Short ventriculoatrial intervals during orthodromic atrioventricular reciprocating tachycardia: what is the mechanism?

Unusual response to His-refractory atrial premature complex: What is the mechanism?

A 32-year-old woman underwent radiofrequency catheter ablation of narrow QRS tachycardia that was terminated with intravenous adenosine.

A case of Wolff-Parkinson-White syndrome presenting spontaneous mutual frequent transition between atrioventricular reciprocating tachycardia and atrioventricular nodal re-entrant tachycardia

Atrioventricular reciprocating tachycardia (AVRT) and atrioventricular nodal re-entrant tachycardia (AVNRT) can coexist and present unidirectional transition (from AVRT to AVNRT, or from AVNRT to AVRT) in a single patient. Actually, such cases have already been reported previously. However, a case with spontaneous bidirectional transition of both tachycardias during supraventricular tachycardia has never been reported. This article describes a case with spontaneous, mutual, and frequent transition between AVRT and AVNRT.

Spontaneous Transition of Double Tachycardias with Atrial Fusion in a Patient with Wolff-Parkinson-White Syndrome

Among patients with Wolff-Parkinson-White syndrome, atrioventricular reciprocating tachycardia (AVRT) and atrioventricular nodal reentrant tachycardia (AVNRT) can coexist in a single patient. Direct transition of both tachycardias is rare; however, it can occur after premature atrial or ventricular activity if the cycle lengths of the two tachycardias are similar. Furthermore, persistent atrial activation by an accessory pathway (AP) located outside of the AV node during ongoing AVNRT is also rare. This article describes a case of uncommon atrial activation by an AP during AVNRT and gradual transition of the two supraventricular tachycardias without any preceding atrial or ventricular activity in a patient with preexcitation syndrome.

A method to noninvasively identify cardiac bioelectrical sources

BACKGROUND

We have introduced a method to guide radiofrequency catheter ablation (RCA) procedures that estimates the location of a catheter tip used to pace the ventricles and the target site for ablation using the single equivalent moving dipole (SEMD).

OBJECTIVE

To investigate the accuracy of this method in resolving epicardial and endocardial electrical sources.

METHODS

Two electrode arrays, each of nine pacing electrodes at known distances from each other, sutured on the left- and right-ventricular (LV and RV) epicardial surfaces of swine, were used to pace the heart at multiple rates, while body surface potentials from 64 sites were recorded and used to estimate the SEMD location. A similar approach was followed for pacing from catheters in the LV and RV.

RESULTS

The overall (RV & LV) error in estimating the interelectrode distance of adjacent epicardial electrodes was 0.38 ± 0.45 cm. The overall endocardial (RV & LV) interelectrode distance error, was 0.44 ± 0.26 cm. Heart rate did not significantly affect the error of the estimated SEMD location (P > 0.05). The guiding process error became progressively smaller as the SEMD approached an epicardial target site and close to the target, the overall absolute error was ∼ 0.28 cm. The estimated epicardial SEMD locations preserved their topology in image space with respect to their corresponding physical location of the epicardial electrodes.

CONCLUSION

The proposed algorithm suggests one can efficiently and accurately resolve epicardial electrical sources without the need of an imaging modality. In addition, the error in resolving these sources is sufficient to guide RCA procedures.

Coexistence of atrioventricular nodal reentrant tachycardia with other forms of arrhythmias

OBJECTIVE

The aim of this retrospective study was to investigate the association of atrioventricular nodal reentrant tachycardia (AVNRT) with other forms of arrhythmia in individual patients and its consequences for treatment.

SUBJECTS AND METHODS

This study comprised 493 consecutive patients aged 16-88 years (296 women and 197 men) who were diagnosed with a form of AVNRT via a standard 4-catheter electrophysiological study (EPS). Patients were clinically followed (range 0.5-12 years) at a single center.

RESULTS

Coexistence of AVNRT with other types of tachycardias was observed in 197 (40%) patients. Atrial fibrillation was found most frequently in 94 (19%) patients as follows: focal atrial tachycardia, n = 40 (8%); atrial flutter, n = 32 (6%), and AV reentrant tachycardia, n = 22 (4%). Double tachycardia was present in 140 (30%) patients, and more than 2 different types of tachycardias were present in 57 (12%) patients. Transitions between AVNRT and other tachycardias occurred in 25 (5%) patients. Two or more tachycardias were ablated in 42 (9%) patients. The majority of patients were free of symptoms at the first follow-up, whereas 130 (26%) patients reported a variety of symptoms.

CONCLUSION

Coexistence of AVNRT with other types of arrhythmias was a common finding among these patients. The most frequently observed double tachycardia was the combination of AVNRT with atrial tachyarrhythmias, such as atrial fibrillation, with a potential significance for further patient management.