Assertion: external pacemaker | /r/HasProperty | based upon observation
Facets:
value: by john callaghan
type: OTHER
value: at toronto general hospital
type: LOCATION
Source sentences:
text: In 1950, Canadian electrical engineer John Hopps designed and built the first external pacemaker based upon observations by cardio-thoracic surgeons Wilfred Gordon Bigelow and John Callaghan at Toronto General Hospital, although the device was first tested at the University of Toronto's Banting Institute on a dog.