Coronary angiography (an x-ray examination of the coronary arteries) is also possible with the commonly used left-heart catheterization procedure. Contrast medium is injected into the coronary arteries to find possible constrictions. Treatment can also be performed during the examination: If narrowed arteries (coronary artery disease, CAD) are found, they can be pushed open using a balloon affixed to the tip of the catheter. The catheter can also be used to implant a metal tissue support (stent) to keep the blood vessel open.
But coronary angiography (left heart catheterization) can't always find out whether a narrowed artery needs to be expanded. Measurements can then be done to see how affected the blood flow is in the narrowed section. A flexible wire with a built-in sensor is pushed through the catheter into the narrowed artery. The sensor measures the pressure before and after the narrowed section: The bigger the pressure difference is, the more affected the blood flow towards the heart is. The measured value is called the myocardial fractional flow reserve (FFR).
Tissue samples can also be taken during right heart and left heart catheterization. Doctors can also check possible causes of arrhythmia. Specialized catheters may be used to measure how much blood the heart pumps in one minute. This can help doctors find out whether the heart is performing poorly.