Aneurysms: Do or Die

By: Khushi Sheth


Image Credit: Flickr: @ Ed Uthman

Most people have a very basic understanding of what an aneurysm is and know they can be fatal. But what happens at the biological level?

An aneurysm occurs when a blood clot forms in an artery. This clot causes the wall of the artery to become very fragile and susceptible to rupture, due to the pressure the clot puts on it. The likelihood that a person experiencing an aneurysm is correctly diagnosed is very rare. Most people associate an aneurysm with a seizure, one of the more obvious symptoms, but fail to react to the other symptoms like dizziness, fatigue, and increased heart rate. The reason why aneurysms are so dangerous is because this clot could lead to a rupture in the brain, legs, aorta, and spleen, causing severe internal bleeding.


Aneurysms can occur throughout the body. The most common site for arterial aneurysms is the aorta, the largest blood vessel in the body, located in the thoracic cavity. While the aorta is the most common site, the most dangerous area for an aneurysm is the brain, as the size of the aneurysm brain is unknown and can form in the blood vessels located deep within the brain. Aneurysms can also occur in the arteries behind the knee, in the spleen, and intestines.


There are several reasons why an aneurysm would develop. Fatty deposits can form blockages that damage tissue in the arteries. This can cause the heart to pump harder than normal in order to push the blood past the fatty buildup causing the clot. The stress of the increased pressure can damage the arteries, making them more susceptible to rupture. People with atherosclerotic disease are at high risk of having an aneurysm because their bodies form a plaque buildup in their arteries. High blood pressure can enlarge and weaken the blood vessels as the increase in pressure stretches and damages the arterial walls.


While aneurysms often go undetected for a long time, they are diagnosed with a CT scan. CT scans are a special type of x-ray technology that uses a computer to get a 2D picture of a person’s soft tissues (like organs, blood vessels, etc). This helps doctors identify irregularities such as blockages and weak spots in the blood vessels. If a patient is diagnosed with an aneurysm in a weak blood vessel in the chest and abdomen, then an endovascular stent graft procedure may be carried out. This procedure repairs and reinforces the damaged blood vessels while simultaneously reducing the likelihood of infection, scarring, and other issues. An endovascular graft is a tube held up by a metal stent that is placed in the aneurysm. When this is done, blood is pumped through the metal stent graft, thus releasing some of the pressure on the vessel and preventing rupture. Other treatments include medications that target high blood pressure and high cholesterol. By lowering blood pressure, there is a greater likelihood the aneurysm won’t rupture.

A team of researchers from Lawrence Livermore National Laboratory made a 3D model of a cerebral (brain) aneurysm and analyzed the model to develop new treatment methods. To develop this model, they casted a thin hydrogel that functioned as the primary base for the model of the aneurysm. They then printed a sacrificial ink onto the base layer to model the shape of the aneurysm and the connecting vascular channels. Another layer of the hydrogel was applied to the whole structure to set the model. When the device was set, the material was liquified and could be suctioned out of the device. The team then used a syringe to inject endothelial cells, which generally lie on a deeper layer of the skin, into the mold. These cells then attached to the walls of the vessels and the dome of the aneurysm created by the molds. Because the cells were suspended in cell growth, they would be able to multiply in the 3D model and create a “living aneurysm.” This complicated device was then connected to a perfusion system, which mimics the circulatory or lymphatic system to an organ or tissue for blood transfer, and cultivated so the cells in the medium could grow and divide. Eventually forming human tissue that would react like a patient’s body and could be experimented on to develop treatments. After the 3D model was complete, the team performed an experimental coiling treatment on the aneurysm structure to test its effectiveness. After a few days, there was slight improvement in the formation of the endothelium. Aneurysms are life-threatening but biomedical engineers are making it possible to biologically manipulate the formation and treatment of an aneurysm using ethical and innovative research practices, an outstanding improvement in modern medicine.


Educational Content

Q: What is plaque?

A: Plaque is a hard substance that can damage the arteries and prevents blood from easily flowing throughout the body. This blood clot buildup can cause heavy pressure on the walls of the arteries, causing it to rupture.


Q: Where can aneurysms occur?

A: Aneurysms can occur in but are not limited to the brain, stomach, thoracic cavity(chest area), spleen, intestines, and the back of the knee. The most dangerous area to have an aneurysm is the brain because of the implications of a loss of blood flow to the brain.


Q: Can an aneurysm occur in the veins, or does it exclusively occur in the arteries?

A: An aneurysm can occur in any blood vessel but most commonly develops in an artery (a vessel that carries blood away from the heart). A lot of venous aneurysms are often misdiagnosed as soft tissue masses or hernias.


Citations

  1. https://www.nextgov.com/emerging-tech/2020/11/first-ever-living-3d-printed-brain-aneurysm-madeand-treated-llnl/169768/

  2. https://www.healthline.com/health/aneurysm

  3. No changes were made to the following image, Temporal Artery Aneurysm | Incidental finding in a temporal … | Flickr, License: Creative Commons Legal Code

  4. https://www.mayoclinic.org/diseases-conditions/brain-aneurysm/symptoms-causes/syc-20361483



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