Following is a list of factors that can affect memory:
--drugs administered during and after surgery can remain in the system for several months;
--the heart/lung machine is extremely hard on your blood, which takes time to recover;
--stress, anxiety and disturbed sleep patterns cause increased forgetfulness;
--post-op depression (etremely common) can cause forgetfulness;
--pain and discomfort make it difficult to attend to what's going on, also resulting in forgetfulness;
--post-op meds like ACE inhibitors and beta blockers can affect memory and mood;
Last but not least, simply worrying about your memory can cause you to be more forgetful!
Regular exercise, eating right, and especially getting enough sleep can help tremendously. As one who had a 14 hour surgery, with 10 hours on a heart lung machine, I know for SURE that these things help.
An excellent book for helping with memory (good techniques and "tricks") is "The Memory Book" by Harry Lorraine.
After your six-month post-op checkup, your memory should be functioning pretty well again. If it is still problematic, I'd be concerned and seek some professional advice. Before six months post-op, I'd say most all patients have some minor degree of memory impairment.
--John