Cr. Kerr et al., ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA IN PATIENTS WITH VENTRICULOATRIAL CONDUCTION BLOCK, Canadian journal of cardiology, 10(2), 1994, pp. 255-258
OBJECTIVE: To demonstrate the reversibility of retrograde ventriculo-a
trial block by isoproterenol in patients with atrioventricular nodal r
eentrant tachycardia (AVNRT). DESIGN: Three case reports and their ele
ctrophysiological features. PATIENTS: Three patients with documented o
r suspected paroxysmal supraventricular tachycardia. INTERVENTIONS: At
routine electrophysiology study, no supraventricular tachycardia was
inducible in the baseline state. Infusion of isoproterenol (1 to 5 mug
/min) was given and stimulation procedures were repeated. RESULTS: At
baseline, all three patients had discontinuous antegrade atrioventricu
lar (AV) nodal conduction, but very poor (two patients) or absent (one
patient) ventriculo-atrial conduction prevented induction of AVNRT. D
uring infusion of isoproterenol, retrograde conduction was enhanced so
that 1:1 retrograde occurred to cycle lengths of 300,340 and 260 ms.
AVNRT was then inducible in all patients, reproducing their clinical s
ymptoms. CONCLUSION: Absent or poor ventriculo-atrial conduction in pa
tients with suspected AV node reentry does not preclude the developmen
t of tachycardia with sympathomimetic enhancement. Isoproterenol shoul
d be given to attempt reversal of block in these patients.