The coronary arteries supply blood to the heart muscle. They become clogged due to build-up of atheromatous plaques and can reduce blood flow to the heart. If a clot blocks the blood flow, it can lead to a heart attack.
An angiogram is an x-ray test that uses dye to visualise the arteries. Normally, the arteries cannot be seen in an ordinary x-ray and when an iodin--based dye is used as a contrast media, the arteries can be visualised. A coronary angiogram is the 'gold standard' for evaluation of coronary heart disease. It is used to identify the exact location and severity of the coronary heart disease.
How is an angiogram used to diagnose cardiovascular disease?
A coronary angiogram is performed with the use of local anaesthesia and intravenous sedation. Cardiac catheterisation is a test used to evaluate your coronary arteries and heart valve function. It identifies the size and location of plaques that may have built up in your arteries from atherosclerosis, the strength of your heart muscle and the adequacy of valve function. In cardiac catheterisation, the interventional cardiologist threads a catheter (thin flexible hollow tube of 2-3 mm) through a blood vessel in your arm or groin and into your heart. The vessels can be visualised by a fluoroscope, which is special x-ray viewing equipment. With the catheter in place, the cardiologist can measure blood pressure, take blood samples and inject dyes containing iodine into your coronary arteries or arteries elsewhere in your body to trace the movement of blood through the arteries and chambers of the heart. By observing the movement of the dye through your heart's chambers and blood vessels, the cardiologist can see whether the arteries are narrowed or blocked and whether the valves are working properly. This helps determine whether you may need bypass, valve surgery, angioplasty or catheter-based valve repair.
Angiogram can look at the arteries of the heart (coronary angiogram), lung (pulmonary angiogram), brain (cerebral angiogram), head and neck (carotid angiogram), legs or arms (peripheral) and the aorta (aortogram).
An angiogram can be used to locate a bulge in a blood vessel (aneurysm) or narrowing or blockage in a blood vessel affecting blood flow.
What does a coronary angiogram show?
- Angiogram images accurately reveal the extent and severity of artery blockages including tear in a blood vessel causing internal bleeding or weaknesses in blood vessel wall (aneurysm).
- For those with severe angina, heart attack or abnormal stress tests, an angiogram is done to find out the extent and location of blockages.
- Detects changes in the blood vessels of injured or damaged organs
- Shows the pattern of blood flow to a tumour, extent of spread and guides treatment
- Shows the condition, and location of blockages of the renal artery
- Helps in detection of blocks on diseased blood vessels of the leg in peripheral artery disease
- Checks on severity of atherosclerosis of coronary arteries
- In some cases, a method called interventional radiology may be used during an angiogram to treat diseases. For example, a catheter can be used to open a blocked blood vessel, deliver medicine to a tumour or stop intestinal bleeding caused by diverticula haemorrhage. To stop intestinal bleeding, the catheter is moved into the small artery where the bleeding is occurring and medicine that narrows the artery or causes the blood to clot is injected through the catheter.
What types of procedures do interventional cardiologists perform?
- Angioplasty and stenting: A long, slender tube is inserted through a blood vessel in your leg or wrist and guided to the heart or elsewhere in your body. A dye is injected through the arteries to guide the cardiologist during the stenting procedure. A balloon at the tip of the catheter is inflated to stretch open the artery and restore increased blood flow to the heart. In most cases, a small metal mesh cylinder called a stent is then placed in the vessel to help keep it open.
- Atherectomy: Devices with tiny blades are sometimes used to cut away plaque deposits caused by atherosclerosis inside the blood vessel.
- Carotid stenting: Similarly, balloons and stents can be used to open the carotid arteries, the main blood vessels to the brain, and thereby lessen the risk of stroke.
- Embolic protection: In some cases, particularly when the narrowing being treated is in a bypass graft or in the carotid arteries, filters and other specialised devices are used to help ensure that pieces of the plaque don’t break off and travel in the blood to cause damage.
- Percutaneous mitral valve repair: A catheter is introduced through a blood vessel in your leg and guided through a vein to the heart. Smaller catheters holding a special clip is guided into place and positioned near to, or actually attached to the mitral valve to make it function properly.
- All test reports, history, allergies, medication and clinical examination is done.
- Blood tests including coagulation profile, renal and liver function tests are done.
- An appointment is fixed for angiogram.
- You will be asked not to eat anything for a few hours before the procedure, as a sedative is usually advised.
- You may be advised to stop anticoagulants.
- Advise on other medication will depend on your specific case.
- An intravenous line will be inserted into a vein to deliver sedatives and any other medication as required.
- Electrodes will be placed on your chest to record heartbeats.
- A blood pressure monitor may be attached to your arm.
Will be done when patient comes with an acute coronary syndrome or a heart attack
- Following angiography, the catheter will be taken out.
- Direct pressure will be applied on the puncture site for about 10-15 minutes to make sure there is no bleeding.
- If the procedure is done by the femoral route, you will be asked to lie on your back for several hours.
- You will be observed for any bleeding at the puncture site.
- If there is no bleeding, the sheath covering the puncture site will be removed.
- You will be advised to drink fluids in a short while. It may take up to 12 hours before you can resume normal work. Patient usually leave the same day or the next day.
- Your doctor will discuss the results with you.