WO1992015240A1 - Determining the instantaneous shear stress on the wall of a blood vessel - Google Patents

Determining the instantaneous shear stress on the wall of a blood vessel Download PDF

Info

Publication number
WO1992015240A1
WO1992015240A1 PCT/US1992/001429 US9201429W WO9215240A1 WO 1992015240 A1 WO1992015240 A1 WO 1992015240A1 US 9201429 W US9201429 W US 9201429W WO 9215240 A1 WO9215240 A1 WO 9215240A1
Authority
WO
WIPO (PCT)
Prior art keywords
blood
instantaneous
sensor means
vessel
shear stress
Prior art date
Application number
PCT/US1992/001429
Other languages
French (fr)
Inventor
Young Cho
Kenneth Kensey
Original Assignee
Kensey Nash Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kensey Nash Corporation filed Critical Kensey Nash Corporation
Publication of WO1992015240A1 publication Critical patent/WO1992015240A1/en

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/02028—Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
    • A61B5/02035—Determining blood viscosity
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/026—Measuring blood flow
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/026—Measuring blood flow
    • A61B5/0275—Measuring blood flow using tracers, e.g. dye dilution

Definitions

  • This invention relates generally to medical instruments for and methods of determining the instantaneous shear stress produced on the wall of a blood vessel of a living being by the flow of blood through that vessel.
  • the apparatus basically comprises sampling means arranged to be disposed within the blood vessel for monitoring a portion of the being's blood at substantially the time that that portion of the blood is flowing through the blood vessel.
  • the sampling means comprises first means, e.g., a pair of solid state transducers, for determining a pressure differential between two longitudinally spaced apart points in the vessel. From that determination and with the inner diameter of the blood vessel known the instantaneous shear stress can be calculated.
  • first means e.g., a pair of solid state transducers
  • the instantaneous shear stress can be calculated.
  • means are provided responsive to the sampling means to utilize a second signal indicative of the inner diameter of the blood vessel and a third signal indicative of the distance between the longitudinally spaced apart points for calculating the instantaneous shear stress.
  • FIG. 1 is a sectional view, partially schematic, showing an implantable apparatus constructed in accordance with this invention for effecting in-vivo determination of the shear stress produced by the flow of blood through a blood vessel of a living being;
  • Fig. 2 is an enlarged sectional view taken along lines 2-2 of Fig. 1.
  • Fig. 1 apparatus constructed in accordance with the subject invention.
  • the apparatus 20 is arranged for effecting the in-vivo measurement of the instantaneous shear stress produced on the wall of a blood vessel, e.g., artery, of a living being by the flow of the blood therethrough.
  • a blood vessel e.g., artery
  • the apparatus 20 basically comprises a pair of components, namely, an implantable monitor unit 22, and an associated externally located control/analysis unit 24.
  • the monitor unit 22 will be described in detail later. Suffice it for now to state that it is arranged to be implanted within a suitable blood vessel 26, e.g., femoral artery, of the being.
  • the monitor unit includes electrical leads, to be described later, connecting it to the control/analysis unit 24. That unit is arranged to be located outside the body of the being and serves to provide electrical signals to the monitor unit and to receive electrical signals therefrom. These signals are used by the control/analysis unit to calculate the instantaneous shear stress on the blood vessel wall. In particular the shear stress is readily calculated by the control/analysis unit 24 using software in it, without requiring manual interaction.
  • the monitor unit 22 basically comprises a small diameter, e.g., 8 or 9 mm, outside diameter, tube 28 formed of any material, e.g., stainless steel, suitable for location within the interior 30 being's blood vessel 26.
