Arteriovenous Fistula: Symptoms, Types, Causes and Treatment

Arteriovenous fistulas (AVFs) are abnormal connections between an artery and a vein, bypassing the capillary system. While some AVFs are created surgically for medical purposes such as hemodialysis, many occur spontaneously or as a result of trauma or disease. Understanding the symptoms, types, causes, and treatment options for AVFs is crucial for early diagnosis and effective management. In this comprehensive guide, we will explore the clinical features, variants, underlying mechanisms, and current management strategies for arteriovenous fistulas, drawing on a wide range of clinical and scientific evidence.

Symptoms of Arteriovenous Fistula

Recognizing the symptoms of an arteriovenous fistula can be challenging, given that they vary significantly depending on the location and size of the fistula. AVFs can be asymptomatic, discovered incidentally, or present with a broad spectrum of clinical features, ranging from minor discomfort to life-threatening events. Early recognition allows for prompt intervention and better outcomes.

Symptom	Description	Location/Type Example	Source(s)
Pulsatile mass	Detectable swelling with a pulse	Peripheral, hemodialysis AVF	10 16
Murmur/Bruit	Vascular sound over fistula site	Pulmonary, peripheral, cranial AVF	1 4 7
Cyanosis	Bluish skin/mucous membranes	Pulmonary AVF	1 4
Neurologic deficits	Weakness, sensory loss, seizures	Brain, spinal, craniocervical AVF	2 3 6 9
Heart failure	Shortness of breath, edema	Large AVFs, mesenteric AVF	5 19
Hemorrhage	Bleeding, hemoptysis, brain hemorrhage	Pulmonary, cerebral, spinal AVF	1 2 4 9
Clubbing	Enlargement of fingers or toes	Pulmonary AVF	1 4
Polycythemia	Increased red blood cell count	Pulmonary AVF	1 4
Abdominal pain	Discomfort, GI bleeding	Mesenteric or renal AVF	5 19
Sphincter disturbances	Urinary or fecal incontinence	Spinal AVF	3 6 8
Asymptomatic	No obvious clinical manifestations	Any AVF, incidentally found	4 5 11

Table 1: Key Symptoms

Symptom Profiles Across AVF Types

General Symptoms and Physical Findings

• Pulsatile mass and murmur/bruit are classic signs of peripheral AVFs or those accessible to physical examination. The turbulent blood flow generates an audible sound and palpable vibration. In hemodialysis AVFs, these findings are part of routine monitoring for patency 10 16.
• Cyanosis and clubbing are often associated with pulmonary AVFs, reflecting chronic hypoxemia due to right-to-left shunting of unoxygenated blood 1 4.
• Polycythemia may develop in response to hypoxemia, as the body attempts to compensate by increasing red blood cell production 1 4.

Neurological and Systemic Presentations

• Neurological deficits such as headaches, seizures, sensory or motor disturbances are prominent in cerebral, spinal, and craniocervical AVFs. These symptoms arise from venous hypertension, ischemia, or hemorrhage 2 3 6 9.
• Sphincter disturbances and gait abnormalities are characteristic of spinal AVFs, reflecting progressive myelopathy resulting from venous congestion in the spinal cord 3 6 8.
• Heart failure can result from large, high-flow AVFs, particularly those in the mesenteric or renal circulation, due to increased venous return and cardiac workload 5 19.
• Hemorrhage may present as hemoptysis in pulmonary AVFs, or as subarachnoid/intracerebral bleeding in intracranial AVFs 1 2 4 9.

Non-Specific and Incidental Presentations

• Some AVFs, especially small or deep-seated ones, may be entirely asymptomatic and discovered only during imaging for unrelated conditions 4 5 11.

Types of Arteriovenous Fistula

AVFs are a heterogeneous group, classified by their anatomical location, etiology, and specific angioarchitectural features. Understanding the main types is essential for accurate diagnosis and appropriate treatment planning.

