The aneurysm (of ancient Greek ἀνεύρυσμα aneurysm / aneǔ̯rysma / , expansion, enlargement '; plurality aneurysms or aneurysms ), also aneurysm or colloquially arterial aneurysm called, is an extension of spindle or bag-shaped, localized permanent the cross-section of arteries (often of veins ) as a result of congenital or acquired wall changes. This distinguishes the aneurysm from ectasia , a permanent expansion of blood vessels (and hollow organs ), which has developed despite the intactness of all the wall layers involved.
A distinction is made between the real aneurysm ( aneurysm verum ), the false aneurysm ( aneurysm spurium = A. falsum ) and the dissecting aneurysm ( aneurysm dissecans ) as a result of a vascular wall dissection . An unspecified aneurysm usually means a verum aneurysm .
In a verum aneurysm , the entire vascular wall with all layers ( intima , media and adventitia ) is enlarged, mostly as a result of arteriosclerosis . Men over the age of 50 are predominantly affected, especially hypertensive patients and patients with peripheral arterial occlusive disease . A tear in the vessel wall, which can occur here due to the weakening of the vessel associated with the expansion ( rupture ), can be life-threatening, depending on the location of the vessel.
Spurium / falsum aneurysm
In the case of a spurium aneurysm (= aneurysm falsum , also pseudoaneurysm ), a tear, the formation of which is usually due to a blunt or sharp injury (like a Seldinger puncture ), runs through the intima and the media , the adventitia remains according to the textbook definition, whereby in in pathological practice the hematoma often crosses the adventitia. A bruise (pulsating hematoma ) develops around this vascular wall leak . The tissue surrounding the vascular wall defect, such as the pleura or peritoneum , can limit the extent of the bruise and thus delay the bleeding death - often only briefly - if large vessels are damaged . If the tamponade remains stable for longer, the pulsating hematoma will be surrounded by a connective tissue capsule within four to six weeks . Since this aneurysmatoid structure originated outside the vessel wall, it is called a false aneurysm ( aneurysm spurium or falsum ). However , there is still a risk of rupture .
The term aneurysm dissecans is misleading in that the present dissection is not an immediate consequence of an aneurysm. Rather, a dissection - be it of the aorta or any artery in general - is the result of an injury to the intima of the vessel wall. If the dissection is not treated or only treated conservatively, in many cases the chronic weakening of the wall results in a secondary expansion of the vascular caliber in the sense of an aneurysm. In these cases, the aneurysm is not the cause but the consequence of the dissection. However, in various textbooks, the term aneurysm dissecans is used for a dissection. This may be due to the fact that autopsy findings of untreated dissections often already show an aneurysmatic dilatation of the vessel and its temporal course could not be differentiated - before the development of computed tomography - at the time this term was formed.
When a vessel is dissected , the blood enters via a so-called entry , penetrates into the vessel wall and divides it ( dissects ) it. This creates a false or pseudo- lumen and a second, artificially created bloodstream. Since the flow is limited via the entry and possible reentries, there is an increase in pressure in the wrong lumen compared to the mean vascular pressure in the real lumen, which leads to a compression of the real lumen. In the case of the aorta, treatment of a dissection therefore aims to close the primary entry in order to lower the pressure in the false lumen in favor of the true lumen and thus improve the perfusion of the internal organs and the lower extremity.
Degenerative vascular wall diseases ( atherosclerosis in over 80% of cases ) are the most important cause . Much less common causes are trauma , infections ( rheumatic fever , syphilis , Lyme borreliosis ), inflammation and congenital weaknesses in connective tissue ( Marfan syndrome , Ehlers-Danlos syndrome ). In around five to seven percent of aneurysm carriers, these occur multiple times in different body locations ( aneurysmatic disease ). Aneurysms of the aorta affecting not only adults, but can as a result of Marfan syndrome or as late effects of volume overload of the aorta in congenital heart defects with right-left shunt or shuntabhängigen perfusion of the lungs to be clinically significant. Furthermore, aneurysms in the coronary arteries can occur after an illness with Kawasaki syndrome . A study published in 2010 also documents a significantly increased risk of brain aneurysms in patients with aorta bicuspid, a relatively common congenital malformation of the aortic valve. In Hughes-Stovin syndrome , it is believed that infected emboli cause aneurysms of the pulmonary vessels. It is known that headbanging increases the number of cases with arterial dilation of the vertebral artery .
Pathogenesis and course
The explosiveness of central aneurysms (such as the infrarenal abdominal aortic aneurysm) lies in their potentially fatal risk of rupture (i.e. risk of rupture ). This increases with the increasing transverse diameter of the aneurysm because, according to the Young-Laplace equation , the elastic restoring forces of the vessel wall are inversely proportional to the radius. The forces therefore decrease as the radius increases.
Aneurysms of the peripheral vessels threaten the limbs mainly through thromboembolic vascular occlusion . As a rule, aneurysms are partially filled with thrombus masses, which are often located at the edge. In the case of an aneurysm in the hollow of the knee, for example, these thrombus masses can be massaged into the peripheral circulation using appropriate movements. This leads to peripheral, sometimes irreversible, vascular occlusions with corresponding consequences.