  • the tube is preferably of very thin wall thickness, e.g., 0.5 mm, and its distal end 32 is tapered so that blood can flow readily into its interior without interference by the distal end of the tube.
  • a pair of solid state, e.g., piezoelectric crystal, pressure transducers 34 and 36 are located within the sidewall of the tube 28 and are flush with the inner surface thereof.
  • the transducers are longitudinally spaced from each other by a fixed, predetermined distance L, e.g., 2 cm.
  • Each transducer is electrically coupled, via an associated conductor 38, to the control/ analysis unit 24 to provide signals indicative of the drop in the pressure of the blood in the distance L between the two transducers. These signals, are provided to a computer and signal processor 40 forming a portion of the control/analysis unit 24.
  • the computer and signal processor 40 can be of any suitable construction, e.g., a microprocessor and associated storage means, having software in it to effect the calculation of the viscosity from the electrical signals provided to it.
  • Those electrical signals constitute the pressure drop signals provided from the transducers 34 and 36, and other electrical signals indicative of the instantaneous velocity of the blood adjacent the pressure transducers (to be described later) .
  • the signals indicative of the instantaneous velocity of the blood flowing through the tube 28 adjacent the transducers is provided by velocity sensing probe means 42 in the unit 22 and an associated velocity probe controller 44 located in the external unit 24.
  • the velocity sensing probe means 42 basically comprises a pair of electrical resistance heating probes 46 and 48 projecting a short distance, e.g., 2 mm, radially inward into the interior of the tube 28 from the inner surface thereof.
  • the probes are longitudinally spaced apart from each other by a predetermined distance, e.g., 2 cm.
  • Each of the probes is connected via a pair of conductors 50 and 52 (although only one of each is shown in the interest of drawing simplicity) to the probe velocity controller 44.
  • the probe velocity controller provides an electrical signal via conductors 50 to the distally located probe 46 to cause that, probe to heat up quickly and thereby produce a heat pulse in the portion of the blood flowing thereby.
  • the propagation of the heat pulse to the proximally located probe 48 resulting from the flow of the heated blood portion thereby is sensed by that probe and a signal indicative thereof is provided via conductors 52 to the probe velocity controller 44.
  • the controller 44 measures the delay or propagation time for the heat pulse produced in the blood of the distal probe to reach the proximal probe and provides output signals via lines 54 to the computer and signal processor 40 to enable the instantaneous velocity of the blood, V, to be calculated thereby.
  • the computer and signal processor 40 has stored therein data representing the distance separating the probes 46 and 48. From the instantaneous blood velocity, V, the computer and signal processor calculates the instantaneous flow rate, Q of the blood. To achieve that end the computer and signal processor 40 also has stored therein data representing the value of inner diameter D of the tube 28.
  • the instantaneous flow rate, Q is calculated by the following formula:
  • the computer and signal processor 40 also has stored therein data representing the value of the distance L separating the transducers 34 and 36. That data, together with the calculated instantaneous flow rate Q of the blood enables the computer and signal processor 40 to calculate the viscosity of the blood.
  • the shear stress on the blood vessel's inner wall is then readily calculated by the computer and signal processor in accordance with the following formula:
  • the computer and signal processor can calculate the instantaneous shear stress on the blood vessel's inner wall in accordance with the following formula:

