title: Mechanism-specific effects of adenosine on ventricular tachycardia.
abstract: BACKGROUND
  There is no universally accepted method by which to diagnose clinical ventricular tachycardia (VT) due to cAMP-mediated triggered activity. Based on cellular and clinical data, adenosine termination of VT is thought to be consistent with a diagnosis of triggered activity. However, a major gap in evidence mitigates the validity of this proposal, namely, defining the specificity of adenosine response in well-delineated reentrant VT circuits. To this end, we systematically studied the effects of adenosine in a model of canine reentrant VT and in human reentrant VT, confirmed by 3-dimensional, pace- and substrate mapping.
  
  
  RESULTS
  Adenosine (12 mg [IQR 12-24]) failed to terminate VT in 31 of 31 patients with reentrant VT due to structural heart disease, and had no effect on VT cycle length (age, 67 years [IQR 53-74]); ejection fraction, 35% [IQR 20-55]). In contrast, adenosine terminated VT in 45 of 50 (90%) patients with sustained focal right or left outflow tract tachycardia. The sensitivity of adenosine for identifying VT due to triggered activity was 90% (95% CI, 0.78-0.97) and its specificity was 100% (95% CI, 0.89-1.0). Additionally, reentrant circuits were mapped in the epicardial border zone of 4-day-old infarcts in mongrel dogs. Adenosine (300-400 μg/kg) did not terminate sustained VT or have any effect on VT cycle length.
  
  
  CONCLUSIONS
  These data support the concept that adenosine's effects on ventricular myocardium are mechanism specific, such that termination of VT in response to adenosine is diagnostic of cAMP-mediated triggered activity.
authors.affiliation: Division of Cardiology, Department of Medicine, Cornell University Medical Center, New York, USA.
authors.forename: Bruce B
authors.initials: BB
authors.lastname: Lerman
authors.forename: James E
authors.initials: JE
authors.lastname: Ip
authors.forename: Bindi K
authors.initials: BK
authors.lastname: Shah
authors.forename: George
authors.initials: G
authors.lastname: Thomas
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Liu
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Ciaccio
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Wit
authors.forename: Jim W
authors.initials: JW
authors.lastname: Cheung
authors.forename: Steven M
authors.initials: SM
authors.lastname: Markowitz
mesh_terms: D000241:Adenosine / Q000008:administration & dosage*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage; D018780:Body Surface Potential Mapping / Q000187:drug effects; D004285:Dogs; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000503:physiopathology*; D016896:Treatment Outcome
chemical_list: D000889:Anti-Arrhythmia Agents; D000241:Adenosine
keywords: adenosine; arrhythmia mechanism; reentry; triggered activity; ventricular tachycardia