He was given the assignment of serving as thesis advisor to William Sewell, a student at Yale School of Medicine who was working on a required research project in which he was attempting to develop a heart pump.
The original pump that was developed used components costing a total $24.80, which included a number of standard laboratory supplies, some assorted hardware and an Erector Set.
[3] Glenn and Sewell presented the results of their experiments at the 1949 annual congress of the American College of Surgeons in Chicago.
[4] The device created using the Erector Set is on display at the Smithsonian Institution's National Museum of American History.
There, he developed improvements to cardiac pacemakers, and created the "Glenn shunt" (or "Glenn Operation") in 1954, a vena cava-pulmonary artery shunt that bypasses the defective right chambers of the heart of "Blue Babies", augmenting the inadequate blood flow to the lungs and thus providing oxygen that, when missing, gives the babies their blue color.