The specialty continues to be based on operative arterial and venous surgery but since the early 1990s has evolved greatly. There is now considerable emphasis on minimally invasive alternatives to surgery. The field was originally pioneered by interventional radiologists, chiefly Dr. Charles Dotter, who invented angioplasty. Of note, Dr. Thomas Fogarty invented the balloon catheter which enabled angioplasty. Further development of the field has occurred via joint efforts between interventional radiology, vascular surgery, and interventional cardiology. This area of vascular surgery is called Endovascular Surgery or Interventional Vascular Radiology, a term that some in the specialty append to their primary qualification as Vascular Surgeon. Endovascular and endovenous procedures (e.g., EVAR) can now form the bulk of a vascular surgeon's practice.