If a patient after heart bypass 2 1/2 weeks ago can take a shower then why cant he set in the swimming pool?

You can't drown in the shower but you can in a swimming pool. There is supposed to be a gradual return to normal activity. Medications and sitting in a pool can cause an unsafe drop in blood pressure and he could drown. Have all of his surgical incisions healed? Call the hospital where he had his surgery. Swimming and holding his breath are out for now.