What is angiography?|
Angiography is a non-invasive method of looking into blood vessels in the heart or lungs. It involves the insertion of a small tube into a blood vessel, a procedure called, catheterisation, and then injection of a special solution that will show up in the x-ray that follows the procedure, this solution is known as 'contrast media'. This process makes it far easier to visualise any blockages or changes in wall thicknesses of any of the blood vessels.
How angiography works
Before the procedure nothing should be eaten or drunk to reduce chances of being nauseous. Usually the catheterisation procedure in adults is done under local anaesthesia. There are two general ways in which catheters are introduced:
- Percutaneous introduction using needles and guide-wires
- Direct introduction after surgically isolating the vessel
In the percutaneous method one of two types of injections are used - either a needle with a sharp beveled edge or one with a non-cutting beveled edge. A guide-wire is then inserted through the needle into the vessel, the needle is then removed only leaving the guide-wire in place. After this the puncture site is enlarged to make a tunnel through the skin so that the catheter can be inserted, leaving it enough room to move around. The catheter is then advanced over the guide-wire into the blood vessel and the wire is then removed.
In both cases, contrast material is introduced into the vessel and an x-ray film is taken. The contrast within the vessel shows up very clearly, isolating areas where there is no blood flow due to a blockage. This diagnostic tool helps medical practitioners to make further decisions on how to manage the problem because the exact cause is isolated. Contrast material can also be introduced into the left ventricle to visualise its function or dysfunction, this is called left ventriculography.
When an angiography is advised
In coronary heart disease
- Asymptomatic patients - these are patients who don't show any symptoms but have had previous heart attacks, coronary bypass surgery or an angioplasty, or patients who are suspected to have coronary heart disease because of an abnormal ECG..
- Symptomatic patients - these are patients who show symptoms that could be due to coronary heart disease; symptoms such as - pain in the chest on exertion (angina pectoris) that does not seem to be responding to medication, increased severity of chronic angina, new onset of angina that is severe or increases despite medical treatment, acute coronary insufficiency with pain at rest, before major vascular surgery, such as repair of an aortic aneurysm or a illio-femoral bypass, after resuscitation from cardiac arrest, angina pectoris in female patients under 40 years of age, male patients under 40 years of age, and or patients under 40 years who have had a heart attack
Atypical chest pain of unknown origin
Single or re-occurring chest pain that is uncomfortable
Acute myocardial infarction (heart attack)
Usually angiography is performed within the first 6 hours after the onset of pain. It is also performed if there are recurrent episodes of pain, especially if the ECG is abnormal.
Valvular heart disease
Angiography is performed if valve surgery is about to be performed, especially if the patient is under 35 years if age or females who are postmenopausal.
Known or suspected congenital heart disease
- Normal results - the results of the angiogram depend on the artery or organ being investigated. Generally it shows a normal unimpeded blood flow.
- Abnormal results - abnormal results of an angiography may display a restricted blood vessel or arterial blood flow or an irregular placement or location of the blood vessel. A radiologist usually interprets these tests.
This procedure is commonly