Indian Pacing Electrophysiol. J.
Indian Pacing Electrophysiol. J. 2008;
Dual Ventricular Response or 1 : 2 Atrioventricular Conduction in Dual Atrioventricular Nodal Physiology
Download PDF 104 KBJohnson Francis, MD, DM, FACC; Krishnan MN, MD, DM, FACC.
Department of Cardiology, Calicut Medical College, Kerala, India.
Address for correspondence: Dr. Johnson Francis, MD, DM, FACC, Professor of Cardiology, Calicut Medical College, Kerala, India. E-mail: francisj/at/cmc.edu.inKey Words: Dual ventricular response; 1:2 atrioventricular conduction; dual atrioventricular nodal physiology.
Dual ventricular response to a single supraventricular impulse is an interesting possibility in the presence of dual atrioventricular nodal physiology. Double His bundle and ventricular responses to a single atrial impulse caused by a simultaneous fast and slow pathway conduction is the hallmark of this condition. One of the earliest descriptions of simultaneous conduction through both atrioventricular (AV) nodal pathways was by Csapo G1, who described various electrocardiographic patterns due to simultaneous conduction through dual AV nodal pathways. Activation through triple AV nodal pathways has also been described2,3. In one case2 an atrial impulse evoked double ventricular response due to simultaneous activation of the slow and fast pathway. The next impulse activated the ventricles through the intermediate pathway, The net result was a narrow QRS tachycardia with irregular RR intervals. In another case3 an incessant form of complex supraventricular tachycardia was noted, with simultaneous conduction over multiple AV nodal pathways. The tachycardia was successfully treated by ablation of intermediate and slow pathways. Over 20 cases non-reentrant supraventricular tachycardia with 1:2 AV conduction during sinus rhythm has been described in literature so far4-19
The major determinants of simultaneous anterograde fast and slow pathway conduction during sinus rhythm are: 1) Retrograde unidirectional block in both pathways 2) Critical conduction delay in the slow pathway and a long enough His-A interval to allow sequential conduction of impulse from both pathways6. The critical delay should be such that the impulse traveling through the slow pathway should reach the His bundle and ventricles after the refractoriness following the fast pathway impulse (activation).
A mistaken diagnosis of atrial fibrillation may be entertained if the dual response is intermittent. Dixit S et al17 found that 3 of the 456 consecutive patients referred for ablation of atrial fibrillation over a 3 year period had runs of dual response. The tachycardias were cured by slow pathway ablation. Hence they have suggested a stimulation protocol to identify such patients whose treatment is much simpler than AF ablation.
Non-reentrant supraventricular tachycardia due to 1:2 AV conduction has been described between 44 - 74 years of age and with duration of symptoms of up to 7 years4-19. It may be inducible with atrial and ventricular extrastimuli4,8,19. Slow pathway may have a longer refractory period than fast pathway8. Sometimes infusion of sympathomimetic agents is needed during atrial stimulation for inducing the tachycardia19. Treatment by slow pathway ablation has been successful in all cases in which it was reported8-19. One of the earlier reports noted disappearance of symptoms with flecainide6.
Even tachycardiomyopathy secondary to non-reentrant atrioventricular nodal tachycardia has been described recently18. Treatment by slow pathway ablation resulted in full recovery of left ventricular function at 11 months of follow up.
In this issue of the journal Laszlo R et al19 describes another case of non-reentrant supraventricular tachycardia due to 1:2 AV conduction, which was cured by slow pathway ablation.While this mechanism is likely in this case, other possibilities must be considered. From the surface ECG, alternating His bundle ectopics with ventricular activation cannot be ruled out. This is more so as the EP study did not include a His bundle electrogram. Ideally an AH jump indicating blockage of the fast pathway conduction during sequential extrastimuli should be demonstrated to establish the presence of a dual pathway. However, consistent reproduction of the tachycardia by atrial stimulaton may indicate that alternating His ectopics are unlikely. This uncommon type of tachycardia has to be considered in the differential diagnosis of paroxysmal supraventricular tachycardia and irregular supraventricular rhythms mimicking atrial fibrillation.
1. Csapo G. Paroxysmal nonreentrant tachycardias due to simultaneous conduction in dual atrioventricular nodal pathways. Am J Cardiol. 1979;43:1033-45.
2. Yokoshiki H, Sasaki K, Shimokawa J, Sakurai M, Tsutsui H. Nonreentrant atrioventricular nodal tachycardia due to triple nodal pathways manifested by radiofrequency ablation at coronary sinus ostium. J Electrocardiol. 2006;39:395-9.
