Evidence of quadruple anterograde atrioventricular nodal pathways in a patient with atrioventricular node reentry.
Functional longitudinal dissociation of the atrioventricular (AV) node exhibiting two discrete discontinuities in AV nodal conduction curves suggestive of triple AV nodal pathways has been described. The authors report here unusual electrophysiologic properties of the AV node in a patient with documented episodes of paroxysmal supraventricular tachycardia. Programmed atrial extrastimuli introduced at A1-A2 coupling intervals of 390 ms with a driven cycle length of 500 ms produced a sudden marked increase of 75 ms at the A2-H2 intervals suggesting failure of the fast pathway with conduction proceeding through a slower pathway with a shorter refractory period. With further decreasing coupling intervals, a second sudden jump of 70 ms and a third one of 150 ms occurred at A1-A2 coupling intervals of 330 and 290 ms, respectively. Beyond the first sudden jump, atrial echoes occurred when sufficiently slow pathway delay permitted recovery of the fast pathway for retrograde conduction. The atrial echo zone was 170 ms. These electrophysiologic demonstrations of reentry within the AV node in a patient with clinically documented supraventricular tachycardia and the existence of four ranges of AH conduction times and refractory periods strongly suggest the presence of quadruple anterograde AV nodal pathways and a variety of potential loops available for the development of sustained AV nodal reentrant tachycardia.
Centurion
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OA
Third Department of Internal Medicine, Nagasaki University School of Medicine, Japan.
Isomoto
S
S
Hayano
M
M
Yano
K
K
D000328:Adult; D001283:Atrioventricular Node / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D005260:Female; D006801:Humans; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis / Q000503:physiopathology*