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| {{Infobox_Disease | | | {{Aneurysm}} |
| Name = Aneurysm |
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| Caption = |
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| DiseasesDB = 15088 |
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| ICD10 = {{ICD10|I|72||i|70}} |
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| ICD9 = {{ICD9|442}} |
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| ICDO = |
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| OMIM = |
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| MedlinePlus = 001122 |
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| eMedicineSubj = |
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| eMedicineTopic = |
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| {{SI}}
| | '''For patient information on this page, click [[Aneurysm (patient information)|here]]''' |
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| {{WikiDoc Cardiology Network Infobox}}
| | {{CMG}}''' Associate Editor-In-Chief:''' {{CZ}} |
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| '''Associate Editor-In-Chief:''' {{CZ}} | |
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| {{Editor Join}}
| | ==[[Aneurysm overview|Overview]]== |
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| ==Overview== | | ==[[Aneurysm classification|Classification]]== |
| An '''aneurysm''' (or '''aneurism''') is a localized, blood-filled dilation (bulge) of a blood vessel caused by disease or weakening of the vessel wall.<ref>{{cite web | url = http://www.kmle.com/search.php?Search=aneurysm | title = ''KMLE Medical Dictionary Definition of aneurysm'' | author = [http://www.kmle.com The American Heritage Stedman's Medical Dictionary]}}</ref> Aneurysms most commonly occur in [[artery|arteries]] at the base of the brain (the [[circle of Willis]]) and in the [[aorta]] (the main artery coming out of the [[heart]]), a so-called [[aortic aneurysm]]. The bulge in a blood vessel can burst and lead to death at any time. The larger an aneurysm becomes, the more likely it is to burst. Aneurysms can usually be treated.
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| ==Classification== | | ==[[Aneurysm causes|Causes]]== |
| Aneurysms may involve arteries or veins and have various causes. They are commonly further classified by shape, structure and location.
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| ===Shape=== | | ==[[Aneurysm differential diagnosis|Differentiating Aneurysm from other Diseases]]== |
| A saccular aneurysm resembles a small bubble that appears off the side of a [[blood vessel]]. The innermost layer of an [[artery]], in direct contact with the flowing blood, is the ''[[tunica intima]]'', commonly called the intima. Adjacent to this layer is the ''[[tunica media]]'', known as the media and composed of [[smooth muscle]] cells and elastic tissue. The outermost layer is the ''[[tunica adventitia]]'' or ''tunica externa.'' This layer is composed of tougher [[connective tissue]]. A saccular aneurysm develops when fibers in the outer layer separate allowing the pressure of the blood to force the two inner layers to balloon through.
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| A fusiform aneurysm is a bulging around the entire circumference of the vessel without protrusion of the inner layers. It is shaped like a football or spindle.
| | ==References== |
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| These aneurysms can result from [[hypertension]] in conjunction with [[atherosclerosis]] that weakens the tunica adventitia, from [[congenital]] weakness of the adventitial layer (as in [[Marfan syndrome]]) or from [[infection]].
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| | [[CME Category::Cardiology]] |
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| ===Structure===
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| In a true aneurysm the inner layers of a vessel have bulged outside the outer layer that normally confines them. The aneurysm is surrounded by these inner layers.
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| A ''false-'' or ''[[pseudoaneurysm]]'' does not primarily involve such distortion of the vessel. It 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 [[thrombus|thrombose]] (clot) enough to seal the leak or it will rupture out of the tougher tissue enclosing it and flow freely between layers of other tissues or into looser tissues. Pseudoaneurysms can be caused by [[physical trauma|trauma]] that punctures the artery and are a known complication of [[percutaneous]] arterial procedures such as arteriography or of arterial grafting or of use of an artery for injection, such as by drug abusers unable to find a usable vein. Like true aneurysms they may be felt as an abnormal pulsatile mass on [[palpation]].
