Against all odds, Mark survived without the need for a heart transplant for 15 years, until changes in medication meant that his thyroid issues flared up again and his situation deteriorated rapidly.
Yn groes i bob disgwyl, goroesodd Mark heb fod angen trawsblaniad am 15 mlynedd, nes bod newidiadau i’w feddyginiaeth yn golygu bod ei broblemau thyroid wedi codi eto, a dirywiodd ei iechyd yn gyflym.