Dear debbie,
If the rapid and irregular heartbeat is due to atrial fibrillation then I think that it is important to try to get him back into sinus rhythm. This will add the atrial "kick" to his filling pressures and should help him feel much better. I suspect the drug his doctor want to try is Tikosyn. This is a new antitachycardia drug that can be very effective in controling atrial fibrillation. Discuss your concerns with his doctor and then make a decision as to what the next best step would be.