This test is done to precisely delineate the anatomy of the arterial tree by injecting dye into it. Angiograms can be done of any artery but they are most commonly done of the abdomen and legs, the carotid arteries or dialysis fistulas.
The principal is to establish remote access to the circulation away from the site of disease. Classically this is via the femoral artery in the groin if disease is in the thigh, knee or abdomen. Access is achieved by placing a sheath or plastic tube over a wire that is introduced through a needle puncture. This is done using local anaesthetic. The sheath may be placed in the brachial artery of the arm in some cases.
Once the sheath is in place further wires and catheters (longer thin silicon tubes) can be passed up the arteries to the area of interest and dye injected.
The procedure is done in catheter laboratory and the patient is awake although they may be given some sedation. The table moves and the C arm or x-ray tube can also move. When x-rays or runs are taken of the abdomen, pelvis or neck the patient is requested to hold their breath to prevent distortion of the images. As the dye passes through the body a warmth is felt.
A diagnostic study is done to simply demonstrate the anatomy, this uses small sheaths and is usually over in 60 minutes. Sometimes a decision is made to intervene or fix a problem that is identified immediately. This however increases the complexity of the study, requires larger sheaths, uses more dye, often other equipment is needed and requires an overnight stay. For these reasons often a diagnostic study is often done prior to a planned intervention at a later date.
At the completion of the angiogram the sheath is removed and the puncture site is either compressed by hand for 10 minutes until there is no bleeding or sealed with a closure device. If manual compression is used the patient needs to rest for 4 hours to reduce the chance of bleeding from the puncture site.
Prior to the angiogram, patients are asked to:
- Drink plenty of water.
- Not have solid food for 6 hours prior to the study.
- Diabetics are requested to withhold Metformin 12 hours before the angiogram.
- Empty your bladder immediately prior to the study.
- Patients on Warfarin will need to inform Dr Holdaway prior to the angiogram so that this can be discontinued or switched to another type of blood thinner.