Method for diagnosing, monitoring and treating hypertension and other cardiac problems

• US 6,540,687 B2
• Filed: 12/15/2000
• Issued: 04/01/2003
• Est. Priority Date: 12/17/1993
• Status: Expired due to Fees

• Current Assignee: Pulse Metric Incorporated
• Original Assignee: Pulse Metric Incorporated
• Inventors: Chio, Shiu-Shin
• Primary Examiner(s): Lacyk, John P.
• Application Number:
  US09/738,192
• Publication Number:
  US 20010016690A1
• Time in Patent Office: 837 Days
• Field of Search: 600/481, 600/485, 600/500, 600/501, 600/504, 600/506, 600/507, 600/526
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence

Abstract

A method is disclosed for diagnosing, monitoring and treating cardiovascular pathologies. Among the hemodynamic parameters of interest are peripheral resistance, compliance, and cardiac (left ventricular) output. Peripheral resistance determined according to the present invention has been found to be a reliable indicator, not only of hypertension, but also of the cause of the hypertension. The determined peripheral resistance can be compared against a predetermined threshold value. This comparison helps to foster a diagnosis of a hypertensive condition.

Claims

1. A method for determining the cardiovascular condition of a patient comprising the steps of

(1) determining the patient'"'"'s systolic, diastolic, and mean arterial pressure from cardiovascular condition information gathered non-invasively,

(2) using the gathered cardiovascular condition information to determine one of the peripheral resistance and the diastolic flow velocity of the patient, and using the determined one of the peripheral resistance and diastolic flow velocity to determine the other of the peripheral resistance and diastolic velocity of the patient, and

(4) assessing the patient'"'"'s cardiovascular condition based on at least one of the determined peripheral resistance and diastolic flow velocity of the patient.

2. The method of claim 1 wherein the step of determining one of the peripheral resistance and diastolic flow velocity of the patient comprises the steps of

(1) using at least one of the determined diastolic, systolic and mean arterial pressures to determine the patient'"'"'s peripheral resistance,

(2) comparing the determined peripheral resistance to a predetermined peripheral resistance threshold value, and

(3) the step of assessing the patient'"'"'s cardiovascular condition comprises the step of diagnosing the patient as having a cardiovascular pathology if the patient'"'"'s determined peripheral resistance exceeds the predetermined peripheral resistance threshold value.

3. The method of claim 2 further comprising the steps of

(1) using at least one of the determined diastolic, systolic and mean arterial pressures to determine the patient'"'"'s cardiac output,

(2) comparing the determined cardiac output to a predetermined threshold value,

(3) diagnosing the patient as hypertensive if the patient'"'"'s cardiac output exceeds the predetermined threshold value.

4. The invention of claim 1 wherein the

(1 ) step of using the gathered cardiovascular condition information to determine one of the peripheral resistance and the diastolic flow velocity of the patient includes the steps of using the gathered cardiovascular condition information to determine the diastolic flow velocity, and to create a series of waveforms from gathered pressure data and pulsation signal data;

and

(2) the step of determining the diastolic flow velocity comprises the step of using at least one of the waveforms to determine diastolic flow velocity.

5. The invention of claim 4 wherein the step of using at least one of the waveforms to determine diastolic flow velocity includes the steps of

(1) using a waveform at a gathered systolic pressure to determine the peak to peak change in pressure over time,

A. using a waveform at a gathered diastolic pressure to determine the diastolic flow change in pressure over time.

6. The invention of claim 4 wherein the step of using at least one of the waveforms to determine diastolic flow velocity includes the step of determining the diastolic flow velocity according to the equation:

$V_o=\left[\frac{\left(4<br><br>\mathrm{\pi <br><br>}\right)<br><br>\left(l_{\mathrm{cuff}}\right)}{T_{\mathrm{pp}}}\right]<br><br>\left[\frac{{\left(\frac{<br><br>P}{<br><br>t}\right)}_{\mathrm{DW}}}{{\left(\frac{<br><br>P}{<br><br>t}\right)}_{\mathrm{pp}}}\right]$

where, $V_o=\text{diastolic flow velocity}$$l_{\mathrm{cuff}}=\text{the effective length of the blood pressure cuff from whichthe data stream is obtained,}$$T_{\mathrm{pp}}=\text{the time between the peak positive slope and the peak negative slope of a systolic wave form}$${\left(\frac{<br><br>p}{<br><br>t}\right)}_{\mathrm{DW}}=\text{the change in pressure over time of the diastolicwave, and}$${\left(\frac{<br><br>p}{<br><br>t}\right)}_{\mathrm{pp}}=\text{the change in pressure over time in the interval betweenthe peak positive slope and the peak negative slope ofthe systolic waveform.}$

