Response to Adenosine Differentiates Focal From Macroreentrant Atrial Tachycardia

Abstract

Background-We previously proposed that adenosine has mechanism-specific effects on atrial tachycardia (AT), such that adenosine terminates AT attributable to triggered activity, transiently suppresses automatic rhythms, and has no effect on macroreentrant AT. This, however, remains controversial, because other studies have reported that adenosine terminates reentrant AT. To clarify this issue, we used 3D electroanatomic mapping to delineate the tachycardia circuit and thereby determine whether the response to adenosine differentiates focal from macroreentrant AT. Methods and Results-We examined the effect of adenosine on 43 ATs in 42 consecutive patients (59Ϯ15 years of age; 26 female) who received adenosine during tachycardia and whose mechanism of AT was characterized by pharmacological perturbation, entrainment, 3D electroanatomic mapping, and results of radiofrequency ablation. Eight tachycardias were macroreentrant (noncavotricuspid isthmus-dependent), and 35 ATs were focal (either triggered or automatic). Adenosine administered during AT (at doses sufficient to result in AV block) terminated or transiently suppressed focal AT in 33 of 35 cases, whereas 8 of 8 macroreentrant ATs were adenosine insensitive (PϽ0.001). Twenty-eight of 35 focal ATs were located along the crista terminalis or tricuspid annulus. Conclusions-The response of AT to adenosine can immediately differentiate atrial tachycardia arising from a focal source from that attributable to macroreentry. This finding can be exploited to facilitate developing a focused, strategic ablative approach at the onset of a procedure.

Unifying Algorithm for Mechanistic Diagnosis of Atrial Tachycardia

“…4 However, other investigators have reported divergent findings, reporting that adenosine also terminates macroreentrant AT, thus suggesting that termination of AT with adenosine is a nonspecific finding, which does not identify tachycardia mechanism. [5][6][7] In light of the challenges of demonstrating entrainment in microreentant AT and of the conflicting data with respect to the mechanistic effects of adenosine in AT, we sought to develop a discriminatory algorithm that could obviate the limitations and ambiguities of overdrive pacing enumerated above and introduce Algorithm for Atrial Tachycardia a methodology that could rapidly distinguish between macroreentrant and focal AT and, more particularly, differentiate microeentrant AT from focal AT caused by triggered activity or automaticity.…”

Distribution of the Origin of Adenosine TriphosphateSensitive Atrial Tachycardias With the Earliest Activation Recorded in the His Bundle Catheter

“…1 On the other hand, Iwai et al examined the response of 43 patients with AT to adenosine and reported that all focal AT were terminated by rapid injection of adenosine, except for those whose etiologies were due to macroreentry. 20 More recently, based on electrophysiological behavior and response to drugs, they suggested that para-Hisian AT was mechanistically consistent with triggered activity. 2 Further investigation is needed to elucidate the mechanism of this type of AT.…”

Electromagnetic Mapping During Complex RF Ablations

“…The published studies involved a limited number of patients, 7 to 120. Focal tachycardias in the right atrium are ablatable with success rate >90% (Kottkamp H et al, 1997;Marchlinski F et al, 1998;Iwai S et al, 2002). The same success rate may be achieved in macroreentrant atrial tachycardia related to post-surgical scar (Iwai S et al, 2002).…”

“…Focal tachycardias in the right atrium are ablatable with success rate >90% (Kottkamp H et al, 1997;Marchlinski F et al, 1998;Iwai S et al, 2002). The same success rate may be achieved in macroreentrant atrial tachycardia related to post-surgical scar (Iwai S et al, 2002). In the left atrium, focal tachycardias were localized to mitral annulus, roof, posterior wall, appendage and septum (Dong J et al, 2005).…”

“…Interestingly, the number of publication describing the use of electroanatomic mapping for ablation of focal tachycardia ablation is much larger (Kottkamp H et al, 1997;Marchlinski FE et al, 1998;Cummings RM et al, 2008). There is also ample of information on the use of this mapping in the ablation of different left atrial tachycardias (Iwai S et al, 2002;Marrouche NF et al, 2002;Kistler PM et al, 2003;Dong J et al, 2005). Left atrial tachycardias may originate on the septum, along the mitral annulus and from the pulmonary veins.…”