title: Electrophysiology of anterograde right-atrial and left-atrial inputs to the atrioventricular node in patients with atrioventricular nodal re-entrant tachycardia.
abstract: OBJECTIVE
  To study anterograde atrioventricular (A-V) nodal electrophysiological properties through the right-atrial (Ri) and left-atrial inputs (Li) under the pharmacological autonomic blockade (AUB) in patients with slow-fast A-V nodal re-entrant tachycardia (AVNRT) and in controls.
  
  
  RESULTS
  Twenty-nine patients with slow-fast AVNRT and 15 control subjects were included. Programmed stimulation with single extrastimulus was performed from the right atrial appendage to test the Ri, and from the posterolateral coronary sinus to test the Li. The AUB was induced with intravenous atropine (0.04 mg/kg) and metoprolol (0.15 mg/kg). The A-V nodal conduction times, refractoriness, discontinuous conduction (≥ 40 ms atrial-His interval 'jump'), and inducibility of AVNRT or reciprocating beats were compared. The A-V nodal conduction times were longer: (i) through the Ri than Li, (ii) in patients than controls, and (iii) in baseline than after AUB--at slow rates in both groups and at fast rates in patients through the right input only (P < 0.05-0.001). A significantly longer slow pathway effective refractory period was demonstrated through the Li than the Ri in patients in baseline (P < 0.05). The discontinuous conduction was demonstrated 94 times in 25 of 29 (83%) patients and 15 times in 6 of 15 (40%) controls (P < 0.01), and was most frequently encountered with the Ri testing. Likewise, inducibility was manifested most frequently with the Ri testing (P = 0.08), and decreased after AUB during this testing only (P = 0.05).
  
  
  CONCLUSIONS
  The inherent magnitude of discordance of A-V nodal conduction velocity, refractoriness, and parasympathetic modulation between the Ri and Li to the A-V node may play a role in the aetiology of AVNRT.
authors.affiliation: Department of Cardiology, University Medical Center, Zaloska 7, SI-1525 Ljubljana, Slovenia. matjaz.sinkovec@kclj.si
authors.forename: Matjaz
authors.initials: M
authors.lastname: Sinkovec
authors.forename: Andrej
authors.initials: A
authors.lastname: Pernat
authors.forename: Zoran
authors.initials: Z
authors.lastname: Rajković
authors.forename: Matevz
authors.initials: M
authors.lastname: Jan
authors.forename: Bor
authors.initials: B
authors.lastname: Antolic
authors.forename: Peter
authors.initials: P
authors.lastname: Rakovec
mesh_terms: D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001283:Atrioventricular Node / Q000503:physiopathology*; D001285:Atropine / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000187:drug effects / Q000503:physiopathology; D002036:Bundle of His / Q000503:physiopathology; D016022:Case-Control Studies; D022062:Electrophysiologic Techniques, Cardiac; D055724:Electrophysiological Phenomena / Q000502:physiology*; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000494:pharmacology; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000209:etiology / Q000503:physiopathology*
chemical_list: D000889:Anti-Arrhythmia Agents; D001285:Atropine; D008790:Metoprolol