Editor: Dr S Venkatesh MD DM
If you have recently visited your doctor with chest pain or have undergone tests for the heart which are ‘positive’, you may be asked to undergo a ‘coronary angiogram’.
In this article, we cover everything there is for you to know about this procedure.[toc]
What Is A Coronary Angiogram?
A coronary angiogram is a special test that is performed to see what your heart arteries look like. It is sometimes called ‘cardiac catheterisation’ and is performed in a hospital setting by cardiologists. It is widely considered the ‘gold standard in diagnosis of coronary artery disease.
When Is A Coronary Angiogram Performed?
The purpose of performing a coronary angiogram is to determine whether there is a disease in the heart arteries that is causing your symptoms. It is an invasive test and requires special preparation to perform.
Some of the situations when a coronary angiogram may be performed include –
1. If you are getting recurrent chest pain that is not settling with medical therapy.
2. If you have recently suffered a heart attack.
3. If you have a positive treadmill test.
4. If you are due to undergo valve surgery.
A coronary angiogram can also help determine how well the heart functions, the state of the heart valves and any diseases of the aorta.
A coronary angiogram is performed before inserting a stent into the arteries (i.e. before performing angioplasty).
Do I Need To Prepare For The Test?
A coronary angiogram is a fairly straightforward test and does not require any special preparation.
Prior to the procedure, you will meet with your cardiologist regarding the need for the procedure and how it is performed. During this meeting, the doctor will go through your history which includes a review of what medication you are taking and the presence of any allergies (such as latex allergy or iodine allergy).
Certain special blood tests known as screening blood tests may be performed such as hepatitis B and HIV testing. This is performed to ensure that adequate precautions are taken during the test by the healthcare professionals.
A coronary angiogram rarely requires admission to hospital and can be performed on a ‘day case’ basis. This means that you be required to come to hospital on the day of the procedure, have certain screening blood tests and undergo the procedure after that.
Once the procedure has concluded, you will be observed for a short period of time before you are discharged home. It is strongly recommended that you have a family member or friend who can take you home. There are rare occasions when you may require admission to the hospital and this of course will be explained to you if the need arises.
You are therefore requested to take with them essential toiletries in case you require admission. Alternatively of course, family members can always fetch your personal belongings later.
Prior to starting the procedure, patients will be asked to change into a hospital gown.
What Happens During A Coronary Angiogram?
When it is time for the coronary angiogram to be performed, you will be led into the cardiac catheterisation laboratory by the nursing staff. You will be asked to lie down on a special table. Above the table is present a large camera and on your left-hand side will be present a number of monitors.
These monitors are used to visualise your heart arteries when the procedure is being performed. You can usually see what is going on on these monitors.
A coronary angiogram may be performed through the groin or through the wrist. These days, most procedures are performed through the wrist as these are safe and easier to do.
Both the wrist and the groin area are cleaned with antiseptic solution. Small ECG electrodes will be attached to your chest so that your heart rate can be monitored throughout the procedure. An oxygen monitoring probe may be inserted on a finger to monitor oxygen levels. You will then be covered in sterile drapes.
The artery through which the procedure is to be performed is located by the cardiologist. Local anaesthetic (lignocaine) is injected into the skin and around the artery in order to numb the area.
You may feel a slight stinging sensation when this injection is being given. Don’t worry, this will only last a few seconds. It ensure you do not experience any pain during the procedure.
A small needle is then inserted into the artery and once in position, a tiny guide wire is inserted. The needle is removed and a plastic ‘introducer’ sheath is inserted into the artery which stays in place throughout the procedure. Through this plastic sheath are passed a series of wires and hollow catheters into the heart arteries. A radio-opaque dye is injected into the catheter that makes the heart arteries visible on x-ray.
The x-ray machine is moved around numerous times so that different views of the heart arteries can be obtained. These images are recorded for future analysis if required.
The image below summarises how a coronary angiogram is performed.
The following image shows what a narrowed heart artery looks like on an angiogram.
Multiple images are taken of both the right coronary artery and the left coronary system. While taking these images, the x-ray machine may move in different directions so that pictures can be taken from different angles.
This will be done by a separate operator who is in control of movement of the x-ray machine.
Once a sufficient number of images have been taken, the wires are removed and the sheath that is present within the artery is also taken out. Tight pressure is applied onto the artery for up to 30 minutes to stop any blood from leaking out of it. This pressure bandage may be applied for a few hours or even overnight sometime.
Following the procedure, the patient is observed for a short period of time and is then discharged home.
The entire procedure can take between 30 min to an hour to complete.
What Information Does The Test Provide?
Coronary angiography is an excellent test to assess the state of the coronary arteries and to find out if there any ‘blockages’. This is because the arteries are directly visualised while the heart is beating under the guidance of x-ray.
Risks Of The Procedure
The common risks include mild bleeding and bruising at the site of injection and sheath insertion. On some occasions, patients may develop an allergic reaction the contrast dye that is used in the procedure.
The contrast dye that is injected into the arteries is removed from the body by a filtration process in the kidneys. This can sometimes cause damage to the kidney within the first 48 hours.
However, since the quantity of dye that is often used is so low, the chances of kidney damage are very low. In patients with kidney disease, a special dye may be used to avoid further damage to the kidneys.
Sometimes however, a coronary angiogram may not be performed if there is kidney disease due to the risk.
More serious complications such as heart attack or stroke may occur but these are extremely rare. Damage to the artery into which the sheath is inserted may also occur and may require treatment.
There is the risk of death from the procedure as well but this is extremely rare. Studies have estimated any sort of serious complication to occur in around 1-2 in 1000 (0.1 – 0.2%) patients.
If you have any concerns, always discuss this with your doctor before going ahead with the procedure.
There are no specific limitations to coronary angiography.
In some cases, access into the arteries may be a bit difficult but this is still achievable through the use of ultrasound if absolutely necessary. Furthermore there are different ports of access that can be used if required. In the case of coronary angiography, clearly the benefits of the procedure and the information obtained outweigh any risks or limitations.