The market for these devices — and more sophisticated versions used by
emergency responders and in hospitals — has been in turmoil since
market leader Medtronic Inc. suspended shipments of its products in
January because of quality issues at its Redmond, Wash., plant.

Cardiac Science Corp., of Bothell, Wash., said domestic sales of
AEDs shot up 83 percent in the second-quarter, compared with the same
quarter last year.

Over the past year, its stock rose 28 percent.

Zoll
Medical Corp., of Chelmsford, Mass., said sales in its North American
pre-hospital market, which includes defibrillators for public places,
increased 43 percent in the third fiscal quarter. But its stock has
performed erratically — up sharply after Physio-Control announced it
was suspending product shipments, but losing steam in recent months.