System for determining values of hemodynamic parameters for a lesioned blood vessel, processor therefor, and method therefor

• US 20030191400A1
• Filed: 04/14/2003
• Published: 10/09/2003
• Est. Priority Date: 01/19/2001
• Status: Abandoned Application

• Current Assignee: Florence Medical Limited
• Original Assignee: Florence Medical Limited
• Inventors: Ortenburg, Michael, Barak, Chen, Dgany, Orly, Dgany, Elhanan, Shalman, Evgeny, Tymonkin, Alexander
• Application Number:
  US10/412,335
• Publication Number:
  US 20030191400A1
• Time in Patent Office: Days
• US Class Current: 600/486
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00

Abstract

Quantification of the change in shape of the dicrotic notches of so-called distal pressure pulses acquired distal to a lesioned section of a lesioned blood vessel relative to the dicrotic notches of so-called proximal pressure pulses acquired proximal thereto enable determination of values of hemodynamic parameters. The envisaged hemodynamic parameters can include so-called Pulse Transmission Coefficients, non-hyperemic substitutes to the clinically accepted Fractional Flow Reserve and Coronary Flow Reserve indices, and a RC time constant indicative of the health of the vascular bed fed by a lesioned blood vessel.

Claims

1. A system for determining the values of hemodynamic parameters for a lesioned blood vessel, the system comprising:

(a) intravascular pressure measurement apparatus for acquiring pressure measurements in a blood vessel during continuous blood flow therethrough; and

(b) a processor for determining the value of at least one hemodynamic parameter based on the change in shape of the dicrotic notches of one or more distal pressure pulses acquired distal to a lesioned section of a lesioned blood vessel with respect to the dicrotic notches of one or more proximal pressure pulses acquired proximal to the lesioned section of the lesioned blood vessel.

4. The system according to claim 1 wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PTC(A) where

PTC(A) α

Adistal/Aproximal

where Adistal is the area of the dicrotic notch of a distal pressure pulse and Aproximal is the area of the dicrotic notch of a proximal pressure pulse.

5. The system according to claim 4 wherein the area of the dicrotic notch of a pressure pulse is approximated as the area of a triangle whose vertices lie thereon.

6. The system according to claim 5 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.

7. The system according to claim 1 wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PCT(B) where

PTC(B) α

(Adistalnotch/Adistalpulse)/(Aproximalnotch/Aproximalpulse)

where Adistalnotch is the area under the leading portion of a distal pressure pulse, and Adistalpulse is its entire area; and

Aproximalnotch is the area under the leading portion of a proximal pressure pulse, and Aproximalpulse is its entire area.

8. The system according to claim 7 wherein the leading portion of a pressure pulse is defined as being prior to the occurrence of its first local post systolic minimum.

9. The system according to claim 1 wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PCT(H) where

PTC(H) α

(Hdistalnotch/Hdistalpulse)/(Hproximalnotch/Hproximalpulse)

where Hdistalnotch is the height of the dicrotic notch of a distal pressure pulse, Hdistalpulse is its maximum height, Hproximalnotch is the height of the dicrotic notch of a proximal pressure pulse, and Hproximalpulse is its maximum height.

10. The system according to claim 9 wherein the height of the dicrotic notch of a pressure pulse is determined at its first local post systolic minimum.

11. The system according to claim 1 wherein the hemodynamic parameter is a non-hyperemic substitute Lesion Severity Index (LSI) for the Fractional Flow Reserve (FFR) index for a lesioned blood vessel, LSI being a function of non-hyperemic PTC and BPG values, and having a <

0.75 cutoff value indicative of the need for intervention.

12. The system according to claim 11 wherein LSI α

(a+bK_LBP+cK_LBP²) where K_LBPα

(log PTC)/BPG, and a, b and c are coefficients.

13. The system according to claim 12 wherein for PTC<

0.3;

LSI α

(a+bK_LBP+cK_LBP²)(d+eK_LBP) where d and e are also coefficients.

14. The system according to claim 12 wherein BPG α

BPG_diastolicmax/P_aortic where BPG_diastolicmax is the measured BPG value acquired at maximum diastole and P_aortic is the aortic pressure.

15. The system according to claim 1 wherein the hemodynamic parameter is a non-hyperemic substitute Lesion Severity Index (LSI_k) for the individual Fractional Flow Reserve (FFR) index for a k^th lesion of a multi-lesioned blood vessel in accordance with the relationship LSI_k α

(log PTC)/BPG_k where PTC is acquired across the entire lesioned section of the multi-lesioned blood vessel, and BPG_k is acquired across its k^th lesion.

16. The system according to claim 1 wherein the hemodynamic parameter is a non-hyperemic substitute for the Coronary Flow Reserve (CFR) index for a lesioned blood vessel, the non-hyperemic CFR value being a function of non-hyperemic PTC and BPG values determined therefrom, and having a <

2 cutoff value indicative of the need for intervention.