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Cardiology (AREA)
  • Biomedical Technology (AREA)
  • Medical Informatics (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Physiology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Physics & Mathematics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Hematology (AREA)
  • Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)

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.

Description

DETERMINING THE INSTANTANEOUS SHEAR STRESS ON THE WALL OF A BLOOD VESSEL
Field of the Invention
This invention relates generally to medical instruments for and methods of determining the instantaneous shear stress produced on the wall of a blood vessel of a living being by the flow of blood through that vessel.
Background Art
Conventional wisdom in the medical community used to be that heart attacks and strokes were primarily attributable to severe narrowing of the arteries due to vascular disease, e.g. , atherosclerosis and/or arteriosclerosis. However, it has been found that even in some patient's free of substantial arterial disease, or other high risk factors, e.g., high cholesterol, high blood pressure, etc. , the risk of heart attack/stroke is still great. Thus, today many investigators are focussing upon the blood's constituents, physical characteristics, and it effects (sometimes referred to as "hemodynamic effects") upon the vascular system and associated organs to identify heart attack/ stroke risk factors and from that knowledge develop effective therapy. Moreover, hemodynamic effects of the blood may, per se, play a role in the etiology of arterial disease.
Thus, one characteristic of the blood now being investigated from a hemodynamic standpoint to determine its affect on vascular disease and the risk of heart attack and/or stroke is the effect of the instantaneous shear stress on the blood vessel wall.
Objects of the Invention
Accordingly, it is the general object of this invention to provide apparatus and method of determining the instantaneous shear stress produced on the wall of a blood vessel by the blood of a living being.
It is a further object of this invention to provide apparatus and methods of determining the instantaneous shear stress produced on the wall of a blood vessel of a living being by the flow of blood therethrough via the use of an implantable device.
It is still a further object of this invention to provide apparatus to effect the in-vivo determination of the instantaneous shear stress produced on the wall of a blood vessel of a living being by the flow of blood therethrough via the use of an implantable device which is simple in construction, and easy to use and accurate.
Summary of the Invention These and other objects of the instant invention are achieved by providing apparatus and a method for determining the instantaneous shear stress produced on the wall of a blood vessel by the flow blood thereby.
The apparatus basically comprises sampling means arranged to be disposed within the blood vessel for monitoring a portion of the being's blood at substantially the time that that portion of the blood is flowing through the blood vessel.
In one preferred embodiment the sampling means comprises first means, e.g., a pair of solid state transducers, for determining a pressure differential between two longitudinally spaced apart points in the vessel. From that determination and with the inner diameter of the blood vessel known the instantaneous shear stress can be calculated. Thus, in accordance with that embodiment means are provided responsive to the sampling means to utilize a second signal indicative of the inner diameter of the blood vessel and a third signal indicative of the distance between the longitudinally spaced apart points for calculating the instantaneous shear stress.
Brief Description of the Drawings Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein: Fig. 1 is a sectional view, partially schematic, showing an implantable apparatus constructed in accordance with this invention for effecting in-vivo determination of the shear stress produced by the flow of blood through a blood vessel of a living being; and
Fig. 2 is an enlarged sectional view taken along lines 2-2 of Fig. 1.
Detailed Description of the Preferred Embodiment
Referring now in detail to the drawing wherein like reference characters refer to like parts, there is shown at 20 in Fig. 1 apparatus constructed in accordance with the subject invention. The apparatus 20 is arranged for effecting the in-vivo measurement of the instantaneous shear stress produced on the wall of a blood vessel, e.g., artery, of a living being by the flow of the blood therethrough.
The apparatus 20 basically comprises a pair of components, namely, an implantable monitor unit 22, and an associated externally located control/analysis unit 24.
