Inquire about dye allergy in all patients undergoing angiography. Special caution in diabetic and renal patients.
- Angiography is the invasive x-ray imaging of the cerebral vasculature using catheters to directly inject contrast into cerebral arteries. Catheters are navigated through the vasculature, usually starting at the femoral or less commonly brachial artery, into the common carotid, internal carotid, and vertebral arteries for imaging of the cervical or cerebral vascular system. Both fluoroscopy and digital subtraction imaging are employed to perform this safely.
- This imaging modality utilizes an iodine-based contrast to image the vasculature as it passes through the arterial, capillary, and venous beds of the head and neck. The individual phases last several seconds each, and each “run” lasts from 5 to 20 seconds.
- Because of its invasive nature and potential risks, angiography should be considered in situations where cerebral vascular disease requires evaluation in greater detail than can be offered by non-invasive testing, including CT and MR angiography. Many situations exist which justify this, and include:
- Suspicion of a cerebrovascular abnormality, including aneurysm, arteriovenous malformation (AVM), or fistula
- Evaluation of a stroke or transient ischemic attack, with consideration of cervical or intracerebral atherosclerotic disease
- Consideration of vasculitis, vasospasm, or venous occlusive disease
- Evaluation of a subarachnoid or unexplained intraparenchymal hemorrhage
- Evaluation of blunt or penetrating vascular injury
- Functional testing for epilepsy surgery, including a Wada test
- Evaluation of spinal vascular disease, including fistula or AVM
- Identification of the spinal artery of Adamkiewicz prior to certain spinal surgeries
Relative to other angiographic modalities, catheter angiography provides greater temporal and spatial resolution than other imaging modalities. It is the most precise mode for imaging of smaller vessels in the head and neck, and allows for imaging of selective beds offering more dedicated imaging. Should an intervention be appropriate, this can be performed in the same setting as the diagnostic study, should that be indicated and appropriate for the disease being considered.
- The images obtained are two-dimensional representations of a three-dimensional structure. Newer computer modes of this imaging can create rotational models of the arterial beds being imaged and as such may now offer true spatial resolution, formerly available with non-invasive modes.
- The study does carry some risk and may be time-consuming for the patient, which should be considered.
- Availability of the angiography equipment may limit the use of this test, as it is often expensive and not immediately available.
- The incidence of vascular or neurologic injury during a catheter angiogram remains low, and is estimated to be below 0.5%. This may be lower in the hands of a skilled and dedicated neuro-angiographer or neuro-interventionalist. The risks may be slightly higher in patients with significant atherosclerotic disease of the aorta or craniocervical vasculature. The risks include injury, such as dissection, and thromboembolism, from either disturbed plaque or de novo thrombus formation of the catheter. While use of heparinization is not standard, prolonged procedures or manipulation may increase this risk.
- Vascular access complications include less serious groin ecchymosis to more serious hematomas or injury. Less commonly, this can be significant enough to justify transfusion or consultation with a vascular surgeon for management or repair.
- Rarer complications can occur and include contrast allergy, infection at the access site, retroperitoneal hematoma, or hemodynamic changes.
There are no absolute contraindications, though renal dysfunction, pregnancy, coagulation disorders, and prior contrast allergies are relative contraindications. Catheter angiography in certain collagen disorders, such as Ehlers–Danlos Type 4, may carry increased risks of dissection or vascular injury.
Preparation/Special Instructions
- Patients should not eat or drink prior to the procedure. Prescribed medications may be continued. Patients with poor renal function should be hydrated prior to the procedure, and dialysis should be timed around the angiogram. Metformin should be held prior to and following the angiogram as there is increased risk of renal failure.
- Following the procedure, the patient is monitored for a short period for groin or systemic complications. The patient is usually kept flat with the hip held straight. Following discharge, routine behavior is acceptable though oral hydration is recommended, as is light function, including limitation of weight lifting and excessive joint movement. These limits are relative and usually applied for 2–5 days following the angiogram.
