Surgery – Truss – Pad
Patent
1994-12-02
1996-08-13
Jaworski, Francis
Surgery
Truss
Pad
12866203, A61B 800
Patent
active
055446566
ABSTRACT:
A closed-loop single-crystal ultrasonic sonomicrometer capable of identifying the myocardial muscle/blood interface and continuously tracking this interface throughout the cardiac cycle using a unique piezoelectric transducer. During steady-state, a reference volume SV.sub.m is adjusted so that it remains within the myocardium while half of an interface volume SV.sub.i is in the myocardium and one-half is in the ventricular chamber. Every 100 ns, a 0.5 .mu.s duration ultrasonic burst of 10 MHz pulses is transmitted from the piezoelectric transducer. Myocardial layers and red blood cells in the ventricular chamber reflect the ultrasonic energy back to the piezoelectric transducer. The echoes are then amplified and applied to a Doppler decoder, which then mixes them with a local oscillator signal having a 2 kHz offset relative to the transmitted signal. When the offset signal is mixed with returning ultrasonic echoes, the resulting Doppler signals are shifted in the frequency domain by 2 kHz. The received Doppler signal is then processed by an amplitude-locked-loop circuit which maintains the steady state throughout the cardiac cycle. Initially, the Doppler decoded signal is sampled at two distinct time intervals corresponding to sample volumes SV.sub.m and SV.sub.i. The outputs from these two sample volumes are then bandpass filtered to remove frequencies contributed by red blood cells. The true RMS values from both sample volumes then are compared and an error signal is generated. The integrated error signal is adjusted for correct depth placement and applied to a voltage-controlled delay circuit. The amplitude-locked-loop circuit continuously adjusts the position of the two sampled volumes SV.sub.m and SV.sub.i, so that they always remain within, and thereby effectively track, the muscle/blood interface. As a result, the apparatus can measure absolute myocardial wall thickness.
REFERENCES:
patent: 4947854 (1990-08-01), Rabinovitz et al.
patent: 4966150 (1990-10-01), Etienne et al.
patent: 4993427 (1991-02-01), Barr et al.
patent: 5243987 (1993-09-01), Shiba
patent: 5289820 (1994-03-01), Beach et al.
patent: 5360006 (1994-11-01), Geiser et al.
Donnerstein, R. et al., "Digital Range-Gated Echocardiographic Tracking", Med. Iustr. vol. 12#3 May-Jun. 1978.
Pitsillides et al., Biotelemetry of Cardiovascular Measurements in Miniswine, IEEE Transactions on Biomedical Engineering, pp. 982-986, Sep. 1992.
Wildi et al., Dynamics and Limitations of Blood/Muscle Interface Detection Using Doppler Power Returns, IEEE Transactions on Biomedical Engineering, pp. 565-573, Oct. 1980.
Hartley et al., Doppler Measurement of Myocardial Thickening with a Single Epicardial Transducer, AM J Physiol 245, pp. H1066-H1072, 1983.
Hartley et al., Range Gate Tracking for Doppler Measurement of Myocardial Thickening, Ultr. Med. Biol. Abstract, Suppl. 1, p. 560, 1985.
Pitsillides et al., Multi-Channel Biotelemetry of Myocardial Hemodynamic Variables in Miniswine, Federation of American Societies of Experimental Biology, Washington DC, 1990.
Longhurst John C.
Pitsillides Koullis F.
Jaworski Francis
O'Banion John P.
The Regents of the University of California
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