Cerebral angiography
What is a cerebral angiogram?
An angiogram is an X-ray test that produces high-resolution images of the blood vessels. Cerebral angiograms produce imaging of the blood vessels of the head and neck.
The test involves insertion of a tube in the groin or wrist that is then navigated through the body to the vessel of interest. An iodine based dye (known as 'contrast') is then injected through the tube.
Why is cerebral angiography performed?
Cerebral angiograms are commonly performed to diagnose diseases of the blood vessels such as:
Cerebral aneurysms
Carotid stenosis
Dural arteriovenous fistulas
They are also used to follow-up diseases previously treated.
Why not just do a CT or MRI?
The image quality is often superior when using angiography, allowing the discovery of diseases that do not show up on alternative scans and allowing the planning of certain procedures. As CT and MRI scans are safer, faster, and usually more pleasant to undergo we only do cerebral angiograms when we need to. Having said that, generally the risk (and degree of unpleasantness) is not usually very great.
Can I eat or drink before the procedure?
In some hospitals you may be given instructions not to eat or drink for a few hours before the procedure. This main reason for this is just in case general anaesthesia or sedation is needed during the procedure. Anaesthetists ideally do not like you to have food or drink in the stomach if you are to have general anaesthesia as there is a risk of regurgitation in to the lungs.
Having said this, the great majority of angiograms do not require general anaesthesia or sedation and so in many other hospitals you are allowed to have a light breakfast before coming to hospital and drink clear fluids until the examination. Exact instructions will be given to you before your angiogram.
Should I take my normal medications?
You should your medication as usual unless instructed otherwise (this includes any aspirin-based or anti-platelet medication, for example clopidogrel). You can take your normal medication with small sips of water.
I have allergies. Can I still take the test?
It is important to inform the staff if you have any allergies. It is especially important to mention allergies to:
Iodine or iodine based contrast agents.
Latex.
Plasters.
Cleaning solutions such as chlorhexidine.
Can I have an angiogram if I am pregnant?
Cerebral angiograms involve small doses of radiation, but usually directed towards the head. The dose to any developing foetus is very low, and can be further lowered by wearing protective lead clothing. Angiograms are sometimes performed in emergency settings where there may be a danger to the mother if they are not performed. However, if the procedure can be avoided by performing an alternative test, or delayed until after the pregnancy this is preferred. If you are pregnant, trying to get pregnant, or if there is any chance that you could possibly be pregnant however unlikely, please inform the staff.
What is it like to have an angiogram?
At least a few days before the procedure you would have routine blood tests performed.
Typically you would enter the hospital on the day of the procedure. A nurse will go through your medical history. You will then be given a gown to wear during the procedure and remove your underwear. You will then be consented for the procedure by a doctor. You should use the toilet before the procedure.
The angiogram is done in a dedicated angiography suite where you will lie flat on the table. In the room there will be members of the team who help to perform the procedure, including a nurse, a radiographer/technologist (who will help operate the machine), and a doctor (usually an interventional neuroradiologist) who will perform the procedure.
The wrist or groin is usually the site that is used for delivery of the instruments for the procedure and this is shaved and cleaned with sterile solution. Drapes are then placed around the site. The doctor will inject a small amount of local anaesthesia (which unfortunately stings when it goes in) to numb the skin. They will then insert a plastic tube in to the artery and navigate a long thin plastic tube called a catheter through the body and in to the blood vessels of the neck. Through this tube 'contrast' dye is injected whilst performing an X-ray to obtain images of the blood vessels. You do not feel the tube as it passes through the blood vessels in your body as they have no sensory receptors. You may feel some pushing and pulling at the groin.
The x-ray machines will move into position over your head. They will move around you during the procedure but will not touch you. You may experience funny sensations such as flashing lights in the eyes, hot or cold over the side of the face, a funny taste in the mouth, or pressure at the back of the head during the examination. These are all normal and tend to pass within a few seconds.. They result from the contrast dye travelling through the blood vessels. The whole examination usually takes less than an hour, although the time can be variable due to the ease or difficulty of the procedure.
It is very important you stay still throughout the procedure to ensure the pictures taken are as clear as possible. If you feel unwell or in pain please let us know. You can talk to your doctor during the exam.
After all the imaging is finished the tube in the access site is removed. If the puncture site was the groin sometimes a collagen "plug" is used to seal the blood vessel. Alternatively, usually just applying firm pressure to the blood vessel for 10 minutes is sufficient as the hole is fairly small. If the puncture site was the wrist then an inflatable compression device is applied for a few hours after.
What happens after the exam?
You will be monitored by a nurse for a few hours after the angiogram. If the access site was the groin you will be instructed to lie flat for a variable length of time (typically over 1 hour but less than 6 hours). The nursing staff will carry out regular observations, including checking your groin site and foot pulses. You should be able to eat and drink on returning to the ward, but please check with nursing staff first. Sometimes patients experience some bruising around the groin. This is nothing to worry about and will fade over a few days.
Most people can go home on the same day as the procedure. It is not advised to use public transport after you’ve had an angiogram in case you feel unwell, so it’s important that you make arrangements for someone to collect you from the ward and take you home by car.
What should I do when I return home?
You should make advance arrangements for someone to stay with you for 24 hours after you get home. To avoid provoking bleeding at the access site avoid strenuous activities such as heavy lifting, running and cycling for 1 week. Do not operate machinery or drive for 48 hours.
When will I receive the results?
Sometimes the doctor can tell you at the end of the procedure. It is not unusual, however, for it to be necessary for the images to be analysed on a computer before they can be interpreted. In this case the final results will be delivered later at a clinic attendance or over the phone.
Does the procedure involve any risk?
A cerebral angiogram is considered safe, however any medical procedure can involve small risks. It is important to understand that the risks involved in not undertaking the test (for example, non-diagnosis of a serious disease) usually outweigh the small risks of the procedure.
The main potential complication of cerebral angiography is of having a stroke, with a rate of approximately 0.5% (or 1 in 200 people). This risk varies with a few different factors and would likely be lower if you are normally in good health and not very elderly. The symptoms can involve one or more of the following: weakness of the face, arms, or legs; difficulty with speech; or difficulty with vision. Strokes can also be of variable severity: from brief and barely noticeable to very severe. They can also be temporary or result in permanent deficit. The good news is that strokes that result from cerebral angiogram often tend to be of the lesser severity with good potential for recovery. As strokes tend to occur during, or shortly after the procedure you are also in the best place (under direct medical supervision) if they were to occur.
The second main risk is of damage to artery at the access site. It is common to get small amounts of bleeding after the procedure and this usually stops spontaneously. If the bleeding is heavier or if there is internal bleeding then sometimes special injections or surgery is required. It is rare for this to be necessary, however. Very rarely the artery can become blocked, resulting in not enough blood getting to the leg. This condition requires surgery to remedy.