In one embodiment described in the specification, a surgically implantable reciprocating pump employs a check valve as the piston, which is driven by a permanent magnet linear electric motor to assist either side of the natural heart. The pump is implanted in the aorta or pulmonary artery using vascular...http://www.google.co.uk/patents/US5879375?utm_source=gb-gplus-sharePatent US5879375 - Implantable device monitoring arrangement and method
