A heart blood vessel that was largely blocked caused the chest pains that put Gov. Jim Edgar in the hospital over the weekend, doctors said. The injury to the tiny blood vessel was characterized as a bruise to the heart that left no major or long-term damage. Dr. James Dove, president of the Prairie Heart Institute at St. John's Hospital, said the problem would be treated with medicine rather than surgery. The Republican governor is being given blood thinner to help prevent clots and medication to prevent spasms in his blood vessels, Dove said. Edgar was hospitalized Saturday after suffering chest pains.