Arterial catheterization is often employed in carrying out certain diagnostic studies upon the heart, and upon the aorta and its branches. Though the retrograde passage of a catheter from the femoral or brachial artery is attended with few mishaps, complications may arise which require recognition and proper surgical treatment. It is the purpose of this paper to discuss the surgical management of such complications. Report of Cases Case 1. —The patient was a 32-year-old woman in whom the diagnosis of mitral and aortic regurgitation was established by cardiac catheterization and cineangiography. These procedures were carried out on Jan. 4, 1960. They included right heart catheterization, transbronchial left atrial puncture and pressure, and angiographic studies performed after retrograde passage of a catheter into the aorta and left ventricle. The catheter was introduced through the right femoral artery by the Seldinger technique using a size 14 thin-walled needle for arterial puncture followed