Heart catheterization

Heart catheterization (also called cardiac catheterization) is a diagnostic procedure that carefully examines how the heart and its blood vessels function. One or more catheters (tubes designed to enter small openings) are insertedinto the organ through a blood vessel in the arm or leg. The procedure gathers information about the pressure, flow, and supply of blood, as well as supplying blood samples and x rays of the heart and surrounding blood vessels.

The primary reason for conducting a heart catheterization is to diagnose andmanage suspected cases of heart disease, a frequently fatal condition that leads to 1.5 million heart attacks annually in the United States.

To understand how heart catheterization is able to diagnose and manage heartdisease, the basic workings of the heart muscle must be understood. Just as the body relies on a constant supply of blood, so does the heart. The organ possesses an intricate web of blood vessels (coronary arteries) that ensure anadequate supply of blood rich in oxygen and nutrients. An abnormality in anyof these arteries can cause the heart's blood flow to decrease, resulting incoronary artery disease.

Typically performed along with angiography (injecting dye into the bloodstream to outline the heart and blood vessels), catheterization can help identify blockages, narrowing, or abnormalities in the coronary arteries. If these signs are visible, the patient may need coronary bypass surgery or othertreatment.

Symptoms and diagnoses that can lead to performing a heart catherization include:

• Chest pain, characterized by prolonged heavy pressure or a squeezing pain
• An abnormal treadmill stress test
• A heart attack
• Heart problems originating from birth
• Valvular heart disease
• A need to measure the heart's ability to pump blood.

Becasue heart catheterization is considered an "invasive" procedure, it is important to consider the following conditions:

• A bleeding disorder, poor kidney function, or weakness. These typically increase risk and may be reason to cancel the procedure.
• Heart valve disease. If this is detected, antibiotics may be given to prevent inflammation of the membrane lining the heart. (endocarditis)

Like all surgical procedures, cardiac catheterization involves some risk of complications. These may include:

• Cardiac arrhythmias (an irregular heartbeat)
• Pericardial tamponade (a condition causing excess pressure in the membrane surrounding the heart)
• In rare cases, a heartattack or stroke may develop due to clotting or rupture of one or more of the heart or brain arteries.

The risk of catheterization increases in patients over the age of 60, those who have severe heart failure, or persons with serious valvular heart disease.

Prior to cardiac catheterization, it is important to relay information to thedoctor or nurse regarding allergies to shellfish (such as shrimp or scallops) that contain iodine or dyes commonly used in other diagnostic tests.

The patient must not eat or drink anything for at least six hours prior to the test. Just before the procedure, the patient will urinate and change into ahospital gown, then lie flat on a padded table that may be tilted to allow the heart to be examined from a variety of angles.

Catheterization typically lasts two to three hours. A patient should expect the following:

• A mild sedative may be given to allow the patient to relax but remain conscious during the procedure.
• An intravenous needlewill be inserted into the arm to administer medication. Electrodes will be attached to the chest to enable the painless procedure known as electrocardiography.
• Prior to inserting a catheter into the arm or leg, the point of entry will be made numb by injecting a local anesthetic. Pressure mayalso be experienced as the catheter travels through the blood vessel.
• After the catheter is guided into the coronary-artery system, a dye is injected to help identify abnormalities of the heart. During this time, the patient may experience a hot, flushed feeling or a quickly passing nausea. Coughing or breathing deeply may alleviate discomfort.
• Medication may be given if chest pain occurs, and nitroglycerin may also be administered to allowexpansion of the heart's blood vessels.
• When the test is complete,the physician will remove the catheter and close the skin with sutures or tape.

While cardiac catheterization may be performed on an out-patient basis, patients may require close monitoring afterward, remaining in hospital for at least 24 hours. The patient will be instructed to rest in bed for at least eighthours. If the catheter was inserted in the leg or groin area, the leg will bekept extended for four to six hours. If a vein or artery in the arm was used, the arm will need to remain extended for a minimum of three hours.

The patient should expect a hard ridge to form over the incision site that diminishes as it heals. Bluish discoloration under the skin at the point of insertion should also be expected but fades in two weeks. It is not uncommon forthe incision site to bleed during the first 24 hours following surgery. If this should happen, the patient should apply pressure to the site with a cleantissue or cloth for 10-15 minutes.