Method for ascertaining the pressure pulse and related parameters in the ascending aorta from the contour of the pressure pulse in the peripheral arteries
First Claim
1. A method of determining systolic and diastolic pressure in the ascending aorta from measurements of pressure in an upper body peripheral artery, said method comprising the steps of:
- A. measuring pressure pulses in a peripheral artery and producing an electrical signal representing the pressure pulses;
B. deriving a Fourier transform for the measured peripheral pulses;
C. dividing the peripheral pulse Fourier transform by a transfer function H(w) relating a Fourier transform of pressure pulses in the peripheral artery and a Fourier transform of pressure pulses in the aorta, thereby producing a Fourier transform associated with the aortic pressure pulse;
D. deriving the inverse of the Fourier transform associated with the aortic pressure pulse, thereby producing an electrical signal representing a synthesized ascending aortic pressure pulse;
E. determining in the signal representing the measured peripheral pulse a point of systolic onset by taking a first derivative of the measured peripheral pulse and locating a zero crossing from negative-to-positive which precedes a maximum point on the first derivative curve;
F. determining the location of a point of incisura in the signal representing the measured peripheral pressure pulse by finding in a signal representing the third derivative of the measured peripheral pulse a zero crossing from positive-to-negative in proximity to the largest maximum point of the third derivative after the peak of a second systolic shoulder;
G. determining in the electrical signal representing the synthesized aortic pressure pulse, the systole and diastole components of the synthesized signal based on the location of the incisura and systolic onset in the signal representing the measured peripheral pulse;
H. determining from the electrical signal representing the synthesized aortic pressure pulse a maximum systolic pressure and a maximum diastolic pressure; and
I. displaying a graph of the electrical signal representing the measured peripheral pulse, the electrical signal representing the synthesized ascending aortic pressure pulse and the related maximum systolic and diastolic pressures.
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Accused Products
Abstract
The system measures the pressure pulses in an upper body peripheral artery and produces an electrical signal which represents the contours of these pulses. It then digitizes the signal and synthesizes the pressure pulses in the ascending aorta using either a frequency-domain or a time-domain calculation method. Next, the system separately averages the signals corresponding to the measured pulses and those corresponding to the synthesized pulses, and forms for each an "average pulse." The system identifies the wave foot in each of the average pulses, identifies the incisura in the average peripheral pulse, determines the amount of time associated with systole and, based on this time, segments the synthesized pulse into systolic and diastolic components. The system then identifies the two pressure peaks and determines their amplitudes using either the average peripheral pulse or the average synthesized pulse, by taking first and third derivatives of the pulses and determining the locations of the relevant minimum and maximum points. The system then determines the peak and mean pressures throughout the wave and at various critical points such as the primary pressure peak, the reflective wave peak, and throughout systole and diastole. Using these peaks and pressures, the system calculates maximum and mean systolic and diastolic pressures, an augmentation index, a measure of subendocardial viability, and the pressure at the end of systole.
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Citations
25 Claims
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1. A method of determining systolic and diastolic pressure in the ascending aorta from measurements of pressure in an upper body peripheral artery, said method comprising the steps of:
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A. measuring pressure pulses in a peripheral artery and producing an electrical signal representing the pressure pulses; B. deriving a Fourier transform for the measured peripheral pulses; C. dividing the peripheral pulse Fourier transform by a transfer function H(w) relating a Fourier transform of pressure pulses in the peripheral artery and a Fourier transform of pressure pulses in the aorta, thereby producing a Fourier transform associated with the aortic pressure pulse; D. deriving the inverse of the Fourier transform associated with the aortic pressure pulse, thereby producing an electrical signal representing a synthesized ascending aortic pressure pulse; E. determining in the signal representing the measured peripheral pulse a point of systolic onset by taking a first derivative of the measured peripheral pulse and locating a zero crossing from negative-to-positive which precedes a maximum point on the first derivative curve; F. determining the location of a point of incisura in the signal representing the measured peripheral pressure pulse by finding in a signal representing the third derivative of the measured peripheral pulse a zero crossing from positive-to-negative in proximity to the largest maximum point of the third derivative after the peak of a second systolic shoulder; G. determining in the electrical signal representing the synthesized aortic pressure pulse, the systole and diastole components of the synthesized signal based on the location of the incisura and systolic onset in the signal representing the measured peripheral pulse; H. determining from the electrical signal representing the synthesized aortic pressure pulse a maximum systolic pressure and a maximum diastolic pressure; and I. displaying a graph of the electrical signal representing the measured peripheral pulse, the electrical signal representing the synthesized ascending aortic pressure pulse and the related maximum systolic and diastolic pressures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of determining pressure in the ascending aorta from measurements of pressure in an upper body peripheral artery, said method comprising the steps of:
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A. non-invasively measuring pressure pulses in a peripheral artery and producing an electrical signal representing the pressure; B. deriving a Fourier transform for the measured peripheral pulses; C. dividing the peripheral pulse Fourier transform by a transform function H(w) relating a Fourier transform of pressure pulses in the peripheral artery and a Fourier transform of pressure pulses in the aorta, thereby producing a Fourier transform associated with the aortic pressure pulse; D. deriving the inverse of the Fourier transform associated with the aortic pressure pulse, thereby producing an electrical signal representing a synthesized ascending aortic pressure pulse; E. determining in the signal representing the measured peripheral pulse a point of systolic onset by taking a first derivative of the measured peripheral pulse and locating a zero crossing from negative-to-positive which precedes a maximum point on the first derivative curve; F. determining the location of a point of incisura in the signal representing the measured peripheral pressure pulse by finding in a signal representing the third derivative of the measured peripheral pulse a zero crossing from positive-to-negative in proximity to the largest maximum point of the third derivative after the peak of a second systolic shoulder; G. separating in the electrical signal representing the synthesized aortic pressure pulse, the systole and diastole components of the synthesized signal based on the location of the incisura and systolic onset in the signal representing the measured peripheral pulse; H. determining from the electrical signal representing the synthesized aortic pressure pulse a maximum systolic pressure and a maximum diastolic pressure; and I. displaying a graph of the electrical signal representing the measured peripheral pulse, the electrical signal representing the synthesized ascending aortic pressure pulse and the related maximum systolic and diastolic pressures. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A method of determining pressure in the ascending aorta from measurements of pressure in an upper body peripheral artery, said method comprising the steps of:
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A. non-invasively measuring pressure pulses in a peripheral artery and producing an electrical signal representing the pressure; B. manipulating the signal to produce a signal representing a synthesized aortic pressure pulse; C. determining in the signal representing the measured peripheral pulse a point of systolic onset by taking a first derivative of the measured peripheral pulse and locating a zero crossing from negative-to-positive which precedes a maximum point on the first derivative curve; D. determining the location of a point of incisura in the signal representing the measured peripheral pressure pulse by finding in a signal representing the third derivative of the measured peripheral pulse a zero crossing from positive-to-negative in proximity to the largest maximum point of the third derivative after the peak of a second systolic shoulder; E. separating in the electrical signal representing the synthesized aortic pressure pulse, the systole and diastole components of the synthesized signal based on the location of the incisura and systolic onset in the signal representing the measured peripheral pulse; F. determining from the electrical signal representing the synthesized aortic pressure pulse a maximum systolic pressure and a maximum diastolic pressure; and G. displaying a graph of the electrical signal representing the measured peripheral pulse, the electrical signal representing the synthesized ascending aortic pressure pulse and the related maximum systolic and diastolic pressures. - View Dependent Claims (23, 24, 25)
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Specification