The monitor unit 22 will be described in detail later. Suffice it for now to state that it is arranged to be implanted within a suitable blood vessel 26, e.g., femoral artery, of the being. The monitor unit includes electrical leads, to be described later, connecting it to the control/analysis unit 24. That unit is arranged to be located outside the body of the being and serves to provide electrical signals to the monitor unit and to receive electrical signals therefrom. These signals are used by the control/analysis unit to calculate the instantaneous shear stress on the blood vessel wall. In particular the shear stress is readily calculated by the control/analysis unit 24 using software in it, without requiring manual interaction.
The monitor unit 22 basically comprises a small diameter, e.g., 8 or 9 mm, outside diameter, tube 28 formed of any material, e.g., stainless steel, suitable for location within the interior 30 being's blood vessel 26. The tube is preferably of very thin wall thickness, e.g., 0.5 mm, and its distal end 32 is tapered so that blood can flow readily into its interior without interference by the distal end of the tube.
A pair of solid state, e.g., piezoelectric crystal, pressure transducers 34 and 36 are located within the sidewall of the tube 28 and are flush with the inner surface thereof. The transducers are longitudinally spaced from each other by a fixed, predetermined distance L, e.g., 2 cm. Each transducer is electrically coupled, via an associated conductor 38, to the control/ analysis unit 24 to provide signals indicative of the drop in the pressure of the blood in the distance L between the two transducers. These signals, are provided to a computer and signal processor 40 forming a portion of the control/analysis unit 24. The computer and signal processor 40 can be of any suitable construction, e.g., a microprocessor and associated storage means, having software in it to effect the calculation of the viscosity from the electrical signals provided to it. Those electrical signals constitute the pressure drop signals provided from the transducers 34 and 36, and other electrical signals indicative of the instantaneous velocity of the blood adjacent the pressure transducers (to be described later) .
The signals indicative of the instantaneous velocity of the blood flowing through the tube 28 adjacent the transducers is provided by velocity sensing probe means 42 in the unit 22 and an associated velocity probe controller 44 located in the external unit 24. The velocity sensing probe means 42 basically comprises a pair of electrical resistance heating probes 46 and 48 projecting a short distance, e.g., 2 mm, radially inward into the interior of the tube 28 from the inner surface thereof. The probes are longitudinally spaced apart from each other by a predetermined distance, e.g., 2 cm. Each of the probes is connected via a pair of conductors 50 and 52 (although only one of each is shown in the interest of drawing simplicity) to the probe velocity controller 44. The probe velocity controller provides an electrical signal via conductors 50 to the distally located probe 46 to cause that, probe to heat up quickly and thereby produce a heat pulse in the portion of the blood flowing thereby. The propagation of the heat pulse to the proximally located probe 48 resulting from the flow of the heated blood portion thereby is sensed by that probe and a signal indicative thereof is provided via conductors 52 to the probe velocity controller 44.
The controller 44 measures the delay or propagation time for the heat pulse produced in the blood of the distal probe to reach the proximal probe and provides output signals via lines 54 to the computer and signal processor 40 to enable the instantaneous velocity of the blood, V, to be calculated thereby. To achieve that end the computer and signal processor 40 has stored therein data representing the distance separating the probes 46 and 48. From the instantaneous blood velocity, V, the computer and signal processor calculates the instantaneous flow rate, Q of the blood. To achieve that end the computer and signal processor 40 also has stored therein data representing the value of inner diameter D of the tube 28.
The instantaneous flow rate, Q, is calculated by the following formula:
Q = πVD2 4
The computer and signal processor 40 also has stored therein data representing the value of the distance L separating the transducers 34 and 36. That data, together with the calculated instantaneous flow rate Q of the blood enables the computer and signal processor 40 to calculate the viscosity of the blood. In particular the instantaneous blood viscosity, η , is calculated by the computer and signal processor 40 in accordance with the following formula, where D is the inner diameter of the tube 28, *P is the pressure drop between transducers 34 and 36, L is the distance between the transducers, and Q is the instantaneous blood volume flow rate: n = ' °4 AP 128 LQ
The shear stress on the blood vessel's inner wall is then readily calculated by the computer and signal processor in accordance with the following formula:
Figure imgf000008_0001
Alternatively the computer and signal processor can calculate the instantaneous shear stress on the blood vessel's inner wall in accordance with the following formula:
Figure imgf000008_0002
Without further elaboration, the forgoing will so fully illustrate our invention that others may, by applying current or future knowledge, readily adopt the same for use under various conditions of service.