Arena G, Bongiorni MG, Soldati E, Gherarducci G, Mariani M. Incessant nonreentrant atrioventricular nodal tachycardia due to multiple nodal pathways treated by radiofrequency ablation of the slow pathways. J Cardiovasc Electrophysiol. 1999;10:1636-42.
Lin FC, Yeh SJ, Wu D. Determinants of simultaneous fast and slow pathway conduction in patients with dual atrioventricular nodal pathways. Am Heart J. 1985;109:963-70.
5. Buss J, Kraatz J, Stegaru B, Neuss H, Heene DL. Unusual mechanism of PR interval variation and nonreentrant supraventricular tachycardia as manifestation of simultaneous anterograde fast and slow conduction through dual atrioventricular nodal pathways. Pacing Clin Electrophysiol. 1985;8:235-41.
6. Kim SS, Lal R, Ruffy R. Paroxysmal nonreentrant supraventricular tachycardia due to simultaneous fast and slow pathway conduction in dual atrioventricular node pathways. J Am Coll Cardiol. 1987;10:456-61.
7. Madle A. A nonreentrant arrhythmia due to a dual atrioventricular nodal pathway. Int J Cardiol. 1990;26:217-9
8. Li HG, Klein GJ, Natale A, Thakur RK, Yee R. Nonreentrant supraventricular tachycardia due to simultaneous conduction over fast and slow AV node pathways: successful treatment with radiofrequency ablation. Pacing Clin Electrophysiol. 1994 ;17:1186-93.
9. Ajiki K, Murakawa Y, Yamashita T, Oikawa N, Sezaki K, Kotsuka Y, Furuse A, Omata M. Nonreentrant supraventricular tachycardia due to double ventricular response via dual atrioventricular nodal pathways. J Electrocardiol. 1996;29:155-60.
10. Verdino RJ, Iuliano S, Tracy CM. Successful ablation of a nonreentrant dual atrioventricular nodal tachycardia. J Interv Card Electrophysiol. 1997;1:159-61.
11. Glotz de Lima G, Roy D, Talajic M, Dubuc M. One-to-two atrioventricular conduction causing nonreentrant tachycardia: successful treatment with radiofrequency ablation. Pacing Clin Electrophysiol. 1998;21:1152-4.
Fraticelli A, Saccomanno G, Pappone C, Oreto G. Paroxysmal supraventricular tachycardia caused by 1:2 atrioventricular conduction in the presence of dual atrioventricular nodal pathways. J Electrocardiol. 1999;32:347-54.
Sorbera C, Cohen M, Dhakam S, Fazio J. Symptomatic atrioventricular dual pathway double responses: a role for slow pathway ablation. Pacing Clin Electrophysiol. 1999;22:958-61.
14. Neumann T, Schulte B, Pitschner HF, Neuss H, Hamm C, Neuzner J. Double ventricular excitation in dual atrioventricular node conduction physiology: catheter ablation of the slow conduction pathway of the dual atrioventricular node. Z Kardiol. 2000;89:1014-8.
15. Nakao K, Hayano M, Iliev II, Doi Y, Fukae S, Matsuo K, Komiya N, Isomoto S, Yano K. Double ventricular response via dual atrioventricular nodal pathways resulting with nonreentrant supraventricular tachycardia and successfully treated with radiofrequency catheter ablation. J Electrocardiol. 2001;34:59-63.
16. Kirchhof P, Loh P, Ribbing M, Wasmer K. Incessant supraventricular tachycardia with constant 1:2 atrioventricular ratio: a longitudinally dissociated atrioventricular node? J Cardiovasc Electrophysiol. 2003;14:316-9.
17. Dixit S, Callans DJ, Gerstenfeld EP, Marchlinski FE. Reentrant and nonreentrant forms of atrio-ventricular nodal tachycardia mimicking atrial fibrillation. J Cardiovasc Electrophysiol. 2006;17:312-6
18. Clementy N, Casset-Senon D, Giraudeau C, Cosnay P. Tachycardiomyopathy secondary to nonreentrant atrioventricular nodal tachycardia: recovery after slow pathway ablation. Pacing Clin Electrophysiol. 2007;30:925-8.
19. Roman Laszlo, Hans-Joerg Weig, Slawomir Weretka, Juergen Schreieck. Narrow complex tachycardia with alternating R-R intervals during physical stress: Double ventricular excitation. Indian Pacing and Electophysiol J. 2008; 8:129-132