What is a cardiac catheterization (also called cardiac cath)?
In cardiac catheterization (often abbreviated as "cath"), a very small catheter (hollow tube) is advanced from a vessel in the groin (or sometimes the arm) up into the heart.
Once the catheter is in place, several diagnostic techniques may be used. The tip of the catheter can be placed into various parts of the heart to measure the pressure within the chambers. The catheter can be advanced into the coronary arteries and a dye injected into the arteries (coronary angiography or arteriography). With the use of fluoroscopy (a special type of X-ray), the doctor can identify blockages in the coronary arteries as the dye moves through them.
You are awake during the procedure, although you will receive a small amount of sedating medication, as well as local anesthesia at the catheter entry site, prior to the procedure.
Due to advances in knowledge, technology, and techniques, cardiac cath is often performed on an outpatient basis, meaning that the procedure is done early in the day and you may be able to go home the same day. Depending on what your doctor finds during the procedure; however, you may have to be admitted to the hospital. This procedure is also often performed on patients who are already in the hospital.
Why is cardiac catheterization done?
Your doctor may schedule you for a cardiac catheterization if you have recently had one or more episodes of cardiac symptoms such as, but not limited to, the following:
- Chest pain
- Shortness of breath
- A combination of any of these symptoms
A screening examination or test such as an EKG or stress test is generally done for initial evaluation of symptoms such as those listed above. If such a test suggests a possibility of some type of heart disease that needs to be explored further, the doctor may determine that a cardiac cath is necessary for more definitive diagnostic data.
Other reasons for the cath procedure include evaluation of myocardial perfusion (blood flow to the heart muscle) after heart attack, heart bypass surgery, coronary angioplasty (the opening of a coronary artery using a balloon or other method), or stent placement (a tiny expandable metal coil placed inside the artery to keep the artery open). There may be other reasons for your doctor to recommend a cath procedure as well.
Cardiac catheterization is also used to detect and evaluate heart conditions or diseases, including the following:
- Coronary artery disease. Coronary artery disease (CAD) is the narrowing of the arteries caused by a buildup of fatty material within the walls of the arteries. This buildup causes the inside of the arteries to become rough and narrowed, limiting the supply of oxygen-rich blood to the heart muscle.
- Valvular heart disease. In order to keep the blood flowing forward during its journey through the heart, there are valves between each of the heart's pumping chambers. The tricuspid valve is between the right atrium and the right ventricle; the pulmonary (or pulmonic) valve is between the right ventricle and the pulmonary artery; the mitral valve is between the left atrium and the left ventricle; and the aortic valve is between the left ventricle and the aorta.
If the heart valves become damaged or diseased, they may not function properly. Dysfunction of heart valves may be either stenotic (narrowed and/or stiff) or regurgitant (leaky). When one or more valves become stiff, or stenotic, the heart muscle must work harder to pump the blood through the valve. Some reasons why heart valves become stenotic include infection (such as rheumatic fever or infections) and aging. If one or more valves become leaky, or regurgitates, blood leaks backwards, which means that less blood is pumped forward. Cardiac catheterization is used to diagnose and evaluate the severity of valvular heart disease.
- Heart failure. Heart failure (HF) is a condition that occurs when the heart is unable to pump blood efficiently. Despite its name, a diagnosis of HF does NOT mean the heart is about to stop beating. The term "failure" refers to the fact that the heart muscle is not able to pump blood in the normal manner because it has become weakened.
HF may develop suddenly after an acute event, such as a heart attack, that severely damages and weakens the heart muscle, or it may progress over a much longer period of time. Measuring the pressure in the chambers of the heart during a cardiac cath can help determine the extent of HF.
- Congenital heart disease. Congenital heart disease refers to one or more of several conditions which are present at birth (birth defects). Cardiac catheterization is performed to determine the presence and severity of congenital cardiac abnormalities and, in some cases, to treat the defect. Some congenital heart conditions include:
- Atrial septal defect (ASD). In this condition, there is a hole between the two upper chambers of the heart. Although blood from the left atrium flows into the right atrium through this defect, there may be few, if any, symptoms of this condition in infants and children, except for a possible heart murmur (an abnormal sound heard through the stethoscope when listening to the heart).
