Raynsford is a former member of the GB wheelchair basketball team
Reigning Paralympic gold-medallist Helene Raynsford has retired from rowing because of a cardiac problem.
The 30-year-old was also single sculls world champion in 2006.
"My passion for rowing is still there but I have to let my body recover fully, something I can't do while continuing to train," she said.
Raynsford's decision comes on the eve of the GB Rowing team trials, which will select for this season's World Cup and World Championships.
The World Cup takes place in Slovenia in May, while the World Championships in New Zealand are in October and November, and the search is on for new talent to compete in these events.
Following Raynsford's retirement, GB Rowing need reinforcements in the women's arms-only single scull as well as the mixed adaptive double scull, something the team's high performance project manager Louise Kingsley is disappointed by.
"It's frustrating that after such an active talent search period we are still looking for rowers who have the potential to fill seats in the women's single and the double scull for London 2012," said Kingsley.
Meanwhile Tom Aggar, the reigning world and Paralympic champion, will face opposition in the men's single scull trial from his Newbury-based team-mate Andy Houghton, who was identified for the squad through a ParalympicsGB post-Beijing talent day in London.