Based on the circle of Willis, Willy hopes to raise awareness about the importance of transcranial Doppler ultrasound (TCD).
The circle of Willis supplies up to 80% of the blood to the brain and is the most important source of collateral circulation. When an artery becomes blocked or damaged due to significant extracranial disease like stenosis, hemorrhage, or stroke, collateral circulation provides alternative routes for blood flow.
Transcranial Doppler ultrasound is the only non-invasive method for continuous, real-time monitoring of blood flowing through this important structure. TCD can detect emboli, the narrowing of blood vessels, vasospasm due to hemorrhage, and much more. Due to the unique and important information provided by TCD, it is a required technology for all comprehensive stroke centers.
Visit us at any of the conferences listed below to receive your free Willy sticker. Take a photo with Willy at your facility and post it on social media with the tags #whereswilly and #novasignal. Together we can spread the word about the importance of TCD!
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The circle of Willis is an important junction of arteries at the base of the brain. The major extracranial arteries which feed the circle of Willis are the bilateral internal carotid arteries and the bilateral vertebral arteries.
The structure of the circle of Willis includes:
Connecting arteries to the circle of Willis include:
The circle of Willis plays a critical role in ensuring the brain receives adequate blood supply. It allows blood to flow from the anterior and posterior hemispheres, as well as from the left and right hemispheres of the brain. In other words, without the circle of Willis blood could not travel across the brain.
The circle of Willis is the most important source of collateral circulation in the presence of significant extracranial disease like stenosis, hemorrhage, or stroke. Collateral circulation provides alternative routes for blood flow when another artery becomes blocked or damaged. The natural structure of the circle allows for bi-directional blood flow in the event of significant changes in pressure in any brain segment. This means blood flow can actually change direction when necessary. These collateral pathways can assure adequate blood supply to all areas of the brain, reducing brain damage or other negative after effects.
Some common structural variations include:
Additional variations include:
Transcranial Doppler (TCD) is a non-invasive, painless ultrasound technique that utilizes high-frequency ultrasound waves to measure the rate and direction of blood flow inside the intracranial blood vessels. The test examines and records the speed of blood flowing in the circle of Willis to facilitate the diagnosis of a wide range of conditions.
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