CARDIAC catheterization is a minimally invasive procedure generally employed to diagnose and treat certain heart conditions. It involves threading a thin flexible tube (catheter) through a blood vessel to the heart. Your doctor can perform diagnostic tests and some procedures on your heart with the help of the catheter.

Diagnostic cardiac catheterization is a procedure that involves insertion of a catheter into the right or left side of the heart, usually through the groin or arm. Cardiac catheterization allows injection of radio-opaque dye for angiography, measurement of intracardiac pressures and oxygen saturations, and also assists the passage of electrophysiological instruments, angioplasty and valvuloplasty balloons.

Based on the placement of the catheter, diagnostic cardiac catheterization can be categorised as:

* Left heart catheterization

* Right heart catheterization

Procedure

The procedure is performed via the arterial route or the venous route, depending on the heart condition, anatomical considerations and the preference of your doctor. The common steps involved in diagnostic cardiac catheterization are as follow:

* The patient is positioned on the operating table and is sedated. The skin overlying an artery or vein is cleaned and sterilised.

* A small incision is made in the skin and a hollow plastic tube is inserted into the blood vessel (artery/vein).

* A catheter is then advanced through the tube into the appropriate heart chamber under fluoroscopic X-ray guidance. The required tests can be performed with the help of the catheters present in the heart chambers.

* After the procedure, the catheter and tube are removed.

* Firm pressure is applied to the incisional area for five to 20 minutes to prevent bleeding.

Following the procedure, the patient has to stay overnight in the hospital and is advised to rest for at least six to 24 hours.

What is right heart catheterization?

During right heart catheterization, the doctor passes the catheter through a large (central) vein in your neck or groin, directly into the right side of the heart. During the procedure, the pressure inside the various heart chambers is measured and used to help with either diagnosis or treatment. Measurements can also be made on the oxygen level in the various heart chambers to see if they are within normal limits. Measurement of cardiac output, left ventricular filling pressure and pulmonary artery wedge pressure; measurement of right heart oxygen saturations; assessment of pulmonary hypertension; to perform an electrophysiological study.

Why would your doctor recommend right heart catheterization?

There are two main groups of patients who may benefit from right heart catheterization:

1. Children or adults with congenital heart disease – to help with confirming diagnosis of various defects, as well as prognosis and to determine if a particular condition is amenable to surgical correction; and

2. Adults with suspected pulmonary hypertension – increased pressure in the blood vessels of the lung.

What is left heart catheterization?

Catheterization of the left side of the heart is performed via an arterial route. It is used to assess:

* Left ventricular function: How well your heart is pumping

* Outflow tract obstruction: Blockage to the outflow of blood from your heart, most commonly from a narrowed valve

* Valve disease

* Coronary artery disease

Cardiac catheterization is also used to perform left ventricular biopsies and electrophysiological studies.

Most commonly, cardiac catheterization is used to give the cardiologist more information about your coronary arteries. It provides a fairly detailed picture of all the blood vessels that bring blood to the heart, and can show where blockages are, and how severe these blockages are. The pictures of the heart are taken using an X-ray, while dye (contrast) is injected directly into the blood vessels of the heart (coronary arteries). The cardiologist performing your coronary angiogram procedure usually passes a catheter through either an artery in the groin or wrist, directly to the coronary artery.

Will you be awake during the procedure? Will it hurt?

A coronary angiogram takes approximately one hour from start to finish – this includes the preparation time and down-time after the procedure. The procedure is not done under general anaesthesia, ie, you will not be put to sleep. Sometimes a light sedative is given to “calm the nerves”, but the procedure is performed under local anaesthesia, similar to “freezing” of the gum during dental procedures. Within a few hours, you are typically up and about, especially if the procedure is performed from the wrist (radial artery approach).

Can a coronary angiogram be performed without inserting these catheters into my arteries?

Yes, currently the procedure can be done using a Computed Axial Tomography (CAT scan) or CT scan. This requires an intravenous (IV) line for the injection of dye and then pictures of the heart and vessels are taken. For this particular procedure, your heart rate has to be slow (between

60-70 beats per minute) to allow for accurate reconstruction of your heart structure and blood vessels. The procedure may be performed and interpreted by a radiologist or cardiologist, who is specially trained in this area. It is less invasive than the regular coronary angiogram, but if a significant blockage is found, you will still need to do the regular coronary angiogram using the cardiac catheterization procedure. We will usually recommend this procedure when we do not have a high index of suspicion that you have a significant blockage. This procedure is currently available in Jamaica and your doctor will make the referral if this test is appropriate for you.

If significant coronary artery blockages are found, what next?

If your coronary angiogram shows significant (more than 70 per cent) blockages, your cardiologist may recommend one of three things, depending on your particular circumstance. We will go into details in the future when we talk about treatment of coronary artery disease (blocked coronary arteries):

1. Continue medications

2. Coronary angioplasty – where tiny balloons are inserted into the blocked area to clear up the blockages

3. Bypass surgery

Dr Claudine Lewis is an adult cardiologist and medical director at Heart Smart Centre in Montego Bay. She is also a cardiologist at the Cornwall Regional Hospital and an associate lecturer with the University of the West Indies. Questions may be sent to questions@heartsmartcentre.com and for additional information call 684-9989 or visit the website www.heartsmartcentre.com