Atrial Fibrillation (A-Fib)

Multiple re-entrant circuits fire simultaneously throughout the atria at rates of 350-600 per minute. The atria quiver instead of contracting effectively. The AV node acts as a gatekeeper, allowing only some impulses through, producing an irregularly irregular ventricular response. Without effective atrial contraction, blood pools in the atria, dramatically increasing the risk of mural thrombi. If a thrombus dislodges, it can embolize to the brain causing stroke — A-fib is responsible for approximately 15-20% of all ischemic strokes.