Abstract: A catheter having a tube and a depth control flange to prevent the catheter tube from being over inserted. The preferred embodiment is a retrograde coronary sinus cardioplegia solution administration catheter. A depth control flange is coupled to the tube at a predetermined distance from the catheter tip. The flange is a disc made of soft plastic material which prevents over-insertion of the catheter tip when the flange abuts the wall of the atrium. The catheter tube further includes an inflatable balloon located between the flange and the catheter tip. After insertion into the coronary sinus, the balloon is inflated thus pinching the atrium wall between the flange and the balloon to prevent cardioplegia solution from flowing back from the coronary sinus into the atrium. A semi-rigid introducer tube surrounds a portion of the catheter tube and is axially movable with respect thereto. One end of the introducer tube includes a receptacle in which the flange is stored in a collapsed position.