Type	Location/Description	Key Features/Examples	Source(s)
Peripheral	Arm/leg vessels, often for hemodialysis	Surgically created, palpable	10 11 12 16
Pulmonary	Between pulmonary artery and vein	Cyanosis, clubbing, polycythemia	1 4
Cerebral	Brain arteries/veins, incl. dural AVFs	Headache, seizures, hemorrhage	2 7 15 17 18
Spinal	Spinal cord vessels (dural, intramedullary, etc.)	Motor/sensory deficits, myelopathy	2 3 6 8 9
Craniocervical	At craniocervical junction (C1-C2 roots)	Hemorrhage, complex angioarchitecture	9
Mesenteric	GI tract arteries/veins (e.g., inferior mesenteric)	Abdominal pain, GI bleeding	5
Renal	Kidney arteries/veins	Hematuria, hypertension	19
Hypoglossal canal	Dural AVF in skull base	Pulsatile tinnitus, ocular symptoms	7

Table 2: Main Types of Arteriovenous Fistula

Classification and Characteristics

Peripheral (Surgically Created) AVFs

• Purpose-built AVFs for hemodialysis are most often found in the forearm or upper arm. They are created by surgically connecting an artery to a vein, providing high blood flow for dialysis. Complications include stenosis, thrombosis, and in rare cases, heart failure with large flows 10 11 12 16.

Pulmonary AVFs

• These are abnormal connections between the pulmonary artery and vein, allowing deoxygenated blood to enter systemic circulation. Most are associated with hereditary hemorrhagic telangiectasia. Multiple lesions may occur, leading to a spectrum of symptoms from asymptomatic to severe hypoxemia and neurological complications 1 4.

Cerebral and Intracranial Dural AVFs

• Occur within the brain, either as direct shunts between cortical arteries and veins or as dural AVFs involving the dura mater. Clinical presentation ranges from seizures and headaches to life-threatening hemorrhages, depending on venous drainage patterns 2 15 17 18.
• Dural AVFs of the hypoglossal canal are a rare subtype, presenting with unique symptoms like pulsatile tinnitus or ocular issues based on venous drainage 7.

Spinal AVFs

• Include dural, intramedullary, epidural, and perimedullary types, classified by the exact location of the shunt. The most common is the spinal dural AVF, usually affecting older men and presenting with progressive myelopathy 2 3 6 8 9.

Craniocervical Junction AVFs

• These are located at the junction of the skull base and upper cervical spine, often exhibiting complex angioarchitecture and frequently presenting with hemorrhage 9.

Mesenteric and Renal AVFs

• Mesenteric AVFs are rare and often secondary to surgery, presenting with abdominal pain, GI bleeding, and sometimes heart failure 5.
• Renal AVFs may be congenital or acquired (e.g., from biopsy or trauma), and present with hematuria or hemodynamic changes 19.

Causes of Arteriovenous Fistula

The development of an AVF can stem from a diverse set of causes. Some are intentionally created for medical management, while others arise spontaneously or from disease or trauma.

Cause	Description	Example/Type	Source(s)
Congenital	Present at birth, usually due to malformations	Pulmonary, cerebral, renal AVF	1 4 19
Hereditary	Genetic syndromes (e.g., HHT)	Pulmonary AVF	1 4
Trauma	Injury to vessels causing abnormal connection	Peripheral, renal AVF	19
Iatrogenic	Resulting from medical/surgical procedures	Hemodialysis AVF, mesenteric AVF	5 10 16
Inflammatory	Vessel wall inflammation, leading to fistula	Hemodialysis AVF	10 14
Neoplastic	Tumor invasion of vessels	Rare, various sites	14
Unknown/Idiopathic	No clear cause identified	Any site	4 5 8

Table 3: Main Causes of Arteriovenous Fistula

How AVFs Develop

Congenital and Hereditary Origins

• Congenital AVFs form due to developmental vascular malformations, often presenting in childhood or early adulthood. These are most common in the pulmonary, cerebral, and renal circulations 1 4 19.
• Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder with a high prevalence of pulmonary AVFs, often associated with telangiectasias elsewhere in the body 1 4.

Acquired Causes

• Trauma: Penetrating or blunt injuries can disrupt adjacent arteries and veins, creating a direct connection 19.
• Iatrogenic: AVFs may result from medical procedures such as vessel catheterization, biopsies (especially renal), or surgical interventions (e.g., intentional creation for hemodialysis, or accidental following bowel surgery) 5 10 16 19.

Pathological and Inflammatory Mechanisms

• Inflammatory processes are implicated in the development and failure of hemodialysis AVFs. Inflammation can lead to vessel wall changes, intimal hyperplasia, and subsequent stenosis or thrombosis 10 14 13.
• Neoplastic invasion: Rarely, tumors can erode into adjacent vessels, causing AVFs 14.

