Method and apparatus for differential lead impedance comparison
US4993423A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 12, 1990 |
| Grant date | Feb 19, 1991 |
| Priority date | — |
| Expiry date | Jan 12, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R17/105
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A differential lead impedance comparison apparatus (10) senses lead impedance and compensates for patient-to-patient and electrode variability. A bridge circuit (12) is connected to one end of electrode conductors (22, 24 and 26) in an ECG Leads I configuration. The other end of the conductors (22, 24 and 26) are connected to a patient (18) via electrodes (RA, LA and LL). Leads formed in part by RA, LA and LL and the respective conductors (22, 24 and 26) have lead impedances (R.sub.b, R.sub.a, and R.sub.c). Constant current sources (11, 12 and 13) are connected to the conductors (22, 24 and 26) and supply constant AC currents (I.sub.1, I.sub.2 and I.sub.3). A first bridge output voltage (V.sub.M) is produced by I.sub.1 and a combination 32 of R.sub.a, R.sub.b, and R.sub.c. A second bridge output voltage (V.sub.P) is produced by I.sub.2 and a combination 34 of R.sub.a, R.sub.b, and R.sub.c. A differential amplifier circuit (14) differentially amplifies the V.sub.M and V.sub.P voltages to produce differential voltages (V.sub.OM and V.sub.OP). Demodulators (DM1 and DM2) demodulate V.sub.OM and V.sub.OP to produce differential impedance voltages (V.sub.1M and V.sub.1P). A first compara…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.