What Causes Poor Memory After Cardiac Catheterization?

my 80 year old mother recently had a heart cath procedure (approx. 2 months ago). no stent, 40% blockage. Immediately after the procedure, and continuing through today, her memory has become significantly worse. She will ask a question again 30 seconds after already asking, and this week can t remember her address. She DID NOT have these memory issues before and was sharp. Additional notes: she was prescribed Ranexa (500 mg) but continued to have major chest pains at several times during the day. They increased her dosage to 1000 mg which (we think) may have helped. However, she is recently HOT all the time. She is scheduled to see a GI specialist next week and primary soon after. Can it be the meds? O2? Need help! Her cardio doctor was not helpful at last visit.