Қан тамыр қабырғасының кеңеюі және түрлері

Bulge in the wall of a blood vessel

An aneurysm is an outward bulging, likened to a bubble or balloon, caused by a localized, abnormal, weak spot on a blood vessel wall. Aneurysms may be a result of a hereditary condition or an acquired disease. Aneurysms can also be a nidus (starting point) for clot formation (thrombosis) and embolization. As an aneurysm increases in size, the risk of rupture, which leads to uncontrolled bleeding, increases. Although they may occur in any blood vessel, particularly lethal examples include aneurysms of the circle of Willis in the brain, aortic aneurysms affecting the thoracic aorta, and abdominal aortic aneurysms. Aneurysms can arise in the heart itself following a heart attack, including both ventricular and atrial septal aneurysms. There are congenital atrial septal aneurysms, a rare heart defect.

The word is from Greek: ἀνεύρυσμα, aneurysma, "dilation", from ἀνευρύνειν, aneurynein, "to dilate".

Aneurysms are classified by type, morphology, or location.

A true aneurysm is one that involves all three layers of the wall of an artery (intima, media and adventitia). True aneurysms include atherosclerotic, syphilitic, and congenital aneurysms, as well as ventricular aneurysms that follow transmural myocardial infarctions (aneurysms that involve all layers of the attenuated wall of the heart are also considered true aneurysms). A false aneurysm, or pseudoaneurysm, is a collection of blood leaking completely out of an artery or vein but confined next to the vessel by the surrounding tissue. This blood filled cavity will eventually either thrombose (clot) enough to seal the leak or rupture out of the surrounding tissue. as a result of percutaneous surgical procedures such as coronary angiography or arterial grafting, or use of an artery for injection.

Aneurysm presentation may range from life threatening complications of hypovolemic shock to being found incidentally on X ray. Symptoms will differ by the site of the aneurysm and can include:

Aneurysms form for a variety of interacting reasons. Multiple factors, including factors affecting a blood vessel wall and the blood through the vessel, contribute. The pressure of blood within the expanding aneurysm may also injure the blood vessels supplying the artery itself, further weakening the vessel wall. Without treatment, these aneurysms will ultimately progress and rupture. Infection. A mycotic aneurysm is an aneurysm that results from an infectious process that involves the arterial wall. A person with a mycotic aneurysm has a bacterial infection in the wall of an artery, resulting in the formation of an aneurysm. One of the causes of mycotic aneurysms is infective endocarditis. The most common locations include arteries in the abdomen, thigh, neck, and arm. A mycotic aneurysm can result in sepsis, or life threatening bleeding if the aneurysm ruptures. Less than 3% of abdominal aortic aneurysms are mycotic aneurysms. Syphilis. The third stage of syphilis also manifests as aneurysm of the aorta, which is due to loss of the vasa vasorum in the tunica adventitia. Copper deficiency. A minority of aneurysms are caused by copper deficiency, which results in a decreased activity of the lysyl oxidase enzyme, affecting elastin, a key component in vessel walls. Copper deficiency results in vessel wall thinning, and thus has been noted as a cause of death in copper deficient humans, chickens, and turkeys.

Aneurysmal blood vessels are prone to rupture under normal blood pressure and flow due to the special mechanical properties that make them weaker. To better understand this phenomenon, we can first look at healthy arterial vessels which exhibit (for a biomaterial in vivo). Unlike crystalline materials whose linear elastic region follows Hooke's Law under uniaxial loading, many biomaterials exhibit a J shaped stress strain curve which is non linear and concave up. It was also found that the ultimate tensile strength, or the strength to withstand rupture, of aneurysmal vessel wall is 50% lower than that of normal aortas. The wall strength of ruptured aneurysmal aortic wall was also found to be 54.2 N/cm2, which is much lower than that of a repaired aorta wall, 82.3 N/cm2.

Diagnosis of a ruptured cerebral aneurysm is commonly made by finding signs of subarachnoid hemorrhage on a computed tomography (CT) scan. If the CT scan is negative but a ruptured aneurysm is still suspected based on clinical findings, a lumbar puncture can be performed to detect blood in the cerebrospinal fluid. Computed tomography angiography (CTA) is an alternative to traditional angiography and can be performed without the need for arterial catheterization. This test combines a regular CT scan with a contrast dye injected into a vein. Once the dye is injected into a vein, it travels to the cerebral arteries, and images are created using a CT scan. These images show exactly how blood flows into the brain arteries.

Historically, the treatment of arterial aneurysms has been limited to either surgical intervention or watchful waiting in combination with control of blood pressure. At least, in the case of abdominal aortic aneurysm (AAA), the decision does not come without significant risk and cost, hence, there is a great interest in identifying more advanced decision making approaches that are not solely based on the AAA diameter, but involve other geometrical and mechanical nuances such as local thickness and wall stress.

