Method for determining a cardiac function

• US 20090187110A1
• Filed: 01/23/2008
• Published: 07/23/2009
• Est. Priority Date: 01/23/2008
• Status: Active Grant

• Current Assignee: Cardiac Profiles, Inc.
• Original Assignee: Cardiac Profiles, Inc.
• Inventors: Voss, Gregory I., Sterling, Bernhard B., Lawrence, Andrew R., Perry, James M., Clinton, Rankin A. III
• Granted Patent: US 8,834,382 B2
• Time in Patent Office: Days
• US Class Current: 600/500
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence

Abstract

A method for determining a cardiac function, comprising (i) determining base anatomical characteristics associated with the subject, (ii) determining pulse delay to a first body site (PD₀₁) and a second body site (PD₀₂) as a function of the anatomical characteristics, wherein the distance via the arterial tree from the aortic valve to the first body site (PD₀₁) is different than the arterial tree distance from the aortic valve to the second body site (PD₀₂), (iii) determining pulse wave velocity between the first body site and the second body site (PWV₁₂), (iv) determining pulse wave velocity between the aortic valve and the first body site (PWV₀₁) as a function of PWV₁₂, and the anatomical characteristics; and (v) determining the pre-ejection period (PEP) as a function of PD₀₁ and PWV₀₁.

Claims

1. A method for determining a cardiac function associated with a subject, comprising the steps of:

determining base anatomical characteristics associated with the subject;

determining pulse delay to a first body site (PD₀₁) and a second body site (PD₀₂) as a function of the anatomical characteristics, wherein the distance via the arterial tree from the aortic valve to said first body site (PD₀₁) is different than the arterial tree distance from said aortic valve to said second body site (PD₀₂);

determining pulse wave velocity between said first body site and said second body site (PWV₁₂);

determining pulse wave velocity between said aortic valve and said first body site (PWV₀₁) as a function of said PWV₁₂, and said anatomical characteristics; and

determining the pre-ejection period (PEP) as a function of said PD₀₁ and PWV₀₁.

2. The method of claim 1, wherein said anatomical characteristics comprise the times required for a pressure wave to travel from said aortic valve to said first and second body sites, and said arterial tree distances from said aortic valve to said first and second body sites.

3. The method of claim 1, wherein said pulse delay to said first body site (PD₀₁) and said second body site (PD₀₂) is determined as a function of said anatomical characteristics and according to the following equations

PD₀₁=PEP+PTT₀₁

and

PD₀₂=PEP+PTT₀₂=PEP+PTT₀₁+(PTT₀₂−

PTT₀₁),

wherein PEP represents the pre-ejection period, PTT₀₁ represents the time required for a pressure wave to travel from the aortic valve to the first body site, PTT₀₂ represents the time required for a pressure wave to travel from the aortic valve to the second body site, and (PTT₀₂−

PTT₀₁) represents the time required for a pressure wave to travel from the first body site to the second body site.

4. The method of claim 3, wherein said pulse wave velocity within said arterial region between said first body site and said second body site (PWV₁₂)is determined according to the following equation

$\begin{array}{c}{\mathrm{PWV}}_{12}=\frac{D_{02}-D_{01}}{{\mathrm{PTT}}_{02}-{\mathrm{PTT}}_{01}}\\ =\frac{D_{02}-D_{01}}{({\mathrm{PD}}_{02}-P}\end{array}$



E 



P ) - ( PD 01 - P 



E 



P ) = D 02 - D 01 PD 02 - PD 01 ,

wherein D₀₁ represents said arterial tree distance from said aortic valve to said first body site, and D₀₂ represents said arterial tree distance from said aortic valve to said second body site.

5. The method of claim 1, wherein said pulse wave velocity between said aortic valve and said first body site (PWV₀₁) is determined according to the following equation

PWV₀₁=f(PWV₁₂, Patient)

wherein f(PWV₁₂, Patient) represents a patient dependant relationship between aortic pulse wave velocity and peripheral pulse wave velocity.

6. The method of claim 1, wherein said pulse wave velocity between said aortic valve and said first body site (PWV₀₁) is determined according to the following equation

PWV₀₁=PWV₁₂*α

_age

wherein α

_age represents an age dependant relationship between aortic pulse wave velocity and peripheral pulse wave velocity.

7. The method of claim 6, wherein said age dependant relationship between said aortic pulse wave velocity and said peripheral pulse wave velocity comprises a ratio of said aortic pulse wave velocity to said peripheral pulse wave velocity.

8. The method of claim 5, wherein said pre-ejection period (PEP) is determined according to the following equation

PEP=PD₀₁−

PTT₀₁,

wherein

$\hspace{1em}<br><br>\begin{array}{c}P<br><br><br><br>T<br><br><br><br>T_{01}=<br><br>\frac{D_{01}}{P<br><br><br><br>W<br><br><br><br>V_{01}}\\ =<br><br>\frac{D_{01}}{f<br><br>\left(P<br><br><br><br>W<br><br><br><br>V_{12},\mathrm{Patient}\right)}\\ =<br><br>\frac{D_{01}}{f<br><br>\left(\frac{D_{02}-D_{01}}{P<br><br><br><br>T<br><br><br><br>T_{02}-P<br><br><br><br>T<br><br><br><br>T_{01}},\mathrm{Patient}\right)}.\end{array}$

9. The method of claim 7, wherein said PEP is determined according to the following equation

$\hspace{1em}$

P 



E 



P = 

P 



D 01 - D 01 P 



W 



V 12 * α

age = 

P 



D 01 - D 01 D 02 - D 01 P 



D 02 - P 



D 01 * α

age = 

P 



D 01 - ( P 



D 02 - P 



D 01 ) * D 01 ( D 02 - D 01 ) * α

age .

