Arteriovenous malformation

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Arteriovenous malformation
Classification and external resources

Micrograph of an arteriovenous malformation in the brain. HPS stain.
ICD-10Q27.3, Q28.0, Q28.2
ICD-9747.6, 747.81
DiseasesDB15235
MedlinePlus000779
eMedicinetopic list
MeSHD001165
 
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Arteriovenous malformation
Classification and external resources

Micrograph of an arteriovenous malformation in the brain. HPS stain.
ICD-10Q27.3, Q28.0, Q28.2
ICD-9747.6, 747.81
DiseasesDB15235
MedlinePlus000779
eMedicinetopic list
MeSHD001165

Arteriovenous malformation or AVM is an abnormal connection between veins and arteries, usually congenital. This pathology is widely known because of its occurrence in the central nervous system, but can appear in any location. An arteriovenous malformation is a vascular anomaly. It is a RASopathy. The Spetzler-Martin grading system developed at the Barrow Neurological Institute is utilized by neurosurgeons to determine operative versus nonoperative management when approaching these lesions.

The genetic transmission patterns of AVM, if any, are unknown. AVM is not generally thought to be an inherited disorder, unless in the context of a specific hereditary syndrome.

Contents

History

Emmanuel, Luschka and Virchow first described arteriovenous malformations in the mid 1800s. Olivecrona performed the first surgical excision of an intracranial AVM in 1932.

Definition

AVMs are lesions of the vasculature that develop such that blood flows directly from the arterial system to the venous system without passing through a capillary system.

Signs and symptoms

Symptoms of AVM vary according to the location of the malformation. Roughly 88%[1] of people affected with AVM are asymptomatic; often the malformation is discovered as part of an autopsy or during treatment of an unrelated disorder (called in medicine "an incidental finding"); in rare cases its expansion or a micro-bleed from an AVM in the brain can cause epilepsy, deficit or pain.

The most general symptoms of a cerebral AVM include headache and epilepsy, with more specific symptoms occurring that normally depend on the location of the malformation and the individual. Such possible symptoms include:[2]

Cerebral AVMs may present in a number of ways

Genetics

Can occur due to autosomal dominant diseases, such as Hereditary Hemorrhagic Telangiectasia.[citation needed]

Pathophysiology

Arteriovenous malformations, also known as AVMs, are deficiencies of the cardiovascular system. In a normal functioning human body, arteries carry oxygen-rich blood away from the heart to the rest of the body, and veins return oxygen-depleted blood to the lungs and heart. An AVM interferes with this cyclical process. Instead of the gradual transition through the capillaries from arteries to veins that is typical of normal functioning vasculature, AVMs cause direct associations of the arteries and veins. AVMs can cause intense pain and lead to serious medical problems. Although AVMs are often associated with the brain and spinal cord, they can develop in any part of the body.

Arteries and veins are part of the human cardiovascular system. Normally, the arteries in the vascular system carry oxygen-rich blood, except in the case of the pulmonary artery. Structurally, arteries divide and sub-divide repeatedly, eventually forming a sponge-like capillary bed. Blood moves through the capillaries, giving up oxygen and taking up waste products, including CO2, from the surrounding cells. Capillaries in turn successively join together to form veins that carry blood away. The heart acts to pump blood through arteries and uptake the venous blood.

An AVM lacks the dampening effect of capillaries on the blood flow; it also causes the surrounding area to be deprived of the functions of the capillaries — removal of CO2 and delivery of nutrients to the cells. The resulting tangle of blood vessels, often called a nidus (Latin for "nest") has no capillaries and abnormally direct connections between high-pressure arteries and low-pressure veins. It can be extremely fragile and prone to bleeding. The resultant sign, audible via stethoscope, is a rhythmic, whooshing sound caused by excessively rapid blood flow through the arteries and veins. It has been given the term "bruit", French for noise. On some occasions a patient with a brain AVM may become aware of the noise, which can compromise hearing and interfere with sleep in addition to causing psychological distress.

