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Heart Catheterization (Cardiac Cath)
Heart catheterization, also called cardiac catheterization or cardiac cath, is used both to diagnose and treat heart problems. In heart catheterization, a thin tube is inserted into a blood vessel and snaked along inside the vessel to the heart.
Diagnostic testing for congenital heart disease using heart catheterization includes the following:
- Coronary angiogram - Also known as an arteriogram, the coronary angiogram is a valuable tool for confirming a defect that has shown up in a physical exam or during echocardiography. The test uses a contrast medium or dye to create detailed X-ray pictures of the structures inside the heart, particularly the arteries and vessels.
- Oxygen levels - Oxygen levels from different parts of the heart measured using cardiac cath can be used to identify abnormal blood patterns such as through a septal defect.
- Blood pressures. Blood pressure measurements from different parts of the heart are used to evaluate blood-flow patterns in the heart and lungs.
- Biopsy - Tissue samples, or biopsies, of heart muscle can be collected for microscopic evaluation in the laboratory to identify diseases of the heart muscle itself, like hypertrophic cardiomyopathy.
- Electrophysiology studies - Heart catheters are used to place electrodes directly on the heart to collect detailed information on the electrical activity of the heart.
Cardiac cath involves guiding an instrument into the heart; therefore this procedure is done in a hospital. The length of the stay depends upon the type of procedure being performed and the medical condition of the individual. An otherwise healthy person can have a diagnostic procedure as an outpatient. For people with other health concerns or who are undergoing more extensive testing or treatment, the hospital stay may be two to three days or longer. The cardiologist will provide specific guidance about preparing for the procedure, including instructions on fasting, use of medications, and showering before arriving at the hospital.
Although catheterization itself only takes about 30 minutes, preparation for the procedure takes two to three hours. Preparation includes having blood taken, having an ECG if one has not been done recently, and discussing the details of the procedure with a member of the catheterization team. The insertion site is then prepared by shaving the hair from a small area in the groin or the inside of an elbow and an intravenous line is started to administer fluids and medications as needed during the procedure. Monitoring equipment including an ECG and blood pressure are also used throughout the procedure. At this time, a mild sedative may be administered to help the patient relax.
Catheterization is done in a specialized suite that is similar to an operating room and is equipped with an X-ray machine. In adults, heart catheterization is done under a local anesthetic with the patient remaining awake throughout the procedure. Typically, the procedure starts with the physician inserting a needle into a small artery of the groin, and snaking a sequence of wires and tubes up through the artery into the heart.
Once the catheter is positioned in an area of interest, the cardiologist will perform various tests and procedures. A biopsy may be collected for microscopic evaluation of the heart muscle fibers. Often, blood oxygen levels and blood pressure readings are measured; the cardiologist may also inject a contrast dye through the catheter to make the heart chambers or blood vessels more visible in X-ray images. This often makes patients feel suddenly warm or flushed for about 30 seconds.
After the physician has all the information needed, the catheter is removed, the insertion site is stitched or bandaged, and the patient will be taken to a recovery room for 30 to 60 minutes before being moved to a hospital room. Usually, activity can gradually resume after resting for one to six hours, depending on the site, number, and size of catheters used. But patients should not drive the day of the procedure. Thanks to the sedating medications and painkillers administered to the injection site, patients undergoing this procedure generally don't experience much pain or discomfort.
The most common complication of heart catheterization is bruising at the site where the catheter was inserted. Other less frequent complications include infection of the insertion site, irritation of the nerve fibers causing a tingling feeling (this is typically temporary), and bulges or even blockage of the artery at the insertion site.
Much more rare complications include irregular heart rhythms, stroke, and even cardiac arrest. The overall risk of developing one these more serious complications is between 1 in 100 and 1 in 1,000 for all individuals undergoing catheterizations. The risk of complications depends upon overall health, the tests being performed, and the skill of the cardiologist. Critically ill patients who undergo heart catheterization on an emergency basis are at highest risk for serious complications.
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