The heart is a muscular pump. It is located within the chest and lies beneath and to the left of the breastbone. In healthy adults, its size is about that of a man’s fist.

The heart has four chambers. It has two chambers (atria) which collects blood while two others (ventricles) are muscular pumps that send blood to various parts of the body. The heart pumps blood into the aorta that is a large artery attached to the top of the heart. The aorta is in turn, joined to an intricate network of blood vessels that transports blood to all the organs and tissues of the body. This is called the blood circulatory system. Central to the system is the heart. Blood then drains back to the heart through an extensive network of vessels called veins. The blood then returns to the atrium. Returning blood, which is depleted of oxygen is then pumped to the lungs from the right heart chambers via the pulmonary arteries. The oxygen-poor blood is replenished with oxygen in the lungs before returning to the left side heart chambers via the pulmonary veins.

Like any other organ, it must also be supplied with oxygen-rich blood. The heart gets its supply of oxygen with blood from three coronary arteries two on the left side and one on the right side.

The blood vessels of the heart are called coronary arteries. Sometimes, fatty material or plaque from cholesterol build-up may narrow the blood vessels of the heart. This plaque reduces the amount of oxygen supply to the heart, causing chest discomfort or spasmodic pain (angina). Normal coronary arteries are widely patent and have large, smooth and regular lumen. However, in patients with coronary artery diseases the inside of one or more of the arteries is normal or blocked by a lot of built-up of a porridge-like material called atheroma within the wall of the artery. A major component of atheroma is cholesterol and calcium. If the build-up of this fat and cholesterol-atheroma (plaque) is extensive enough, oxygen supply to the heart is reduced causing chest discomfort, pressure, or spasmodic pain (angina). Other symptoms of CAD include irregular heartbeat, breathlessness and tireness.

Prolonged chest pain occurs when the narrowed arteries are blocked off suddenly and completely. This is due to the lack of oxygen in the heart cells resulting in their death - a condition called myocardial infarction or more commonly, heart attack.

Medical research has identified some risk factors for CAD. People with the following risk factors have a higher chance of getting CAD:

• To determine the function of the heart and its sur rounding blood vessels through x-ray imaging.
• To confirm if the patient has CAD and to locate the exact site of blockage. 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.

A catheter is inserted into a vein or an artery (blood vessels) of the arm or groin. The catheter is then passed through the blood vessel into a heart chamber or to an artery supplying blood to the heart.

Special x-ray fluid, called dye or contrast, is injected through the catheter. The dye allows the doctor to see images of the heart chambers, valves, or coronary arteries on a TV screen or in the form of x-ray films.

Essential Document

1. Identity card or birth certificate (if you are under 12 years old) or passport (if you are a foreigner)
2. Inpatient admission form
3. Medical benefits identification documents
4. Letter of Guarantee / Hospitalisation Identification Card
5. Completed Medisave Authorisation Form and Medisave account holder’s NRIC for verification.
6. Civil Service Card or Medical Benefit Identity Memo (MBIM) for civil servants
7. CPF membership, valid work permit or employment pass and employer’s letter for work permit / employment pass holders
8. Letter from Blood Transfusion Service and Blood Donor Card or Blood Donor Nominee Card for blood donor or blood donor nominees.

Personal Items

1. Slippers
2. Toiletries such as toothbrush, toothpaste, comb, etc.
3. Pyjamas or dressing gown - if you prefer not to use the hospital’s pyjamas.
4. All current medications

You will be admitted to a ward of your choice. The doctor will take your medical history and consent for the procedure. Please inform your doctor or nurse of the following:

• the name and dosage of all your current medications
• if you are allergic to iodine, shellfish or any medicines.

You will be required to fast before the procedure. If it is scheduled in the morning, you will not be allowed to eat or drink anything after midnight on the eve of the procedure. Check with your doctor if you can continue your usual medicines. If you can continue to take your medicines, you may take it with sips of water. You will be given a light breakfast if the procedure is to be carried out in the afternoon.

Some tests will be done to assess your fitness before the cardiac catheterisation. Table 1 lists the laboratory tests to be done.

Table 1: Pre-cardic catheterisation laboratory testing