Abstract:
An apparatus for measuring and imaging blood perfusion in tissue comprises a monochromatic laser light source (A2); means for shaping the laser light beam; means for irradiating a section of the surface of the tissue (A4) with the laser light beam; means for collecting (A5, A1, A8) light scattered from the irradiated section; an image sensor (A3) comprising a plurality of photodetectors, each photodetector of the sensor being able to receive collected light from a predetermined sub area of the section of the tissue surface and produce a corresponding electrical output signal linearly related to the detected instantaneous laser light intensity; means for processing (4) the electrical output signals from the plurality of photodetectors; means for calculating the average Doppler frequency shift for each sub area from which scattered light is detected; means for producing an image (5) of the blood perfusion in the tissue section irradiated from the processed output signals; and an image display means. The apparatus enables fast tissue blood perfusion imaging to sub second times.
Abstract:
A device and method for measuring fluid flow within a vessel having fluctuating elastic walls, such as, for example, an artery. The device includes catheter (22); an internal stabilizer or frame (30) for establishing an invariant cross-section in the vessel wall; and a fluid velocity detecting system, such as, for example, a Doppler crystal transducer (32). The method for measuring includes the steps of stabilizing the vessel wall and measuring the velocity of fluid passing through the stabilized cross-section of the vessel wall. A method of treating and a method of diagnosing vascular disease by employing the device of this invention is also part of the invention.
Abstract:
An intracardiac blood flow velocity measurement device comprises a catheter means (10) adapted to be inserted through a blood vessel (31) into the heart, at least two electrodes (12, 13) made of two different biocompatible materials being mounted onto the catheter means (10) at a detecting position which is located in the desired detecting area (35) when said catheter means (10) is inserted into the heart for detecting the blood flow velocity, wherein at least one of said electrodes (first electrode 13) being formed as a polarizable electrode and being arranged in said detecting position and another one (second electrode 12) being located in an axially spaced relationship to said first electrode (13). The variation of overvoltage or of galvanic voltage is used as blood flow velocity signal.
Abstract:
A processing system (50) and method are provided for deriving an improved hemodynamic indicator from cardiac wall acceleration signals. The cardiac wall acceleration signals are provided by a cardiac wall motion sensor (52) that responds to cardiac mechanical activity. The cardiac wall acceleration signals are integrated over time by an integrator circuit (56) to derive cardiac wall velocity signals, which are further integrated over time by an integrator circuit (60) to derive cardiac wall displacement signals. The cardiac wall displacement signals correlate to known hemodynamic indicators, and are shown to be strongly suggestive of hemodynamic performance. An implantable cardiac stimulating device (300) which uses cardiac wall displacement signals to detect and discriminate cardiac arrhythmias is also provided.
Abstract:
The invention relates to a method and to a system for reducing the distance-dependent amplification factor when measuring fluid flow movements with the aid of an image-producing laser-Doppler technique, in particular when measuring blood perfusion through tissue. A laser beam source (1) directs a laser beam (2) onto a measurement object (5), which scatters and reflects the beam (2). The reflected light is received by a detector (9) which senses the broadening in frequency caused by the Doppler effect. Means, preferably in the form of one or more lenses (12: 15, 16) are placed in the path of the beam (2) and are intended to maintain constant the number of coherence areas on the detecting surface of the detector and independent of the distance between detector and measurement object.
Abstract:
An apparatus (20) for determining the viscosity of the whole blood of a living being comprises a monitor unit (22) arranged to be coupled to a blood vessel (26) for monitoring the transit time of a portion of the blood when it flows through the vessel. In one embodiment the sampling unit (22) is implantable in the blood vessel (26) and uses a pair of transducers (34, 36) for measuring a pressure drop within the vessel, a device (42) for determining the instantaneous blood velocity therein, and circuitry (24) for calculating the blood viscosity. In another embodiment a sampling unit includes a needle (110) and associated syringe-like body (108), plural pairs of pressure transducers (120-122 and 126-128) and associated calculation circuitry (40) to determine the pressure drop at different flow rates so that blood viscosity can be calculated therefrom.
Abstract:
The invention concerns a method for measuring at least one dimension of a conductive volume, in which a measuring sensor (10) is placed inside a cavity present in a conductive or non-conductive homogeneous body (11), this cavity having large dimensions and high resistivity compared to the respective dimensions and resistivity of the volume to be measured, the sensor having features which vary according to the immediate volume in which it is found, this medium being a medium with electromagnetic losses. The invention also concerns a device for implementing this method.
Abstract:
A removable implanted device (10) is provided which monitors the blood flow in a vessel (22) and can be removed through the insertion wound (20) without additional surgery. The device has an elongated probe body (12) which contains a Doppler-type ultrasonic transducer (40) attached to the probe body at an angle so as to enable monitoring of blood flow when attached to the vessel (22). The device has a flexible tube (18) which extends out of the body through the insertion wound (20). The device is held in place against the vessel (22) by sutures (38) which are secured to the probe body (12) by a suture attachment wire (24, 26) which may be bent or looped to form two substantially equal lengths (24, 26). Alternate embodiments use a release wire (62) or a balloon (70) to secure the sutures (38) to the probe body (12).
Abstract:
An apparatus (20) for determining the instantaneous shear stress produced on a portion of the inner wall of a blood vessel (26) by the blood flow through that vessel comprises a tube (28) arranged longitudinally within the vessel (26) which has a pair of longitudinally spaced pressure transducers (34, 36) for measuring the pressure drop therein. Electronic circuitry (24) receives a signal from a sampling unit (22), and a signal indicative of the inner diameter of the blood vessel, and a signal indicative of the distance between the longitudinally spaced pressure transducers (34, 36) to calculate the instantaenous shear stress.