Acquired coronary cameral fistula--a report of two cases.

Background: Coronary cameral fistulas (CCF) are an uncommon clinical entity; encountered occasionally during cardiac catheterization. These fistulas most commonly result from congenital abnormalities leading to neovascularization. Other possible etiologies include trauma during surgery or coronary intervention. These fistulas usually terminate directly in a cardiac chamber, most often in the right ventricle.

Case Presentation: We describe two cases of CCF where a previous coronary angiogram did not show the presence of the abnormality. Cardiac catheterization in our first patient revealed the presence of a fistula from the right coronary artery draining into the right ventricle. A coronary angiogram performed three years prior to this procedure revealed no obstructive coronary artery disease and no evidence of this fistula. In contrast our second case had an aortic valve replacement for severe aortic stenosis. A cardiac catheterization prior to the surgery revealed normal coronaries with no fistula. The patient's subsequent angiogram three years later revealed the acute marginal branch of the right coronary artery draining into the right atrium.

Conclusion: Coronary cameral fistula is a rare clinical entity and can be acquired during an individual's lifetime. The puzzling presentation in our first patient is unique because CCF was acquired despite lack of previous instrumentation or trauma to the right coronary artery. The exact mechanism of fistula formation is unknown. However a possible hypothesis is secondary to hypoxia-induced angiogenesis, which has not been described to date.