What Happens During a Cardiac Catheterization?

Cardiac catheterization (heart cath) is used to look directly at the inside of the heart and its arteries when less invasive testing has not answered the question. The American Heart Association (Circulation journal) describes it as most often performed after a history and physical exam and noninvasive cardiac testing — an ECG (electrocardiogram, a tracing of the heart's electrical activity), an echocardiogram (an ultrasound of the heart) or a stress test (exercise or medication test) — to evaluate symptoms such as chest pain, shortness of breath, fatigue, dizziness or palpitations.

The conditions it is most commonly used to diagnose or assess, according to the National Heart, Lung, and Blood Institute, include coronary heart disease (narrowed heart arteries), heart attack, heart valve disease such as aortic stenosis (a stiff, narrowed valve) or mitral regurgitation (a leaking valve), cardiomyopathy (disease of the heart muscle), pulmonary hypertension (high pressure in the lung arteries) and arrhythmia (irregular heart rhythm).

Those earlier noninvasive tests are the usual first step, and noninvasive imaging of the coronary arteries is sometimes used before a cath as well. Whether one of them is reasonable in your case depends on your symptoms, your age, your kidney function and your other conditions — ask your cardiologist why a catheterization is being recommended now rather than another test.

• 7 days before: Call the ordering cardiologist's office and ask, item by item, which of your medicines to hold and for how long. The American Heart Association (Circulation journal) notes that certain oral anticoagulants — for example warfarin (Coumadin) or dabigatran (Pradaxa) — and injectable anticlotting drugs should be held before the procedure as directed by the managing clinician. Holding, timing and restarting are physician-directed decisions; do not change any dose on your own.
• 7 days before: Tell the office, yes or no, whether you have ever reacted to contrast dye (X-ray dye) or iodine, and whether you have kidney disease or diabetes.
• 3 days before: Arrange a licensed adult driver to take you home, and arrange for someone to stay with you the first night. Sedation rules out driving yourself.
• The day before: Ask the facility for your exact fasting start time. MedlinePlus (NIH) states that in most cases you should not eat or drink for a set period before the test, though your cardiologist may give different directions — get the hour in writing.
• The morning of: Bring a written list of every prescription, over-the-counter drug and supplement you take, plus your ID. Leave rings and jewelry at home.
• Confirm with your own team: Prep protocols vary by hospital and physician. Before you fast or hold anything, confirm the fasting window, the medication list and your arrival time with the cath lab or the ordering provider.

1. Check-in and prep. You change into a gown, and staff place monitors on your chest and a blood pressure cuff. An IV is placed in a vein in your arm, according to the National Heart, Lung, and Blood Institute, to give medicine during the procedure.
2. Site preparation. The access site — most often the wrist (radial) or the upper thigh/groin (femoral), and sometimes the neck or under the collarbone — is cleaned and shaved if needed.
3. Sedation and numbing. MedlinePlus (NIH) describes a mild sedative given beforehand to help you relax, with a local anesthetic (numbing medicine) at the insertion site; you will most likely be awake during the procedure. Some labs use moderate (conscious) sedation; general anesthesia is unusual for a straightforward adult diagnostic cath. Ask which your lab plans to use.
4. Catheter insertion. A small tube is placed in the artery and a thin catheter is guided up to the heart using X-ray. You should not feel the catheter moving inside the vessel; pressure at the access site is common, and contrast dye can cause a brief warm flush.
5. Pictures and measurements. Dye is injected to outline the coronary arteries, and pressures inside the heart chambers may be recorded. You may be asked to hold your breath or cough briefly.
6. Finishing. The catheter is removed and the site is closed with firm pressure, a compression device or a closure device. The American Heart Association (Circulation journal) notes that after a radial (wrist) procedure, a band on the wrist maintains pressure and wrist movement is restricted for several hours.

Typical duration: about 45 minutes for the procedure itself (American Heart Association, Circulation journal). MedlinePlus (NIH) notes a left heart catheterization may last from less than an hour to several hours, depending on what is found and whether treatment is added.

Routine and expected

• Several hours of monitored bed rest or restricted movement. After radial access, wrist movement is restricted for several hours while the compression band is in place (American Heart Association, Circulation journal). After femoral (groin) access, you will usually lie flat for a period set by your physician.
• A small bruise and tenderness at the access site are normal, according to the National Heart, Lung, and Blood Institute.
• Grogginess, mild nausea or a dry mouth from sedation for the rest of the day.
• If angioplasty (balloon opening of an artery, often with a stent) is done during the cath, MedlinePlus (NIH) states people can generally walk around within a short time afterward and that complete recovery takes about a week or less. A diagnostic cath without treatment is generally the shorter end of that.
• MedlinePlus (NIH) advises keeping the insertion area dry for a specified period and avoiding sexual activity for a specified period — ask your doctor for your exact number of days, as it depends on the access site and what was done.

Not expected — contact your care team

• A lump at the site that is growing, or pain that is worsening rather than easing.
• Fever, spreading redness or drainage from the site.
• The hand or leg below the site turning cold, pale or numb.
• Returning chest discomfort, new breathlessness or fainting.

Discharge timing, driving, lifting limits and return-to-work advice vary by facility and by access site. Confirm your own restrictions in writing before you leave.

The American Heart Association (heart.org) describes cardiac cath as usually very safe, with major complications very rare, and the American Heart Association (Circulation journal) calls it a common diagnostic procedure in the United States with minimal risk. MedlinePlus (NIH) presents the risk of serious complications from coronary angiography as a range rather than a single fixed figure. Your own risk depends on your age, kidney function, heart function and other conditions — ask your cardiologist to put a number to your situation.

Common, usually minor

• Bleeding or hematoma (a collection of blood) at the puncture site — the most common risk (American Heart Association, Circulation journal).
• Bruising and tenderness at the site.
• Reaction to contrast dye, and nausea or vomiting from sedation medicines (American Heart Association, heart.org).

Rarer, reported complications

The National Heart, Lung, and Blood Institute lists allergic reaction to dye, irregular heart rhythm, blood clots, collapsed lung (pneumothorax), damage to blood vessels, heart valves or the heart, low blood pressure, infection, need for blood transfusion and need for emergency surgery such as coronary artery bypass graft. MedlinePlus (NIH) also lists cardiac tamponade (fluid compressing the heart), injury to a heart artery, stroke and heart attack. The American Heart Association (Circulation journal) describes heart attack, stroke, need for emergent cardiac surgery and death as extremely rare.

Call 911 or go to the ER now

• Bleeding from the access site that cannot be stopped with firm pressure — the National Heart, Lung, and Blood Institute says to seek help immediately, as this may signal a serious problem.
• Chest pain or pressure, severe shortness of breath, fainting.
• Sudden weakness or numbness on one side, slurred speech or facial drooping.

Call your cardiologist the same day for fever, a growing lump, spreading redness, drainage, or a hand or foot that is cold, pale or numb.