Arteriovenous fistula - Misplaced Pages

Abnormal passageway between a vein and artery This article is about AV fistulas in general. For the surgical procedure, see Cimino fistula. "Arteriovenous shunt" redirects here. For nonpathologic AV shunts, see metarteriole and glomus body. Medical condition

Arteriovenous fistula

Illustration of an arteriovenous fistula
Specialty	Cardiology

An arteriovenous fistula is an abnormal connection or passageway between an artery and a vein. It may be congenital, surgically created for hemodialysis treatments, or acquired due to pathologic process, such as trauma or erosion of an arterial aneurysm.

Clinical features

Pathological

Hereditary hemorrhagic telangiectasia is a condition where there is direct connection between arterioles and venules without intervening capillary beds, at the mucocutaneous region and internal bodily organs. Those who are affected by this conditions usually do not experience any symptoms. Difficulty in breathing is the most common symptom for those who experience symptoms.

Just like berry aneurysm, a cerebral arteriovenous malformation can rupture causing subarachnoid hemorrhage.

Causes

The cause of this condition include

Congenital (developmental defect)
Rupture of arterial aneurysm into an adjacent vein
Penetrating injuries
Inflammatory necrosis of adjacent vessels
Complication of catheter insertion rarely causes arteriovenous fistula. It is usually caused by brachial artery puncture because brachial artery is located between two brachial veins.

Surgically created Cimino fistula is used as a vascular access for hemodialysis. Blood must be aspirated from the body of the patient, and since arteries are not easy to reach compared to the veins, blood may be aspirated from veins. The problem is that the walls of the veins are thin compared to those of the arteries. The AV fistula is the solution for this problem because, after 4–6 weeks, the walls of the veins become thicker due to the high arterial pressure. Thus, this vein can now tolerate needles during hemodialysis sessions.

Mechanism

When an arteriovenous fistula is formed involving a major artery like the abdominal aorta, it can lead to a large decrease in peripheral resistance. This lowered peripheral resistance causes the heart to increase cardiac output to maintain proper blood flow to all tissues. The physical manifestations of this typically consist of a relatively normal systolic blood pressure accompanied by decreased diastolic blood pressure, resulting in a wider pulse pressure.

Normal blood flow in the brachial artery is 85 to 110 milliliters per minute (mL/min). After the creation of a fistula, the blood flow increases to 400–500 mL/min immediately, and 700–1,000 mL/min within 1 month. A brachiocephalic fistula above the elbow has a greater flow rate than a radiocephalic fistula at the wrist. Both the artery and the vein dilate and elongate in response to the greater blood flow and shear stress, but the vein dilates more and becomes "arterialized". In one study, the cephalic vein increased from 2.3 mm to 6.3 mm diameter after 2 months. When the vein is large enough to allow cannulation, the fistula is defined as "mature".

An arteriovenous fistula can increase preload. AV shunts also decrease the afterload of the heart. This is because the blood bypasses the arterioles which results in a decrease in the total peripheral resistance (TPR). AV shunts increase both the rate and volume of blood returning to the heart.

Diagnosis

The diagnosis of this condition can be done via ultrasound

References

"Arteriovenous Fistulas: Background, Pathophysiology, Etiology". 2017-01-07.
"Arteriovenous fistula - Symptoms and causes". Mayo Clinic. Retrieved 2019-12-05.
Meier NM, Foster ML, Battaile JT (June 2018). "Hereditary hemorrhagic telangiectasia and pulmonary arteriovenous malformations: clinical aspects". Cardiovascular Diagnosis and Therapy. 8 (3): 316–324. doi:10.21037/cdt.2017.12.07. PMC 6039799. PMID 30057878.
Park, Myung K. (2002). Pediatric cardiology for practitioners. With a contribution by R. George Troxler (4th ed.). St. Louis: Mosby. ISBN 978-0-323-01444-1.
^ Kumar, Vinay; Abbas, Abul K.; Aster, Jon C.; Turner, Jerrold R.; Perkins, James A.; Robbins, Stanley L.; Cotran, Ramzi S., eds. (2021). Robbins & Cotran pathologic basis of disease (10th ed.). Philadelphia, PA: Elsevier. p. 487. ISBN 978-0-323-53113-9.
Watson N, Jones H (2018). Chapman and Nakielny's Guide to Radiological Procedures. Elsevier. p. 228. ISBN 9780702071669.
Vascular, Vol. 14, Supl. 1, Nov. 2006, p. S1
"Pulmonary: Heart Failure". Archived from the original on 1 February 2009. Retrieved 2008-12-21.

