Cardiac pacemaker sense amplifier
US4379459A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 9, 1981 |
| Grant date | Apr 12, 1983 |
| Priority date | — |
| Expiry date | Apr 9, 2001 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61N1/365
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A demand cardiac pacemaker of the type having sense amplifier circuitry for detecting the occurrence of natural heart activity which establishes a first level representative of sensed extraneous repetitive noise and a second level greater in absolute value than the reference by an amount representative of sensed heart activity. Circuitry differentially responsive to the difference between the reference and second level detects the occurrence of natural heart activity. The sense amplifier circuitry is blanked, that is disconnected from the terminals coupled to the heart, for a blanking interval following stimulation to avoid saturation of the sense amplifier stages and the erroneous detection of a pacing stimulus. Any reference level voltages developed by extraneous repetitive noise are retained during blanking to prevent the differential circuitry from interpreting the noise signal sensed at the end of the blanking interval as a heart signal. The amount by which the reference and second level must differ to indicate natural heart activity is established by a bias circuit, the bias being alterable to establish one of a preselected plurality of sensitivities.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.