Demonstration of a left atrial input to the atrioventricular node in humans.
BACKGROUND
During right atrial stimulation, the anterior and posterior approaches provide inputs to the atrioventricular (AV) node. The purpose of the present study was to determine how activation proceeding from the left atrium reaches the AV node.


RESULTS
We studied AV nodal conduction during right and left atrial (coronary sinus) stimulation in 46 patients (27 women and 19 men; mean age, 46+/-4 years) who had structurally normal hearts. At an identical cycle length (600 ms), left atrial stimulation resulted in shorter A-H intervals than right atrial stimulation (73+/-3 ms versus 99+/-3 ms; P<0.05). In addition, atrial electrograms recorded close to the His bundle changed from near to far field potentials when stimulation was shifted to the left atrium. The A-H interval prolonged as the site of pacing was progressively moved from the distal to the proximal coronary sinus. During constant pacing from the distal coronary sinus, atrial activation close to the His bundle could be advanced by late extrastimuli delivered at the anterior and posterior approaches (up to 11+/-2 ms and 9+/-1 ms, respectively), without altering His bundle activation time. In contrast, late extrastimuli delivered at the inferoparaseptal mitral annulus advanced both the A and H electrograms in 19 of 20 patients, which is consistent with a left-sided input to the AV node. Right and left atrial stimulation resulted in similar AV nodal function.


CONCLUSIONS
The mitral annulus provides a left atrial input to the human AV node.
Gonzalez
Mario D
MD
Division of Cardiovascular Medicine, University of Florida College of Medicine, Gainesville, FL 32610-0277, USA. gonzamd@medicine.ufl.edu
Contreras
Leonardo J
LJ
Cardona
Francisco
F
Klugewicz
Christopher J
CJ
Conti
Jamie B
JB
Curtis
Anne B
AB
Morey
Timothy E
TE
Dennis
Donn M
DM
D001282:Atrial Flutter / Q000503:physiopathology / Q000601:surgery; D016275:Atrial Function; D001283:Atrioventricular Node / Q000503:physiopathology*; D002036:Bundle of His / Q000503:physiopathology; D006328:Cardiac Catheterization; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D013610:Tachycardia / Q000503:physiopathology / Q000601:surgery; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology / Q000601:surgery