An angiogram (or arteriogram) is a specialized diagnostic imaging test that uses X-rays to create detailed pictures of the body’s blood vessels. Healthcare providers use this procedure to check for blockages, narrowing, or other abnormalities in arteries and veins, such as those supplying the heart, brain, or limbs. While the procedure is generally considered safe, a stroke is a recognized, though rare, complication. This risk is typically associated with the mechanical process of inserting and manipulating the catheter inside the blood vessels.
Understanding the Angiogram Procedure
The angiogram procedure begins with the patient receiving a local anesthetic before a small incision is made, usually near the groin (femoral artery) or the wrist (radial artery). A catheter is then inserted into the artery through this access point. Using X-ray guidance, the physician carefully navigates the catheter through the body’s arterial network until its tip reaches the area of interest, such as the coronary arteries around the heart or the carotid arteries leading to the brain.
Once the catheter is positioned correctly, a special substance called contrast dye is injected through the tube. This dye flows into the blood vessels, making them visible on the X-ray images and allowing the doctor to detect any narrowed or blocked sections. The entire process provides detailed information about blood flow.
How Stroke Complications Arise
The majority of strokes that occur following an angiogram are ischemic, meaning they are caused by a blockage in a blood vessel that stops blood flow to the brain. The primary mechanism involves thromboembolism, where the movement of the catheter dislodges material from the inner walls of the arteries. As the catheter travels up the aorta, it can scrape against atherosclerotic plaques or existing clots, releasing tiny fragments of debris or thrombi. These fragments can then travel upstream into the cerebral circulation, leading to a stroke.
Another possible cause is direct vessel injury, where the catheter or its guidewire causes trauma to the arterial wall. This trauma can result in a dissection, which is a tear in the inner lining of the artery, leading to either a blockage or the formation of a clot that subsequently travels to the brain. The contrast dye itself, while generally safe, can rarely cause a temporary neurological effect known as postprocedural encephalopathy. This reaction is thought to involve a temporary disruption of the blood-brain barrier, although it usually resolves without lasting damage.
Evaluating the Overall Risk and Frequency
The incidence of stroke following a diagnostic angiogram is very low. For diagnostic coronary angiography, the rate is reported to be between 0.05% and 0.1% of procedures. The risk is slightly higher for cerebral angiography, which specifically targets the vessels supplying the brain, with rates ranging from approximately 0.3% to 1.2%.
Certain patient factors significantly increase the likelihood of this complication. Individuals with pre-existing conditions such as advanced age, a history of prior stroke, severe atherosclerosis, uncontrolled high blood pressure, or diabetes mellitus are at greater risk. Performing the procedure under emergency conditions also correlates with a higher risk compared to elective procedures. Ultimately, the diagnostic information gained from the angiogram, which helps identify and treat serious conditions like coronary artery disease or aneurysms, usually outweighs the small, quantifiable risk of stroke.