External links

Media related to Arteriovenous fistula at Wikimedia Commons

Classification	D ICD-10: I28.0, I77.0 ICD-9-CM: 414.19, 417.0, 447.0, 747.3 MeSH: D001164 DiseasesDB: 32435 SNOMED CT: 439470001
External resources	eMedicine: med/169

Vascular anomalies

Vascular tumors

Benign	Infantile hemangioma / Hemangioma of infancy Congenital hemangioma Tufted angioma Spindle-cell hemangioma Epithelioid hemangioma Pyogenic granuloma
Locally aggressive or borderline	Kaposiform hemangioendothelioma
Malignant	Angiosarcoma Epithelioid hemangioendothelioma

Vascular malformations

Simple

Capillary malformations	Nevus simplex Cutaneous and/or mucosal CM ("port-wine" stain) Reticulate CM
Lymphatic malformations (LM) Incorrect name: Lymphangioma	Common (cystic) LM Macrocystic LM Microcystic LM Mixed cystic LM Generalized lymphatic anomaly Kaposiform lymphangiomatosis LM in Gorham-Stout disease Channel type LM “Acquired” progressive lymphatic anomaly Primary lymphedema Nonne-Milroy syndrome
Venous malformations	Common VM Familial VM cutaneo-mucosal Blue rubber bleb nevus syndrome Glomuvenous malformation Cerebral cavernous malformation Familial intraosseous vascular malformation Verrucous venous malformation
Arteriovenous malformations	Sporadic In HHT In CM-AVM
Arteriovenous fistula	Sporadic In HHT In CM-AVM

Combined

Lymphatic-venous malformation
Capillary-arteriovenous malformation

Associated with other anomalies

Klippel-Trenaunay syndrome
Parkes Weber Syndrome
Servelle-Martorell syndrome
Sturge-Weber syndrome
Limb CM + congenital non-progressive limb overgrowth
Maffucci syndrome
Macrocephaly - CM (M-CM / MCAP)
Microcephaly - CM (MICCAP)
CLOVES syndrome
Proteus syndrome
Bannayan-Riley-Ruvalcaba syndrome
CLAPO syndrome

Cardiovascular disease (vessels)

Arteries, arterioles
and capillaries

Inflammation	Arteritis Aortitis Buerger's disease
Arteriosclerosis	Atherosclerosis Foam cell Fatty streak Atheroma Cholesterol LDL Oxycholesterol Trans fat Monckeberg's arteriosclerosis Hyaline arteriolosclerosis Hyperplastic arteriolosclerosis
Peripheral artery disease	Stenosis Carotid artery stenosis Renal artery stenosis Aortoiliac occlusive disease Critical limb ischemia Degos disease Erythromelalgia Fibromuscular dysplasia Hepatic artery thrombosis Intermittent claudication Raynaud's phenomenon
Aneurysm / dissection / pseudoaneurysm	torso: Aortic aneurysm Abdominal aortic aneurysm Thoracic aortic aneurysm Aneurysm of sinus of Valsalva Aortic dissection Aortic rupture Coronary artery aneurysm head / neck Intracranial aneurysm Intracranial berry aneurysm Carotid artery dissection Vertebral artery dissection Familial aortic dissection
Vascular malformation	Arteriovenous fistula Arteriovenous malformation Telangiectasia Hereditary hemorrhagic telangiectasia Generalized essential telangiectasia
Vascular nevus	Cherry hemangioma Halo nevus Spider angioma

Veins

Inflammation	Phlebitis
Venous thrombosis / Thrombophlebitis	primarily lower limb Deep vein thrombosis abdomen Hepatic veno-occlusive disease Budd–Chiari syndrome May–Thurner syndrome Portal vein thrombosis Renal vein thrombosis upper limb / torso Mondor's disease Paget–Schroetter disease Pulmonary embolism head Cerebral venous sinus thrombosis Post-thrombotic syndrome
Varicose veins	Gastric varices Portacaval anastomosis Caput medusae Esophageal varices Hemorrhoid Varicocele
Other	Chronic venous insufficiency Chronic cerebrospinal venous insufficiency Superior vena cava syndrome Inferior vena cava syndrome Venous ulcer

Arteries or veins

Blood pressure

Hypertension	Hypertensive heart disease Hypertensive emergency Hypertensive nephropathy Essential hypertension Secondary hypertension Renovascular hypertension Benign hypertension Pulmonary hypertension Systolic hypertension White coat hypertension
Hypotension	Orthostatic hypotension Shock (circulatory)

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