Cardiac catheterization is an invasive diagnostic procedure that reveals vital information about the heart’s structure and function. 

It usually entails employing a procedure known as coronary angiography or arteriography to take X-rays of the heart’s arteries (coronary arteries). 

Coronary angiograms or arteriograms are the images that arise.

Complications 

Cardiac catheterization and coronary angiography are generally considered to be relatively safe procedures. 

However, like with any surgery, there are some dangers to consider, including: 

a very small risk of more serious complications, such as damage to the artery in the arm or leg where the catheter was inserted, heart attack, or stroke – this is uncommon, allergies, bleeding under the skin where the catheter was inserted – this should stop after a few days. Medical follow up is recommended.

Source: NHS