CLEVELAND -- Hall of Fame pitcher Bob Feller, already going through leukemia treatments, is also dealing with a heart issue that has landed him in the Cleveland Clinic.

Feller, 91, had a pacemaker installed last week to regulate his heartbeat, according to a close family friend. Feller is said to be resting comfortably and is hopeful of a release from the hospital later this week.

It has been a difficult couple of months for the usually indefatigable Feller, who was diagnosed with acute myeloid leukemia in August and has been receiving regular chemotherapy treatments. He also had a bout with vertigo. The family friend, who wished to remain anonymous, said Feller fainted while getting treatment for the vertigo and his heart stopped for 20 seconds.

Feller is reportedly in good spirits and keeping tabs on his beloved Indians on TV.

Over 18 seasons with the Indians between 1936 and 1956, Feller compiled a 266-162 record, setting the team record for victories. He led the American League in strikeouts seven times, was an eight-time All-Star, pitched three no-hitters -- including the only Opening Day no-hitter in history -- and 12 one-hitters. He missed three years of his prime while serving in the Navy during World War II.

Feller was inducted into the Hall of Fame in 1962. He is the third-oldest living member of the Hall and the longest-tenured living member.