17. The system according to claim 1 wherein the hemodynamic parameter is a RC time constant for the vascular bed fed by the lesioned blood vessel being a function of non-hyperemic PTC and BPG values determined therefrom.

18. The system according to claim 15 wherein

RC time constant α

(a K_LBP+b)

where K_LBP=(log PTC)/BPG, and a and b are constants.

2. The system according to claim I wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PTC(E) where

PTC(E) α

Edistal/Eproximal

where Edistal is the energy of the high frequency component of the dicrotic notch of a distal pressure pulse and Eproximal is the energy of the high frequency component of the dicrotic notch of a proximal pressure pulse.

3. The system according to claim 2 wherein the energy of the high frequency component of a dicrotic notch 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.

19. For use with intravascular pressure measurement apparatus capable of acquiring pressure measurements in a blood vessel during continuous blood flow therethrough, a processor capable of executing the following steps:

(a) processing information relating to the shape of the dicrotic notches of one or more proximal pressure pulses acquired proximal to a lesioned section of a lesioned blood vessel;

(b) processing information relating to the shape of the dicrotic notches of one or more distal pressure pulses acquired distal to the lesioned section of the lesioned blood vessel; and

(c) determining the value of at least one hemodynamic parameter based on the change in shape of the dicrotic notches of one or more distal pressure pulses acquired distal to a lesioned section of a lesioned blood vessel with respect to the dicrotic notches of one or more proximal pressure pulses acquired proximal to the lesioned section of the lesioned blood vessel.

20. The processor according to claim 19 wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PTC(E) where

PTC(E) α

Edistal/Eproximal

where Edistal is the energy of the high frequency component of the dicrotic notch of a distal pressure pulse, and Eproximal is the energy of the high frequency component of the dicrotic notch of a proximal pressure pulse.

21. The processor according to claim 20 wherein the energy of the high frequency component of a dicrotic notch 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.

22. The processor according to claim 19 wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PTC(A) where

PTC(A) α

Adistal/Aproximal

where Adistal is the area of the dicrotic notch of a distal pressure pulse, and Aproximal is the area of the dicrotic notch of a proximal pressure pulse.

23. The processor according to claim 22 wherein the area of the dicrotic notch of a pressure pulse is approximated as the area of a triangle whose vertices lie thereon.

24. The processor according to claim 23 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.

25. The processor according to claim 19 wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PCT(B) where

PTC(B) α

(Adistalnotch/Adistalpulse)/(Aproximalnotch/Aproximalpulse)

where Adistalnotch is the area under the leading portion of a distal pressure pulse, and Adistalpulse is its entire area; and

Aproximalnotch is the area under the leading portion of a proximal pressure pulse, and Aproximalpulse is its entire area.

26. The processor according to claim 25 wherein the leading portion of a pressure pulse is defined as being prior to the occurrence of its first local post systolic minimum.

27. The processor according to claim 19 wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PCT(H) where

PTC(H) α

(Hdistalnotch/Hdistalpulse)/(Hproximalnotch/Hproximalpulse)

where Hdistalnotch is the height of the dicrotic notch of a distal pressure pulse, Hdistalpulse is its maximum height Hproximalnotch is the height of the dicrotic notch of a proximal pressure pulse, and Hproximalpulse is its maximum height.

28. The processor according to claim 27 wherein the height of the dicrotic notch of a pressure pulse is determined at its first local post systolic minimum.

29. The processor according to claim 19 wherein the hemodynamic parameter is a non-hyperemic substitute Lesion Severity Index (LSI) for the Fractional Flow Reserve (FFR) index for a lesioned blood vessel, LSI being a function of non-hyperemic PTC and BPG values, and having a <

0.75 cutoff value indicative of the need for intervention.

30. The processor according to claim 29 wherein LSI α

(a+bK_LBP+cK_LBP²) where K_LBP α

(log PTC)/BPG, and a, b and c are coefficients.

31. The processor according to claim 30 wherein for PTC<

0.3;

LSI α

(a+bK_LBP+cK_LBP²)(d+eK_LBP) where d and e are also coefficients.

32. The processor according to claim 30 wherein BPG α

BPG_diastolicmax/P_aortic where BPG_diastolicmax is the measured BPG value acquired at maximum diastole and P_aortic is the aortic pressure.

33. The processor according to claim 19 wherein the hemodynamic parameter is a non-hyperemic substitute Lesion Severity Index (LSI_k) for the individual Fractional Flow Reserve (FFR) index for a k^th lesion of a multi-lesioned blood vessel in accordance with the relationship LSI_k α

(log PTC)/BPG_k where PTC is acquired across the entire lesioned section of the multi-lesioned blood vessel, and BPG_k is acquired across its k^th lesion.

34. The processor according to claim 19 wherein the hemodynamic parameter is a non-hyperemic substitute for the Coronary Flow Reserve (CFR) index for a lesioned blood vessel, the non-hyperemic CFR value being a function of non-hyperemic PTC and BPG values determined therefrom, and having a <

2 cutoff value indicative of the need for intervention.

