Interventional cardiology is a subspecialty of cardiology that focuses on the catheter-based treatment of structural heart diseases. Following the development of angioplasty by interventional radiologist Charles Dotter, Andreas Gruening is regarded as the father of interventional cardiology. Catheterization allows for a wide range of procedures on the heart. This usually entails inserting a sheath into the femoral artery but in practise any large peripheral artery or vein can be used, as well as cannulating the heart under X-ray visualisation, most commonly fluoroscopy.