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Heart Catheterization (Cardiac Cath)
Heart catheterization can be used to both diagnose and treat heart problems. Diagnostic testing for cardiomyopathy using heart catheterization includes the following.
Coronary angiogram. Also known as an arteriogram, a coronary angiogram is a valuable tool for evaluating the degree of obstruction in the blood flow path in the heart. The test uses a contrast medium to create highly detailed X-ray pictures of the structures inside the heart, particularly the ventricles and arteries.
Oxygen levels. Oxygen levels from different parts of the heart can be measured using cardiac cath and used to identify abnormal blood patterns within the heart.
Heart pressures. Pressure measurements within different parts of the heart are used to evaluate blood flow patterns in the heart. These measurements are critical to determining how much fluid buildup is present, and which part of the heart (e.g. left or right side) is causing the most problems.
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 or restrictive cardiomyopathy.
Because cardiac cath involves inserting a thin tube into a vein or artery that ultimately is guided into the heart, this procedure is performed in a hospital. The exact length of the stay depends upon the type of procedure being performed and the medical condition of the individual. An otherwise healthy person having a minor procedure may have the procedure done as an outpatient. In other cases, a hospital stay of two to three days may be necessary. The cardiologist will provide specific guidance about preparing for the procedure, including instructions on fasting, medication use, and showering prior to arriving at the hospital.
Although the catheterization itself takes only about 30 minutes, the preparations take two to three hours. These include drawing a blood sample, obtaining an ECG if one has not been done recently, and discussing the details of the procedure. The insertion site is then prepared by shaving the hair from a small area in the groin or the inside of an elbow. An intravenous line is inserted to administer fluids and medications as needed during the procedure. At this time, a mild sedative may be administered to help the patient relax. Also, the patient is hooked up to monitoring equipment, including ECG electrodes and a blood pressure cuff.
Catheterization is done in a specialized suite that is similar to an operating room but 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. A sequence of wires and tubes are snaked through the insertion site, up through the artery, into the heart. However, sometimes an artery in the arm is used for catheterization.
Once the catheter is accurately 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 agent through the catheter to make the heart chambers or blood vessels visible in X-ray images. This often causes patients to feel suddenly warm or flushed for about 30 seconds. Once the physician has all the information needed, the catheter is removed and the insertion site is stitched or bandaged. Thanks to the sedating medications and painkillers administered to the injection site, patients undergoing this procedure generally don't experience much pain or discomfort.
After the catheter has been removed, 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 a period of approximately six hours, but patients should not drive the day of the procedure.
The most common complication 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 typically is temporary), and bulges or even blockage of the artery at the insertion site.
Much more rare are complications such as 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 people undergoing catheterizations. An individual's risk depends upon his or her overall health, the actual tests being performed, and the skill of the cardiologist. Critically ill people who undergo heart catheterization on an emergency basis are at highest risk for serious complications; the risk is typically lower for an otherwise healthy person having a scheduled catheterization.
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