Diagnosis

An arterial venous malformation of the left kidney and a simple cyst of the right kidney
An arterial venous malformation of the left kidney leading to aneurysmal dilatation of the left renal vein and inferior vena cava

AVMs can occur in various parts of the body:

AVMs may occur in isolation or as a part of another disease (for example, Von Hippel-Lindau disease or hereditary hemorrhagic telangiectasia).

AVMs have been shown to be associated with Aortic Stenosis.[13]

Bleeding from an AVM can be relatively mild or devastating. It can cause severe and less often fatal strokes. If a cerebral AVM is detected before a stroke occurs, usually the arteries feeding blood into the nidus can be closed off to avert the danger. However, interventional therapy may also be relatively risky


Treatment

Treatment for brain AVMs can be symptomatic, and patients should be followed by a neurologist for any seizures, headaches or focal deficits. AVM-specific treatment may also involve endovascular embolization, neurosurgery or radiation therapy.[2] Embolization, that is, cutting off the blood supply to the AVM with coils or particles or glue introduced by a radiographically guided catheter, can be used in addition to either, but is rarely successful in isolation except for in smaller AVMs. The neurological risk of any such intervention is roughly 10%. For unruptured brain AVMs, the benefit for endovascular, neurosurgical or radiation therapy is as yet unknown. Therefore, the best way to follow an unruptured brain AVM is to join the NIH/NINDS funded international study designed for patients with an unruptured brain AVM.[14]

Epidemiology

The estimated detection rate of AVM in the US general population is 1.4/100,000 per year.[15] This is approximately one fifth to one seventh the incidence of intracranial aneurysms. An estimated 300,000 Americans have AVMs, of whom 12% (approximately 36,000) will exhibit symptoms of greatly varying severity.[2]

Society and culture

Research directions

Despite many years of research, the central question of whether to treat AVMs has not been answered. All treatments, whether involving surgery, radiation, or drugs, have risks and side-effects. Therefore, it might be better in some cases to avoid treatment altogether and simply accept a small risk of coming to harm from the AVM itself. This question is currently being addressed in clinical trials.[22] Interested patients are welcome to contact participating centers worldwide.


