Abstract: A fluid pressure sensor for a lead or catheter intended for placement in a living organism, such as a human heart, includes a rigid annular or tubular supporting structure and a piezoelectric element disposed on at least a portion of the outer surface thereof. The piezoelectric element delivers an electrical signal when subjected to a pressure variation, and exhibits circumferential sensitivity. The rigidity of the sensor is defined to satisfy predetermined criteria to ensure that the sensor, when sensing pressure transferred to the sensor through an on-growth of tissue on the sensor, which is at least 90% of the signal which the sensor would emit without the on-growth.

Abstract: In an apparatus for determining the actual status of a piezoelectric sensor in a medical implant, electrical charges generated in the sensor, in response to changes in acceleration and/or gravitational force or other loads acting on the sensor, are continuously detected and the charges are then removed from the sensor, thereby maintaining the voltage across the sensor at a substantial constant zero level. The detected charges, both negative and positive, are integrated, thereby providing a resulting integrated signal representing the actual status of the sensor. The integrated signal is then evaluated for determining the physical activity and/or the posture of a patient in whom the medical implant is implanted.

Abstract: A medical implant has an element with at least a part thereof which is composed of piezoelectric material. The piezoelectric material is suitable for contact with body tissue and/or body fluids, and has the formula NaxKyNbO3, with 0≦x≦0.8, 0.2≦y≦1, and x+y=1.

Abstract: A biocompatible medical implant has at least one part thereof composed of ceramic material with the formula NaxKyNbO3, wherein 0≦x≦0.8, 0.2≦y≦1, and x+y=1. The ceramic material can be polarized to give the implant spatially varying piezoelectric properties. Signals can be measured from the respective piezoelectric regions of the selectively polarized ceramic material to provide an indication of the degree of fixation of the implant to surrounding tissue.