Cardiac catheterisation
Cardiac catheterisation is a very common diagnostic test performed thousands of times a day.
It is a special x-ray study of the heart that involves the insertion of soft narrow plastic tubes called catheters via blood vessels into the heart.
This procedure is carried out at the Cardiac Catheterisation Laboratory to determine the function of the heart and its surrounding blood vessels through x-ray imaging.
It is usually carried out after preliminary tests such as electrocardiogram (ECG), echocardiography, treadmill exercise test (stress test), and Holter Ambulatory ECG monitoring, show evidence of an abnormal heart rate or rhythm.
During cardiac catheterisation, your physician will insert a long, thin tube into a blood vessel in your groin or arm. The tube will be gently directed to the heart and to the origin of the coronary arteries.
Dye is then injected into the coronary artery while x-ray pictures are taken producing special "pictures" of the arteries that supply blood to the heart (the coronary arteries) and of the main pumping chamber of the heart (the left ventricle).
There may be several injections of the dye, and the catheter may be moved around during the procedure. This is necessary to get different views of your heart and coronary arteries. The entire time in the cath lab will probably be less than one hour.
These images can reveal if one or more of the coronary arteries are blocked or if the left ventricle is functioning properly and pumping blood throughout the body. Additional information can be obtained about the pressure in the different chambers of the heart and about whether the heart valves are working normally.
The dye in the coronary arteries is seen by the x-ray as a white line. A disruption of the white line may signify an area of plaque build-up inside the wall of the artery.
For most patients, the primary determining factor is whether a partial or complete blockage in the coronary arteries is present. The doctor and patient must decide whether these blockages should be treated with angioplasty (the balloon procedure) or bypass surgery. The patient must decide whether he or she is willing to undergo one of these revascularisation procedures. If the patient is not willing, there is often little reason to undergo a cardiac catheterisation.
Generally accepted reasons for patients to undergo a cardiac catheterisation include the following:
- Angina pains (i.e., the discomfort from blocked coronary arteries), that are not easily controlled with medication or that interfere daily life.
- Chest pains of uncertain cause that repeatedly recur and defy diagnosis despite other tests
- Angina that occurs at rest despite medical therapy
- Recurrent angina after a heart attack
- Markedly abnormal stress test results
- Heart failure, when the suspected cause is coronary artery disease
- Disease of one or more of the heart valves causing symptoms such as shortness of breath
Not everyone with angina needs a cardiac catheterisation. Patients who have very rare or easily controlled episodes of angina may desire to continue with medical therapy rather than undergo angioplasty or bypass surgery. Many patients who have suffered a heart attack can initially undergo a stress test rather than cardiac catheterisation.
The risks of cardiac catheterisation are low, but sound medical reason should always determine whether to undergo a cardiac catheterisation procedure.
Occasionally, patients have an allergic reaction to the iodine-based dye used during cardiac catheterisation. People who have had a previous reaction to intravenous dye or who have allergies to shellfish are at increased risk for allergic reaction. The doctor should be aware of the patient's risk for allergic reactions before performing the procedure. Such patients usually are given a steroid and other medications before the procedure to reduce the chance of serious allergic reaction to the dye.
In rare cases, the dye used during the procedure can produce kidney damage, including kidney failure requiring dialysis. People with an increased risk for this complication include those with diabetes or pre-existing kidney disease. Patients at higher risk of dye-induced renal failure are sometimes admitted to the hospital the night before the procedure to receive intravenous hydration beforehand. Good hydration before and during the procedure may decrease the chances of dye-induced kidney failure.
In general, the risk for serious complications, such as stroke, heart attack or death, is very low - approximately one in 1000 in the general population.
Although cardiac catheterisation is regarded as a relatively safe procedure, complications do occasionally occur. These can include:
- Bleeding at the site of sheath insertion. (This commonly produces a small bruise in the groin, but in rare cases, can lead to more serious internal bleeding).
- Infection at the site of sheath insertion
- Damage to the blood vessels in the groin
- Allergic reaction to the iodine-based dye
- Kidney damage and/or kidney failure
- Stroke
- Heart attack
- Death
Sources:
http://www.cgh.com.sg/health_public/pamphlet/surgery/cardiac/cardiac.html
http://www.cardiologychannel.com/cardiaccath/
http://www.hgcardio.com/cardcath.htm
http://www.isaccd.org/patients/guide-2.php
http://www.med.umich.edu/1libr/tests/testc08.htm#what
http://www.siemensmedical.com/default.asp