The descending septal branch (Bonapace's branch). A case report and literature review of this often forgotten branch. First description in vivo.

We present a 51-year-old female with exertional angina pectoris and a normal coronary angiogram who had a prominent descending septal branch originating from the proximal right coronary artery. This branch was perfused in the antegrade direction and did not show the tortuosity typical of coronary collaterals. The branch was almost 1 mm in diameter and supplied the middle third and basal two-thirds of the interventricular septum. The right coronary artery and this branch were free of coronary obstructions. The descending septal branch, described in 1921 by Crainicianu in a postmortem study, occurs in 12 to 85% of human hearts, but is still widely unknown. A review of the literature is also provided with special consideration of the functional importance of the condition and its prevalence in human and animal hearts. As far as we are aware, such a well developed descending septal branch in human hearts has not been described before. This is also the first description of a descending septal branch in vivo.