dr. strada gently removes the heavily infected valve. can you see already how bad the damage is? y bad, extremely bad. god knows how they survive in these conditions. >> ward: he carefully positions the artificial valve and then, stitch by stitch, secures it firmly in place. >> strada: okay, flow down. >> okay, flow's down >> ward: the operator of the bypass machine begins restoring the blood flow to the heart. now, the heart is about to start beating for itself again? >> strada: hopefully. >> ward: hopefully. >> strada: okay, stop. >> pump's off. >> strada: cannula is out. >> ward: is that the hardest part over? >> strada: yeah. >> ward: sufiatu will spend the next few days in an intensive care unit. even if the operation is successful, she will rely on emergency for drugs and medical care for the rest of her life. but that still beats the alternative. without this surgery, how long could she have survived? >> strada: well, from one day to three months. >> ward: but not longer than three months. >> strada: no. >> ward: so how many heart surgeries have you done? >> strada: well, a