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| ===Location===
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| Most non-intracranial aneurysms (94%) arise distal to the origin of the [[kidney|renal]] arteries at the infrarenal [[abdominal aorta]], a condition mostly caused by [[atherosclerosis]].
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| The [[thoracic aorta]] can also be involved.
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| One common form of thoracic aortic aneurysm involves widening of the proximal aorta and the aortic root, which leads to [[aortic insufficiency]].
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| Aneurysms occur in the legs also, particularly in the deep vessels (e.g., the [[popliteal]] vessels in the knee). Arterial aneurysms are much more common, but [[venous]] aneurysms do happen (for example, the popliteal venous aneurysm).
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| * While most aneurysms occur in an isolated form, the occurrence of berry aneurysms of the [[anterior communicating artery]] of the [[circle of Willis]] is associated with autosomal dominant [[polycystic kidney disease]] (ADPKD).
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| * 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]].
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| ==Differential Diagnosis by Underlying Mechanism==
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| ===Familial===
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| *Clustering of [[intracerebral aneurysm]]s
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| *[[Polycystic kidney disease]]
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| *[[Osler-Weber-Rendu Syndrome]]
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| *[[Neurofibromatosis]]
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| ===[[Hypertension]]===
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| ===[[Trauma]]===
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| ===Collagen vascular disease===
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| *[[Marfan's syndrome]]
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| *[[Ehlers-Danlos syndrome]]
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| ===Lipid abnormalities===
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| ===Infectious and inflammatory conditions===
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| * [[Takayasu's arteritis]]
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| * [[Giant Cell Arteritis]]
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| * [[Syphilis]]
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| * [[Reiter's syndrome]]
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| * [[SLE]]
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| * [[Polychondritis]]
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| * [[Behçet's disease]]
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| * [[Rheumatoid arthritis]]
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| ==Differential Diagnosis by Anatomic Location==
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| === Thoracic Aortic Aneurysm ===
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| * [[Marfan's syndrome]]
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| * Trauma
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| * [[Ehlers-Danlos syndrome]]
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| * Infection
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| *:* [[Syphilis]]
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| *:*Other bacterial or mycotic infections
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| * Degenerative changes
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| *:* [[Arteriosclerosis]]
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| *:* Cystic medial necrosis
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| * Inflammation
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| *:* [[Kawasaki disease]]
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| *:* [[Polychondritis]]
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| *:* [[Aortitis]]
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| *:* [[Behçet's disease]]
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| * [[Hypertension]]
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| === Abdominal Aortic Aneurysm ===
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| * Polycystic disease
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| * [[Marfan's syndrome]]
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| * [[Atherosclerosis]]
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| * Lipid metabolism disorders
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| * [[Hypertension]]
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| * [[Aortic dissection]]
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| * Mycotic infection
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| * [[Cystic medial necrosis]]
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| * [[Ehlers-Danlos syndrome]]
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| === Peripheral Arteries ===
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| * [[Arteriosclerosis]]
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| * [[Takayasu's arteritis]]
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| * [[Trauma]]
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| * [[Syphilis]]
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| * [[Marfan's syndrome]]
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| * [[Kawasaki disease]]
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| === Coronary Arteries ===
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| * [[Atherosclerosis]]
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| * Bacterial infection
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| * [[Ehlers-Danlos syndrome]]
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| * Congenital [[syphilis]]
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| * [[Scleroderma]]
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| * [[Polyarteritis nodosa]]
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| * Septic [[emboli]]
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| * [[Kawasaki disease]]
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| ==Risk Factors for an Aneurysm==
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| * [[Diabetes]]
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| * [[Obesity]]
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| * [[Hypertension]]
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| * [[Tobacco smoking]]
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| * [[Alcoholism]]
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| * [[Arteriosclerosis]]
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| * Lipid metabolism disorder
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| * Male gender
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| * Increasing age
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| * [[Chronic obstructive pulmonary disease]]
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| ==Pathology Findings==
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| == Complications of Aneurysms ==
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| Rupture and blood clotting are the risks involved with aneurysms. Rupture leads to drop in blood pressure, rapid heart rate, and lightheadedness. The risk of death is high except for rupture in the extremities.
