Non-invasive determination of aortic flow velocity waveforms
First Claim
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1. A method for determining an aortic flow velocity waveform, including the steps of:
- a. measuring non-invasively at a peripheral site a blood pressure pulse waveform;
b. calibrating said blood pressure pulse waveform by reference to systolic and diastolic pressures measured at a site comparable to said peripheral site; and
c. calculating the calibrated aortic pressure pulse waveform at the ascending aorta using said calibrated blood pressure pulse waveform and a predetermined transfer function;
d. calculating the aortic flow velocity waveform from said aortic pressure pulse waveform by reference to predetermined values for age dependent impedance modulus and phase difference between said aortic pressure pulse waveform and said aortic flow velocity waveform.
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Abstract
A method is disclosed for determining the aortic flow velocity waveform non-invasively. A calibrated ascending aorta pressure waveform can be derived from peripheral measurements, for example at the radial artery, and calibrated from conventional syphgmomanometry, for example at the brachial artery. From the calibrated ascending aorta pressure waveform the flow velocity waveform in the ascending aorta can be determined, by using the Fourier transform of the pressure waveform and the age-related phase and modulus values. The method can also be used for invasively measured pressure waveforms to provide a flow waveform.
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Citations
22 Claims
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1. A method for determining an aortic flow velocity waveform, including the steps of:
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a. measuring non-invasively at a peripheral site a blood pressure pulse waveform; b. calibrating said blood pressure pulse waveform by reference to systolic and diastolic pressures measured at a site comparable to said peripheral site; and c. calculating the calibrated aortic pressure pulse waveform at the ascending aorta using said calibrated blood pressure pulse waveform and a predetermined transfer function; d. calculating the aortic flow velocity waveform from said aortic pressure pulse waveform by reference to predetermined values for age dependent impedance modulus and phase difference between said aortic pressure pulse waveform and said aortic flow velocity waveform. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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- 8. A method for determining an aortic flow velocity waveform from a measured or derived ascending aortic pressure pulse waveform, comprising calculating the aortic flow velocity waveform from said aortic pressure pulse waveform by reference to predetermined values for age dependent impedance modulus and phase difference between said aortic pressure pulse waveform and said aortic flow velocity waveform.
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15. A method for representing an aortic flow velocity waveform by calculating parameters defining an aortic flow velocity waveform as a function of:
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parameters defining an ascending aortic pressure pulse waveform and predetermined values for age dependent impedance modulus and phase difference between said aortic pressure pulse wavefom and said aortic flow velocity waveform; and plotting an aortic flow velocity waveform defined by said aortic flow velocity waveform parameters. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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Specification