Claims

CLAIMS What is claimed is:
1. Apparatus for determining the instantaneous shear stress produced on a portion of the inner wall of a blood vessel of a living being by the flow of blood past said wall portion, said apparatus comprising sampling means and means responsive thereto, said sampling means being arranged to be disposed within said blood vessel for monitoring a portion of the being's blood at substantially the time that that portion of the blood is flowing through the blood vessel to provide a first signal, said means responsive being coupled to said sampling means for utilizing said first signal to determine said instantaneous shear stress.
2. The apparatus of Claim l wherein said sampling means comprises first means for determining a pressure differential between two longitudinally spaced apart points in said vessel and wherein said first signal is representative of said pressure differential.
3. The apparatus of Claim 2 wherein said means responsive is arranged to utilize signals indicative of the inner diameter of said blood vessel and the distance between said longitudinally spaced apart points for calculating said instantaneous shear stress.
4. The apparatus of Claim 2 wherein said first means comprises a pair of solid state transducers.
5. The apparatus of Claim 3 wherein said first means comprises a pair of solid state transducers.
6. The apparatus of Claim 3 wherein said means responsive provides an electrical output signal indicative of said instantaneous shear stress.
7. The apparatus of Claim 4 wherein said means responsive provides an electrical output signal indicative of said instantaneous shear stress.
8. The apparatus of Claim 5 wherein said means responsive provides an electrical output signal indicative of said instantaneous shear stress.
9. The apparatus of Claim 4 wherein said sampling means comprises a tubular member having a longitudinal axis and being of sufficiently small diameter that it may be located within said vessel with said longitudinal axis extending longitudinally within said vessel, said pressure transducers being located within said tubular member.
10. The apparatus of Claim 5 wherein said sampling means comprises a tubular member having a longitudinal axis and being of sufficiently small diameter that it may be located within said vessel with said longitudinal axis extending longitudinally within said vessel, said pressure transducers being located within said tubular member.
11. The apparatus of Claim 10 wherein said tubular member includes an inner surface and wherein said pressure transducers are mounted within said tubular member flush with said inner surface.
12. The apparatus of Claim 11 wherein said tubular member includes an inner surface and wherein said pressure transducers are mounted within said tubular member flush with said inner surface.
13. The apparatus of Claim 2 wherein said sampling means comprises additional means for determining the instantaneous velocity of said blood and for providing a signal indicative thereof, said means responsive being arranged to utilize said signal indicative of said instantaneous velocity to calculate the viscosity of said blood, whereupon from the calculated viscosity of said blood and a signal indicative of the inner diameter of said blood vessel said means responsive calculates said instantaneous shear stress.
14. The apparatus of Claim 13 wherein said first means comprises a pair of solid state transducers.
15. The apparatus of Claim 13 wherein said means responsive provides an electrical output signal indicative of said instantaneous shear stress.
16. The apparatus of Claim 15 wherein said means responsive provides an electrical output signal indicative of said instantaneous shear stress.
17. The apparatus of Claim 13 wherein said sampling means comprises a tubular member having a longitudinal axis and being of sufficiently small diameter that it may be located within said vessel with said longitudinal axis extending longitudinally within said vessel, said pressure transducers being located within said tubular member.
18. The apparatus of Claim 14 wherein said sampling means comprises a tubular member having a longitudinal axis and being of sufficiently small diameter that it may be located within said vessel with said longitudinal axis extending longitudinally within said vessel, said pressure transducers being located within said tubular member.
19. The apparatus of Claim 17 wherein said tubular member includes an inner surface and wherein said pressure transducers are mounted within said tubular member flush with said inner surface.
20. The apparatus of Claim 18 wherein said tubular member includes an inner surface and wherein said pressure transducers are mounted within said tubular member flush with said inner surface.
21. The apparatus of Claim 13 wherein said additional means comprises first sensor means for providing a signal at a time that a first portion of said blood passes thereby, and second sensor means located downstream of said first sensor means, said second sensor means for providing a signal when said first blood portion passes thereby, said means responsive operating on said signals to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
22. The apparatus of Claim 14 wherein said additionnal means comprises first sensor means for providing a signal at a time that a first portion of said blood passes thereby, and second sensor means located downstream of said first sensor means, said second sensor means for providing a signal when said first blood portion passes thereby, said means responsive operating on said signals to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
23. The apparatus of Claim 15 wherein said additional means comprises first sensor means for providing a signal at a time that a first portion of said blood passes thereby, and second sensor means located downstream of said first sensor means, said second sensor means for providing a signal when said first blood portion passes thereby, said means responsive operating on said signals to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
24. The apparatus of Claim 16 wherein said additional means comprises first sensor means for providing a signal at a time that a first portion of said blood passes thereby, and second sensor means located downstream of said first sensor means, said second sensor means for providing a signal when said first blood portion passes thereby, said means responsive operating on said signals to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
25. The apparatus of Claim 17 wherein said additional means comprises first sensor means located within said tubular member for providing a signal at a time that a first portion of said blood passes thereby, and second sensor means located downstream of said first sensor means, said second sensor means for providing a signal when said first blood portion passes thereby, said means responsive operating on said signals to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
