One member of St. Jude's lead safety panel, Dr. Bruce Wilkoff of the Cleveland Clinic, said in an e-mail that he did not "have specific recollections of how many patient scenarios" had been presented but added that he was aware of the conditions that could result in a patient's death. Four other specialists on that board either did not respond to repeated requests for comment or declined to comment on the number of patient deaths St. Jude officials had presented to the panel. In a telephone interview last week, the company's chief medical officer, Dr. Mark D. Carlson, said that some patient deaths were inevitable because defibrillators occasionally fail; he added that the types of insulation problems with the Riata were common. However, other heart device specialists said they were disturbed by St. Jude's explanations, adding that the number of Riata-related deaths appeared unusually high compared with other leads and pointed to a troubling pattern.