Apparatus and method of assessing a narrowing in a fluid filled tube

Patent metadata

Field	Value
Publication number	US-10624544-B2
Application number	US-201715723182-A
Country	US
Kind code	B2
Filing date	Oct 3, 2017
Priority date	Jan 6, 2011
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

An apparatus and method of assessing a narrowing in a fluid filled tube having a fluid flow pressure wave having a backward-originating pressure component and a forward-originating pressure component without taking a flow velocity measurement, comprising: taking pressure measurements in the tube; separating the pressure components into the backward-originating pressure component and the forward-originating pressure component; identifying a time window when the differential of flow velocity (dU) is minimal or absent; and deriving the backward and forward pressure components for pressure measurements taken in at least the time window.

First claim

The invention claimed is:

1. A system of assessing a narrowing in a blood vessel, the system comprising:
at least one pressure-sensing probe sized and shaped for positioning within the blood vessel; and
a processor in communication with the at least one pressure-sensing probe, the processor configured to:
receive pressure measurements obtained by the at least one pressure-sensing probe positioned within the blood vessel not during hyperaemia; and
calculate a pressure ratio using the pressure measurements obtained during a wave free period to provide an assessment of a severity of the narrowing in the blood vessel, the wave free period corresponding to when a differential of flow velocity within a cardiac cycle is below a threshold.

2. The system of claim 1 , wherein a start of the wave free period occurs after a first characteristic of a pressure waveform of the received pressure measurements.

3. The system of claim 2 , wherein the first characteristic of the pressure waveform is a peak pressure.

4. The system of claim 2 , wherein an end of the wave free period occurs before a second characteristic of the pressure waveform of the received pressure measurements.

5. The system of claim 4 , wherein the second characteristic is an end of the pressure waveform.

6. The system of claim 1 , wherein the wave free period includes a time window between a peak pressure time (t Pmax ) and an end of pressure waveform time (t Pend ).

7. The system of claim 6 , wherein the time window extends from t Pmax +150 ms to t Pend −50 ms.

8. The system of claim 6 , wherein the time window is a mid-window between t Pmax and t Pend .

9. The system of claim 8 , wherein the time window is a mid ⅗ window between t Pmax and t Pend .

10. The system of claim 1 , wherein the wave free period has a length of at least 100 ms.

11. The system of claim 1 , wherein the wave free period has a predetermined duration.

12. The system of claim 1 , wherein the threshold of the differential of flow velocity (dU) is a predetermined deviation from zero.

13. The system of claim 12 , wherein the predetermined deviation is ±2×10 −4 .

14. The system of claim 1 , wherein the threshold of the differential of flow velocity (dU) is a percentage of a maximum differential of flow velocity (dU max ).

15. The system of claim 1 , wherein the threshold is 20% or less than a maximum differential of flow velocity (dU max ).

16. The system of claim 1 , wherein the at least one pressure-sensing probe comprises a pressure-sensing wire.

17. The system of claim 1 , wherein the at least one pressure-sensing probe comprises a pressure transducer.

18. The system of claim 1 , wherein the processor is in wired communication with the at least one pressure-sensing probe.

19. The system of claim 1 , wherein the processor is in wireless communication with the at least one pressure-sensing probe.

20. The system of claim 1 , wherein the processor is further configured to:
identify the wave free period based on the received pressure measurements.

Assignees

• Medsolve Ltd
• Imperial College Sci Tech & Medicine

Inventors

• Davies Helen
• Davies Justin

Classifications

• A61B5/0215 Primary

  by means inserted into the body · CPC title

• A61B5/7278

  Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals · CPC title

• A61B5/021 Primary

  Measuring pressure in heart or blood vessels · CPC title

• A61B5/02125

  of pulse wave propagation time · CPC title

• A61B5/103

  Measuring devices for testing the shape, pattern, {colour,} size or movement of the body or parts thereof, for diagnostic purposes (measuring instruments specially adapted for dentistry A61C19/04) · CPC title