Aneurysm Classification and external resources
ICD-10	I72.
ICD-9	442
DiseasesDB	15088
MedlinePlus	001122
MeSH	D000783

An aneurysm (or aneurism) is a localized, blood-filled dilation (balloon-like bulge) of a blood vessel caused by disease or weakening of the vessel wall. The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The International Statistical Classification of Diseases and Related Health Problems 10th Revision ( ICD -10) is a coding of diseases and signs symptoms abnormal findings I00-I99 - Diseases of the Circulatory system (I00-I02 Acute rheumatic fever ( Rheumatic fever without mention of Heart The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. The Diseases Database is a free Website that provides information about the relationships between medical conditions Symptoms, and Medications. MedlinePlus, with the MedlinePlus Medical Encyclopedia, is a website network containing Health information from the world's largest medical Library Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Aneurysms most commonly occur in 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. Arteries are Blood vessels that carry blood away from the Heart. The circle of Willis (also called the cerebral arterial circle or arterial circle of Willis) is a circle of arteries that supply blood to the Brain The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic 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.

Contents 1 Shape 2 Structure 3 Location 4 Risks 5 Formation 6 Treatment 6.1 Treatment of aneurysms 6.2 Treatment of aortic and peripheral aneurysms 7 See also 8 References 9 External links

Shape

A saccular aneurysm resembles a small bubble that appears off the side of a blood vessel. The blood vessels are part of the Circulatory system and function to transport Blood throughout the body The innermost layer of an artery, in direct contact with the flowing blood, is the tunica intima, commonly called the intima. Arteries are Blood vessels that carry blood away from the Heart. The tunica intima (or just intima) is the innermost layer of an Artery or Vein. Adjacent to this layer is the tunica media, known as the media and composed of smooth muscle cells and elastic tissue. The tunica media (or just media) ( middle coat) is the middle layer of an Artery or Vein. Smooth muscle is a type of non- Striated muscle, found within the Tunica media layer of large and small Arteries and Veins, the bladder The outermost layer is the tunica adventitia or tunica externa. The tunica externa, also known as the tunica adventitia, is the outermost layer of a Blood vessel, surrounding the Tunica media. This layer is composed of tougher connective tissue. Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, Muscle, and Nervous 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.

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.

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. Hypertension, also referred to as high blood pressure, HTN or HPN, is a medical condition in which the Blood pressure is chronically elevated Atherosclerosis is a Disease affecting arterial Blood vessels It is a chronic inflammatory response in the walls of arteries in large part due to the accumulation A congenital disorder is a disease or disorder that is present at birth Marfan syndrome (or Marfan's syndrome is a genetic disorder of the Connective tissue. An infection is the detrimental Colonization of a host Organism by a foreign Species.

Structure

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.

A false- or pseudoaneurysm does not primarily involve such distortion of the vessel. A pseudoaneurysm, also known as a false Aneurysm, is the result of trauma to all three layers of an artery resulting in a hematoma that contains the bleed 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 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. A thrombus, or blood clot, is the final product of the Blood coagulation step in Hemostasis. Pseudoaneurysms can be caused by 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. Treatment of physical trauma is described here and in First aid. In Surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin rather than by using an "open" Like true aneurysms they may be felt as an abnormal pulsatile mass on palpation. Palpation used as part of a Physical examination in which an object is felt (usually with the hands of a Healthcare practitioner to determine its size shape firmness

Location

Most non-intracranial aneurysms (94%) arise distal to the origin of the renal arteries at the infrarenal abdominal aorta, a condition mostly caused by atherosclerosis. The kidneys are complicated organs that have numerous biological roles The abdominal aorta is the largest Artery in the Abdominal cavity. Atherosclerosis is a Disease affecting arterial Blood vessels It is a chronic inflammatory response in the walls of arteries in large part due to the accumulation The thoracic aorta can also be involved. The thoracic aorta is contained in the Posterior mediastinal cavity One common form of thoracic aortic aneurysm involves widening of the proximal aorta and the aortic root, which leads to aortic insufficiency. 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). In the Circulatory system, a vein is a Blood vessel that carries Blood back toward the Heart (as opposed to Artery, a blood vessel

• 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). In Human anatomy, the anterior communicating artery is a Blood vessel of the Brain that connects the left and right anterior cerebral arteries The circle of Willis (also called the cerebral arterial circle or arterial circle of Willis) is a circle of arteries that supply blood to the Brain Polycystic kidney disease ( PKD, also known as polycystic kidney syndrome is a progressive ciliopathic, Genetic disorder of the Kidneys
• 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. Syphilis is a Sexually transmitted disease caused by the spirochetal Bacterium Treponema pallidum pallidum. The vasa vasorum is a network of small Arterioles capillaries and Venules that supply the outer tissues of large Blood vessels like the Aorta The tunica externa, also known as the tunica adventitia, is the outermost layer of a Blood vessel, surrounding the Tunica media.

Risks

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.

