Cardiac Angiogram – Angiography Explained
|Image Credit http://www.cvtsa.com/
Fatty deposits in a persons Coronary Arteries (right) can impede the amount of blood reaching the heart muscle. When this occurs a patient can most commonly experience Angina, Shortness of Breath or Palpitations. If the blockage completely occludes a vessel, the part of the heart that it supplies will start to die. Commonly known as a heart attack, complications of this event can lead to a persons death.
An Angiogram is an imaging technique that allows us to picture the coronary arteries
and investigate the extent of any blockages
. The angiogram is used to determine which treatment option would be best for that patient.
A Coronary Angiogram normally takes around 15-30 minutes though you may be in the laboratory where it is performed slightly longer, it is performed under local anaesthetic. The patient lays flat on there back before the necessary parts of the body are sterilised and draped with sterile cloth. The bed sits just under a large Flouroscope (giant X-ray video camera) that takes the images during the procedure. The Cardiologist makes a small incision over an artery (most commonly the Femoral or Radial arteries) and passes a catheter (long thin tube) along the network of blood vessels until the tip of it is in the root of the Aorta. A bit like feeding a wire around the U-bend in a blocked sink/toilet :/
The base of the Aorta is where the Coronary Arteries sprout from. Once in position the tip of the Catheter is put into the origin of one of the coronary arteries and the contrast (dye) is injected whilst the images are recorded. This is repeated several times for each artery.
How Does an Angiogram Work?
A Coronary Angiogram is a type Fluoroscopy or ‘video X-ray’ where a dye is injected into the Coronary Arteries that shows up the LUMEN of the arteries on X-ray. The ‘LUMEN’ is the hole that runs through the centre of the blood vessel. The DYE shows up clearly on X-RAY.
In the video below you can see how the contrast (dye) is injected into the Coronary Artery causing the LUMEN to light up.
If the LUMEN is reduced in size at a point along the blood vessel, we can assume that this is because of an atheroma (fatty deposit).
This is demonstrated in a still taken from the above video.
I have circled an area of interest where we can see that the blood vessel is narrowed. We can see that the blockage itself does not show on the image, but by looking at the rest of the blood vessel we can analyse the extent of the blockage.
During an Angiogram the Coronary Arteries are ‘imaged’ from multiple different angles, there is a a very good reason for this. A single image of the blood vessel could create the illusion that an artery is clear when in actual fact it isn’t.
Lets consider this 50% blockage
. If we look at it from the correct angle, we get a fair assessment of the blockage. However if we were to look at the the blockage from the ‘top’ then the contrast (dye) that is passing over the blockage would create the illusion that the artery is clear. If we were to look at the blockage from ‘below’ then the contrast passing over the top of the blockage again creates the illusion that the artery is clear.
Treatment Following an Angiogram
Depending on the extent and position of the blockage
treatment options vary. The most common options are:
- No Treatment Required
- Medical Management (Medications Required)
- Angioplasty/Stenting – Flattening and Forcing Open the Artery
- Coronary Artery Bypass Graft – Heart Bypass
Risks of Coronary Angiogram
A relatively ‘safe’ procedure minor complications do include bleeding and bruising, whilst more serious complications do include Heart Attack, Stroke and Death.
According to the NHS website The risk of a serious complication occurring is estimated to be around 2 in 1,000. It is usually the result of serious underlying heart disease. If you have any concerns then please discuss these with your Cardiologist!
|Image Courtesy of http://phc.org.au/
I will finish on a picture of an Angiogram taking place!
In the future I will explain Angioplasty and Stenting of blockages as these are incredibly common! I hope that has cleared up a little bit on Angiograms for now!