Method and apparatus for determination of central aortic pressure

• US 20070185400A1
• Filed: 12/17/2004
• Published: 08/09/2007
• Est. Priority Date: 12/17/2003
• Status: Active Grant

• Current Assignee: Atcor Medical Pty Ltd (CardieX Ltd.)
• Original Assignee: Atcor Medical Pty Ltd (CardieX Ltd.)
• Inventors: O'Rourke, Michael
• Granted Patent: US 7,628,758 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

Methods for determining central systolic pressure are disclosed. A first method determines the time of peak in a measured carotid waveform and then determines the pressure in a measured radial waveform at the corresponding time. A second method utilises only a measured radial waveform. The waveform is analysed to determine a time indicative of lower body waveform and determines the pressure at this time. In each case, the determined pressure is substantially the same as the central systolic pressure.

Claims

1. A method for determining central systolic pressure, including the steps of:

determining a time t from pressure wave foot to peak in a central carotid artery;

measuring a radial pressure waveform; and

locating the pressure wave foot in the radial pressure waveform and determining the corresponding pressure at time t after the wave foot;

wherein said corresponding pressure is substantially the central systolic pressure.

5. An apparatus programmed for determining central systolic pressure according to the method of any one of the preceding claims.

6. A software product for programming a device to determine central systolic pressure according to the method of any one of claims 1 to 4.

2. A method for determining central systolic pressure, including the steps of:

measuring a radial pressure waveform;

locating the time of start of a component of said waveform attributable to lower body wave reflection; and

determining the central systolic pressure by taking the value of the pressure waveform at said time.

3. The method according to claim 2, wherein said step of locating the time includes the following steps:

determining the peak of said measured waveform;

determining if there is a minimum of a first derivative of said waveform before said peak;

if a minimum is determined then the time is located at the occurance of the determined peak;

if no minimum is determined then;

searching for a first zero crossing of a second derivative of said waveform from positive to negative after said peak and before incisura;

if a first zero crossing is found then the time is located at said first zero crossing;

if a first zero crossing is not found then;

searching for a zero crossing of a third derivative of said waveform from positive to negative before said peak;

if a zero crossing is found then the time is located at the occurance of the determined peak;

if a zero crossing is not found then;

searching for a first zero crossing of the third derivative from positive to negative after said peak and locating the time at said zero crossing.

4. The method according to claim 3, wherein said step of determining if there is a minimum of a first derivative of said waveform before said peak includes determining if there is a zero crossing of a second derivative from negative to positive before said peak.