For example, the catheter could make a hole in a blood vessel, and you might need immediate surgery to repair it. The catheter could disrupt your heartbeat or cause a heart attack. Fluid could build up in your lungs and make breathing difficult. A blood clot could travel to your brain and cause a stroke, or lodge in a lung and disable it, or settle in an arm or leg and prevent the blood from reaching it. Your kidneys could also be affected.
Doctors watch closely for any sign of a developing problem.
On the other hand, if you don't have the test, a serious heart condition may go undetected, leaving you in danger of a heart attack. If you've been told to take aspirin daily, do not stop without asking first. If you are taking a blood thinner, you may need to stop 2 or 3 days before the test. Check with your doctor, however, before you stop taking this or any medicine. A dye will be used during the test to show up the parts of your heart better.