Europace Advance Access originally published online on October 3, 2008
Europace 2008 10(12):1445-1446; doi:10.1093/europace/eun272
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
SHORT COMMUNICATIONS
A ‘Regularly Irregular’ tachycardia: what is the diagnosis?
1 CHU Rennes, Service de Cardiologie et Maladies Vasculaires, Rennes F-35000, France; 2 Université de Rennes 1, LTSI, Rennes F-35000, France; 3 INSERM, U642, Rennes F-35000, France; 4 INSERM, CIC-IT 804, Rennes F-35000, France; 5 Hôpital Lariboisière, Service de Cardiologie, AP-HP, Université de Paris 7, Paris, France
Manuscript submitted 16 July 2008. Accepted after revision 8 September 2008.
* Corresponding authors. Tel: +33 2 99 28 25 25; fax: 33 2 99 28 25 10. E-mail address: tournoux{at}gmail.com (F.T.) or philippe.mabo{at}chu-rennes.fr (P.M.)
 |
Abstract |
|---|
 Top Abstract CaseDiscussionReferences |
|---|
We report the case of a 46-year-old female presented to the emergency room with sustained palpitations. Her ECG showed a narrow QRS regularly irregular tachycardia. This tachycardia was immediately terminated by a single dose of adenosine, and sinus rhythm was restored. Diagnosis of atrial tachycardia, orthodromic reciprocating tachycardia, and atrial nodal reentrant tachycardia (AVNRT) are discussed. An electrophysiological study was performed for further evaluation, and our final hypothesis was AVNRT with triple nodal pathways. A single application of radiofrequency energy in the posterior septum near the coronary sinus ostium effectively eliminated the tachycardia.
Key Words: AVNRT, Triple pathways
|
Case |
|---|
|
TopAbstractCaseDiscussionReferences |
|---|
A 46-year-old female presented to the emergency room with sustained palpitations. The physical examination was completely normal except for fast heart rate. A 12-lead ECG showed a narrow QRS regularly irregular tachycardia (175 bpm). This tachycardia was immediately terminated by a single dose of adenosine, and sinus rhythm was restored. Chest X-ray and echocardiogram were normal. An electrophysiological study was performed for further evaluation.
One catheter was positioned at the His bundle region (His), a second at the coronary sinus (CS), and finally an ablation (Abl) catheter at the apex of the right ventricle. Atrio-His interval was 58 ms and His-ventricular 40 ms. Programmed atrial stimulation with an extra-stimulus highlighted a conduction jump and reproducibly induced an unsustained narrow complex tachycardia, similar to the clinical tachycardia (Figure 1). During decremental ventricular pacing, ventriculo-atrial (VA) conduction time was incremental. A ventricular extra-stimulus (S1S1 = 500 ms; S1S2 = 400 ms) produced the response displayed in Figure 2.
|
|
|
Discussion |
|---|
|
TopAbstractCaseDiscussionReferences |
|---|
The ECG reading during the clinical tachycardia shows an RR interval alternans. Complementary observation of Figures 1 and 2 provides the following information: (a) Figure 1 shows an irregular rhythm, around 175 bpm, but with the repetition of a constant pattern of two RR intervals; (b) atrial and ventricular activation were simultaneous during the tachycardia (Figure 1); and (c) Figure 2 shows that, at the end of programmed ventricular stimulation, the extra-stimulus was followed by two echo beats (V1 and V2). The differential diagnosis consists of atrial tachycardia, orthodromic reciprocating tachycardia (AVRT),1
and atrial nodal re-entrant tachycardia (AVNRT).
An atrial tachycardia conducted to the ventricles by two different pathways2 would result in a regularly irregular ventricular response in the setting of a regular atrial rhythm. However, this would have led to different VA coupling intervals during tachycardia. The presence of constant VA interval in Figure 1 despite the irregular ventricle-ventricle response goes against the diagnosis of atrial tachycardia. AVRT with anterograde conduction alternating between fast pathway and slow pathway is excluded as well because the ventricular and atrial electrograms are nearly simultaneous. Therefore, by exclusion, AVNRT is the most likely mechanism. The electrophysiological study leads to a complementary hypothesis.
At the end of the programmed ventricular stimulation, Figure 2 shows that the extra-stimulus (S2) conducted to a retrograde atrial activation (A'). This atrial activation was followed by a first His complex (H1), a first ventricular response (V1), and a second H2V2 response. This is compatible with the presence of three different nodal pathways: one slow pathway (SP1) for VA' conduction, one fast pathway for A'H1V1 conduction and finally a second slow pathway (SP2) for A'H2V2 conduction. If the extra-stimulus (S2) was able to conduct from the right ventricle to the atria in absence of an accessory pathway, it must have used one nodal pathway. This atrial activation led afterwards to a double ventricular response which necessarily required two other nodal pathways, the first one used being still in its refractory period. Although the absence of ventricular pre-excitation and the incremental VA conduction time are not suggestive of conduction through an accessory pathway, Figure 2 does not exclude this diagnosis. However, even if present, it cannot account for the retrograde limb of the tachycardia since the VA interval would be then expected as significantly longer than what was observed during the tachycardia. Alternating QRS patterns during the tachycardia were probably related to the known phenomena of QRS alternans during high-rate tachycardia. Our final hypothesis was AVNRT with triple nodal pathways.
Incidence of multiple AV nodal pathways (
3) is not very well known (from 5 to 40%)3,4 and may depend on the stimulation protocol used. More than 90% of the patients with three or more AV nodal pathways exhibit the slow–fast form of AVNRT and only 16% showed either both slow–fast and fast–slow form of AVNRT or a slow–fast and a slow–slow form of AVNRT.5 To our knowledge, this case is the first report of AVNRT with triple nodal pathways exhibiting a ‘Regularly Irregular’ tachycardia. Previous reports showed that not all the slow pathways were involved in the initiation or maintenance of tachycardia.5 Even in the case of multiple nodal pathways, radiofrequency catheter ablation is known to be safe and effective to cure AVNRT. In our case, a single application of radiofrequency energy in the posterior septum near the CS ostium eliminated the tachycardia.
Conflict of interest: None declared.
|
References |
|---|
|
TopAbstractCaseDiscussionReferences |
|---|
[1] Roten L, Delacretaz E. QRS alternans and cycle length oscillation during narrow QRS tachycardia. Europace (2008) 10:681–2.
[2] Amasyali B, Kose S, Celik T. Atrioventricular nodal re-entrant tachycardia with QRS voltage and cycle length alternation and aberrant conduction due to two distinct antegrade slow pathways. Europace (2006) 8:134–7.
[3] Tai CT, Chen SA, Chiang CE, Lee SH, Chiou CW, Ueng KC, et al. Electrophysiologic characteristics, electropharmacologic responses and radiofrequency ablation in patients with decremental accessory pathway. J Am Coll Cardiol (1996) 28:725–31.[Abstract]
[4] Weismüller P, Braunss C, Ranke C, Trappe HJ. Multiple AV nodal pathways with multiple peaks in the RR interval histogram of the Holter monitoring ECG during atrial fibrillation. Pacing Clin Electrophysiol (2000) 23(Pt 2):1921–4.[Medline]
[5] Heinroth KM, Kattenbeck K, Stabenow I, Trappe HJ, Weismüller P. Multiple AV nodal pathways in patients with AV nodal reentrant tachycardia—more common than expected? Europace (2002) 4:375–82.
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||