cardiac catheterization

Cardiac catheterization is the technique of guiding a long, thin tube — a catheter — through a blood vessel and into the heart itself, so that the heart can be measured and pictured from the inside. Entering at the wrist or groin, the operator steers the catheter under X-ray guidance up the vessels to the chambers and great arteries. It is the foundation on which most invasive cardiac diagnosis and many treatments are built.

Once inside, a catheter can do several things. It can record the pressures within each chamber and vessel and sample oxygen levels, revealing how the heart pumps, whether valves obstruct flow, and whether blood is shunting through abnormal holes — the discipline of invasive hemodynamics. It can inject contrast to film the coronary arteries or a ventricle. Through the same access, therapeutic tools pass to perform angioplasty, place stents, repair or replace valves, close defects, or take a tissue biopsy.

A right-heart catheter, threaded through veins to the right side and pulmonary artery, measures pressures and cardiac output; a left-heart catheter, advanced up an artery, studies the coronaries and left ventricle. The procedure is generally safe in skilled hands but, being invasive, carries small risks of bleeding, vessel or heart injury, arrhythmia, contrast reaction, and kidney strain. It is reserved for when its detailed, direct information will change management.