26. The apparatus of Claim 21 wherein said additional sensor means is arranged to provide a pulse of heat to said first portion of said blood as it flows thereby to heat said first blood portion and to provide a signal indicative thereof, and wherein said second sensor means is arranged to sense the passage of said heated blood portion thereby and to provide a signal indicative thereof, said means responsive operating on said signals to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
27. The apparatus of Claim 22 wherein said additional sensor means is arranged to provide a pulse of heat to said first portion of said blood as it flows thereby to heat said first blood portion and to provide a signal indicative thereof, and wherein said second sensor means is arranged to sense the passage of said heated blood portion thereby and to provide a signal indicative thereof, said means responsive operating on said signals to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
28. The apparatus of Claim 23 wherein said first sensor means is arranged to provide a pulse of heat to said first portion of said blood as it flows thereby to heat said first blood portion and to provide a signal indicative thereof, and wherein said second sensor means is arranged to sense the passage of said heated blood portion thereby and to provide a signal indicative thereof, said means responsive operating on said signals to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
29. The apparatus of Claim 24 wherein said first sensor means is arranged to provide a pulse of heat to said first portion of said blood as it flows thereby to heat said first blood portion and to provide a signal indicative thereof, and wherein said second sensor means is arranged to sense the passage of said heated blood portion thereby and to provide a signal indicative thereof, said means responsive operating on said signals to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
30. The apparatus of Claim 25 wherein said first sensor means is arranged to provide a pulse of heat to said first portion of said blood as it flows thereby to heat said first blood portion and to provide a signal indicative thereof, and wherein said second sensor means is arranged to sense the passage of said heated blood portion thereby and to provide a signal indicative thereof, said means responsive operating on said signals to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
31. A method of determining the instantaneous shear stress produced on a portion of the inner wall of a blood vessel of a living being by the flow blood by said wall portion, said method comprising inserting sampling means within said blood vessel to provide a first signal and utilizing said first signal to determine said instantaneous shear stress.
32. The method of Claim 31 wherein said sampling means is utilized for determining a pressure differential between two longitudinally spaced apart points in said vessel and for providing said first signal indicative thereof, said first signal being used to calculate said instantaneous shear stress.
33. The method of Claim 32 including the step of utilizing the inner diameter of said blood vessel portion and the distance between said longitudinally spaced epart points in said vessel for calculating said instantaneous shear stress.
34. The method of Claim 32 additionally comprising providing an output signal indicative of said instantaneous shear stress.
35. The method of Claim 33 additionally comprising providing an output signal indicative of said instantaneous shear stress.
36. The method of Claim 32 wherein said calculation of said instantaneous shear stress is effected by means disposed outside of said blood vessel.
37. The method of Claim 33 wherein said calculation of said instantaneous shear stress is effected by means disposed outside of said blood vessel.
38. The method of Claim 34 wherein said calculation of said instantaneous shear stress is effected by means disposed outside of said blood vessel.
39. The method of Claim 35 wherein said calculation of said instantaneous shear stress is effected by means disposed outside of said blood vessel.
40. The method of Claim 32 additionally comprises determining the instantaneous velocity of said blood and for providing an additional signal indicative thereof, utilizing said additional signal to calculate the viscosity of said blood, whereupon from the calculated viscosity of said blood and a signal indicative of the inner diameter of said blood vessel said instantaneous shear stress is calculated.
41. The method of Claim 40 wherein said calculation of said instantaneous shear stress is effected by means disposed outside of said blood vessel.
42. The method of Claim 40 wherein said instantan¬ eous velocity of said blood is determined by utilizing first sensor means located within said vessel for providing a signal at a time that a first portion of said blood passes thereby, and second sensor means located downstream of said first sensor means, said second sensor means for providing a signal when said first blood portion passes thereby.
43. The method of Claim 41 wherein said instantan¬ eous velocity of said blood is determined by utilizing first sensor means located within said vessel for providing a signal at a time that a first portion of said blood passes thereby, and second sensor means located downstream of said first sensor means, said second sensor means for providing a signal when said first blood portion passes thereby.
44. The method of Claim 42 including the steps of providing a pulse of heat to said first portion of said blood by said first sensor means as said blood flows thereby to heat said first blood portion and to provide a signal indicative thereof, sensing the passage of said heated blood portion by said second sensor means and providing a signal indicative thereof to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
45. The method of Claim 43 including the steps of providing a pulse of heat to said first portion of said blood by said first sensor means as said blood flows thereby to heat said first blood portion and to provide a signal indicative thereof, sensing the passage of said heated blood portion by said second sensor means and providing a signal indicative thereof to calculate the instantaneous blood velocity and from that the instantaneous flow rate.
PCT/US1992/001429 1991-03-04 1992-02-20 Determining the instantaneous shear stress on the wall of a blood vessel WO1992015240A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US66427491A 1991-03-04 1991-03-04
US664,274 1991-03-04

