You are the nurse working in an anticoagulation clinic. One of your patients is K.N., who has a long-standing history of an irregular heartbeat, known as atrial fibrillation or A-fib, for which he takes the oral anticoagulant warfarin (Coumadin)

Question

Recently K.N. had his mitral heart valve replaced with a mechanical valve.

How does atrial fibrillation differ from a normal heart rhythm?

Answer 1

When the heart is beating with a normal rhythm, the atria contract together, pumping blood into the
ventricles, then the ventricles contract, pumping blood into the pulmonary arteries and aorta. With
atrial fibrillation, the atria beat in a disorganized manner, at a rate of 350 to 600 times per minute—
as if they are "quivering." The result is no atrial contractions with an irregular ventricular response;
in fact, the ventricles often beat with a rapid rate in response to the increased number of atrial
impulses. The rapid yet irregular ventricular rate decreases ventricular filling and reduces cardiac
output.