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What Is Digital Subtraction Angiography?

Digital subtraction angiography is a minimally invasive test to check for abnormalities of the blood vessels of the brain such as narrowing and blockage, or malformations. It is a type of X-ray involving an injected dye, where images are taken before and after the dye. One image is subtracted from the other with a computer, allowing bones and other structures to be removed from the image so the arteries are more clearly viewed.

  1. Significance

    • Physicians rely on cerebral angiography to diagnose conditions that can lead to significant health problems, particularly stroke. Often angiography is used after another test, such as a CT or computed tomography, scan has indicated a problem. Angiography can detect and diagnose an acute stroke and provides images not available through any other procedure.

    Function

    • Before the procedure, a patient will remove all clothing and jewelry and put on a hospital gown. A local anesthetic will be given at the site where an incision will be made for the insertion of the catheter. The catheter is a long flexible tube which will be inserted in the leg or arm, and dye will be injected into the carotid arteries leading to the brain. Then X-ray images will be taken of the brain. The patient may feel a warm sensation during the test.

    Time Frame

    • Prior to the procedure, patients are to refrain from eating or drinking for 12 hours. During the digital subtraction angiography procedure, a technologist and a radiologist will be with the patient at all times. The procedure can take one to two hours, but may take several hours depending on the area being tested. After the catheter is removed, the area must be compressed for 10 to 20 minutes. Patients may be required to lie flat for several hours after the procedure to minimize the risk of bleeding. Patients are advised to drink plenty of fluids to flush out the dye. Sometimes they may need to stay overnight in the hospital.

    Benefits

    • Besides the advantages of detecting problems in the blood vessels of the brain, some problems can be treated during the procedure. For instance, narrowed arteries can be opened or blockages can be removed. A stent, or tube of wire mesh, can be placed in an artery to keep it open. Torn or weak areas in vessels can also be repaired.

    Considerations

    • If at any time the patient feels discomfort, the physician or technologist should be informed. Occasionally, people have allergic reactions to the dye. Problems at the injection site can include bleeding, infection or pain. Rarely, damage can be done to a blood vessel by the catheter. Serious complications are rare, but include kidney damage, seizures or shock and possibly even cardiac arrest. Sometimes heart arrhythmia occurs, where the heart may slow or skip a beat. This is more common among older patients.

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