7. The invention of claim 6 wherein the step of using the gathered cardiovascular condition information to determine one of the peripheral resistance and the diastolic flow velocity of the patient and using the determined one of the peripheral resistance and diastolic flow velocity to determine the other of the peripheral resistance and diastolic velocity of the patient, includes the step of determining the systemic peripheral resistance according to the equation:

${\mathrm{PR}}_1=\frac{\mathrm{SYS}-\mathrm{DIA}}{V_o}$

where

PR₁=the systemic peripheral resistance,

SYS=the patient'"'"'s systolic pressure,

DIA=the patient'"'"'s diastolic pressure and,

V_o=the determined diastolic flow velocity.

further comprising the step of determining at least a partial cardiac output according to the equation $\mathrm{CO}=\frac{\mathrm{MAP}}{{\mathrm{PR}}_1},$

where

CO=cardiac output, and

MAP=the determined mean arterial pressure.

8. The invention of claim 6 wherein the step of using the gathered cardiovascular condition information to determine one of the peripheral resistance and the diastolic flow velocity of the patient and using the determined one of the peripheral resistance and diastolic flow velocity to determine the other of the peripheral resistance and diastolic velocity of the patient, includes the step of determining the distal peripheral resistance according to the equation:

${\mathrm{PR}}_2=\frac{\mathrm{MAP}-\mathrm{DIA}}{V_o}$

where

PR₂=the distal peripheral resistance,

MAP=the patient'"'"'s mean arterial pressure,

DIA=the patient'"'"'s diastolic pressure, and

V_o=the determined diastolic flow velocity;

further comprising the step of determining at least a partial cardiac output according to the equation $\mathrm{CO}=\frac{\mathrm{MAP}}{{\mathrm{PR}}_2},$

where

CO=cardiac output, and

MAP=the patient'"'"'s mean arterial pressure.

9. The invention of claim 1, wherein the step of using the gathered cardiovascular condition information to determine one of the peripheral resistance and the diastolic flow velocity of the patient and using the determined one of the peripheral resistance and diastolic flow velocity to determine the other of the peripheral resistance and diastolic velocity of the patient, includes the step of determining the diastolic flow velocity,

further comprising the step of using the determined diastolic flow velocity to determine the patient'"'"'s cardiac output, wherein the step of determining peripheral resistance comprises the step of using a data processing device to determine systemic peripheral resistance according to the equation:

${\mathrm{PR}}_1=\frac{\mathrm{SYS}-\mathrm{DIA}}{V_o}$

where

PR₁=the systemic peripheral resistance,

SYS=the patient'"'"'s systolic pressure,

DIA=the patient'"'"'s diastolic pressure, and

V_o=the determined diastolic flow velocity.

10. The invention of claim 1, wherein the step of using the gathered cardiovascular condition information to determine one of the peripheral resistance and the diastolic flow velocity of the patient and using the determined one of the peripheral resistance and diastolic flow velocity to determine the other of the peripheral resistance and diastolic velocity of the patient, includes the step of determining each of the diastolic flow velocity and peripheral resistance, further comprising the step of using the determined diastolic flow velocity to determine the patient'"'"'s cardiac output, wherein the step of determining peripheral resistance comprises the step of determining distal peripheral resistance according to the equation:

${\mathrm{PR}}_2=\frac{\mathrm{MAP}-\mathrm{DIA}}{V_o}$

where

PR₂=the distal peripheral resistance

MAP=the patient'"'"'s mean arterial pressure

DIA=the patient'"'"'s diastolic pressure and

V_o=the determined diastolic flow velocity.

11. The invention of claim 1, wherein the step of using the gathered cardiovascular condition information to determine one of the peripheral resistance and the diastolic flow velocity of the patient and using the determined one of the peripheral resistance and diastolic flow velocity to determine the other of the peripheral resistance and diastolic velocity of the patient, includes the step of determining the peripheral resistance, and

the step of assessing the patient'"'"'s cardiovascular condition comprises the step of diagnosing the patient as having a high cardiac output type hypertension if:

(1) the determined peripheral resistance is less than about 0.6 (mmHg)(sec/cm); and

(2) at least one of the following;

(a) the patient'"'"'s mean arterial pressure is greater than about 108 mmHg,

(b) the patient'"'"'s systolic pressure is greater than about 140 mmHg; and

(c) the patient'"'"'s diastolic pressure is greater than about 90 mmHg.