Publications (1)

Publication Number Publication Date
WO1992015240A1 true WO1992015240A1 (en) 1992-09-17

Family

ID=24665342

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1992/001429 WO1992015240A1 (en) 1991-03-04 1992-02-20 Determining the instantaneous shear stress on the wall of a blood vessel

Country Status (2)

Country Link
AU (1) AU1569492A (en)
WO (1) WO1992015240A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999015075A1 (en) * 1997-09-25 1999-04-01 Medtronic, Inc. Cardiac flow sensor

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2345716A1 (en) * 1976-03-27 1977-10-21 Weber Gerhard PROCESS FOR DETERMINING THE RHEOLOGICAL BEHAVIOR OF LIQUIDS FOR A MEDICAL OR PHARMACEUTICAL PURPOSE, AND APPARATUS FOR IMPLEMENTING THE PROCESS
WO1983003348A1 (en) * 1982-03-25 1983-10-13 Hood, Robert, Gordon Vascular prosthesis
EP0126931A2 (en) * 1983-04-21 1984-12-05 The Board Of Trustees Of The Leland Stanford Junior University Method and apparatus for measuring flow

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2345716A1 (en) * 1976-03-27 1977-10-21 Weber Gerhard PROCESS FOR DETERMINING THE RHEOLOGICAL BEHAVIOR OF LIQUIDS FOR A MEDICAL OR PHARMACEUTICAL PURPOSE, AND APPARATUS FOR IMPLEMENTING THE PROCESS
WO1983003348A1 (en) * 1982-03-25 1983-10-13 Hood, Robert, Gordon Vascular prosthesis
EP0126931A2 (en) * 1983-04-21 1984-12-05 The Board Of Trustees Of The Leland Stanford Junior University Method and apparatus for measuring flow

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JOURNAL OF PHYSICS E -SCIENTIFIC INSTRUMENTS vol. 13, no. 9, September 1980, LONDON (GB) pages 973 - 976; G.E. MILLER: 'Position sensitivity of hot-film shear probes' *
Sections 2, 4 and 5 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999015075A1 (en) * 1997-09-25 1999-04-01 Medtronic, Inc. Cardiac flow sensor

Also Published As

Publication number Publication date
AU1569492A (en) 1992-10-06

Similar Documents

Publication Publication Date Title
US20180064411A1 (en) Method and system for measuring pulmonary artery circulation information
CA1327388C (en) Noninvasive continuous mean arterial blood pressure monitor
US6471656B1 (en) Method and system for pressure based measurements of CFR and additional clinical hemodynamic parameters
US7818053B2 (en) Devices, systems and methods for plaque type determination
EP2661216B1 (en) Apparatus and method of assessing a narrowing in a fluid filled tube
US8715195B2 (en) System and method for accurate placement of a catheter tip in a patient
US8666472B2 (en) Arterial endothelial function measurement method and apparatus
US4664125A (en) Flow-occluding method for the diagnosis of heart conditions
US8165656B2 (en) Systems and methods for measuring pulse wave velocity with an intravascular device
WO1998035611A1 (en) Blood vessel cross-sectional area detector and compliance measurement device and method
WO2000053081A1 (en) A method and system for pressure based measurements of cfr and additional clinical hemodynamic parameters
US20030220577A1 (en) Methods and systems for distal recording of phonocardiographic signals
US20100152607A1 (en) Devices, systems, and methods for measuring parallel tissue conductance, luminal cross-sectional areas, fluid velocity, and/or determining plaque vulnerability using temperature
US5690115A (en) Detecting vascular stenosis in chronic hemodialysis patients
WO1997012545B1 (en) Apparatus and method for measuring an induced perturbation to determine a physiological parameter
WO1997012545A3 (en) Apparatus and method for measuring an induced perturbation to determine a physiological parameter
Kornet et al. Conductance method for the measurement of cross-sectional areas of the aorta
WO2000055579A2 (en) A system and method for detection and characterization of stenosis, blood vessels flow and vessel walls properties using vessel geometrical measurements
WO1992015239A1 (en) Apparatus and method for determining viscosity of the blood of a living being
EP0057681A1 (en) Apparatus and method for measuring blood vessel and cardiac characteristics
JP2002513309A (en) Method and apparatus for estimating pulmonary artery wedge pressure per beat
WO1999056612A1 (en) Apparatus and method for identification and characterization of lesions and therapeutic success by flow disturbances analysis
WO1992015240A1 (en) Determining the instantaneous shear stress on the wall of a blood vessel
WO1992015241A1 (en) Apparatus and method for determining in vivo the instantaneous velocity of the flow of blood in a living being
JP3092027B2 (en) Ventricular volume measuring method and catheter for measurement

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU BB BG BR CA FI HU JP KP KR LK MG MW NO RO RU SD

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE BF BJ CF CG CH CI CM DE DK ES FR GA GB GN GR IT LU MC ML MR NL SE SN TD TG

NENP Non-entry into the national phase

Ref country code: CA