Mechanical cardiac valvular prostheses.

Mechanical cardiac valvular prostheses currently enjoy a 60% to 40% market-share advantage over tissue prostheses in the United States and worldwide. Only the Starr-Edwards caged Silastic (Dow Corning) ball, Medtronic-Hall, St. Jude Medical, and Omniscience valves remain available in the United States. Although each valve has certain advantages and disadvantages, no design has achieved functional mechanical perfection. Late follow-up of valve-related complications from the literature favors the St. Jude Medical and Medtronic-Hall valves.