Arteriovenous fistula is a condition where blood skips the capillary and goes directly to the vein. It can be congenital or acquired, and symptoms vary depending on the location and size of the fistula. Diagnosis is done through physical exams and imaging tests, and treatment depends on the severity of the condition.
Arteriovenous (AV) fistula is a potentially serious condition characterized by abnormal formation of arteries and veins. Treatment for this condition depends on the location and size of the fistula. Complications associated with AV fistula formation include blood clots and heart failure.
Within the circulatory system, blood flows through a set path consisting of arteries, capillaries, and veins. Sequentially, the blood begins its journey in the artery and passes through a capillary before reaching the intended vein. In the presence of an arteriovenous fistula, an individual’s blood skips the passage through the capillary and goes directly to the vein. These small vessels normally serve to supply the body’s tissues with oxygenated blood; thus, when capillaries are deprived of blood and nutrients, so are their related tissues.
Arteriovenous fistula is a condition that can be congenital, meaning it is present at birth or it can be acquired. When an AV fistula is diagnosed as a congenital condition, it is usually most pronounced within the lungs and results from the presence of a secondary condition, such as Rendu-Osler-Weber disease (ROWD). Individuals who have had surgical procedures, such as a cardiac catheterization, may develop an AV fistula as a complication. The occurrence of deep puncture wounds, such as those sustained by a gunshot wound, can also contribute to the formation of AV fistulas. An arteriovenous fistula can also be created artificially for therapeutic purposes, as is sometimes necessary with dialysis.
Individuals who develop an AV fistula in their limbs often remain asymptomatic, meaning they do not experience any symptoms. Asymptomatic individuals generally require no treatment and have no further complications. Those who develop more prominent fistulas that are larger in size tend to experience varied and persistent signs and symptoms.
Often, if the fistula is in one’s limbs, she or he may develop swelling in the affected appendix. The skin in the affected area may also take on a ruddy hue or show veiny swelling. When an AV fistula develops in the lungs, the symptoms manifest differently and can lead to life-threatening complications.
Individuals with a pulmonary arteriovenous fistula may experience shortness of breath, frequent nosebleeds, and occasionally may cough up blood. Due to the oxygen deprivation that often occurs with this form of fistula, an individual may develop cyanosis, which is a bluish tint to the skin. Additionally, individuals with a pulmonary arteriovenous fistula may also be at increased risk for heart valve infections, such as mitral valve stenosis.
There are several diagnostic tests that can be done to diagnose an arteriovenous fistula. During a physical exam, a doctor will listen to the individual’s heart to determine if there are any abnormalities, such as a ringing sound that often occurs with an arteriovenous fistula. If a ringing or other abnormality is found, the individual is usually referred for further testing. Imaging tests, such as computed tomography (CT) angiography and Doppler ultrasound, may be done to evaluate blood flow through the individual’s arteries and confirm the presence of an arteriovenous fistula.
For many individuals with an AV fistula, treatment is to monitor their condition for any changes. Those whose AV fistula is large may undergo a procedure known as catheter embolization, which involves inserting a stent, made of synthetic material, to bypass blood flow around the fistula. Arteriovenous fistulas that cannot be treated with stent placement may require additional corrective and surgical measures. The surgical approach depends entirely on the location and size of the fistula and the overall health of the individual.
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