12. The invention of claim 1, wherein the step of using the gathered cardiovascular condition information to determine one of the peripheral resistance and the diastolic flow velocity of the patient and using the determined one of the peripheral resistance and diastolic flow velocity to determine the other of the peripheral resistance and diastolic velocity of the patient, includes the step of determining the peripheral resistance, and

the step of assessing the patient'"'"'s cardiovascular condition comprises the step of diagnosing the patient as being at risk of having coronary artery disease if the determined peripheral resistance is greater than about 0.6 (mmHg)(sec/cm).

13. The method of claim 1, wherein the step of using the gathered cardiovascular condition information to determine one of the peripheral resistance and the diastolic flow velocity of the patient and using the determined one of the peripheral resistance and diastolic flow velocity to determine the other of the peripheral resistance and diastolic velocity of the patient, includes the step of determining the diastolic flow velocity, and

further comprising the step of determining an elasticity constant of an artery of interest through the steps of:

(a) determining a cross sectional area of the artery of interest, and

(b) using the determined cross sectional area and diastolic flow velocity to determine the elasticity constant.

14. The method of claim 13 where the steps of determining the elasticity constant comprises the step of determining the elasticity constant through the equation:

15. The method of claim 13, further comprising the step of:

using the determined elasticity constant to determine the compliance of the artery of interest through the equation;

$C=\frac{1}{\mathrm{Ke}}$

where

C=the compliance and

Ke=the elasticity constant.

16. A method for determining the cardiovascular condition of a patient comprising the steps of:

(1) determining the patient'"'"'s systolic, diastolic, and mean arterial pressure from cardiovascular condition gathered non-invasively,

(2) using the gathered cardiovascular condition information to determine one of the peripheral resistance and the diastolic flow velocity of the patient, and using the determined one of the peripheral resistance and diastolic flow velocity to determine the other of the peripheral resistance and diastolic velocity of the patient,

(4) using the determined peripheral resistance and mean arterial pressures to determine the patient'"'"'s cardiac output,

(5) comparing the determined cardiac output to a predetermined cardiac output threshold value, and the determined mean arterial pressure to a mean arterial pressure threshold value, and

(6) diagnosing the patient as hypertensive if at least one of the determined cardiac output exceeds the predetermined cardiac output threshold value, and the determined mean arterial pressure exceeds the predetermined mean arterial pressure threshold value.

17. The method of claim 16 wherein the step of diagnosing the patient comprises the step of diagnosing the patient as having a high cardiac output type hypertension if the determined mean arterial pressure exceeds the predetermined mean arterial pressure threshold value, and the determined peripheral resistance is below the predetermined peripheral resistance threshold value.

18. A non-invasive device for aiding in the assessment of the cardiovascular condition of a patient, the device comprising

(1) a data processor for processing patient pulsation signal data for determining at least one of the patient'"'"'s systolic, diastolic, and mean arterial pressure;

and

(2) a data processor means for processing pulsation signal data taken from at least one of the supra-systolic pressure and sub-diastolic pressure to determine one of the peripheral resistance and the diastolic flow velocity of the patient.

19. A device for aiding in the assessment of the cardiovascular condition of a patient, the device comprising

(1) a data processor for determining the patient'"'"'s systolic, diastolic, and mean arterial pressure from pulsation signal waveforms,

(2) a data processor for determining the diastolic flow velocity of the patient from at least one of the patient'"'"'s pulsation signal waveforms, and

(3) a data processor for using the determined diastolic flow velocity to determine the peripheral resistance of the patient.

20. The device of claim 19 wherein the data processor for determining diastolic flow velocity includes

(1) a program for using the waveform at a systolic pressure to determine the peak to peak change in pressure over time,

(2) a program for using the waveform at a diastolic pressure to determine the diastolic flow change in pressure over time.

