Blood flow meter apparatus and method of use
First Claim
1. An apparatus for repeatedly estimating blood flow in a vessel over a period of time, the apparatus comprising:
- one or more transducers;
a source of electrical excitation signal that is applied to at least one of the one or more transducers for an active period of a control signal sufficient to obtain a blood flow estimate and is removed from the at least one of the one or more transducers for an idle period of the control signal until a subsequent blood flow estimate is to be obtained.
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Accused Products
Abstract
A strobed blood flow meter provides periodic measurements of blood flow velocity or volumetric blood flow over a cardiac cycle at reduced average power consumption, which is advantageous for reducing battery size, and extending device battery life, such as in an implantable application. Continuous wave Doppler, pulsed Doppler, laser Doppler, transit time, electromagnetic flow, and thermal dilution techniques are included. Strobing provides higher level excitation during active periods, which improves signal-to-noise ratio, and provides a low power standby mode during an idle time between active periods. The invention may be used for chronic or acute applications. Doppler or other signals may be telemetered from an implanted portion of the flow meter for further signal processing to extract velocity or volumetric flow. Alternatively, such signal processing is also implanted, such that the velocity signal can be telemetered to an remote monitor.
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Citations
20 Claims
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1. An apparatus for repeatedly estimating blood flow in a vessel over a period of time, the apparatus comprising:
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one or more transducers; a source of electrical excitation signal that is applied to at least one of the one or more transducers for an active period of a control signal sufficient to obtain a blood flow estimate and is removed from the at least one of the one or more transducers for an idle period of the control signal until a subsequent blood flow estimate is to be obtained. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for obtaining a Doppler-shifted ultrasonic energy signal for repeatedly estimating blood flow, the apparatus comprising:
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a control circuit that provides an electrical ultrasonic-frequency signal containing ultrasonic-frequency components during an active period of a control signal that is of sufficient duration to obtain a blood flow estimate, and contains substantially no ulstrasonic-frequency components during an idle period of the control signal between the active period and a subsequent active period; an amplifier having an amplifier input, which is electrically coupled to the control circuit for receiving the strobed ultrasonic-frequency signal, and an amplifier output providing an electrical strobed amplified ultrasonic-frequency signal in response thereto; an ultrasound transducer having a transducer electrical input, which is electrically coupled to the amplifier output for receiving the amplified ultrasonic-frequency signal, and having a transducer ultrasound output, for providing strobed ultrasonic energy to the blood vessel in response to the amplified ultrasonic-frequency signal, and having a transducer ultrasound input, for receiving a reflected Doppler-shifted ultrasonic energy signal from the blood vessel, and having a transducer electrical output, for providing an electrical received Doppler-shifted signal in response thereto; and a receiver having a receiver input electrically coupled to the transducer electrical output for receiving the received Doppler-shifted signal and having a receiver output for providing a buffered Doppler-shifted signal in response thereto. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification