Sewell built the pneumatically powered pump for his medical thesis at Yale University. He graduated in 1950. The object of the pump was to by-pass the right side of a dog's heart, and to look for any abnormalities the pump may have caused to the heart or the blood.
A cannula was inserted into the animal’s jugular vein and maneuvered into the right auricle and finally into the vena cava. Compressed air was used to pump blood through the dog's system. The first experiment took place in June 1949. The artificial heart worked and the dog made a complete recovery.
The total cost of the pump came to $24.80. The most expensive part at $9.00 was the erector set and motor.