Apparatus for diagnosing lesion severity, and method therefor

• US 20020052553A1
• Filed: 10/17/2001
• Published: 05/02/2002
• Est. Priority Date: 10/19/2000
• Status: Active Grant

• Current Assignee: Florence Medical Limited
• Original Assignee: Florence Medical Limited
• Inventors: Dgany, Orly, Dgany, Elhanan, Shalman, Evgeny, Tymonkin, Alexander
• Granted Patent: US 6,558,334 B2
• Time in Patent Office: Days
• US Class Current: 600/486
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00

Abstract

Apparatus for diagnosing lesion severity of a lesion in an arterial lumen supplying blood to a muscle in its non-hyperemic state of a human subject based on processing information relating to the shape of the dicrotic notch of at least one pressure pulse of his proximal non-hyperemic pressure waveform and either the absence of dicrotic notches along his distal non-hyperemic pressure waveform or the shape of the dicrotic notch of at least one pressure pulse of his distal non-hyperemic pressure waveform if present to calculate the value of a PTC parameter indicative of the severity of the lesion.

Claims

1. Apparatus for diagnosing lesion severity of a lesion in an arterial lumen supplying blood to a muscle in its non-hyperemic state of a human subject, the apparatus comprising:

(a) an intravascular pressure measurement device for deployment adjacent the lesion in the arterial lumen supplying blood to the muscle in its nonhyperemic state;

(b) a pressure monitoring system connected to said intravascular pressure measurement device for measuring a non-hyperemic pressure waveform acquisitioned proximal to the lesion, and a non-hyperemic pressure waveform acquisitioned distal thereto, the former consisting of a series of pressure pulses each including a dicrotic notch, and the latter consisting of a series of pressure pulses each potentially including a dicrotic notch depending on the severity of the lesion; and

(c) a Pulse Transmission Coefficient (PTC) processor for processing information relating to the shape of the dicrotic notch of at least one pressure pulse of said proximal non-hyperemic pressure waveform and either the absence of dicrotic notches along said distal non-hyperemic pressure waveform or the shape of the dicrotic notch of at least one pressure pulse of said distal nonhyperemic pressure waveform if present to calculate the value of a PTC parameter indicative of the severity of the lesion.

2. Apparatus according to claim 1 wherein said PTC parameter is denoted PTC(E) where PTC(E) a Edistal/Eproximal, Edistal being the energy of the high frequency component of the dicrotic notch of a pressure pulse of the distal non-hyperemic pressure waveform and Eproximal being the energy of the high frequency component of the dicrotic notch of a pressure pulse of the proximal non-hyperemic pressure waveform.

3. Apparatus according to claim 2 wherein the energy of the high frequency component of the dicrotic notch of a pressure pulse is given by the standard deviation of dP(t) where dP(t)=P(t)−

Plow(t), P(t) being a measured pressure pulse and Plow(t) its low pass filtered derivative.

4. Apparatus according to claim 3 wherein said low pass filtered derivative Plow(t) contains between five to seven of the first harmonics of said measured pressure pulse P(t).

5. Apparatus according to claim 4 wherein said low pass filtered derivative Plow(t) contains the first six harmonics of said measured pressure pulse P(t).

6. Apparatus according to claim 1 wherein said PTC parameter is denoted PTC(A) where PTC(A) α

Adistal/Aproximal, Adistal being the area of the dicrotic notch of a pressure pulse of said distal non-hyperemic pressure waveform and Aproximal being the area of the dicrotic notch of a pressure pulse of said proximal non-hyperemic pressure waveform.

7. Apparatus according to claim 6 wherein the area of the dicrotic notch of a pressure pulse is approximated as the area of a triangle whose vertices lie thereon.

8. Apparatus according to claim 7 wherein the vertices of the triangle are as follows:

(T1,P1) where T1 corresponds to the occurrence of the first local post systolic minimum of the pressure pulse;

(Tnmax,Pnmax) corresponds to the occurrence of the local maximum pressure of the dicrotic notch; and

(T2,P2) where T2=T1+(Tmax−

T0)/3 where Tmax corresponds to the occurrence of maximum pressure Pmax of the pressure pulse, and T0 corresponds to the occurrence of minimum pressure.

9. A method for diagnosing lesion severity of a lesion in an arterial lumen supplying blood to a muscle in its non-hyperemic state of a human subject, the method comprising the steps of:

(a) deploying an intravascular pressure measurement device adjacent the lesion in the arterial lumen supplying blood to the muscle in its non-hyperemic state;

(b) measuring a non-hyperemic pressure waveform acquisitioned proximal to the lesion, and a non-hyperemic pressure waveform acquisitioned distal thereto, the former consisting of a series of pressure pulses each including a dicrotic notch, and the latter consisting of a series of pressure pulses each potentially including a dicrotic notch depending on the severity of the lesion; and

(c) processing information relating to the shape of the dicrotic notch of at least one pressure pulse of the proximal non-hyperemic pressure waveform and either the absence of the dicrotic notches along the distal non-hyperemic pressure waveform or the shape of the dicrotic notch of at least one pressure pulse of the distal non-hyperemic pressure waveform if present to calculate the value of a PTC parameter indicative of the severity of the lesion.

10. The method according to claim 9 wherein the PTC parameter is denoted PTC(E) where PTC(E) α

Edistal/Eproximal, Edistal being the energy of the high frequency component of the dicrotic notch of a pressure pulse of the distal nonhyperemic pressure waveform and Eproximal being the energy of the high frequency component of the dicrotic notch of a pressure pulse of the proximal non-hyperemic pressure waveform.

11. The method according to claim 10 wherein the energy of the high frequency component of the dicrotic notch of a pressure pulse is given by the standard deviation of dP(t) where dP(t)=P(t)−

Plow(t), P(t) being the measured pressure pulse and Plow(t) its low pass filtered derivative.

12. The method according to claim 11 wherein the low pass filtered derivative Plow(t) contains between five to seven the first harmonics of the measured pressure pulse P(t).

13. The method according to claim 12 wherein the low pass filtered derivative Plow(t) contains the first six harmonics of the measured pressure pulse P(t).

14. The method according to claim 9 wherein the PTC parameter is denoted PTC(A) where PTC(A) α

Adistal/Aproximal, Adistal being the area of the dicrotic notch of a pressure pulse of the distal non-hyperemic pressure waveform and Aproximal being the area of the dicrotic notch of a pressure pulse of the proximal non-hyperemic pressure waveform.

15. The method according to claim 14 wherein the area of the dicrotic notch of a pressure pulse is approximated as the area of a triangle whose vertices lie thereon.

16. The method according to claim 15 wherein the vertices of the triangle are as follows:

(T1,P1) where T1 corresponds to the occurrence of the first local post systolic minimum of the pressure pulse;

(Tnmax,Pnmax) corresponds to the occurrence of the local maximum pressure of the dicrotic notch; and

(T2,P2) where T2=T1+(Tmax−

T0)/3 where Tmax corresponds to the occurrence of maximum pressure Pmax of the pressure pulse, and TO corresponds to the occurrence of minimum pressure.