Large epicardial hematoma after percutaneous coronary intervention: multimodality imaging

: Vieussens' ring is an embryologic remnant that acquires clinical significance as an intercoronary collateral vessel in advanced coronary artery disease. Its origin as a peritruncal structure early in embryologic development, and its association with congenital pulmonary artery fistula, provides a crucial insight into the early stages of the coronary circulation. This review describes the embryologic basis of Vieussens' ring in relation to the formation of the coronary arteries, which explains its location, appearance, and clinical importance.