What a valve does
The heart has four valves that act as one-way doors, keeping blood moving forward. Disease, often from rheumatic fever in earlier decades or from age-related changes, can make a valve too narrow to open fully or too leaky to close. Before the 1950s a badly damaged valve generally could not be fixed in any lasting way. The history of artificial heart valves is about finding a replacement that opens easily, closes tightly and does not wear out or cause clots.
Prerequisites: open-heart surgery
A valve cannot be replaced while blood is flowing through it. Replacement of the aortic or mitral valve became realistic only after the heart-lung machine, first used successfully by John Gibbon in 1953, allowed surgeons to stop the heart for a while. Safer anesthesia and clean surgical practice, rooted in surgical anesthesia and antiseptic surgery from the nineteenth century, were also essential foundations.
Hufnagel and the first artificial valve
Charles Hufnagel, a surgeon in Washington, D.C., developed a ball valve in the early 1950s, made of a plastic tube holding a small ball. In 1952 it was implanted in the descending aorta of a patient with aortic regurgitation. The valve was not placed where the natural valve sits, so it only partially helped, but it is usually regarded as the first successful artificial valve in a human. It was also noisy: patients are described as having an audible click.
The ball-and-cage valve
In 1960, two designs reached patients. Dwight Harken reported replacing the aortic valve with a caged-ball design, and in Portland, Oregon, the surgeon Albert Starr and the engineer Lowell Edwards developed a mitral valve with a silicone rubber ball in a metal cage. The first human mitral replacement with the Starr-Edwards design took place in 1960. Early patients were gravely ill, and many early outcomes were poor, but enough survived for the design to be developed and used widely through the 1960s and beyond. Some patients with Starr-Edwards valves lived for decades.
The ball-and-cage design had several drawbacks. The ball partly blocked flow, the profile was tall, and blood clots could form on the structure, which led to strokes. Patients needed long-term anticoagulant drugs, commonly warfarin, a requirement that applies to most mechanical valves today. In some early valves the silicone balls absorbed fats from the blood and changed shape, which was one reason the materials were revised.
Materials: the difference between success and failure
Valve design is as much about materials as geometry. A mechanical valve must survive hundreds of millions of cycles and resist corrosion, and its surfaces should encourage as little clotting as possible. Early valves combined silicone rubber, metals such as cobalt-based alloys and fabric sewing rings made of polyester or similar cloth, which the surgeon stitches to the patient’s tissue. Material choices drew on knowledge from other fields: the use of stainless steel and similar alloys in orthopedic implants, and the development of synthetic fibers for sewing cuffs.
A later and important material was pyrolytic carbon, a hard, smooth form of carbon that is relatively gentle on blood. It became the standard surface for many mechanical valves from the 1970s.
Tilting discs and bileaflet valves
To improve flow, designers moved from balls to discs. The Björk-Shiley tilting disc valve, introduced in 1969, opened to a lower profile and allowed better flow. One later version, the convexo-concave model, was associated with fractures of a strut in some patients, and it was withdrawn in the 1980s after reports of failures. It is a standard case study in valve safety and in how long-term data can reveal problems that early testing misses.
The bileaflet valve, introduced in 1977 by St. Jude Medical, used two half-discs hinged in a ring and made with pyrolytic carbon. It offered good flow and durability and became the most widely used mechanical design in later decades.
Tissue valves
The other family uses biological tissue. Donald Ross in London performed aortic valve replacement with a human valve (a homograft) in 1962 and later introduced the operation that bears his name, in which a patient’s own pulmonary valve is used in the aortic position. Valves from pigs, treated with chemicals to preserve them and fixed on a stent, were developed in the 1960s and 1970s, with the surgeon Alain Carpentier among those closely associated with their development. Valves made from cow pericardium followed.
Tissue valves generally do not require lifelong blood-thinning treatment, which is their advantage, but they tend to wear out over time, especially in younger patients. The choice between mechanical and tissue valves has therefore long involved trading durability against anticoagulation.
Beyond open surgery
In 2002, Alain Cribier performed the first transcatheter aortic valve implantation in a person, delivering a collapsible valve through a catheter. That approach has since grown widely, particularly for older patients, and it shows how long the valve story has continued.
This article is history only. Valve choice for any patient depends on medical circumstances, and a cardiologist is the proper source of advice.