Idiopathic and Other Factors

• In some cases, the cause remains unclear, especially when the AVF is discovered incidentally without a clear precipitating event 4 5 8.
• Hemodynamic and shear stress: Abnormal blood flow dynamics, especially in surgically created AVFs, can promote maladaptive remodeling and stenosis 12 13 14.

Treatment of Arteriovenous Fistula

The approach to treating AVFs is tailored to the type, location, underlying cause, and clinical impact of the fistula. Treatments range from observation to sophisticated surgical and endovascular interventions.

Treatment Option	Indication/Use	Key Considerations	Source(s)
Surgical excision/disconnection	Symptomatic or high-risk AVFs	Pulmonary, spinal, GI, some brain AVFs	1 4 6 8 19
Endovascular embolization	Preferred for many cerebral, spinal, GI AVFs	Less invasive, high cure rates	5 7 15 17 18 19
Balloon angioplasty	Stenosis in hemodialysis AVF	Salvage of failing AVF	16
Observation	Asymptomatic, low-risk AVFs	Select dural/hypoglossal canal AVFs	7 4
Radiosurgery	Select intracranial AVFs	Adjunct or alternative	15 18
Medical management	Supportive care, treat heart failure	Large AVFs, awaiting intervention	5 19

Table 4: Main Treatment Approaches

Comprehensive Management Strategies

Surgical Approaches

• Surgical excision or disconnection is often the treatment of choice for accessible AVFs, particularly in the lung, spinal cord, and gastrointestinal tract. The goal is to remove or disconnect the abnormal shunt while preserving organ function 1 4 6 8 19.
  • In pulmonary AVF, surgery is usually curative and recommended even in asymptomatic cases due to the risk of brain abscess or hemorrhage 4.
  • For spinal AVFs, direct ligation of the fistula results in symptom improvement or stabilization in most patients 6 8.

Endovascular Techniques

• Embolization using coils, liquid agents (e.g., Onyx), or other materials is increasingly the first-line treatment for many cerebral, dural, spinal, mesenteric, and renal AVFs 5 7 15 17 18 19.
  • Transvenous and transarterial approaches are selected based on anatomy and venous drainage patterns 17 18.
  • Embolization is especially effective for intracranial dural AVFs with cortical venous drainage, and for AVFs in locations where surgery would carry high risk 15 18.
  • In mesenteric and renal AVFs, embolization offers a less invasive alternative to surgery, with high efficacy 5 19.

Interventions for Hemodialysis AVFs

• Balloon angioplasty addresses stenotic lesions in failing hemodialysis AVFs, often restoring function and prolonging access patency 16.
• Surgical revision or ligation may be needed for persistent failure or severe complications.

Observation and Conservative Management

• Observation may be appropriate for small, asymptomatic AVFs, especially in locations where spontaneous regression is possible, such as certain hypoglossal canal dural AVFs 7.
• Medical management includes treating heart failure in high-flow AVFs or managing complications while preparing for definitive treatment 5 19.

Radiosurgery and Adjuvant Therapies

• Radiosurgery is used in select cases of intracranial AVFs, especially when conventional surgery or embolization is not feasible 15 18.
• Adjunctive therapies: For complex or recurrent AVFs, combinations of surgical, endovascular, and radiosurgical treatments may be necessary.

Conclusion

Arteriovenous fistulas represent a diverse group of vascular abnormalities with varied clinical implications depending on their location, size, and etiology. Understanding their presentation, types, causes, and management options is crucial for optimizing patient outcomes.

Key Points:

• Symptoms of AVFs range from asymptomatic to severe, including murmurs, cyanosis, neurologic deficits, and heart failure.
• Types span peripheral (hemodialysis), pulmonary, cerebral, spinal, mesenteric, renal, and rare craniocervical and hypoglossal canal variants.
• Causes include congenital malformations, hereditary syndromes, trauma, iatrogenic injury, inflammation, and rarely, neoplasia.
• Treatment is individualized and may involve surgical excision/disconnection, endovascular embolization, angioplasty, observation, radiosurgery, or supportive care.

A multidisciplinary, patient-centered approach, informed by advances in imaging and intervention, continues to improve the outlook for individuals with arteriovenous fistulas. Early recognition and tailored management remain the cornerstones of effective care.