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| Blood clots from popliteal arterial aneurysms can travel downstream and impair perfusion to tissue. Only if the resulting pain and/or numbness are ignored over a significant period of time will such extreme results as amputation be needed. Clotting in popliteal venous aneurysms are much more serious as the clot can embolise and travel to the heart, or through the heart to the lungs (a [[pulmonary embolism]]).
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| ==Examples==
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| <div align="left">
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| <gallery heights="125" widths="125">
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| Image:CT.Apical aneurysm.png|Computerized Tomography image shows a left ventricular apical aneurysm. Complication of acute myocardial infarction.
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| Image:Calcified-ventricular-aneurysm-001.jpg|Chest X-Ray: Calcified ventricular aneurysm
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| </gallery>
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| </div>
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| <div align="left">
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| <gallery heights="125" widths="125">
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| Image:Calcified-ventricular-aneurysm-005.jpg|Chest X-Ray: Calcified ventricular aneurysm
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| Image:Calcified-ventricular-aneurysm-002.jpg|Computerized Tomography: Calcified ventricular aneurysm
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| </gallery>
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| </div>
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| <div align="left">
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| <gallery heights="125" widths="125">
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| Image:Calcified-ventricular-aneurysm-003.jpg|Computerized Tomography: Calcified ventricular aneurysm
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| Image:Calcified-ventricular-aneurysm-004.jpg|Computerized Tomography: Calcified ventricular aneurysm
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| </gallery>
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| </div>
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| ==Formation==
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| Most frequent site of occurrence is in the anterior cerebral artery from the circle of Willis.
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| The occurrence and expansion of an aneurysm in a given segment of the arterial tree involves local hemodynamic factors and factors intrinsic to the arterial segment itself.
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| The human [[aorta]] is a relatively low-resistance circuit for circulating blood. The lower extremities have higher arterial resistance, and the repeated trauma of a reflected arterial wave on the distal aorta may injure a weakened aortic wall and contribute to aneurysmal degeneration. Systemic hypertension compounds the injury, accelerates the expansion of known aneurysms, and may contribute to their formation.
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| Aneurysm formation is probably the result of multiple factors affecting that arterial segment and its local environment.
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| Hemodynamically, the coupling of aneurysmal dilation and increased wall stress is approximated by the [[law of Laplace]]. Specifically, the Laplace law states that the (arterial) wall tension is proportional to the pressure times the radius of the arterial conduit (T = P X R). As diameter increases, wall tension increases, which contributes to increasing diameter. As tension increases, risk of rupture increases. Increased pressure (systemic hypertension) and increased aneurysm size aggravate wall tension and therefore increase the risk of rupture.
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| In addition, the vessel wall is supplied by the blood within its lumen in humans. Therefore in a developing aneurysm, the most [[ischemic]] portion of the aneurysm is at the farthest end, resulting in weakening of the vessel wall there and aiding further expansion of the aneurysm. Thus eventually all aneurysms will, if left to complete their evolution, rupture without intervention. In dogs, collateral vessels supply the vessel and aneurysms are rare.
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| ==Treatment of Aneurysms==
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| Historically, the treatment of arterial aneurysms has been surgical intervention, or watchful waiting in combination with control of [[blood pressure]]. Recently, [[endovascular]] or minimally invasive techniques have been developed for many types of aneurysms.
