Sanchez has not played since and after consulting a heart specialist in Hamburg in March he decided to undergo a "complicated" operation.
"At the moment it seems we are winning 1-0," he said.
"It was a first victory, but not only for me, for everyone. The club, who have supported me in everything, helped me make the decision because it's not a decision you should take alone.
"Thanks to my family, (Sevilla sporting director) Monchi, the president, team-mates, and also myself, I decided to go ahead with the operation and to at least have the opportunity to play again.
"I will be able to live without problems, it's confirmed that everything went perfectly. The first prognosis indicates that I should be able to play again, but this is a long process.
"Now comes the hard part: working and gaining strength, following the plans of the doctors and being patient. But, we have hope and I hope at the end that all this effort will be rewarded on the pitch."