Prosthetic Heart Valves

A prosthetic heart valve is an artificial device implanted to replace a diseased native valve. Prostheses fall into two broad families: mechanical valves, built from durable synthetic materials, and biological (bioprosthetic) valves, fashioned from animal or human tissue. The choice between them turns on a central trade-off — the long durability of mechanical valves against their need for lifelong anticoagulation, versus the freedom from anticoagulation of tissue valves against their finite lifespan.

Definition

A prosthetic heart valve is a mechanical or biological device that replaces a native cardiac valve to restore competent, unidirectional blood flow; mechanical valves use synthetic occluders requiring lifelong anticoagulation, while bioprosthetic valves use animal or human tissue and are subject to gradual structural deterioration.

Scope

The entry covers the two prosthesis types, their construction and the trade-off in durability and anticoagulation that distinguishes them, the principal modes of prosthetic valve failure, and the considerations that inform prosthesis selection. It is a device-focused reference; it does not provide anticoagulation regimens, dosing, or individualized advice on which valve a particular patient should receive.

Core questions

• How do mechanical and biological prostheses differ in durability and anticoagulation requirements?
• What are the principal modes of prosthetic valve failure?
• What factors inform the choice of prosthesis type?

Key concepts

• Mechanical valve
• Bioprosthetic (tissue) valve
• Lifelong anticoagulation
• Structural valve deterioration
• Prosthesis-patient mismatch
• Prosthetic valve thrombosis and endocarditis
• Valve durability

Mechanisms

Mechanical valves use rigid synthetic occluders — historically a caged ball, then a tilting disc, and now most commonly two pivoting leaflets (bileaflet design) — that are extremely durable but present thrombogenic surfaces, so they require lifelong anticoagulation to prevent valve thrombosis and thromboembolism. Bioprosthetic valves use chemically treated animal pericardium or porcine valve tissue, mounted on a stent or stentless; they are far less thrombogenic and generally avoid long-term anticoagulation, but the tissue undergoes structural valve deterioration — calcification and leaflet tearing — that limits their lifespan and is more rapid in younger patients. Beyond these intrinsic behaviours, any prosthesis can fail through thrombosis, infective endocarditis, paravalvular leak, or prosthesis-patient mismatch, in which an effectively too-small valve leaves a residual gradient. The selection of a valve therefore balances expected durability, the bleeding and thrombotic risks of anticoagulation, patient age, and preference.

Clinical relevance

Prosthesis choice is one of the defining decisions in valve replacement, and guidelines frame it around patient age, the durability of tissue valves, and the lifelong commitment and risks of anticoagulation, decided jointly with the patient. This entry describes the devices and their trade-offs for reference; it does not specify anticoagulation targets or recommend a prosthesis for any individual.

Epidemiology

Across populations there has been a marked shift over recent decades toward bioprosthetic valves, including in progressively younger patients, driven by the wish to avoid anticoagulation and by the prospect of later transcatheter valve-in-valve treatment of a degenerated bioprosthesis. Comparative cohort data inform how the durability-versus-anticoagulation trade-off plays out by age.

History

The modern era of valve replacement opened around 1960 with the caged-ball Starr-Edwards valve, the first widely successful prosthesis. Mechanical design then evolved through tilting-disc to bileaflet valves with improved haemodynamics, while bioprosthetic valves developed in parallel using glutaraldehyde-treated tissue. The advent of transcatheter valve-in-valve procedures, which treat a degenerated bioprosthesis without reoperation, has further influenced the balance toward tissue valves.

Debates

Mechanical versus bioprosthetic valve in younger patients

Mechanical valves last longer but commit the patient to lifelong anticoagulation, whereas tissue valves avoid anticoagulation but deteriorate sooner; observational comparisons suggest the age at which the balance shifts has been moving younger, but the optimal threshold remains debated.

Key figures

• Albert Starr
• Miles Lowell Edwards

Seminal works

• goldstone-2017

Frequently asked questions

What is the main trade-off between mechanical and tissue valves?

Mechanical valves are very durable but require lifelong anticoagulation to prevent clot formation; tissue valves usually avoid long-term anticoagulation but wear out over time, more quickly in younger patients. The choice weighs durability against the burden and risks of anticoagulation.

Why do bioprosthetic valves eventually fail?

Their tissue leaflets undergo structural valve deterioration — progressive calcification and tearing — which causes the valve to become stenotic or regurgitant over years. This process is faster in younger patients, which is why durability is a key factor in prosthesis choice.