Abstract: A housing for a sensor apparatus for investigating characteristics of a blood vessel comprises a base for holding one or more sensor components, at least one appendage joined to the base and capable of being attached to the blood vessel by means of thread, and an attachment point for pulling means, wherein the at least one appendage is shaped or fabricated so as to allow the pull-removal of the housing from the blood vessel without removal of the thread from the blood vessel.

Abstract: Pulsed ultrasound sensor 10, connected to means 11 for controlling its passage and positioning along and within an exogenous conduit 13 sited within a bodily tract 15 with access to the extracorporeal environment, transmits into a blood vessel 14 and times its acquisition of signals scattered from the blood flow F to probe two or more adjacent locations 16 and 18 within the blood vessel 14. Signals returned from the blood vessel (e.g. energy or Doppler shift due to blood flow F) can be monitored to align the transmission path of the sensor with the blood vessel axis (FIGS. 4 and 5). The apparatus can be used to measure cardiovascular parameters in a non-invasive, non-surgical manner with minimal intervention from a physician.

Abstract: A method and device for use in assessing the state of blood vessels within the human or animal body is provided. A vessel segment is identified for investigation, and at least one blood pressure responsive device is used to obtain pulse volume recordings of different sites, representing pressure at sites proximal and distal to the vessel segment. From the waveform signals obtained, Fourier transform spectra are determined for the respective sites and the transfer function between them is calculated. This is then analyzed to determine a clinically significant parameter, such as the integral of the transfer function, and this can be compared with a predetermined value to provide an indication as to the state of the vessel segment.

Abstract: The invention provides a probe and method for measuring parameters of fluid flow in a conduit within a human or animal body, with specific application to non-invasive measurement of the cross-sectional area of blood vessels, particularly the ascending aorta (24). A probe (1) contains an ultrasound transducer (2) and an acoustic reflector (4) drivable in an oscillatory manner by an electric motor (8). A narrow ultrasound beam (15) is directed downwardly via the suprasternal notch and swept by the reflector through an arc. The probe has an external dimension transverse to the ultrasound beam path which reduces substantially from the region of the transducer to the region where the beam exits the probe. The invention has application in monitoring cardiac output.

Abstract: The present invention relates to a device to allow access of a medical sensor probe to a selected location within a patient's body. A disposable elongated tubular sheath (2) is releasably attached at its closed distal end (10) to the wall of a blood vessel (1) during surgery. The sheath leads out of the patient's body and provides an access path through which a sensor probe, such as an ultrasound probe (3), can be introduced in order to allow monitoring of blood flow within the vessel. The probe can be easily removed and replaced without contamination. When monitoring is complete, the releasable attachment means are operated and the sheath can be pulled out of the patient's body without further surgery.

Abstract: A method and apparatus for measuring the cross-sectional area of blood vessels, particularly the ascending aorta, is provided. An ultrasound probe (20) producing a divergent beam is directed downwardly via the suprasternal notch (14) and Doppler signals from the moving blood in the aorta (11) are detected. Signal processing means determine the Doppler power at successive ranges and the resulting power curve is correlated against stored curves representing a range of known aorta cross-sectional areas to find the closest fit. The velocity is also measured from the Doppler signal and hence the cardiac output can be determined.

Abstract: A probe for use within a catheter is disclosed. The probe transducer portion is constructed of a crystal hollow cylinder with an inside lead attached to the inner surface of the crystal cylinder. One end of the outside lead is positioned close to the outer surface, in a plane tangential to the outer surface, and is coupled to the outer surface of the crystal cylinder by a thin sputtered layer of conductive material. The probe transducer also includes a layer of acoustically absorbing material on the proximal end of the crystal, and layer of acoustically coupling material on the distal end of the crystal cylinder. The transducer element simultaneously generates an axially oriented signal beam at one frequency and a radially oriented signal beam at 2 different frequency. The signal beams are analyzed to calculate the blood flow area and the blood flow velocity, the product of which is the blood flow rate.

Abstract: A probe for use within a catheter is disclosed. The probe transducer portion is constructed of a crystal hollow cylinder with an inside lead attached to the inner surface of the crystal cylinder. One end of the outside lead is positioned close to the outer surface, in a plane tangential to the outer surface, and is coupled to the outer surface of the crystal cylinder by a thin sputtered layer of conductive material. The probe transducer also includes a layer of acoustically absorbing material on the proximal end of the crystal, and layer of acoustically coupling material on the distal end of the crystal cylinder. The transducer element simultaneously generates an axially oriented signal beam at one frequency and a radially oriented signal beam at 2 different frequency. The signal beams are analyzed to calculate the blood flow area and the blood flow velocity, the product of which is the blood flow rate.

Abstract: A device for sensing blood flow in a human aorta and a method for its use. The device includes two arrays, each array including one or more ultrasonic transducers for transmitting and/or receiving ultrasonic pulses. By appropriate weighting and phasing of the two ultrasonic arrays, a wide beam for insonifying the entire aorta, and a narrow beam for insonifying only a portion of the interior of the aorta, are produced. In addition, signals from the arrays can be processed to produce a signal indicating the direction to move the device so that the wide beam insonifies the entire aorta and the narrow beam insonifies only an interior portion of the aorta. The direction-finding array can be made from sensors arranged in a north-south-east-west pattern or as four sectors of an annulus.