Which of the following are relative indications for mechanical, as opposed to tissue, valve replacement?

A. Patient younger than 30 years

DISCUSSION: Age younger than 30 years is a relative indication for mechanical valves because of an increased incidence of calcification of tissue valves in younger persons. A young female who desires children would be a relative contraindication to mechanical replacement because of the risk of teratogenesis and hemorrhage during pregnancy secondary to warfarin therapy. Advanced age is a relative indication for biologic valves to avoid complications of anticoagulation and because the probability of reoperation is low. Tricuspid valve replacement is a relative contraindication to mechanical valve replacement, owing to the increased incidence of tricuspid valve thrombosis with a mechanical prosthesis.