Heart valves galore, to Tin Man's delight
In The Wizard of Oz, Tin Man longs for a heart. That's a problem Manuel "Manny" Villafaña has rarely had—he has collected pieces of many hearts.
Millions of people are collectors. You may be one of them. People amass everything from postcards to erasers, tea cups to motorcycles. Here at the National Museum of American History, the curators in the Division of Medicine and Science collect patent medicines, toothbrushes, surgical instruments, and much more.
Manuel "Manny" Villafaña, an entrepreneur, inventor, and donor to the museum, collects artificial heart valves. In 2015 Villafaña donated over 50 artificial heart valves to the Division of Medicine and Science.
Villafaña explained in an interview that he likes to collect: "I've always had an affinity for collecting things. I used to be a stamp collector. I used to be a coin collector. I even used to collect envelopes. . . . I collect things I think are unique and meaningful." Besides artificial heart valves, he also has a pacemaker collection.
How does one go about collecting artificial heart valves? It helps that Villafaña is the founder of six medical device companies, including Cardiac Pacemakers Inc., St. Jude Medical, ATS Medical, and his latest startup company, Medical 21.
So he knows a fair amount about the history of artificial valves and how they function! A few of the valves in the collection are from Villafaña's companies, but the majority of them represent dozens of different designs and come from different manufacturers. Many of these valves were given to him from the engineers and physicians who designed them.
Designing a reliable and effective artificial heart valve, one as efficient as a human valve, has proven to be a formidable task. Finding biocompatible materials like Pyrolytic carbon, silicone, Teflon, and Dacron that a patient's body would not reject was especially difficult. Tissue valves were one of the answers proposed. Made from the biological tissue of pig valves and the tissue surrounding a cow's heart, these valves must be kept in a sealed container with fluid to maintain viability.
Good design is imperative when trying to prevent the destruction of blood cells, which can produce clots and thromboembolism. An artificial valve also needs to be efficient and structurally sound so that it can withstand years of wear. The shape and design are the elements that allow blood to move more effectively through the valve. Or, as Villafaña puts it in the case of the ball and cage design, the design has to "get the ball out of the way so we have a nice central flow."
There are three main types of artificial valves: the ball and cage, the tilting disc, and the by-valve.
Every design is unique—but some I think are more unique than others, like the artificial valve that looks like it came from the inside of a toilet bowl, or the Lemole-Cooley mitral valve that is oval in shape like the natural mitral valve.
The Hufnagel Trileaflet Aortic Heart Valve was designed to look like a natural human heart valve, but the leaflets would stiffen and eventually would not open and close.
There are a few valves in the collection like this Braunwald-Cutter valve that were explanted from patients. Take a look and you'll see that the fabric on the struts has worn down or completely come off. The valve also shows wear on the poppet and has a large crack. As Villafaña says, "This is not a collection that looks pretty because some of these things are just a piece of plastic."
Our Mending Broken Hearts: Innovation Inside the Body display explores the development of artificial heart valves. It is on view in the museum's first floor through March 19, 2017. Explore the virtual exhibition.
Judy M. Chelnick is the curator of medical and dental instrumentation in the Division of Medicine and Science at the National Museum of American History.
Update: Thanks to you, our Kickstarter campaign to "Keep Them Ruby" was a success and we have the support we need to conserve and display Dorothy's Ruby Slippers from The Wizard of Oz. Stay tuned for updates on the project. But our journey on the yellow brick road isn't over yet. Help us conserve Scarecrow's costume from the 1939 movie so that it can join the Ruby Slippers on display and help support a new exhibition devoted to the arts, music, sports, and entertainment. Your support will help to make this project a reality.