One of the more familiar operations used by Congenital Cardiac surgeons is the Glenn Shunt (Also known as the Glenn Procedure, the word “Shunt” means “detour”.) Despite being revised from its original form and falling out of favor for a time, the Glenn is often used in the repair of defective hearts.
Developed by Dr. William Glenn in the 1950’s, the original operation may not be recognized by today’s doctors. In what is now known as the Classic Glenn or the Unidirectional Glenn, the Superior Vena Cava (SVC) would be sewn closed near its junction with the Right Atrium. The Right Pulmonary Artery (RPA) is then cut and sewn into the SVC, and the open end of the Pulmonary Artery would be sewn closed. In this configuration, the Glenn Shunt only sends blood to the right lung. Here’s a good diagram of the Classic Glenn Shunt and here’s what I think is an even better drawing. The second link contains links to important information about both versions of the Glenn, worth your time to read. For the record, my first heart operation in 1967 was the Classic Glenn Shunt.
The Glenn fell out of favor after the Fontan Procedure was introduced. After years of neglect (I was told in 1977 by a surgical assistant that “we rarely do the Glenn any more”) it was looked at again when the early versions of the Fontan tended to not deliver the expected results. By then the operation had evolved into the Bidirectional Glenn Shunt. In the Bidirectional Glenn, the Superior Vena Cava is cut, and then re-sewn into the Right Pulmonary Artery. This is makes it bidirectional, as blood now flows to both lungs. Here’s a good photo of the Bidirectional Glenn (.pdf file) and here is a .pdf report on modeling a Bidirectional Glenn to study it’s affects on the individual patient. This report may appeal more to readers with a mathematical background, as the first part of the article is a complex discussion of the formulas needed to create the model.
Currently, the Bidirectional Glenn Shunt can be used as an option to repair most of the right-sided heart defects. It is also the second operation of the Norwood Procedure to repair Hypoplastic Left Heart Syndrome. (HLHS) It was first used in the Norwood in 1989; until then, the Norwood repair was a two surgery procedure.
And finally, here is a visual reminder to learn the anatomy of the heart yourself and not trust everything you find on the Internet: The text on this page correctly describes the Bidirectional Glenn Shunt, but the illustration is of a Blalock-Taussig Shunt!
8/2/2009 Update: I listed the same link twice when referring to two drawings of the Glenn Shunt! That has been corrected!