Descending septal artery: an important artery for collateral coronary circulation.

We present a case report of a 40-year-old male who underwent elective cardiac catheterization secondary to complaints of intermittent chest pain and inducible ischemia in the anterior wall. Diagnostic catheterization revealed severe coronary artery disease including an occluded mid left anterior descending (LAD) artery. There was a rarely described descending septal artery (Bonapace's branch) originating from a separate ostium in the right aortic sinus. This artery was a very important source of collateralization to the LAD. This artery has been reported once in vivo, while it has been described more frequently in postmortem studies. The descending septal artery is postulated to have an important role in the perfusion of the conduction system and in collateral circulation in patients with coronary artery disease. A literature review confirms the functional importance of this artery.