There are currently two treatment options for brain aneurysms: surgical clipping or endovascular coiling. There is currently debate in the medical literature about which treatment is most appropriate given particular situations. Surgical clipping was introduced by Walter Dandy of the Johns Hopkins Hospital in 1937. It consists of a craniotomy to expose the aneurysm and closing the base or neck of the aneurysm with a clip. The surgical technique has been modified and improved over the years. Endovascular coiling was introduced by Italian neurosurgeon Guido Guglielmi at UCLA in 1989. It consists of passing a catheter into the femoral artery in the groin, through the aorta, into the brain arteries, and finally into the aneurysm itself. Platinum coils initiate a clotting reaction within the aneurysm that, if successful, fills the aneurysm dome and prevents its rupture. A flow diverter can be used, but risks complications.

For aneurysms in the aorta, arms, legs, or head, the weakened section of the vessel may be replaced by a bypass graft that is sutured at the vascular stumps. Instead of sewing, the graft tube ends, made rigid and expandable by nitinol wireframe, can be easily inserted in its reduced diameter into the vascular stumps and then expanded up to the most appropriate diameter and permanently fixed there by external ligature. New devices were recently developed to substitute the external ligature by expandable ring allowing use in acute ascending aorta dissection, providing airtight (i. e. not dependent on the coagulation integrity), easy and quick anastomosis extended to the arch concavity Less invasive endovascular techniques allow covered metallic stent grafts to be inserted through the arteries of the leg and deployed across the aneurysm.

Renal aneurysms are very rare consisting of only 0.1–0.09% while rupture is even more rare. Conservative treatment with control of concomitant hypertension being the primary option with aneurysms smaller than 3 cm. If symptoms occur, or enlargement of the aneurysm, then endovascular or open repair should be considered. Pregnant women (due to high rupture risk of up to 80%) should be treated surgically.

Incidence rates of cranial aneurysms are estimated at between 0.4% and 3.6%. Those without risk factors have expected prevalence of 2–3%. Intracranial aneurysms are rare in childhood, with over 95% of all aneurysms occurring in adults. In the past, aneurysms were modeled as rigid spheres with linear inlets and outlets. As technology advances, the ability to detect and analyze aneurysms becomes easier. Researchers are able to CT scan a patient's body to create a 3D computer model that possesses the correct geometry. Aneurysms can now be modeled with their distinctive "balloon" shape. Nowadays researchers are optimizing the parameters required to accurately model a patient's aneurysm that will lead to a successful intervention. Current modeling is not able to take into account all variables though. For example, blood is considered to be a non Newtonian fluid. Some researchers treat blood as a Newtonian fluid instead, as it sometimes has negligible effects to the analysis in large vessels. When analyzing small vessels though, such as those present in intracranial aneurysms. Similarly, sometimes it is difficult to model the varying wall thickness in small vessels, so researchers treat wall thickness as constant. Researchers make these assumptions to reduce computational time. Nonetheless, making erroneous assumptions could lead to a misdiagnosis that could put a patient's life at risk.

U. S. Senator Joe Biden, who later became President, had two brain aneurysms in 1988. He recovered after successful surgeries to correct them. Lucille Ball died from an aortic rupture in the abdominal area days after having undergone apparently successful heart surgery for a dissecting aortic aneurysm. Laura Branigan died of a cerebral aneurysm. David Cone had an aneurysm and missed most of the 1996 baseball season. Davie Cooper died in 1995 following a subarachnoid hemorrhage whilst filming a football television series. John Olerud had an aneurysm in 1989 and has worn a batting helmet on the field all of his career since then. Albert Einstein died from a repaired aortic aneurysm. Thomas Mikal Ford died from a ruptured aneurysm in his abdomen at age 52. Charles de Gaulle died from a ruptured aneurysm within his neck. Richard Holbrooke died from a thoracic aortic aneurysm. Édith Piaf died from an aneurysm due to liver failure. Stuart Sutcliffe died from an aneurysm in his brain's right hemisphere. Raymond F. Boyce died in 1974 as a result of an aneurysm. John Ritter died in 2003 of a misdiagnosed thoracic aortic dissection (aortic aneurysm). Isabel Granada died of a cerebral aneurysm. Geoffrey Thompson died of a brain aneurysm at his daughter's wedding, hosted at his theme park, Blackpool Pleasure Beach. Edwin Rosario died of an aneurysm in 1997. Joni Mitchell had a brain aneurysm in 2015 and survived. Grant Imahara died from a brain aneurysm in July 2020. Dr. Dre had a brain aneurysm in January 2021. Jovit Baldivino died from a brain aneurysm in December 2022. Tom Sizemore died from a brain aneurysm in March 2023.