The present invention tackles the challenging anatomic characteristics of the coronary artery disease in the bifurcation point and the origin of side-branch. The invention has a specifically designed angioplasty balloon catheter, particularly the balloon shape and profile, to be used in the diseased vessels at these difficult anatomic locations. In stent implanting into a coronary artery, a balloon catheter application is an inseparable requirement. A stent is a passive device that cannot be deployed in a diseased or stenosed artery without a pre-stent, with-stent and/or post-stent balloon dilatation. In majority (more than 95%) of available coronary stents, a stent is deployed by balloon expandable mode, meaning that the stent is delivered and expanded inside a vessel lumen by expanding a delivery balloon. This is done by crimping a stent over a folded balloon for delivery into a coronary artery. When expanded by balloon inflation, a stent is expanded and shaped passively by the inflated balloon shape and profile. The balloon catheter is designed to do angioplasty in the bifurcation and side-branch anatomy of coronary arteries, while minimizing the side effect. This specially designed balloon catheter is not only for balloon angioplasty dilatation of the bifurcation and side-branch anatomy, but is also for delivering and deploying specially designed bifurcation or side-branch stents into these difficult anatomic locations, as a stent delivery system.