35. The processor according to claim 19 wherein the hemodynamic parameter is a RC time constant for the vascular bed fed by the lesioned blood vessel as a function of non-hyperemic PTC and BPG values determined therefrom.

36. The processor according to claim 35 wherein

RC time constant α

(a K_LBP+b)

where K_LBP=(log PTC)/BPG, and a and b are constants.

37. A method for determining the values of hemodynamic parameters for a lesioned blood vessel, the method comprising the steps of

(a) deploying an intravascular pressure measurement apparatus for acquiring pressure measurements in a blood vessel during continuous blood flow therethrough;

and

(b) determining the value of at least one hemodynamic parameter based on the change in shape of the dicrotic notches of one or more distal pressure pulses acquired distal to a lesioned section of a lesioned blood vessel with respect to the dicrotic notches of one or more proximal pressure pulses acquired proximal to the lesioned section of the lesioned blood vessel.

38. The method according to claim 37 wherein the hemodynamic dynamic is a Pulse Transmission Coefficient index PTC(E) where

PTC(E) α

Edistal/Eproximal

where Edistal is the energy of the high frequency component of the dicrotic notch of a distal pressure pulse, and Eproximal is the energy of the high frequency component of the dicrotic notch of a proximal pressure pulse.

39. The method according to claim 38 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.

40. The method according to claim 37 wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PTC(A) where

PTC(A) α

Adistal/Aproximal

where Adistal is the area of the dicrotic notch of a distal pressure pulse, and Aproximal is the area of the dicrotic notch of a proximal pressure pulse.

41. The method according to claim 40 wherein the area of the dicrotic notch of a pressure pulse is approximated as the area of a triangle whose vertices lie thereon.

42. The method according to claim 41 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.

43. The method according to claim 37 wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PCT(B) where

PTC(B) α

(Adistalnotch/Adistalpulse)/(Aproximalnotch/Aproximalpulse)

where Adistalnotch is the area under the leading portion of a distal pressure pulse, and Adistalpulse is its entire area; and

Aproximalnotch is the area under the leading portion of a proximal pressure pulse, and Aproximalpulse is its entire area.

44. The method according to claim 43 wherein the leading portion of a pressure pulse is defined as being prior to the occurrence of its first local post systolic minimum.

45. The method according to claim 37 wherein the hemodynamic parameter is a Pulse Transmission Coefficient index PCT(H) where

PTC(H) α

(Hdistalnotch/Hdistalpulse)/(Hproximalnotch/Hproximalpulse)

where Hdistalnotch is the height of the dicrotic notch of a distal pressure pulse, Hdistalpulse is its maximum height, Hproximalnotch is the height of the dicrotic notch of a proximal pressure pulse, and Hproximalpulse is its maximum height.

46. The method according to claim 45 wherein the height of the dicrotic notch of a pressure pulse is determined at its first local post systolic minimum.

47. The method according to claim 37 wherein the hemodynamic parameter is a non-hyperemic substitute Lesion Severity Index (LSI) for the Fractional Flow Reserve (FFR) index for a lesioned blood vessel, LSI being a function of non-hyperemic PTC and BPG values, and having a <

0.75 cutoff value indicative of the need for intervention.

48. The method according to claim 47 wherein LSI α

(a+bK_LBP+cK_LBP²) where K_LBP α

(log PTC)/BPG, and a, b and c are coefficients.

49. The method according to claim 48 wherein for PTC<

0.3;

LSI α

(a+bK_LBP+cK_LBP²)(d+eK_LBP) where d and e are also coefficients.

50. The method according to claim 48 wherein BPG α

BPG_diastolicmax/P_aortic where BPG_diastolicmax is the measured BPG value acquired at maximum diastole and P_aortic is the aortic pressure.

51. The method according to claim 37 wherein the hemodynamic parameter is a non-hyperemic substitute Lesion Severity Index (LSI_k) for the individual Fractional Flow Reserve (FFR) index for a k^th lesion of a multi-lesioned blood vessel in accordance with the relationship LSI_k=(log PTC)/BPG_k where PTC is acquired across the entire lesioned section of the multi-lesioned blood vessel, and BPG_k is acquired across its k^th lesion.

52. The method according to claim 37 wherein the hemodynamic parameter is a non-hyperemic substitute for the Coronary Flow Reserve (CFR) index for a lesioned blood vessel, the non-hyperemic CFR value being a function of non-hyperemic PTC and BPG values determined therefrom, and having a <

2 cutoff value indicative of the need for intervention.

53. The method according to claim 37 wherein the hemodynamic parameter is a RC time constant for the vascular bed fed by the lesioned blood vessel as a function of non-hyperemic PTC and BPG values determined therefrom.

54. The method according to claim 53 wherein

RC time constant α

(a K_LBP+b)

where K_LBP=(log PTC)/BPG, and a and b are constants.