21. The device of claim 19 wherein the data processor for using at least one of the patient'"'"'s pulsation signal waveforms to determine diastolic flow velocity includes a program for determining the diastolic flow velocity according to the equation:

$V_o=\left[\frac{\left(4<br><br>\mathrm{\pi <br><br>}\right)<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(l_{\mathrm{cuff}}\right)}{T_{\mathrm{pp}}}\right]<br><br>\text{\hspace{1em}<br><br>}\left[\frac{{\left(\frac{<br><br>P}{<br><br>t}\right)}_{\mathrm{DW}}}{{\left(\frac{<br><br>P}{<br><br>t}\right)}_{\mathrm{pp}}}\right]$

where, $V_o=\text{diastolic flow velocity}$$l_{\mathrm{cuff}}=\text{the effective length of the blood pressure cuff from whichthe data stream is obtained,}$$T_{\mathrm{pp}}=\text{the time between the peak positive slope and the peak negative slope of a systolic wave form}$${\left(\frac{<br><br>p}{<br><br>t}\right)}_{\mathrm{DW}}=\text{the change in pressure over time of the diastolicwave, and}$${\left(\frac{<br><br>p}{<br><br>t}\right)}_{\mathrm{pp}}=\text{the change in pressure over time in the interval betweenthe peak positive slope and the peak negative slope ofthe systolic waveform}$

22. The device of claim 21 wherein the data processor for determining peripheral resistance includes a computer program for determining systemic peripheral resistance according to the equation:

${\mathrm{PR}}_1=\frac{\mathrm{SYS}-\mathrm{DIA}}{V_o}$

where

PR₁=the systemic peripheral resistance,

SYS=the patient'"'"'s systolic pressure,

DIA=the patient'"'"'s diastolic pressure, and

V_o=the determined diastolic flow velocity,

and a program for determining at least a partial cardiac output according to the equation $\mathrm{CO}=\frac{\mathrm{MAP}}{{\mathrm{PR}}_1},$

where

CO=cardiac output, and

MAP=the patient'"'"'s mean arterial pressure.

23. The device of claim 21 wherein the data processor for determining peripheral resistance includes a program for determining distal peripheral resistance according to the equation:

${\mathrm{PR}}_2=\frac{\mathrm{MAP}-\mathrm{DIA}}{V_o}$

where

PR₂=the distal peripheral resistance,

MAP=the patient'"'"'s mean arterial pressure,

DIA=the patient'"'"'s diastolic pressure, and

V_o=the determined diastolic flow velocity,

and a program for determining cardiac output according to the equation $\mathrm{CO}=\frac{\mathrm{MAP}}{{\mathrm{PR}}_2},$

where

CO=cardiac output, and

MAP=the patient'"'"'s mean arterial pressure.

24. A non-invasive device for aiding in the assessment of the cardiovascular condition of a patient, the device comprising

(1) a data processor for determining the patient'"'"'s systolic, diastolic, and mean arterial pressure,

(2) a data processor for determining each of the patient'"'"'s peripheral resistance and the patient'"'"'s diastolic flow velocity, and

(4) a data processor for determining the patient'"'"'s cardiac output by using the determined diastolic flow velocity, wherein the data processor for determining peripheral resistance includes a program for determining systemic peripheral resistance according to the equations:

${\mathrm{PR}}_1=\frac{\mathrm{SYS}-\mathrm{DIA}}{V_o}$

and

25. A device for aiding in the assessment of the cardiovascular condition of a patient, the device comprising

(1) a data processor for determining the patient'"'"'s systolic, diastolic, and mean arterial pressure,

(2) a data processor for determining the peripheral resistance and the diastolic flow velocity of the patient, and

(3) a data processor for determining the patient'"'"'s cardiac output by using the determined diastolic flow velocity,

wherein the data processor for determining peripheral resistance includes a program for determining distal peripheral resistance according to the equation:

${\mathrm{PR}}_2=\frac{\mathrm{MAP}-\mathrm{DIA}}{V_o}$

where

PR₂=the distal peripheral resistance,

MAP=the patient'"'"'s mean arterial pressure,

DIA=the patient'"'"'s diastolic pressure, and

V_o=the determined diastolic flow velocity.

26. A device for aiding in the assessment of the cardiovascular condition of a patient, the device comprising

(1) a data processor for determining the patient'"'"'s systolic, diastolic, and mean arterial pressure,

(2) a data processor for determining one of the peripheral resistance and the diastolic flow velocity of the patient and

(3) a data processor for determining an elasticity constant of a section of an artery of interest comprising:

(a) a program for using a determined cross sectional area of a section of the artery of interest,

(b) a program for determining the diastolic flow velocity of blood through the section of the artery of interest, and

(c) a program for using the determined cross sectional area and diastolic flow velocity to determine the elasticity constant.

27. The device of claim 26 where the data processor for determining the elasticity constant comprises a program for determining the elasticity constant through the equation:

28. The device of claim 27, further comprising:

a data processor for using the determined elasticity constant to determine the compliance of the artery of interest through the equation;

$C=\frac{1}{\mathrm{Ke}}$

where

C=the compliance and

Ke=the elasticity constant.