large vessels on top of the heart are the veins.
I think you are talking about the Aorta.
the heart
Artery
Aorta.
aorta
The large blood vessel is called the aorta.
Aorta
An artery.
pancreas
Descending aorta
pulmonary trunk
massive heart atttack usually involves either multiple vessels and destroys a large part of the heart or a very large vessel that supplies a large portion of blood to the heart.