Adenosine-sensitive atrial tachycardia originating from the para-Hisian region with the entrance of a slow conduction zone at the noncoronary aortic sinus

Adenosine-sensitive atrial tachycardia originating from the para-Hisian region with a slow conduction zone in the anteroseptal left atrium

Adenosine-sensitive atrial tachycardias (ATs) originating from the para-Hisian region have been reported, and the responsible mechanism is considered to be reentry. As an alternative strategy to ablation at the earliest activation site (EAS) close to the atrioventricular node, previous reports safely eliminated these ATs at the entrance of the slow conduction zone, indicated by a manifest entrainment-guided strategy, but no report has successfully ablated those ATs using the same strategy in the left atrium. We describe a case of adenosine-sensitive AT originating from the para-Hisian region that could be eliminated at a remote site from the EAS indicated by the demonstration of manifest entrainment from the high anteroseptal left atrium. <Learning objective: Previous reports safely eliminated adenosine-sensitive atrial tachycardias (ATs) originating from the vicinity of the atrioventricular (AV) node at the entrance of the slow conduction zone (SCZ), indicated by a manifest entrainment-guided strategy. There may be cases with the SCZ in the left atrium (LA), but radiofrequency application on the anteroseptum of the LA near the AV annulus has a potential risk of causing an AV block. Therefore, that strategy in the LA can be a reasonable option.>.

An unusual location of the origin of an adenosine-sensitive atrial tachycardia: The lateral mitral annulus

A 56-year-old woman underwent an electrophysiological study and radiofrequency catheter ablation of a narrow QRS tachycardia. Programmed atrial extrastimulation reproducibly induced the tachycardia. During the tachycardia, differential atrial overdrive pacing exhibited no ventriculoatrial (VA) linking, and ventricular overdrive pacing exhibited VA dissociation. Entrainment of the tachycardia with atrial overdrive pacing was not demonstrable because the tachycardia cycle length varied from 262 to 320 ms. An intravenous bolus of 5 mg of adenosine reproducibly terminated the tachycardia without atrioventricular (AV) block. Based on these findings, the clinical tachycardia was diagnosed as an adenosine-sensitive atrial tachycardia (AT). Activation mapping during the AT using the EnSite Precision system and Advisor HD Grid mapping catheter (Abbott, Minneapolis, MN, USA) exhibited a centrifugal pattern with the earliest activation along the lateral mitral annulus. A radiofrequency application at the earliest activation during the AT successfully terminated the AT. Adenosine-sensitive ATs generally originate from the vicinity of the AV node and tricuspid annulus. We present a case with an unusual location of the origin of an adenosine-sensitive AT, which was successfully ablated at the lateral mitral annulus. Since the AT was sensitive to adenosine, the AT substrate appeared to have been calcium channel-dependent tissue along the mitral annulus. <Learning objective: Adenosine-sensitive atrial tachycardias (ATs) generally originate from the right-sided atrioventricular (AV) annulus and are eliminated by ablation at the vicinity of the AV node, tricuspid annulus, proximal coronary sinus, and non-coronary sinus of Valsalva. This case report described a rare type of an adenosine-sensitive AT originating from the lateral mitral annulus. A radiofrequency application targeting the earliest activation on the activation map during the AT terminated the AT.>.