Blood clots from popliteal arterial aneurysms can travel downstream and suffocate tissue. A thrombus, or blood clot, is the final product of the Blood coagulation step in Hemostasis. 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). Pulmonary embolism (PE is a blockage of the Pulmonary artery or one of its branches usually occurring when a venous Thrombus (blood clot from a vein Risk factors for an aneurysm are diabetes, obesity, hypertension, tobacco smoking, alcoholism, and Copper deficiency. Diabetes mellitus (ˌdaɪəˈbiːtiːz or /ˌdaɪəˈbiːtəs/ /məˈlaɪtəs/ or /ˈmɛlətəs/ often referred to simply as diabetes ( Ancient Greek: grc Obesity is a condition in which excess Body fat has accumulated to such an extent that health may be negatively affected Hypertension, also referred to as high blood pressure, HTN or HPN, is a medical condition in which the Blood pressure is chronically elevated Tobacco Smoking is the inhalation of smoke from burned dried or cured leaves of the Tobacco plant most often in the form of a Cigarette. Alcoholism is a term with multiple and sometimes conflicting definitions Copper deficiency can cause a Syndrome of Anemia or Pancytopenia and a neurodegeneration in humans or other mammals

A minority of Aneurysms are caused by a copper deficiency. Numerous animal experiments have shown that a copper deficiency can cause diseases affected by elastin ^[1] tissue strength [Harris]. Elastin is a Protein in Connective tissue that is elastic and allows many tissues in the body to resume their shape after stretching or contracting The lysyl oxidase that cross links connective tissue is secreted normally, but its activity is reduced ^[2], due, no doubt, to some of the initial enzyme molecules (apo-enzyme or enzyme without the copper) failing to contain copper ^{[3] [4]}. Lysyl oxidase, also known as LOX, is a human Gene. Aneurysms of the aorta are the chief cause of death of copper deficient chickens, and also depleting copper produces aneurysms in turkeys ^[5]. Men who die of aneurysms have a liver content which can be as little as 26% of normal ^[6]. The median layer of the blood vessel (where the elastin is) is thinner but its elastin copper content is the same as normal men. The overall thickness is not different ^[7]. The body must therefore have some way of preventing elastin tissue from growing if there is not enough activated lysyl oxidase for it. Men are more susceptible to aneurysms than young women, probably because estrogen increases the efficiency of absorption of copper. Estrogens (US otherwise oestrogens or œstrogens) are a group of Steroid compounds named for their importance in the Estrous cycle, However, women can be affected by some of these problems after pregnancy, probably because women must give the liver of their babies large copper stores in order for them to survive the low milk copper. A baby’s liver has up to ten times as much copper as adult livers ^[8]. Elastin is about as flexible as a rubber band and can stretch to two times its length ^[9]. Collagen is about 1000 times stiffer. Collagen is the main Protein of Connective tissue in Animals and the most abundant protein in Mammals making up about 50% of the whole-body protein A healthy artery requires about 1000 mm of mercury or 10 times the normal mean blood pressure in order to rupture ^[10]. Therefore keeping strength of arteries up would seem to be even more important than keeping blood pressure down.

Formation

Most frequent site of occurrence is in the anterior cerebral artery from the circle of Willis. 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.

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.

Aneurysm formation is probably the result of multiple factors affecting that arterial segment and its local environment.

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. 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. In Medicine, ischemia ( Greek ισχαιμία, isch- is restriction hema or haema is Blood) is a restriction 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.

Treatment

Historically, the treatment of arterial aneurysms has been surgical intervention, or watchful waiting in combination with control of blood pressure. Blood pressure is also the title of a short story by Damon Runyan in Guys and Dolls and Other Stories Recently, endovascular or minimally invasive techniques have been developed for many types of aneurysms.

Treatment of aneurysms

Currently there are two treatment options for brain aneurysms: surgical clipping or endovascular coiling. A cerebral aneurysm or brain aneurysm is a cerebrovascular disorder in which weakness in the wall of a cerebral Artery or Vein Surgical clipping was introduced by Walter Dandy of the Johns Hopkins Hospital in 1937. Walter Edward Dandy ( April 6, 1886 -- April 19, 1946) was an American Neurosurgeon and scientist Johns Hopkins University|Johns Hopkins University School of Medicine|Greenspring StationThe Johns Hopkins Hospital is a Teaching hospital in Baltimore Maryland 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").

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)

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 variability internationally in the use of surgical clipping versus endovascular coiling.

Treatment of aortic and peripheral aneurysms

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 that is sutured at vascular stumps. Instead of sewing, the graft tube ends, made rigid and expandable by nitinol wireframe, can be much more simply and quickly inserted into the vascular stumps and there permanently fixed by external ligature[1] ^[11]. Less invasive endovascular techniques allow covered metallic stent grafts to be inserted through the arteries of the leg and deployed across the aneurysm. Abdominal aortic aneurysm

See also

• Aortic aneurysm
• Aortic dissection
• Cerebral aneurysm
• Charcot-Bouchard aneurysms
• Rasmussen aneurysm
• Aneurysm of sinus of Valsalva

References

External links

• Diagram showing what an aneurysm looks like
• Addressing the Challenges Faced as a Result of Brain Haemorrhage
• Brain Blood Vessel Disorder Help & Info Site
• @neurIST - Integrated Biomedical Informatics for the Management of Cerebral Aneurysms
• Story of Aneurysm Survival

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