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Publication Number
US-7963920-B2
Publication Date
2011-06-21
Expiration Date
Abstract
A system for monitoring blood flow confined by at least one vessel wall, the system including: at least one implantable diffraction-grating transducer being embedded within or adjacent to a vessel wall, the diffraction-grating transducer being suitable for emitting ultrasound into or receiving Doppler shifted ultrasound from the blood flow; and, a source for pulse-exciting the implantable diffraction grating; wherein, the Doppler shift is indicative of the blood flow.
Core Innovation
The invention relates to an implantable blood-flow monitoring system for blood flow confined by at least one wall of a vessel. The system includes at least one implantable diffraction-grating transducer configured for being implanted on or within and parallel to the wall of a vessel through which blood flows, or disposed adjacent and parallel to the wall. The diffraction-grating transducer emits an ultrasound beam into the blood flow, and an excitation source drives the transducer with one or more frequency components.
The system uses Doppler-shifted signals scattered from blood passing through the ultrasound beam produced by the diffraction-grating transducer. At least one implantable substantially planar slab transducer is configured for being implanted on or within and parallel to the wall of the vessel, or adjacent and parallel, and receives the ultrasound emissions at substantially right angles relative to the wall of the vessel. The Doppler shift is indicative of scattering blood velocity, so the Doppler-shifted signals provide blood-flow information.
The document further describes multiple diffraction-grating transducer geometries and configurations, including double-beam arrangements, slab transducers in different planes, and higher-order diffraction-grating transducer operation for additional direction or velocity resolution in curved vessels. In various implementations, the system supports determining blood flow direction from the received ultrasound signals, including directional determination via phased sub-grids and asymmetric single-slab configurations.
Claims Coverage
The independent claims cover implantable blood-flow monitoring systems built around diffraction-grating transducers and substantially planar slab transducers. Across the independent claims, the inventive features include parallel placement relative to a vessel wall, emission and reception of ultrasound at substantially right angles, excitation with one or more frequency components, and Doppler-shift information indicative of scattering blood velocity.
Implantable diffraction-grating transducer parallel to vessel wall emitting ultrasound
At least one implantable diffraction-grating transducer is configured for being implanted on or within and parallel to a wall of a vessel through which blood flows, or disposed adjacent and parallel to the wall, and emits an ultrasound beam into the blood flow.
Excitation source providing one or more frequency components
A source excites the implantable diffraction-grating transducer, or at least one substantially planar slab transducer, with a driving signal having one or more frequency components.
Substantially planar slab transducer receiving Doppler-shifted scattered signals at right angles
At least one implantable substantially planar slab transducer is configured for being implanted on or within and parallel to the vessel wall, or adjacent and parallel, and receives ultrasound emissions at substantially right angles relative to the wall, including Doppler-shifted signals scattered from blood passing through the ultrasound beam, wherein the Doppler shift is indicative of scattering blood velocity.
Direction determination from received ultrasound signals
The received ultrasound signals indicate a blood flow direction.
Transducer placement in different planes
The substantially planar slab transducer and the diffraction-grating transducer are located in different planes.
Artificial graft vessel context
The vessel through which blood flows is an artificial graft.
Multiple diffraction-grating transducers
The system includes multiple diffraction-grating transducers.
Planar slab transducer transmitting ultrasound emissions at right angles
At least one substantially planar slab transducer is configured for transmitting ultrasound emissions at right angles relative to the wall of the vessel to the at least one diffraction-grating transducer.
The independent claims are defined by implantable diffraction-grating transducers emitting ultrasound into blood while positioned parallel to a vessel wall, excitation with one or more frequency components, and substantially planar slab transducers receiving Doppler-shifted scattered signals at substantially right angles so that Doppler shift indicates scattering blood velocity. Additional refinements include direction indication, different-plane transducer placement, artificial graft vessels, multiple diffraction-grating transducers, and planar slab transducers transmitting ultrasound at right angles to the diffraction-grating transducer.
Stated Advantages
Enables Doppler-shift based monitoring of blood flow velocity using Doppler-shifted signals scattered from blood.
Provides blood flow direction indications from the received ultrasound signals.
Describes consistent Doppler frequency proportional to velocity from multi-frequency pulsed excitation.
Documented Applications
Implantable blood-flow monitoring for blood flow confined by at least one wall of a vessel, including prosthetic/artificial graft vessels.
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