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| === Treatment of Brain Aneurysms ===
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| Currently there are two treatment options for [[Cerebral aneurysm|brain aneurysms]]: surgical clipping or endovascular coiling. Surgical clipping was introduced by Walter Dandy of the [[Johns Hopkins Hospital]] in 1937. It consists of performing a craniotomy, exposing the aneurysm, and closing the base of the aneurysm with a clip. The surgical technique has been modified and improved over the years. Surgical clipping remains the best method to permanently eliminate aneurysms. Endovascular coiling was introduced by Guido Guglielmi at UCLA in 1991. 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. Once the catheter is in the aneurysm, platinum coils are pushed into the aneurysm and released. These coils initiate a clotting or thrombotic reaction within the aneurysm that, if successful, will eliminate the aneurysm. In the case of broad-based aneurysms, a stent is passed first into the parent artery to serve as a scaffold for the coils ("stent-assisted coiling").
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| At this point it appears that the risks associated with surgical clipping and endovascular coiling, in terms of stroke or death from the procedure, are the same. The major problem associated with endovascular coiling, however, is the high recurrence rate and subsequent bleeding of the aneurysms. For instance, the most recent study by Jacques Moret and colleagues from Paris, France, (a group with one of the largest experiences in endovascular coiling) indicates that 28.6% of aneurysms recurred within one year of coiling, and that the recurrence rate increased with time. (Piotin M et al., ''Radiology'' 243(2):500-508, May 2007) These results are similar to those previously reported by other endovascular groups. For instance Jean Raymond and colleagues from Montreal, Canada, (another group with a large experience in endovascular coiling) reported that 33.6% of aneurysms recurred within one year of coiling. (Raymond J et al., ''Stroke'' 34(6):1398-1403, June 2003) The long-term coiling results of one of the two prospective, randomized studies comparing surgical clipping versus endovascular coiling, namely the International Subarachnoid Aneurysm Trial (ISAT) are turning out to be similarly worrisome. In ISAT, the need for late retreatment of aneurysms was 6.9 times more likely for endovascular coiling as compared to surgical clipping. (Campi A et al., ''Stroke'' 38(5):1538-1544, May 2007)
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| Therefore it appears that although endovascular coiling is associated with a shorter recovery period as compared to surgical clipping, it is also associated with a significantly higher recurrence and bleeding rate after treatment. Patients who undergo endovascular coiling need to have annual studies (such as MRI/MRA, CTA, or angiography) indefinitely to detect early recurrences. If a recurrence is identified, the aneurysm needs to be retreated with either surgery or further coiling. The risks associated with surgical clipping of previously-coiled aneurysms are very high. Ultimately, the decision to treat with surgical clipping versus endovascular coiling should be made by a cerebrovascular team with extensive experience in both modalities. At present it appears that only older patients with aneurysms that are difficult to reach surgically are more likely to benefit from endovascular coiling. These generalizations, however, are difficult to apply to every case, which is reflected in the wide variabilty internationally in the use of surgical clipping versus endovascular coiling.
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| ===Treatment of peripheral aneurysms===
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| For aortic aneurysms or aneurysms that happen in the vessels that supply blood to the arms, legs, and head (the peripheral vessels), surgery involves replacing the weakened section of the vessel with an artificial tube, called a graft. More recently, covered metallic stent grafts can be inserted through the arteries of the leg and deployed across the aneurysm.
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| ==See also==
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| * [[Aortic aneurysm]]
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| * [[Aortic dissection]]
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| * [[Cerebral aneurysm]]
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| * [[Charcot-Bouchard aneurysms]]
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| * [[Rasmussen's aneurysm]]
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| * [[Aneurysm of sinus of Valsalva]]
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| ==References==
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| <!-- ----------------------------------------------------------
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| See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for a
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| <div class="references-small">
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| == External links ==
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| *[http://www.brainhelp.co.uk/ Addressing the Challenges Faced as a Result of Brain Haemorrhage]
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| *[http://www.brain-aneurysm.com/ Brain Blood Vessel Disorder Help & Info Site]
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| *[http://www.aneurist.org/ @neurIST - Integrated Biomedical Informatics for the Management of Cerebral Aneurysms]
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| *[http://danielhaggard.com/11/11/ Story of Aneurysm Survival]
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| {{Circulatory system pathology}}
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| [[Category:Gross pathology]]
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