What happens during an endovascular bilateral cerebral angiogram?

Endovascular Bilateral Cerebral Angiogram: Procedural Overview

An endovascular bilateral cerebral angiogram is a catheter-based diagnostic procedure where contrast dye is injected through arterial access (typically the femoral artery in the groin) to visualize the blood vessels of both sides of the brain in real-time using X-ray fluoroscopy. 1, 2

Pre-Procedure Preparation

• Arterial access is obtained, most commonly through the femoral artery in the groin using a needle puncture, though radial artery access is increasingly used 2
• The patient is positioned supine on an angiography table with fluoroscopic imaging equipment
• Local anesthesia is administered at the access site
• Conscious sedation may be provided depending on patient cooperation and institutional protocols 2

Catheter Navigation and Imaging Sequence

A thin catheter is advanced from the groin through the aorta into each of the major neck vessels that supply the brain, guided by real-time X-ray imaging 1, 2:

• The catheter is selectively positioned in the right internal carotid artery, left internal carotid artery, and both vertebral arteries to image the posterior circulation 1
• For each vessel, iodinated contrast material is injected while rapid-sequence X-ray images (digital subtraction angiography) are obtained 1, 2
• Multiple projections and angles are captured to visualize the three-dimensional vascular anatomy from different perspectives 1, 2

What the Procedure Visualizes

The angiogram captures both arterial and venous phases of blood flow through the brain 1:

• Arterial phase: Shows arteries filling with contrast, including the internal carotid arteries, middle cerebral arteries, anterior cerebral arteries, and posterior circulation vessels 1
• Capillary/parenchymal phase: Demonstrates contrast perfusing through brain tissue 1
• Venous phase: Visualizes cortical veins, deep venous structures, and dural sinuses as contrast drains from the brain 1
• Normal venous filling occurs within 7-8 seconds after contrast injection into the carotid artery, with early veins opacifying at 4-5 seconds 1

Temporal and Spatial Resolution Advantages

Cerebral angiography remains the gold standard for vascular imaging because it provides 1, 2, 3:

• Highest spatial resolution of any vascular imaging modality, allowing detection of small vessel abnormalities that CT or MR angiography may miss 1, 2
• Real-time dynamic flow information showing blood flow patterns, collateral circulation, and flow direction 2, 4
• Ability to repeat injections to clarify subtle findings or evaluate specific vascular territories in greater detail 2
• Three-dimensional rotational angiography capabilities for precise anatomic delineation 1

Post-Procedure Management

• The catheter is removed and manual pressure is applied to the groin for 15-20 minutes to achieve hemostasis 2
• The patient remains flat for several hours with the leg extended to prevent access-site bleeding 2
• Neurological monitoring occurs for 24 hours as procedure-related complications typically manifest within this timeframe 5, 6
• Hydration is encouraged to facilitate contrast excretion and reduce nephropathy risk 2

Complication Rates and Risks

The procedure carries a low but measurable risk of complications 5, 2, 6:

• Permanent neurological deficit (stroke): 0.14-0.2% in large series 5, 6
• Transient neurological symptoms: Additional 0.2-2.4% 5, 6
• Access-site hematoma: 4.2-5%, the most common complication overall 5
• Death: 0.06% 5
• Contrast-induced nephropathy, arterial dissection, and allergic reactions occur rarely 2

Risk Factors for Complications

Patients at higher risk for neurological complications include those with 5:

• Atherosclerotic cerebrovascular disease (2.5-fold increased risk)
• Recent subarachnoid hemorrhage (2.5-fold increased risk)
• Frequent transient ischemic attacks (1.7-fold increased risk)
• Age over 55 years 2

Complication rates have decreased over time with improved catheter technology and operator experience 5

Clinical Indications for Bilateral Imaging

Common reasons for performing bilateral cerebral angiography include 6, 3:

• Subarachnoid hemorrhage evaluation for aneurysm detection and characterization
• Ischemic stroke workup to identify vessel occlusions or stenoses
• Arteriovenous malformation or vascular malformation assessment
• Evaluation of cerebral venous thrombosis
• Pre-surgical planning for brain tumors or epilepsy surgery
• Surveillance of previously treated vascular lesions

The procedure detects new, clinically meaningful findings in 43% of diagnostic cases and provides more precise anatomic information than noninvasive imaging in approximately 23% of studies 3