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Narrow complex tachycardia with alternating R-R intervals. What is the mechanism?

Foo D, Ng KS, Qu L, Sutandar A - Indian Pacing Electrophysiol J (2006)

View Article: PubMed Central - PubMed

Affiliation: The Heart Institute, Tan Tock Seng Hospital, Singapore. david_foo@ttsh.com.sg

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The surface ECG revealed a narrow complex supraventricular tachycardia with alternating R-R intervals at 310ms and 360ms (Figure 1)... The intracardiac electrogram showed a macro-reentrant circuit with the earliest retrograde atrial activation located at CS 1-2... On close inspection of the intracardiac electrogram, two different alternating A-H intervals were observed, which presented as alternating R-R intervals on the surface ECG... The A-H intervals were 110ms and 160ms consecutively... We deduced that the antegrade limb of this macro-reentrant circuit involved both the fast and slow AV nodal pathways alternating with each other... Radiofrequency ablation of the left lateral pathway via a retrograde aortic approach was performed... Further electrophysiology studies confirmed the presence of dual AV nodal pathways... There were no further inducible arrhythmias even with isoproterenol infusion... The slow pathway was thus not ablated... The mechanism for this supraventricular tachycardia with alternating R-R intervals involved two alternating antegrade limbs (fast and slow AV nodal pathways) with different conduction times and a common retrograde concealed left sided accessory pathway... This electrophysiological mechanism had been postulated previously based on appearance of the surface ECG without intracardiac recordings.

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Intracardiac electrogram. HRA = high right atrial electrogram; HIS p and HIS d = proximal and distal HIS-bundle electrogram respectively; CS 1-2, CS 3-4, CS 5-6, CS 7-8, CS 9-10 = distal bipole, bipole 3-4, bipole 5-6, bipole 7-8, proximal bipole respectively; RVa = right ventricular apex electrogram; Stim 2 = stimulus channel
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Figure 2: Intracardiac electrogram. HRA = high right atrial electrogram; HIS p and HIS d = proximal and distal HIS-bundle electrogram respectively; CS 1-2, CS 3-4, CS 5-6, CS 7-8, CS 9-10 = distal bipole, bipole 3-4, bipole 5-6, bipole 7-8, proximal bipole respectively; RVa = right ventricular apex electrogram; Stim 2 = stimulus channel

Mentions: A decapolar catheter was placed in the coronary sinus with the distal and proximal pair of electrodes configured as CS 1-2 and CS 9-10 respectively. Quadripolar catheters were positioned in the high right atrium, His-bundle region and right ventricular apex. During straight atrial pacing with a drive-cycle length of 340ms, the following arrhythmia was induced (Figure 1). The corresponding electrogram is shown in Figure 2. What is the mechanism?


Narrow complex tachycardia with alternating R-R intervals. What is the mechanism?

Foo D, Ng KS, Qu L, Sutandar A - Indian Pacing Electrophysiol J (2006)

Intracardiac electrogram. HRA = high right atrial electrogram; HIS p and HIS d = proximal and distal HIS-bundle electrogram respectively; CS 1-2, CS 3-4, CS 5-6, CS 7-8, CS 9-10 = distal bipole, bipole 3-4, bipole 5-6, bipole 7-8, proximal bipole respectively; RVa = right ventricular apex electrogram; Stim 2 = stimulus channel
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1586162&req=5

Figure 2: Intracardiac electrogram. HRA = high right atrial electrogram; HIS p and HIS d = proximal and distal HIS-bundle electrogram respectively; CS 1-2, CS 3-4, CS 5-6, CS 7-8, CS 9-10 = distal bipole, bipole 3-4, bipole 5-6, bipole 7-8, proximal bipole respectively; RVa = right ventricular apex electrogram; Stim 2 = stimulus channel
Mentions: A decapolar catheter was placed in the coronary sinus with the distal and proximal pair of electrodes configured as CS 1-2 and CS 9-10 respectively. Quadripolar catheters were positioned in the high right atrium, His-bundle region and right ventricular apex. During straight atrial pacing with a drive-cycle length of 340ms, the following arrhythmia was induced (Figure 1). The corresponding electrogram is shown in Figure 2. What is the mechanism?

View Article: PubMed Central - PubMed

Affiliation: The Heart Institute, Tan Tock Seng Hospital, Singapore. david_foo@ttsh.com.sg

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

The surface ECG revealed a narrow complex supraventricular tachycardia with alternating R-R intervals at 310ms and 360ms (Figure 1)... The intracardiac electrogram showed a macro-reentrant circuit with the earliest retrograde atrial activation located at CS 1-2... On close inspection of the intracardiac electrogram, two different alternating A-H intervals were observed, which presented as alternating R-R intervals on the surface ECG... The A-H intervals were 110ms and 160ms consecutively... We deduced that the antegrade limb of this macro-reentrant circuit involved both the fast and slow AV nodal pathways alternating with each other... Radiofrequency ablation of the left lateral pathway via a retrograde aortic approach was performed... Further electrophysiology studies confirmed the presence of dual AV nodal pathways... There were no further inducible arrhythmias even with isoproterenol infusion... The slow pathway was thus not ablated... The mechanism for this supraventricular tachycardia with alternating R-R intervals involved two alternating antegrade limbs (fast and slow AV nodal pathways) with different conduction times and a common retrograde concealed left sided accessory pathway... This electrophysiological mechanism had been postulated previously based on appearance of the surface ECG without intracardiac recordings.

No MeSH data available.