Naming difficulties may be rank ordered along a continuum. Items are rank ordered in terms of their ability to be named, which is correlated with their frequency. This type of picture-naming test is also useful in the examination of children with learning disabilities and the evaluation of brain-injured adults.
The Jarvik-7 heart was developed by American scientist Robert Jarvik and his mentor, Willem Kolff. In 1982, Seattle dentist Dr. Barney Clark was the first person implanted with the Jarvik-7, the first artificial heart intended to last a lifetime.
An artificial heart is distinct from a ventricular assist device designed to support a failing heart. It is also distinct from a cardiopulmonary bypass machine, which is an external device used to provide the functions of both the heart and lungs and are used only for a few hours at a time, most commonly during cardiac surgery.