10. A method of determining a cardiac function associated with a subject, comprising the steps of:

determining base anatomical characteristics associated with the subject;

determining pulse delay to a digit (PD_Digit) and an ear (PD_Ear) as a function of said anatomical characteristics;

determining peripheral pulse transit time (PTT_Peripheral) as a function of said PD_Digit and PD_Ear;

determining peripheral pulse wave velocity (PWV_Peripheral) as a function of said PTT_Peripheral and the arterial distances from the aortic valve to said digit and ear;

determining central pulse wave velocity (PWV_Central) as a function of said PWV_Peripheral and a standard ratio of PWV_Peripheral to PWV_Central (α

_v); and

determining the pre-ejection period (PEP) as a function of PWV_Central and the arterial said distance from said aortic valve to said ear.

11. The method of claim 10, wherein said base anatomical characteristics are selected from the group comprising the times required for a pressure wave to travel from the aortic valve to the tip of said digit and a pressure wave to travel from said aortic valve to said ear, and distances from the second intercostal space to suprasternal notch, said suprasternal notch to the base of the right ear, said suprasternal notch to the tip of said digit, and the arterial distances from said aortic valve to said digit and ear.

12. The method of claim 11, wherein said pulse delay to said digit (PD_Digit) and ear (PD_Ear) on said subject'"'"'s body is determined as a function of said anatomical characteristics and according to the following equations

PD_Digit=PEP+PTT_Digit=PEP+PTT_Ear+PTT_Digit

and

PD_Ear=PEP+PTT_Ear,

wherein PEP represents said pre-ejection period, PTT_Digit represents said time required for a pressure wave to travel from said aortic valve to said digit, and PTT_Ear represents said time required for a pressure wave to travel from said aortic valve to said ear.

13. The method of claim 12, wherein said PTT_Peripheral is determined according to the following equation

PTT_Peripheral=PD_Digit−

PD_Ear=PTT_Digit−

PTT_Ear

14. The method of claim 13, wherein said peripheral pulse wave velocity (PWV_Peripheral) is determined according to the following equation

${\mathrm{PWV}}_{\mathrm{Peripheral}}=\frac{D_{12}}{\left({\mathrm{PD}}_{\mathrm{Digit}}-{\mathrm{PD}}_{\mathrm{Ear}}\right)},$

wherein D₁₂ represents the difference between the arterial tree distances from said aortic valve to said digit and ear.

15. The method of claim 14, wherein said central pulse wave velocity (PWV_Central) is determined according to the following equation

${\mathrm{PWV}}_{\mathrm{Central}}={\alpha }_{}$

v ×

PWV Peripheral = D 12 ×

α

v ( PD Digit - PD Ear ) .

16. The method of claim 15, wherein said α

_v=0.68

17. The method of claim 15, wherein said α

_v is adjusted as a function of age according to the following equation

${\mathrm{\alpha <br><br>}}_v=\frac{553<br><br><br><br>\frac{\mathrm{cm}}{\sec }+(\left({\mathrm{Age}}_{\text{yrs}}-{18}_{\text{yrs}}\right)\times <br><br>6.10<br><br><br><br>\frac{\mathrm{cm}}{\sec }/\text{yrs}}{817<br><br><br><br>\frac{\mathrm{cm}}{\sec }+(\left({\mathrm{Age}}_{\text{yrs}}-{18}_{\text{yrs}}\right)\times <br><br>0.10<br><br><br><br>\frac{\mathrm{cm}}{\sec }/\text{yrs}}$

18. The method of claim 15, wherein said PEP is determined according to the following equation

$\begin{array}{c}P\end{array}$



E 



P = PD Ear - D 01 PWV Peripheral * α

v = D 01 D 02 - D 01 PD Digit - PD Ear * α

v = ( PD Digit - PD Ear ) * D 01 ( D 02 - D 01 ) * α

v

wherein D₀₁ represents said arterial tree distance from said aortic valve to said ear, and D₀₂ represents said arterial tree distance from said aortic valve to said digit.

19. A method of determining pre-ejection period (PEP), comprising the step of determining PEP according to the following equation

$\begin{array}{c}P\end{array}$



E 



P = PD Ear - D 01 PWV Peripheral * α

v = D 01 D 02 - D 01 PD Digit - PD Ear * α

v 

= ( PD Digit - PD Ear ) * D 01 ( D 02 - D 01 ) * α

v ,

wherein PD_Ear represents pulse delay to an ear, PD_Digit represents pulse delay to a designated digit, D₀₁ represents arterial tree distance from the aortic valve to said ear, D₀₂ represents arterial tree distance from said aortic valve to said digit, PWV_Peripheral represents peripheral pulse wave velocity, and α

_v represents a standard ratio of PWV_Peripheral to central pulse wave velocity (PWV_Central).