Electrophysiological mapping and action potential recording were performed on the right atrioventricular ring of rats. It was found that in the presence of the sinus node, the right atrioventricular ring only serves as an electrical conduction region; after sinus node removal, it can initiate autonomous pacing and exhibit pacemaker-characteristic action potentials. These findings demonstrate that the right atrioventricular ring possesses ectopic pacemaker potential and is a potential origin site of atrial tachycardia.

A ) Electrical activation mapping was performed on the posterior wall of the right atrium of rats with an intact sinus node, revealing that the sinus node is the earliest activation site, and electrical signals propagate from the sinus node to the entire right atrium and the right atrioventricular ring.
B ) Electrical activation mapping was performed on the isolated right atrioventricular ring after resection of the sinus node and atrioventricular node. Spontaneous electrical activation was observed in the right atrioventricular ring, with the earliest activation site located within the tissue; multiple pacemaker sites were identified, and exit block occurred in some specimens.
C ）Intracellular action potentials were recorded from the pacemaker sites of the rat right atrioventricular ring and sinus node using sharp microelectrodes. The right atrioventricular ring was found to generate spontaneous action potentials characterized by diastolic depolarization, whose electrophysiological characteristics were highly similar to those of the sinus node, except for a lower pacing frequency.

Journal of the American Heart Association ( IF5.3 )

DOI: 10.1161/JAHA.113.000246.