Purpose:
Digital subtraction angiography may be done for diagnostic purposes, and also as a visual guide during interventional procedures. It may be indicated in the following cases:

1. Diagnosis of several blood vessel diseases, like:

• Obstructive vascular diseases (blockage or narrowing of arteries and veins)

• Brain aneurysm (a weakness in the wall of a blood vessel in the brain, causing it to bulge and fill with blood)

• Bleeding blood vessels

• Arteriovenous malformations (abnormal connections between the veins and arteries)

• Study of blood vessel system in cancerous tumors

2. Arterial stenting: An arterial stent, which is a small, metal mesh tube, is usually placed inside a coronary artery (the main artery of the heart) to open the artery for better blood flow, and prevent it from closing again.

3. Arterial balloon angioplasty: It is a procedure done to open the blocked or narrowed arteries. A balloon is attached to a flexible tube, known as a catheter, and inserted into a blocked artery, and the balloon is inflated to open the artery.

4. Thrombectomy: This is a surgical procedure done to remove a blood clot from inside a vein or artery.

5. Endovascular embolization: This is a procedure done to treat the abnormal blood vessels in the brain, and other body parts by cutting off the blood supply to a certain part of the body.

6. Endovascular aneurysm repair: This is a minimally invasive surgery that is used to treat an aortic aneurysm, which is a balloon-like bulge in the aorta (a large artery carrying blood from the heart through the chest and torso region).

A digital subtraciton angiography should be carried out in the following cases:

• Pain in specific areas

• Back or leg pain

• Hypertension

• Rapid onset of headache

• Cranial nerve deficits

Digital Subtraction Angiography is a diagnosis for blood vessel imaging.

• The hospital room should be equipped with monitoring equipment and a crash cart.
• The patient’s heart rate and blood oxygenation are monitored continuously, and the blood pressure is measured intermittently during the procedure.
• The procedure is performed in aseptic (sterile) conditions.
• The procedure is performed under conscious sedation (a combination of medications given to block pain and help the patient relax), local anesthesia (the area of the procedure is numbed), or general anesthesia (the patient is asleep during the procedure), depending on the condition of the patient and the type of procedure being performed.
• The patient is placed comfortably on the treatment bed, with the head on one end of the bed.
• A radiographic dye is injected into either the arterial or venous circulation. Less dye is required for arterial angiography.
• X-ray film is taken before and after dye injection is superimposed on one another, all matching images are subtracted.
• Therefore, only the dye-enhanced cerebral vessels are left for studying and evaluation.
• This procedure eliminates the distortions and shadows of the bone or other material that sometimes blocks the viewing of the cerebral vessels.
• After the completion of the procedure, the catheter will be removed.
• Pressure is applied to the puncture site for many minutes and a sterile dressing is applied.

The risks involved in a Digital Subtraction Angiography are:

• Bleeding from the site of puncture
• Damage to the nearby tissues
• Blood clot (a mass of blood) formation
• Pseudoaneurysm (when the wall of the blood vessel is injured and the blood leaks in the surrounding tissue)
• Arteriovenous fistula (an abnormal connection between an artery and a vein)
• Air embolism (blockage of an artery or a vein when one or more air bubbles enter inside)
• Thromboembolism (the obstruction of a blood vessel by a blood clot that becomes dislodged from another site in the circulation)
• Blood vessel dissection (a tear inside the wall of a blood vessel)
• Contrast mediated nephrotoxicity (worsening of the kidney function due to the administration of iodinated contrast material)

After a Digital Subtraction Angiography, it is advised to:

• Post-procedure care depends on the nature of the procedure performed, and whether it was performed as an outpatient procedure (the patient goes home on the day of the procedure) or inpatient procedure (the patient stays in the hospital following the procedure).
• The patient is immobilized for four to six hours after the procedure and kept in a supine position (lying on the back).
• The patient’s vital signs and neurological (nerve-related) status are monitored after the procedure.
• Frequent observations are needed after the procedure to look for puncture site hematoma (bleeding from the puncture site), which is the most common complication after the procedure.
• The patient is instructed to increase the intake of fluids for the first 24 hours after the procedure.
• The patient should be observed for any allergic reactions like nausea, vomiting, or urticaria (rashes on the skin) after the procedure.