See also

References

  1. ^ National Institute of Neurological Disorders and Stroke
  2. ^ a b c Arteriovenous Malformation Information Page at NINDS
  3. ^ Stapf C, Mast H, Sciacca RR, et al. (May 2006). "Predictors of hemorrhage in patients with untreated brain arteriovenous malformation". Neurology 66 (9): 1350–5. doi:10.1212/01.wnl.0000210524.68507.87. PMID 16682666. http://www.neurology.org/cgi/pmidlookup?view=long&pmid=16682666. 
  4. ^ Choi JH, Mast H, Hartmann A, et al. (December 2009). "Clinical and morphological determinants of focal neurological deficits in patients with unruptured brain arteriovenous malformation". J. Neurol. Sci. 287 (1-2): 126–30. doi:10.1016/j.jns.2009.08.011. PMC 2783734. PMID 19729171. http://linkinghub.elsevier.com/retrieve/pii/S0022-510X(09)00762-X. 
  5. ^ Agrawal A, Whitehouse R, Johnson RW, Augustine T (December 2006). "Giant splenic artery aneurysm associated with arteriovenous malformation". J. Vasc. Surg. 44 (6): 1345–9. doi:10.1016/j.jvs.2006.06.049. PMID 17145440. http://linkinghub.elsevier.com/retrieve/pii/S0741-5214(06)01369-3. Retrieved 2008-06-01. 
  6. ^ Chowdhury UK, Kothari SS, Bishnoi AK, Gupta R, Mittal CM, Reddy S (February 2008). "Successful Lobectomy for Pulmonary Arteriovenous Malformation Causing Recurrent Massive Haemoptysis". Heart Lung Circ 18 (2): 135–9. doi:10.1016/j.hlc.2007.11.142. PMID 18294908. http://linkinghub.elsevier.com/retrieve/pii/S1443-9506(07)01113-4. Retrieved 2008-06-01. 
  7. ^ Barley FL, Kessel D, Nicholson T, Robertson I (2006). "Selective embolization of large symptomatic iatrogenic renal transplant arteriovenous fistula". Cardiovasc Intervent Radiol 29 (6): 1084–7. doi:10.1007/s00270-005-0265-z. PMID 16794894. 
  8. ^ Kishi K, Shirai S, Sonomura T, Sato M (March 2005). "Selective conformal radiotherapy for arteriovenous malformation involving the spinal cord". Br J Radiol 78 (927): 252–4. doi:10.1259/bjr/50653404. PMID 15730991. http://bjr.birjournals.org/cgi/pmidlookup?view=long&pmid=15730991. 
  9. ^ Bauer T, Britton P, Lomas D, Wight DG, Friend PJ, Alexander GJ (May 1995). "Liver transplantation for hepatic arteriovenous malformation in hereditary haemorrhagic telangiectasia". J. Hepatol. 22 (5): 586–90. doi:10.1016/0168-8278(95)80455-2. PMID 7650340. http://linkinghub.elsevier.com/retrieve/pii/0168-8278(95)80455-2. Retrieved 2008-06-01. 
  10. ^ Rivera PP, Kole MK, Pelz DM, Gulka IB, McKenzie FN, Lownie SP (November 2006). "Congenital intercostal arteriovenous malformation". AJR Am J Roentgenol 187 (5): W503–6. doi:10.2214/AJR.05.0367. PMID 17056881. http://www.ajronline.org/cgi/pmidlookup?view=long&pmid=17056881. 
  11. ^ Shields JA, Streicher TF, Spirkova JH, Stubna M, Shields CL (March 2006). "Arteriovenous malformation of the iris in 14 cases". Arch. Ophthalmol. 124 (3): 370–5. doi:10.1001/archopht.124.3.370. PMID 16534057. http://archopht.ama-assn.org/cgi/pmidlookup?view=long&pmid=16534057. 
  12. ^ Sountoulides P, Bantis A, Asouhidou I, Aggelonidou H (2007). "Arteriovenous malformation of the spermatic cord as the cause of acute scrotal pain: a case report". J Med Case Reports 1: 110. doi:10.1186/1752-1947-1-110. PMC 2194703. PMID 17939869. http://www.jmedicalcasereports.com/content/1//110. 
  13. ^ Batur, P.; Stewart, WJ; Isaacson, JH (2003). "Increased Prevalence of Aortic Stenosis in Patients with Arteriovenous Malformations of the Gastrointestinal Tract in Heyde Syndrome". Archives of Internal Medicine 163 (15): 1821–4. doi:10.1001/archinte.163.15.1821. PMID 12912718. 
  14. ^ http://www.arubastudy.org
  15. ^ Stapf C, Mast H, Sciacca RR, et al. (May 2003). "The New York Islands AVM Study: design, study progress, and initial results". Stroke 34 (5): e29–33. doi:10.1161/01.STR.0000068784.36838.19. PMID 12690217. http://stroke.ahajournals.org/cgi/pmidlookup?view=long&pmid=12690217. 
  16. ^ "Sen. Johnson recovering after brain surgery". AP. December 14, 2006. http://www.msnbc.msn.com/id/16199440/. 
  17. ^ "Mike Patterson's Collapse Reportedly Related To Brain AVM"
  18. ^ ClinicalTrials.gov NCT00389181 A Randomized Trial of Unruptured Brain AVMs (ARUBA)
  19. ^ "Ricardo Montalban tribute" YouTube, acceptance speech video of Easter Seals Lifetime Achievement Award
  20. ^ Mahalo Answers: Ricardo Montalban
  21. ^ NNDB: Ricardo Montalban
  22. ^ Research trials in arterio-venous malformations; Rustam Al-Shahi Salman


External links