Approximately 24,000 heart transplantations have been preformed in the United States during the past decade, with advances in surgical techniques and immunosuppressive medications producing increased survival rates.

Dr. Diederik van de Beek and colleagues at the Mayo Clinic College of Medicine studied 315 consecutive patients who underwent heart transplants from January 1988 through June 2006. They found eight patients (3 percent) developed central nervous system infections within four years after transplantation.

Three patients developed cryptococcal meningitis, two had progressive multifocal leukoencephalopathy, two had varicella-zoster virus encephalitis and one had Aspergillus fumigatus infection.

"Because the mortality and morbidity rates are high, aggressive diagnosis and intervention are warranted in heart transplant recipients with suspected central nervous system infection," the medical scientists said.

The research is to appear in the December issue of the journal Archives of Neurology.