US4926868A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for cardiac hemodynamic monitor
Assignee: Individual
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Filing: 1987-04-15
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Granted: 1990-05-22
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Expires: 2007-04-15
Abstract
Abstract A method and apparatus for cardiac hemodynamic monitoring is described. It is based on the complex field amplitudes of microwaves propagated through and scattered by thoracic cardiovascular structures, particularly the heart chambers, as a function of time during the cardiac cycle. Movement artifact and signal leakage are controlled by the use of closely coupled, flexible, light weight, passivated, conformal microstrip antennas that operate in the UHF band. The basic measurement technique is vector network analysis of the power wave scattering parameter in forward scatter configurations of various projections such as posterioanterior (PA), left anterior oblique (LAO), and right anterior oblique (RAO). Non-invasive evaluation of hemodynamic aspects of cardiovascular function is provided. Calibration is possible in human subject without invasive methods.
Inventors
- 👤 Lawrence E. Larsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:57
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/05; A61B5/0507; A61B5/02; A61B5/026; A61B5/0265; A61B5/029; G; G01; G01K; G01K11/00; G01K11/006; H; H01; H01Q; H01Q21/00; H01Q21/28
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
171 words
Apparatus for cardiac hemodynamic monitoring, comprising (a) flexible transmitting antenna means adapted for mounting adjacent to the back of a patient; (b) transmitter means connected with said transmitting antenna means for generating a signal having a frequency between 900 and 930 MHz which is transmitted by said transmitting antenna means through the mediastinum of the patient, said signal being altered as a function of cardiac hemodynamic operation; (c) receiving antenna means adapted for mounting adjacent to the chest of the patient for receiving said altered signal, said transmitting and receiving antenna means providing close coupling to the chest wall of the patient; (d) means connected with said receiving antenna means for processing said received signal to produce outputs representing the magnitude and phase angle, respectively, of a bistatic scattering parameter (S 21 l) as functions of time on a heartbeat by heartbeat basis; and (e) display means for displaying said outputs representing the magnitude and phase angle of said bistatic scattering parameter to provide a visual indication of cardiac hemodynamic operation.
Claim 2
Dependent Claim
171 words
Apparatus for cardiac hemodynamic monitoring, comprising (a) flexible transmitting antenna means adapted for mounting adjacent to the back of a patient; (b) transmitter means connected with said transmitting antenna means for generating a signal having a frequency between 900 and 930 MHz which is transmitted by said transmitting antenna means through the mediastinum of the patient, said signal being altered as a function of cardiac hemodynamic operation; (c) receiving antenna means adapted for mounting adjacent to the chest of the patient for receiving said altered signal, said transmitting and receiving antenna means providing close coupling to the chest wall of the patient; (d) means connected with said receiving antenna means for processing said received signal to produce outputs representing the magnitude and phase angle, respectively, of a bistatic scattering parameter (S 21 l) as functions of time on a heartbeat by heartbeat basis; and (e) display means for displaying said outputs representing the magnitude and phase angle of said bistatic scattering parameter to provide a visual indication of cardiac hemodynamic operation.
Claim 3
Dependent Claim
38 words
Apparatus as defined in claim 1, wherein said transmitting and receiving antenna means each comprise (1) a microstrip antenna; and (2) a passivation device comprising a thin randome of low inertia and low profile surrounding the microstrip antenna.
Claim 4
Dependent Claim
36 words
Apparatus as defined in claim 1, wherein said transmitting and receiving antenna means are portable, and further comprising an equipment vest containing said transmitting and receiving antenna means for mounting said antenna means on the patient.
Claim 5
Dependent Claim
18 words
Apparatus as defined in claim 1, wherein said processing means comprises a homodyne receiver with quadrature in-phase outputs.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-05-21 | 1993-11-20 | 1994-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-21 | 1997-11-20 | 1998-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-21 | 2001-11-20 | 2002-05-22 | $7700.00 | Window Closed / Lapsed |