Heart Attack and lack of oxegen to the brain?

your question isn't terribly clear, having a heart attack and having the heart stop without circulation, or with Poor circulation can cause major issues with organs. Including your Brain as well as your Liver function.... It is very common place for post surgery Pt's to have loss of function, brain damage, as well as organ damage as well, one of the issues here is you say you had a heart attack in recovery /rehab after having 45% of your heart muscle damaged you "were pushed" to do 45 minutes of exercise.. I would say WHO Pushed you and was this a stress test? One man's stress test can surely be another mans Forced Death march.... either way this caused a 2nd heart attack, your low blood pressure was caused by the 2nd heart attack?? The point is when one "gets shut down" lack of oxygen to the brain and organs depends on every aspect, I survived an aortic dissection, my pressure walking in was 60/30 they literally put me ON ICE while they rebuilt the dissection the Mammalian reaction is what saves Humans especially kids who fall through the ice , the effect of the cold slows down the degradation in the organs, The first Time I spoke with my Thoracic Cardiologist, he was amazed that I could even have a conversation much less an intelligent one, Yes, I Know what happened because I have pieced together what happened 18 months ago, I Have 0 recollection of specifically that day or events leading up to or during my situation.. I have all my long term memory I cannot say The day before My dissection.... I cut the gr... I woke up, in My Room in ICU after they de-intubated me so I have X Number of Foggy hours (days) I have trouble sometimes with lists of say names like 6 people I worked with equals Mike, Ed, MIke Andy, Paul, and whats his name and of course I know the name and so forth BUt the harder I try the harder it is to recall... MY Doctor says I am 1% of people who survive my issue because Of the fact I retained much of anything.. Typically YOUR issue is Less an issue, Unless there was a long period without CPR being done , or Problems with circulatory actions.. (each situation is different).. Many people who have Aortic's pre diagnosed have low survival numbers, much less UN diagnosed Like mine.. Its LUCK I live in the states 15 minutes drive from one of the top 8 Cardiac teaching hospitals in the country, I used to live literally 6 miles away an d had i lived there I would not have survived because there 1st responders are volunteer here we have Paid Paramedics, I had 5 Paramedics at my house within 3 minutes, in the other town it could have been a 15 minute time span to get ANYONE at my home, much different standard of Care, on that side I doubt I would have ended up at the same Hospital as I did too.. Hopefully this will help you to understand that every little factor can make a difference... Don't have pity on yourself, there are things you can do to work on your Brain function, even if you don't get back 100% exercising and working on them