I am a 64 year old male who has had his second by-pass surgery in almost 13 years. After this recent surgery (3 1/2) weeks ago) I am experiencing dizziness while lying down and have actually passed out for a second or two while trying to sit up. I have had tests such as 24 hour holter monitor, Cat Scan of the head, Cat Scan of the chest, Echo of the heart. The results of the tests were all negative. My right Carotid Artery is 40% clogged. My blood pressure does not materially change while lying down and feeling dizzy position to a non dizzy siting up position. My doctor has discontinued my Atenolol and replaced it with Norvasc 5mg, Lipitor 40mg, Aspirin 325mg. I am scheduled for another Cat Scan of the head except this time it will be with and without contrast. My doctor seems to be leaning in the direction of a problem with my inner ear. I've never had any inner ear problem before the surgery but he has now given me a prescription for Meclizine 25mg two times a day. I was on a heart lung machine during surgery and did not receive a blood transfusion. Can you add anything to help me understand what may be actually causing my problem.