Method and apparatus for calculating the fetal heart rate
First Claim
1. A method for determining a heart rate from a signal having a plurality of frequency components at least one of which is indicative of heart beats, the method comprising the steps of:
- (a) processing said signal to produce first and second signals having different frequency characteristics;
(b) identifying which of said first and second signals contains the more reliable, or higher quality, indication of said heart rate; and
(c) generating a heart rate signal on the basis of the signal identified as containing the more reliable indication of said heart rate, said heart rate signal indicative of said heart rate.
5 Assignments
0 Petitions
Accused Products
Abstract
Determining the fetal heart rate comprises irradiating an ultrasound beam in the direction of the fetal heart. The moving parts of the fetal heart cause a Doppler shift which is used to determine the fetal heart rate via an autocorrelation function. Moving parts of the fetal heart with different velocities and Doppler shifts originating from other physiological sources generate secondary maxima in the autocorrelation function, so that an accurate heart rate determination becomes nearly impossible. This problem is overcome by parallel processing of the demodulated ultrasound signal in various pass-bands, for which purpose the signal is fed to filters (28, 30) of different frequency characteristics. The output of the pass band with the better result is used for fetal heart rate circulation.
53 Citations
33 Claims
-
1. A method for determining a heart rate from a signal having a plurality of frequency components at least one of which is indicative of heart beats, the method comprising the steps of:
-
(a) processing said signal to produce first and second signals having different frequency characteristics; (b) identifying which of said first and second signals contains the more reliable, or higher quality, indication of said heart rate; and (c) generating a heart rate signal on the basis of the signal identified as containing the more reliable indication of said heart rate, said heart rate signal indicative of said heart rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A method for determining the heart rate of a fetus, comprising the steps of:
-
(a) generating a high-frequency ultrasound signal; (b) irradiating said ultrasound signal into fetal tissue in the general direction of the fetal heart; (c) receiving an ultrasound signal reflected by the fetal tissue; (d) demodulating the received ultrasound signal; (e) feeding the demodulated ultrasound signal to at least two filters in parallel; (f) assessing the quality of the filtered signals; (g) selecting the filtered signal with the higher quality; and (h) producing a heart rate signal based upon the selected filtered signal, said heart rate signal indicative of the fetal heart rate.
-
-
17. An apparatus for determining a heart rate from a signal having a plurality of frequency components at least one of which is indicative of heart beats, comprising:
-
(a) first and second processing means for processing said signal to produce first and second signals having different frequency characteristics; (b) selection means for identifying which of said first and second signals contains the more reliable, or higher quality, indication of said heart rate; and (c) third processing means for generating a heart rate signal on the basis of the signal identified as containing the more reliable indication of said heart rate, said heart rate signal indicative of said heart rate. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
-
-
31. An apparatus for determining the heart rate of a fetus, comprising:
-
(a) means for generating a high-frequency ultrasound signal; (b) means for irradiating said ultrasound signal into fetal tissue in the general direction of the fetal heart; (c) means for receiving an ultrasound signal reflected by the fetal tissue; (d) means for demodulating the received ultrasound signal; (e) means for feeding the demodulated ultrasound signal to at least two filters in parallel; (f) means for assessing the quality of the filtered signals; (g) means for selecting the filtered signal with the higher quality; and (h) means for generating a heart rate signal based upon the selected filtered signal, said heart rate signal indicative of the fetal heart rate.
-
-
32. An apparatus for monitoring a periodically-moving object, the apparatus having means for transmitting an ultrasound signal towards moving parts of the object and receiving a reflected signal, said apparatus characterized by:
-
means for filtering said complex signal to output filtered signals with different frequency characteristics; means for enhancing periodic components of each filtered signal and suppressing non-periodic components of each filtered signal; means for assessing the quality of each enhanced signal; means for selecting a desired enhanced signal with the highest quality; and means for calculating a rate of said periodic movement based upon said enhanced signal with the highest quality.
-
-
33. A method for monitoring a periodically-moving object, the method including transmitting an ultrasound signal towards moving parts of the object and receiving a reflected signal, said method characterized by the steps of:
-
filtering said complex signal to output filtered signals with different frequency characteristics; enhancing periodic components of each filtered signal and suppressing non-periodic components of each filtered signal; assessing the quality of each enhanced signal; selecting a desired enhanced signal with the highest quality; and calculating a rate of said periodic movement based upon said enhanced signal with the highest quality.
-
Specification