Haemodynamic data estimation

• US 20120123246A1
• Filed: 03/11/2010
• Published: 05/17/2012
• Est. Priority Date: 03/13/2009
• Status: Active Grant

• Current Assignee: BlueDop Medical Ltd.
• Original Assignee: BlueDop Medical Ltd.
• Inventors: King, David H., Al-Qaisi, Mohammed
• Granted Patent: US 10,966,617 B2
• Time in Patent Office: Days
• US Class Current: 600/419
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/0263 using NMR
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/4245 involving determining the position of the probe, e.g. with respect to an external reference frame or to the patient
• CPC Class Codes: G01R 33/56308 Characterization of motion or flow; Dynamic imaging

Abstract

Techniques exist for measuring local blood velocity of flow rate waveforms in, for example, mammalian vascular segments. A method and system for deriving information on disease in vascular segments, for example mean pressure, drop in mean pressure and/or hydraulic resistance, from such measured waveforms is described. The waveforms can, for example, be measured non-invasively using Doppler ultrasound or magnetic resonance techniques. Form factors (Vff, Pff) for the velocity waveform and the centreal arterial pressure are determined. Stenosis may be detected by detecting changes e.g in Vff/Pff.

Claims

1. A system for deriving haemodynamic data from a segment of a vascular system of a mammal including:

means for receiving a first signal representative of a velocity or flow rate waveform of blood flow in the segment;

means for deriving a first measure indicative of a shape of the velocity or flow rate waveform;

means for receiving a second signal representative of a second measure of shape of a pressure waveform originating from a heart of the mammal;

means for deriving the haemodynamic data based on the first and second measures; and

means for storing or displaying the haemodynamic data.

2. A system as claimed in claim 1 in which the first measure includes a ratio of a difference between a maximum and a minimum of the velocity or flow rate waveform to an average magnitude of the waveform.

3. A system as claimed in claim 1 further comprising:

means for deriving the haemodynamic data based on a ratio of the first and second measures.

4. A system as claimed in claim 3 including a pressure sensor for sensing a central pressure waveform and means for deriving the second measure of shape from the central pressure waveform.

5. A system as claimed in claim 3 including a pressure sensor for sensing a central systolic and diastolic pressure and means for deriving the second measure of shape of the pressure waveform based on the central systolic and diastolic pressure.

6. A system as claimed in claim 1 in which the measure or measures of shape are representative of an AC component of the waveform or waveforms relative to a mean DC magnitude of the waveform or waveforms.

7. A system as claimed in claim 1 including means for sensing the velocity or flow rate waveform.

8. A system as claimed in claim 7 including means for non-invasive measurement of the velocity or flow rate waveform by placing a probe on a location on the mammal.

9. A system as claimed in claim 8 including a Doppler ultrasound system for measuring the velocity or flow rate waveform.

10. A system as claimed in claim 8 including image capture device for capturing an image of at least part of the mammal and means for registering a location of the probe on the mammal with the image.

11. A system as claimed in claim 10 in which the probe includes an electromagnetic or visual marker adjacent to a sensing end of the probe.

12. A system as claimed in claim 10 including means for displaying an indication of the haemodynamic data on the image at the location.

13. A system as claimed in claim 1 including a magnetic resonance system and means for deriving a velocity/time or flow/time waveform from magnetic resonance data coupled to the means for deriving the velocity/time or flow/time waveform.

14. A system as claimed in claim 13 in which the magnetic resonance system is an imaging system, wherein the means for obtaining the velocity/time or flow/time waveform for a voxel or group of voxels of an image obtained by the magnetic resonance system and associating the haemodynamic data with the voxel or voxels.

15. A system as claimed in claim 1 in which the haemodynamic data includes a value representative of absolute mean pressure and/or a drop of mean pressure.

16. A system as claimed in claim 1 in which the haemodynamic data includes a value representative of resistance and the system includes means for estimating an average flow rate in the segment.

17. A system as claimed in claim 16 in which the value is a measure between a left side of the heart and a location at which the measures are taken.

18. A system as claimed in claim 16 in which the value is a measure between a location at which the measures are taken and the right side of the heart.

19. A system as claimed in claim 1 including means for obtaining and storing values for a quantity derived from the measures obtained at a plurality of measurement locations, in which the haemodynamic data includes a change in a quantity between locations.

20. A system as claimed in claim 19 in which the quantity includes one or more of mean pressure, a drop in mean pressure, a haemodynamic resistance of the arterial supply pathway, resistance of the vascular bed, a ratio of resistances upstream and downstream of a measurement location, resistance per unit length of blood vessel, and a measure of blood viscosity.

21. A system as claimed in claim 19 in which the quantity includes a ratio of the first and second measures.

22. A system as claimed in claim 1, in which the haemodynamic data includes a value representative of a ratio of mean ankle pressure and mean brachial pressure.

23. A system as claimed in claim 22, in which the value is calculated as an inverse of a sum of a ratio of the second measure to the first measure and unity.

24. A system as claimed in claim 1, in which the haemodynamic data includes one or more of a ratio of resistances upstream and downstream of a measurement location, resistance per unit length of blood vessel, and a measure of blood viscosity.

25. A system for estimating maximum energy output of a muscle of a subject including means for deriving a measure of shape of a central blood pressure waveform and a blood velocity/time or flow/time waveform in an artery supplying the muscle, means for comparing the measures and means for measuring an energy output rate related to a muscle'"'"'s activity responsive to a signal indicating that a ratio of the measures approaches or substantially equals unity.

26. A method for deriving information on the presence of a lesion in a vascular segment of a subject including:

receiving a signal representative of a velocity or flow rate waveform of blood flow in the segment;

deriving a first measure indicative of a first shape of the velocity or flow rate waveform;

receiving a signal representative of a second measure of a second shape of a pressure wave form originating from a heart of the subject;

deriving the information based on the first and second measures; and

storing or displaying the information.

27. A system for deriving haemodynamic data from a segment of a vascular system of a mammal including:

a first receiver for receiving a signal representative of a velocity or flow rate waveform of blood flow in the segment;

a processing unit deriving a first measure indicative of a shape of the velocity or flow rate waveform;

a second receiver for receiving a signal representative of a second measure of shape of a pressure waveform originating from a heart of the mammal;

the process deriving the haemodynamic data based on the first and second measures and storing or displaying the haemodynamic data.