A Texas-based medical device maker failed to report the death of a 4-year-old patient fitted with a one-of-its-kind pediatric heart pump, according to a warning letter by the U.S. Food and Drug Administration. In the letter, the agency said MicroMed Cardiovascular should have reported that the DeBakey VAD Child Device may have caused or contributed to the death of the child. MicroMed maintains that the device worked properly and played no role in the patientâ??s death.