- Ventricular septal defect (VSD). In this condition, a hole occurs between the two lower chambers of the heart. Because of this hole, blood from the left ventricle flows back into the right ventricle, due to higher pressure in the left ventricle. This causes an extra volume of blood to be pumped into the lungs by the right ventricle, which can create congestion and fluid buildup in the lungs.
- Patent ductus arteriosus (PDA). In the fetus, a connection occurs naturally between the pulmonary artery and the aorta. However, shortly after birth, this connection closes on its own. Sometimes, the hole does not close, which means that oxygen-rich blood from the aorta returns back to the lungs through the pulmonary artery, causing congestion in the lungs, increased workload on the heart, and may lead to an enlarged heart.
- Obstruction defects. This general term refers to several different congenital conditions that cause an obstruction in the flow of blood through the heart. Obstructive defects include:
- Aortic stenosis. A narrowing of the aortic valve (the valve between the left ventricle and the aorta).
- Pulmonary stenosis. A narrowing of the pulmonary (or pulmonic) valve (the valve between the right ventricle and the pulmonary artery).
- Bicuspid aortic valve. A defect in the aortic valve, in which there are only two cusps (flaps) in the valve instead of the normal three. This defect predisposes a person to aortic stenosis.
- Subaortic stenosis. A narrowing of the left ventricle just below the aortic valve, usually from the septum, the tissue that separates the right and left sides of the heart.
- Hypertrophic cardiomyopathy. A genetic disorder that leads to abnormal tissue growth in the heart. This excess tissue can block blood flow out of the heart to the body.
- Coarctation of the aorta. A narrowing or constriction of the aorta, which obstructs blood flow from the heart to the rest of the body.
- Tetralogy of Fallot. In this condition, there are actually four separate defects occurring at the same time: ventricular septal defect, pulmonary stenosis, overriding aorta (the outflow tract of the aorta begins just above the ventricular septal defect instead of at the normal location in the left ventricle), and right ventricular hypertrophy (enlargement of the muscle of the right ventricle)
- Transposition of the great vessels. In this condition, the outflow tracts of the aorta and the pulmonary artery are switched during fetal development. This means that unoxygenated blood flows out to the body through the pulmonary artery and oxygenated blood flows back into the lungs through the aorta. By itself, this condition cannot sustain life after birth. However, there are usually accompanying defects that permit some oxygenated blood to reach the rest of the body.
- Tricuspid atresia. In this condition, the tricuspid valve between the right atrium and right ventricle is poorly developed. By itself, this would mean that blood could not be pumped into the lungs efficiently to receive oxygen; however, there are usually accompanying defects that allow some blood to go to the lungs.
How is a cardiac catheterization done?
Before the cardiac cath procedure, you will receive instructions on what to do the night before the test. These instructions may include nothing to eat or drink for a period of six or more hours before the procedure and changes in the directions for taking some of your medications.
Once you arrive for your procedure, an intravenous (IV) line will be started in your hand or arm prior to the procedure for injection of medication and to administer IV fluids if needed. The area designated as the cath site (groin, arm, or wrist) will be shaved if needed and washed with an antiseptic soap. You will receive a sedative medication in your IV before the procedure to help you relax. The pulses in your feet will be checked and the location where the pulses are felt will be marked on the skin with a marker. This is done in order to be able to compare the strength of these pulses after the procedure.
Once the preparations for the procedure have been completed, you will be taken to the room where the procedure will actually take place. The room will feel cool. You will lie on a firm but padded X-ray table and will be connected to equipment that will monitor your heart rhythm, blood pressure, and oxygen levels. A nurse or doctor will accompany you at all times. Please feel free to ask questions at any time.
You will lie flat on your back during the entire procedure. There will be several monitor screens in the room, showing your vital signs (EKG, heart rate, blood pressure, breathing rate, and oxygen level), the images of the catheter being moved through the body into the heart, and the structures of the heart as the dye is injected.
