The machine that Dr O'Brien and Dr Frazier have designed to get round these constraints consists of a transmitter that sends out a pulse of sound at a frequency of 6 kilohertz, and an array of 52 receivers that collect the reflections from anything buried beneath the surface.

ECONOMIST: Archaeology

The continuous pumping means the patient's pulse is replaced by a constant whir - similar to the sound of a washing machine.

BBC: Image of heart failure