EKG & Heart Rate
The amplifier shown is a dual purpose SC and EKG Heart Rate amplifier. EKG Heart rate is also available on its own if required. The amplifiers require a single USB cord for both power and data.
Heart Rate may also be measured with the Peripheral Pulse amplifier.
To measure EKG, electrodes are attached to the body in positions such that the heart is between them. Ideally they are placed on the body (see picture which shows convenient placements), alternatively they may be positioned on either wrist. These electrodes are plugged into the white and black sockets on the amplifier. The green socket should be connected to a third electrode at any convenient position. EL126 snap leads and EL204 electrodes are used (standard disposable hospital type dot snapper).
T wave suppression using a 10Hz HP filter improves reliability of heart rate measurement. It is advisable to standardise electrode positions and also black / white lead polarity.
The EKG amplifier is optically isolated both from the computer and also from the SC channel, with single fault leakage current less than 50uA to comply with CE and UL safety requirements for equipment connected across the heart.
ECG Amplifier Specification:
NoiseLevel < 1uV RMS unfiltered R.T.I.
nput Impedance >1000 M Ohm, 20pF
Hum Filter 50/60 Hz > 60 dB
Subject Isolation > 6000V, 100 M Ohm
Leakage current <1uA
Single fault current max 40uA
Control of gain: 500uV, 1mV, 2mV
Control of filter: HP filter 1Hz, 10Hz
LP filter: 40Hz fixed.
The two lead configuration provides clear PQRST which can be recorded, and is also used to trigger an internal Inter Beat Interval (R-R) timer. 1000Hz or higher internal cycle speed provides <1mS IBI resolution.
For ambulatory use, SC-EKG is currently available with 12Mb of internal memory. While the internal ratemeter uses 1000Hz, so that IBI is accurate to 1mS, sampling may be set lower without losing IBI accuracy. At 80Hz sampling, which is sufficient for both SC and Heart Rate, SC-EKG provides > 5 hours recording time. SC-EKG may be used in combination with any other devices in the range. A synchronization port is provided to allow multiple devices to be operated together, and to accomodate precise hardware event timing.
Analogue output for SC and ECG is provided on a 15 way canon connector, +/-5V.