Antarctic Explorer Shackleton Hindered by Heart Defect, Docs Say

It's been a century since Sir Ernest Shackleton led some of the first major expeditions to Antarctica, but today, medical sleuths suggest Shackleton might have had a hole in his heart, possibly explaining the health problems he had all his life. A famed explorer, Shackleton led the Nimrod Expedition of 1907 to 1909, members of which were the first people to climb Mount Erebus in Antarctica, the southernmost active volcano on Earth. The Endurance expedition was the third of four Antarctic expedit