coronary sinus rhythm

cor·o·nar·y si·nus rhyth·m

an ectopic atrial rhythm supposedly originating from a pacemaker at the mouth of the coronary sinus; recognized in the electrocardiogram by P-waves that are inverted in leads II, III, and aVF with a normal or prolonged P-R interval; an ectopic ("lower") atrial rhythm.
References in periodicals archive ?
It may be the site of origin of so called "coronary sinus rhythm".