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Effects of a Blocked Atrial Beat on the Atrioventricular Nodal Recovery Property in Patients with Dual Nodal Pathways
Author(s) -
LEE PICHANG,
WU JINGMING,
WOLFF GRACE S.,
YOUNG MINGLON
Publication year - 2003
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1046/j.1460-9592.2003.00325.x
Subject(s) - refractory period , medicine , effective refractory period , cardiology , beat (acoustics) , nodal , anesthesia , physics , acoustics
Dual AVN physiology can be demonstrated by a variety of maneuvers. To determine whether AVN recovery times following a blocked extrastimulus facilitate or obscure detection of dual AVN physiology, 11 patients (9–17 years) were studied with dual AVN pathways by using single and double atrial extrastimuli. With a single atrial extrastimuli, the premature atrial stimulus (A 2 ) was coupled to basic atrial beats (A 1 ). The fast and slow AVN recovery curves were constructed with plots of the nodal conduction time against the recovery time (A 1 A 2 ,A 2 H 2 ). With double atrial extrastimuli, a fixed blocked A 2 beat (A 2B ) was followed by a scanning atrial beat (A 3 ). The nodal recovery property post‐A 2B was studied by plots of A 2B A 3 ,A 3 H 3 . In all patients the recovery curve of the fast pathway post‐A 2B had a leftward shift when compared to that of the pre‐A 2B curve (i.e., the AH was shortened at the same recovery time). The window of slow pathway conduction post‐A 2B disappeared totally in five patients and decreased significatly in six patients (post‐A 2B : 26 ± 42 ms; pre‐A 2B : 80 ± 65 ms, P < 0.05). In the six patients that still had slow pathway conduction post‐A 2B , the slow pathway effective refractory period post‐A 2B was significantly less than that of pre‐A 2B (215 ± 38 vs 268 ± 16 ms, P < 0.05). The fast pathway effective refractory period post‐A 2B was also diminished significantly (235 ± 62 vs 357 ± 76 ms, P < 0.0001). The authors conclude that blocked atrial beats decrease the visibility of the slow pathway conduction. (PACE 2003; 26:2091–2095)