Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
In fact there are two procedures:
1. Angiography: it is just putting a guide wire into a major vessel , then forwarding it into the heart, and just seeing if there is any narrowing . this is simple process and done even without
anesthesia.If there is any narrowing a
stent cab be placed that area to widen the vessel,this is called
angioplasty. in both of these cases neither heart is stopped nor bypassed.
2. CABG (Coronory
artery bypass graft): this is a surgical procedure , done in which a vessel taken from the leg or chest is attached to the vessel of the heart to bypass the narrow vessel . It is mostly done as by pass surgery in which heart is temporarily stopped and a machine works as heart for that time. However these days it can also be done without stopping the heart ( called beating heart surgery)
Hope I have answered your query.
Let me know if I can assist you further.