechanism is very infrequently documented. During isoproterenol infusion, the present tachycardia turned into a typical slow–fast AVNRT tachycardia, with a regular retrograde 1:1 conduction. The AP antegrade effective refractory period shortened to 260 milliseconds. With the diagnosis of slow–fast AVNRT, ablation of the slow AV nodal pathway with radiofrequency applications in low positions of the Koch triangle was performed, rendering it noninducible. Ablation of the AP was also performed.
References 1. Nihei K, Shinomiya N, Kabayama H, Ikeda C, Hosono T, Aoki T, Matsuo N: Wolff-Parkinson-White (WPW) syndrome in isolated noncompaction of the ventricular myocardium (INVM). Circ J 2004;68: 82-84. 2. Hamdan MH, Kalman JM, Lesh MD, Lee RJ, Saxon LA, Dorostkar P, Scheinman MM: Narrow complex tachycardia with VA block: Diagnostic and therapeutic implications. Pacing Clin Electrophysiol 1998;21:1196-1206. 3. Padanilam BJ, Manfredi JA, Steinberg LA, Olson JA, Fogel RI, Prystowsky EN: Differentiating junctional tachycardia and atrioventricular node re-entry tachycardia based on response to atrial extrastimulus pacing. J Am Coll Cardiol 2008;52:1711-1717.
