Cardiac catheterization, or “heart cath,” is a procedure used to directly visualize the arteries that supply blood to the heart. During the procedure, a long, thin tube (catheter) about 2 millimeters wide is placed in a blood vessel in the groin or wrist and is threaded up to the heart. Through the catheter, special dye is injected down the heart’s blood vessels, which allows the vessels to be seen on X-ray. This procedure is called coronary angiography.
The dye shows areas of narrowing or blockage in the arteries that can be responsible for chest pain (angina) or heart attacks. If blockage is found on the angiography, it can sometimes be opened with a balloon and a stent (angioplasty/percutaneous coronary intervention).
The catheter can also be advanced into the left ventricle (the main pumping chamber of the heart) to take pictures of the heart pumping. This may be helpful to assess heart function or to look for heart valve disease.
Sometimes it is important to measure the pressures within the heart and to assess heart valve function more precisely. In these cases, a right heart catheterization may be performed. In this procedure the catheter is advanced through a vein in the neck or the leg, up to the right chambers of the heart. This can provide useful information in assessing patients with valve disease, unexplained shortness of breath, or severe leg swelling.
A cardiac catheterization may be recommended for many reasons, but the most common is to evaluate patients suspected of having blockages in the heart arteries. Cholesterol and scar tissue deposits (plaque) can clog up arteries (coronary artery disease) and limit the blood supply to the heart muscle, which may result in symptoms such as pain, fatigue with exertion, increased shortness of breath, or decreased stamina. Prior to the heart catheterization, patients may have had symptoms strongly suggestive of blockage in the arteries or a stress test or cardiac CT scan that shows evidence of limited blood flow to the heart. In these patients, catheterization and angioplasty can be very effective in improving symptoms.
If an artery closes abruptly, a heart attack will occur. Emergent catheterization and angioplasty can save lives and limit the amount of damage to the heart muscle.
A cardiac catheterization may also be advised to evaluate the cause of heart failure or to exclude major blockages in the arteries prior to heart valve surgery.
In patients with unexplained shortness of breath, elevated blood pressures in the lungs (pulmonary hypertension), or swelling in the legs and belly, a right cardiac catheterization (referenced above) may be needed.
During a cardiac catheterization, you will have anesthesia, so the discomfort and pain will be minor. It may be a local anesthetic, just at the site where the doctor will insert the catheter into your groin or arm. You’ll remain awake and be able to follow the doctor’s instructions.
These procedures generally can take between 30 minutes to several hours. You’ll remain on your back throughout the procedure.
If angioplasty or stents are performed, you will stay in the hospital at least overnight. If only a heart catheterization is performed, you may be able to go home several hours after the procedure is completed.
During the catheterization, you will receive 3-4 ounces of X-ray dye, or contrast. Rarely, patients can be allergic to this. It is critical to let your doctor know if you have had prior allergic reactions to X-ray contrast or iodine-based dyes.
In addition, if you are diabetic and take the medication Metformin (Glucophage), it is very important to stop taking the drug on the day prior to the procedure and to not resume it for at least 48 hours after the procedure.
For several days after the procedure, it is best to avoid heavy (>30 pounds) lifting to allow the puncture site to heal. You may take a shower the day after the procedure, but should avoid soaking the catheterization site (e.g., bath tub, hot tub or pool) for 4-5 days.
What are the possible side effects and complications?
Cardiac catheterizations are routine and low-risk procedures, but as with all invasive procedures, there is a small risk of complications. In addition to the allergic reactions noted above, the contrast may also decrease kidney function. You should notify your doctor if you have kidney disease, especially if you are diabetic.
Procedures using a cardiac catheter may cause arrhythmia (irregular heartbeats). As with all operations, bleeding and infection are risks. The risk of serious complication is low, but in rare circumstances, heart attack, death and stroke can occur.
The risk of catheterization increases in elderly patients, patients with significant peripheral vascular disease, patients with diabetes—especially in diabetic patients with kidney disease—and in patients having a catheterization performed emergently.
You can learn more about cardiac catheterization at the National Heart Lung and Blood Institute.