A wireless atrial pacemaker at Bachmann bundle

Bachmann bundle (BB) is a group of fibers arising near the crista terminalis and the origin of the sinus node. It traverses the roof of the right atrium and crosses the interatrial septum anteriorly. Within the left atrium, it courses toward the left atrial (LA) appendage and posteriorly between the pulmonary veins. As such, it acts as the major connection between the right and left atrium. In the past, the right atrial (RA) appendage (RAA) was the target site for implantation of atrial pacing leads.