The cath lab is a sterile area, so everyone in the room will wear gowns, masks, and caps. The doctor and assistants actually performing the procedure will also wear sterile gloves. A large X-ray camera will be above the table to take pictures of the procedure.
The cath site (groin or arm) will be cleansed again with antiseptic soap, and then sterile towels and a sheet will be placed around this area. A numbing medication (lidocaine, or xylocaine) will be injected into the cath site.
Once the numbing medication has taken effect, the doctor will insert a catheter into the artery or vein and advance it into the heart. It will be very important for you to remain still during the procedure so that the catheter placement is not disturbed and to keep from causing damage to the insertion site.
The catheter is inserted into the blood vessel. The doctor advances the catheter through the blood vessels into the heart. This is done by watching the catheter on the monitor and guiding it into the proper structures. The catheter may be advanced into either the right or left side of the heart, or both sides, depending on what the doctor is looking for.
Pressures are obtained at various locations within the heart structures. Blood samples may be withdrawn to assess oxygen levels at various places in the heart. Dye may be injected into one or more of the heart's chambers to assess blood flow and the heart's structure. When the dye is injected, you may notice a feeling of warmth or even a hot flash. This sensation will last for only a few seconds. The catheter may be advanced to the coronary arteries, where dye is injected to determine if there are any blockages and where the blockages, if any, are located.
At certain points during the procedure, you may be asked to take in a deep breath and hold it for a few seconds. You may also be asked to cough during the procedure. If you notice any discomfort or pain, such as chest pain, neck or jaw pain, back pain, arm pain, shortness of breath, or breathing difficulty, let the doctor know immediately, but do not move your arms or legs or try to sit up.
Once the doctor has obtained the information, the catheter will be removed from the insertion site. The doctor or an assistant will hold pressure on the insertion site for about 15 to 20 minutes, so that the blood can begin to form a clot at the site and stop the bleeding. Once the doctor or assistant is satisfied that the bleeding has stopped, a tight bandage will be placed on the site.
Typically, the insertion site will be closed with a closure device that uses collagen to seal the opening in the artery, with the help of sutures or a special clip. Your doctor will determine which method is appropriate for your condition.
You will be assisted to slide from the table onto a stretcher so that you can be taken to the recovery area. NOTE: If the insertion site was in the groin, you will not be allowed to bend your leg nearest the insertion site or to sit up for several hours. To help you remember to keep your leg straight, the knee of the affected leg will be covered with a sheet and the ends will be tucked under the mattress on both sides of the bed to remind you not to bend the leg.
Once the procedure is complete, you will go to a recovery area for a few hours, where a nurse will monitor the circulation of your arm or leg, and check your puncture site for signs of bleeding. The nurse will also monitor your heart rhythm and blood pressure.
Notify your nurse immediately if you notice warmth, bleeding, pain at the catheter site, chest pressure or tightness, or other pain after the procedure. If you need to cough, sneeze, or laugh, hold pressure on the bandage on the insertion site. During this time, you will still have your leg or arm immobilized, and will need to remember not to bend the leg or arm.
You will be encouraged to drink fluids after the procedure to aid in flushing the cath dye from your system. The cath dye will remain in your system for a few hours and will cause you to urinate frequently. Please ask the nurse to assist you, as it is essential that the cath site not be bent during this time. You may also be given a light meal after the procedure.
You may raise the head of the bed and move around once you have completed the mandatory time for bed rest. You will require a nurse's assistance when you initially stand up to walk. Before you are discharged home, your nurse or doctor will give you instructions on care of the catheter site, problems or symptoms to report, and instructions regarding activities (including driving, which can place stress on the groin access site) and medications.
If the procedure is done on an outpatient basis, you will be allowed to leave after you have completed the recovery process, usually about four to six hours after the procedure is finished.
You will most likely feel tired for a day or so after the procedure. The catheter site in your leg or arm may be sore for a few days. You may have other pain or discomfort for a day or so due to lying still for a long period of time during the procedure and the recovery period.
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