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  • Abscess: An infected, inflamed area in the body where pus collects.
  • Amblyopia:  Poor vision due to non-use of an eye caused by underdevelopment of the visual pathway to the brain.
  • Aneurysm: A weakened dilated blood vessel that is prone to rupture (hemorrhage).
  • Angiogenesis: Development of blood vessels.
  • Angiogram: A test/procedure used to examine blood vessels of an organ such as the brain or lung. A small tube(catheter) is inserted into a vein or artery. A dye is then injected which highlights all the blood vessels and high-speed x-ray pictures are taken.
  • Angioid Streaks:  Lines resembling blood vessels.
  • Angioma: Any malformation made up of blood vessels. These could be veins or a combination of arteries and veins (arteriovenous malformations or AVMs).
  • Anticonvulsant: Any medication that counteracts seizures.
  • Arterial Blood Gases (ABG): As part of the testing for PAVMs, blood is taken from an artery in the wrist to measure the oxygen level.
  • Arteriogram: See angiogram
  • Arteriovenous Malformation: An abnormal, direct connection (like a short circuit)between an artery and a vein.
  • Asymptomatic: Having no obvious symptoms.
  • Autosomal Dominant: A genetic term describing a disorder that affects men and women equally and has a 50% chance to be passed to each of ones offspring.
  • AVM: See arteriovenous malformation.