 A cannula or catheter inserted into an artery may be used to measure pulse pressure or pulmonary wedge pressures.Angiography, which involves injecting a dye into an artery to visualise an arterial tree, can be used in the heart (coronary angiography) or brain.At the same time as the arteries are visualised, blockages or narrowings may be fixed through the insertion of stents, and active bleeds may be managed by the insertion of coils.