Symptoms and Findings
Most of the abdominal aortic and pelvic aneurysm carriers are asymptomatic. The diagnosis is usually made by chance as part of a routine examination or an abdominal examination. With ultrasound , the diagnosis of abdominal or pelvic artery examinations can be made with great accuracy. If these aneurysms become symptomatic, back pain or diffuse abdominal pain occurs. They are typical of the expanding aneurysm with bleeding into the wall. The intra-abdominal aneurysms can rupture freely into the abdominal cavity, resulting in the formation of a large intraperitoneal hematoma ( hemascosis ) and often the patient bleeding to death . However, the retroperitoneum (the vessels are located in the retroperitoneal space ) can often hold back this bleeding. The patient presents with severe flank pain and symptoms of shock ( differential diagnosis : renal colic , pancreatitis ). In the case of peripheral aneurysms, the focus is not on the rupture, but on the thrombotic closure of the aneurysm or the embolic closure of the distal vessels. The symptoms are often acute. Distal embolisms can also be chronic and oligosymptomatic for a long time (the patient notices little or nothing).
With cerebral aneurysms (located in the brain) (so-called brain aneurysms ), the pressure that an aneurysm exerts on a nerve can lead to paralysis in the face. If such an aneurysm ruptures, a stroke or subarachnoid hemorrhage (cerebral hemorrhage) is the result.
- Peripheral aneurysms are often easily identified by inspection (viewing) and palpation (palpation).
- In slim patients, the abdominal aortic aneurysm can be palpated (palpated) as an expansively pulsating tumor in the middle abdomen during the examination. In obese (obese) people, this is however rarely possible.
- The ultrasound allows a non-invasive and inexpensive aneurysm diagnosis. It works well as a screening method for asymptomatic people.
- The computed tomography are morphologically precise and geometrically reproducible measurements of the aneurysm. The type of thrombosis , the nature of the wall and the relation of the aneurysm to the neighboring organs can also be represented graphically.
- The angiography serves not only the aneurysm detection, but is approximately used for the detection of occlusive diseases in the peripheral or central vessels such as the renal arteries concomitantly.
Endovascularly, surgically (for details, see the section "Special aneurysms" below) or by changing your diet
An aneurysm of the main artery ( aorta ) is called an aortic aneurysm . One differentiates between aneurysms of the aorta at the level of the chest and abdominal variants. If the aneurysm is advanced, there is a risk of rupture with a high mortality rate.
An abdominal aortic aneurysm (BAA) or abdominal aortic aneurysm (AAA) is an anterioposterior diameter of the abdominal aorta below the exit of the renal arteries to over 30 mm. Clinically, a distinction is made between asymptomatic, symptomatic and ruptured aneurysms. An asymptomatic (pain-free) aneurysm is an incidental finding. In the symptomatic aneurysm, the symptoms and in the ruptured the circulatory situation are in the foreground.
The need for surgical treatment of a thoracic aortic aneurysm (TAA) depends on the increase in normal diameter of over 50%, especially in children. The critical size in adults is reached at a diameter of 50 to 55 mm. Various surgical procedures are available for this.
When aortic dissection refers to a splitting of the layers of the wall of the aorta.
Cerebral aneurysms occur on cerebral arteries. The normalized disease incidence ( prevalence ) is three percent. Cerebral aneurysms are more common in people over 40 years of age. Women are affected more often than men in a ratio of 5: 3.
The main danger of a cerebral aneurysm is rupture, i.e. bursting, which results in an unhindered escape of blood into the brain space. Such a subarachnoid hemorrhage causes a stroke ( apoplexy ) and is fatal in 50% of cases. 46% of the survivors are permanently restricted in their quality of life due to neurological failures or neuropsychological deficits.
The cause of cerebral aneurysms is unclear. Exogenous factors that favor its development are smoking and excessive alcohol consumption.
The three most important therapies for the treatment of cerebral aneurysms, which are used depending on their location, shape and size, are briefly explained below.
- In conservative therapy , no intervention is made; instead, the aneurysm is observed through regular monitoring using imaging tests (usually angiographies). This is an option especially for small, non-symptomatic aneurysms due to the low risk of rupture.
- In endovascular therapy , so-called coils (spirals made of a platinum alloy) are brought into the aneurysm sac by means of a hollow micro -catheter via the inguinal artery . These coils only fill the aneurysm to about 10% to 30%, but cause thrombus formation and thus prevent further blood circulation in the aneurysm and thus a rupture. One advantage of the procedure is that no open brain surgery has to be performed.
- In neurosurgical therapy , the aneurysm is treated with a craniotomy (open brain surgery). The aneurysm sac is clamped off with a clip. Thus the aneurysm is excluded from the bloodstream. Alternatively, stents can also be used to strengthen the arterial wall or to change the flow properties and thus promote thrombosis.
Inferior vena cava aneurysm
As of 2019, 55 cases of aneurysm of the inferior vena cava had been described.
The oldest written description of aneurysms can be found in the Ebers papyrus from ancient Egypt . The first precise anatomical descriptions come from the autopsy studies of Andreas Vesalius and William Harvey in the 16th and 17th centuries. Antonio Scarpa was the first to distinguish between real and false aneurysms in 1804 . In ancient times it was recommended to treat aneurysms by compression (according to Galenus the contents would flow back into the normal arterial vascular system). Around the 3rd century AD, the Greek doctor Antyllos described a method of operating the aneurysms by extirpation , whereby the artery is tied above and below the aneurysm and the sac is then removed by incision. In the 18th century, the British surgeon John Hunter advocated ligating the affected vessel upstream of the aneurysm. In the 1950s, aneurysms were still surgically wrapped to prevent the life-threatening bleeding. In the 20th century, stents and prostheses finally became established as a treatment method. The American surgeon William Wayne Babcock (1872–1963) also developed special techniques for the operation of aortic aneurysms and thoracic aneurysms.
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