Electronic stethoscope for monitoring the operation of a prosthetic valve implanted in a patient's heart
First Claim
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1. A stethoscope for monitoring a prosthetic valve for a heart, said stethoscope including a transducer comprising:
- a casing;
a generally S-shaped spring member of magnetic material having a center portion mounted to an interior surface of said casing and a pair of free arm portions;
a weighted housing mounted to said spring member free arm portions;
a magnetic circuit mounted to said housing and adapted to move therewith, said circuit including an air gap and a coil whereby changes in said air gap induce a voltage change in an output voltage induced in said coil;
said spring including a portion disposed with respect to said housing for varying said air gap in response to movement of said housing with respect to said spring, said spring having a length and stiffness cooperating with the mass of said housing to produce a mechanical circuit having a resonant frequency substantially equal to the operating frequency of the valve to be monitored.
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Abstract
An electronic stethoscope for monitoring prosthetic valves for hearts includes a casing to which the center portion of a spring member is mounted. A weighted housing is mounted to the ends of the spring member and contains an opening therethrough in which a magnetic circuit comprising a pole piece, magnet and coil are positioned. The air gap between the pole piece and magnet is varied as the relative distance between the center of the spring and housing vary in response to the operation of a prosthetic heart valve thereby resulting in an induced voltage in the coil which may be amplified and monitored.
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4 Claims
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1. A stethoscope for monitoring a prosthetic valve for a heart, said stethoscope including a transducer comprising:
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a casing; a generally S-shaped spring member of magnetic material having a center portion mounted to an interior surface of said casing and a pair of free arm portions; a weighted housing mounted to said spring member free arm portions; a magnetic circuit mounted to said housing and adapted to move therewith, said circuit including an air gap and a coil whereby changes in said air gap induce a voltage change in an output voltage induced in said coil; said spring including a portion disposed with respect to said housing for varying said air gap in response to movement of said housing with respect to said spring, said spring having a length and stiffness cooperating with the mass of said housing to produce a mechanical circuit having a resonant frequency substantially equal to the operating frequency of the valve to be monitored. - View Dependent Claims (2, 3, 4)
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Specification