How Specialists at Cardiac ‘Cath Lab’ Diagnose, Treat Coronary Artery Disease

Millions of cardiac catheterization procedures are performed every year in the U.S. to confirm suspected coronary artery disease and/or other related cardiovascular disorders.

Known more commonly as Cath Labs, Cardiac Catheterization Labs – such as the one at Baptist Health Miami Cardiac & Vascular Institute -- are equipped with the latest technology and a diverse team of interventional specialists. Cath Labs serve critical roles as a stopover on the road to recovery from a heart attack or blockages in the arteries or structural problems with the heart’s valves.

Marcus St. John, M.D., interventional cardiologist and medical director of Baptist Health Miami Cardiac & Vascular Institute‘s Cardiac Catheterization Lab (Cath Lab).

As a diagnostic procedure, the interventionalist at a Cath Lab guides a catheter into a blood vessel, via the wrist or groin, and injects contrast dye to visualize blood flow in the coronary arteries that carry blood to the heart muscle, explains Marcus St. John, M.D., an interventional cardiologist, the medical director of the Cath Lab at Baptist Health Miami Cardiac & Vascular Institute. This diagnostic procedure is called a coronary angiography.

Minimally invasive procedures can be done during or after a “cardiac cath,” including an angioplasty in which a tiny balloon is inflated at the tip of the catheter to push plaque buildup against the artery wall and improve blood flow. In a stent placement procedure, the interventionalist expands a tiny metal mesh coil or tube at the end of the catheter inside an artery to keep it open.

“The combination of symptoms, plus an abnormal diagnostic non-invasive test, is probably the ideal scenario that should then lead to an elective, more invasive evaluation with an interventional cardiologist,” explains Dr. St. John. “And then that evaluation involves the cardiac catheterization with the coronary angiography, which is just the taking of pictures. Then we confirm what is or isn't there. And then that provides the key information upon which to base whatever treatment therapy or surgery is needed.”

A cardiac cath can also lead to a referral to a cardiac surgeon for coronary artery bypass surgery or to a structural heart specialist to treat valvular defects.

Emergency Cases and Elective Outpatient Referrals

Usually, two types of cases make their way to the Cath Lab, said Dr. St. John. Many involve urgent cases where patients are transported from the ER with potentially life-threatening, cardiac-related events.

Dr. St. John emphasizes that no one should ignore telltale symptoms of a heart attack, such as chest pain or pressure, shortness of breath, nausea or vomiting, profuse sweating, dizziness, or fainting.

“It’s not that every time you get a discomfort in your chest you need to run to the emergency department,” said Dr. St. John. “But discomforts that are severe, that are associated with shortness of breath, nausea, vomiting, sweatiness, and that don't go away quickly -- they really do warrant urgent attention. And if you are in doubt about whether this could be a heart attack, going to the emergency room is really the best strategy.”

The other types of Cath Lab cases are elective outpatient referrals, typically patients with symptoms or with irregular findings from non-invasive testing, including electrocardiograms (ECGs or EKGs), calcium scores, stress tests or other evaluations.

“If they are referred to us, then they have had a number of risk factors that led to an evaluation and/or symptoms, like chest pain or shortness of breath,” explains Dr. St. John. “Sometimes, there are no symptoms, but there’s been a change in an EKG or a diagnostic test such as a calcium score, for example, that leads to additional testing. Often, it’s a coronary CT (computerized tomography) angiogram or a stress test that earns someone a referral to the Cath Lab.”

Many patients don’t realize that the Cath Lab procedures have evolved so much in recent years that most are performed on an outpatient basis.

“Most people who come in for a cardiac catheterization now expect to go home the same day,” said Dr. St. John. “It used to be that if you get a cath and a stent as an outpatient, you then spent the night. And we realized over the last decade or so that spending the night really is not adding a lot of value, especially as cath techniques have evolved.”

What to Expect During Cardiac Catheterization

Here's the general process for a typical cardiac cath followed by a stent placement, as described by Dr. St. John:

1. The patient comes in for the procedure in the morning after discussing with his or her cardiologist which meds to hold and which to take on that day.
2. You will get an IV (intravenous) line to provide mild sedation and fluids.
3. In the room, there's a physician, a technologist, and usually one or two nurses. "The nurse is there for the patient's safety and sedation. They'll give you moderate sedation. You can think of it as light enough sedation that you're breathing on your own. So, there's no general anesthesia, usually."
4. "The physician will place the catheter in the wrist, and then it is positioned up to the heart and an X-ray dye is injected. Most commonly, but not always, the way that we get to the heart arteries these days is through the wrist artery, or the radial artery. That ends up being a more comfortable experience for patients. Pictures are then taken with an X-ray camera, and that shows us the arteries."
5. "If there's a serious blockage that we think is causing symptoms, and that we can help by safely putting in a stent, we would do that at the same time. The stent is a metal coil that then gets permanently implanted. If you get a stent, then you do need to be placed on blood thinners at least for six months. "
6. "At the end of the procedure, the catheter comes out of the wrist, the pressure bandage is placed on the wrist for about two hours. And then, even if you've gotten a stent, we usually observe the patient for three to six hours, but you can go home the same day. I do always discuss with patients the risks of serious complications, which are uncommon."