Method and apparatus for endoscopic blood flow detection by the use of ultrasonic energy

Claim 1

A system for endoscopic detection of blood flow in intracorporeal blood vessels, said system comprising: (a) a catheter including an elongated tube having a longitudinal axis, said tube being constructed of flexible material and having a tip at one end, a cylindrical ultrasonic probe carried by said tube adjacent its tip, and flexible conductive means electrically connected to said probe and disposed within and extending along the length of said tube, said catheter being sized to pass through the biopsy channel of an endoscope, said proble providing an unfocused, radial ultrasonic field transverse to the longitudinal axis near the tip of said tube; (b) an isolation circuit means for providing electrical isolation and RFI suppression that is connected to said flexible conductive means; and, (c) a Doppler circuit connected to said isolation circuit means, said Doppler circuit including: a transmitting means and a receiving means coupled to said isolation circuit means, said transmitting means for providing a pulsed, high-frequency electrical signal to said ultrasonic probe that causes said probe to transmit a burst of ultrasonic energy, said receiving means for receiving and amplifying a high-frequency electrical signal produced by said probe as a result of returns of said transmitted burst of ultrasonic energy; means varying the gain of said receiving means with time, such that, said gain being substantially attenuated during said pulsed, high-frequency electrical signal from said transmitting means, said gain thereafter increasing at a variable rate to compensate for dispersion and attenuation losses of said ultrasonic energy, and said gain being thereafter substantially attenuated at a selectable time corresponding to a desired maximum range from said ultrasonic probe; means producing a Doppler signal from said received and amplified electrical signal; and, means filtering said Doppler signal to provide a filtered Doppler signal, said filtered Doppler signal containing either those frequencies produced by: primarily venous blood flow; by venous and arterial blood flow; or, by primarily arterial blood flow, said filtering means being selectable to produce any one of said filtered Doppler signals.

Claim 2

A system for endoscopic detection of blood flow in intracorporeal blood vessels, said system comprising: (a) a catheter including an elongated tube having a longitudinal axis, said tube being constructed of flexible material and having a tip at one end, a cylindrical ultrasonic probe carried by said tube adjacent its tip, and flexible conductive means electrically connected to said probe and disposed within and extending along the length of said tube, said catheter being sized to pass through the biopsy channel of an endoscope, said proble providing an unfocused, radial ultrasonic field transverse to the longitudinal axis near the tip of said tube; (b) an isolation circuit means for providing electrical isolation and RFI suppression that is connected to said flexible conductive means; and, (c) a Doppler circuit connected to said isolation circuit means, said Doppler circuit including: a transmitting means and a receiving means coupled to said isolation circuit means, said transmitting means for providing a pulsed, high-frequency electrical signal to said ultrasonic probe that causes said probe to transmit a burst of ultrasonic energy, said receiving means for receiving and amplifying a high-frequency electrical signal produced by said probe as a result of returns of said transmitted burst of ultrasonic energy; means varying the gain of said receiving means with time, such that, said gain being substantially attenuated during said pulsed, high-frequency electrical signal from said transmitting means, said gain thereafter increasing at a variable rate to compensate for dispersion and attenuation losses of said ultrasonic energy, and said gain being thereafter substantially attenuated at a selectable time corresponding to a desired maximum range from said ultrasonic probe; means producing a Doppler signal from said received and amplified electrical signal; and, means filtering said Doppler signal to provide a filtered Doppler signal, said filtered Doppler signal containing either those frequencies produced by: primarily venous blood flow; by venous and arterial blood flow; or, by primarily arterial blood flow, said filtering means being selectable to produce any one of said filtered Doppler signals.