Case Study _ Anticoagulant Therapy You are the nurse working in an anticoagulant clinic. Ken Nettles is a patient who has longstanding irregularly irregular heartbeat, atrial fibrillation, for which he takes oral anticoagulant warfarin. Recently Mr. Nettles has had a mitral heart valve replaced with a mechanical valve. You know that there are different PT/INR goal recommendations based on th indication for anticoagulation. Atrial fibrillation carries an INR therapeutic goal range of 2.0 to 3.0. Mechanical valves in the mitral position are considered at greater thromboembolic risk the the aortic site. Therefore Mr. Nettles will need his PT/INR to be kept at a higher goal range of 2.5 to 3.5. Mr. Nettles calls your anticoagulation clinic to report a nosebleed that is hard to stop. asks to come into the office to check his clotting time. When you get the results, his INR is The physician has asked you to inform Mr. Netters that the level is too high. 1. Explain the rationale why the goal range is high for a patient with a mechanical mitral valve