Cardiac stimulator 4427 Easypace - Instructions for use
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Any dangerous situation is signalled by a “beep” sound at intervals of 2 seconds, and by a
flashing DANG message on display.
CAUTION !
The testing circuit which verifies the catheter connection is not able to detect
a poor contact with the heart wall, which is cause for inefficient stimulation .
It is thus indispensable to carry out periodic checks of the stimulation
threshold in case of prolonged use of the stimulator.
11.3. Checking the maximum stimulation rate
The stimulator has been designed to provide rates - the period of which is controlled
by a quartz-microprocessor - whose maximum value is 180 ppm.
In case of microprocessor failure - and in order to avoid any dangerous high-rate
stimulation - provision has been made for a suitable anti run-away circuit, disengaged by
the microprocessor and calibrated to a rate of 200 ppm, capable of limiting the stimulation
rate.
The circuit is automatically cut off at a pressure of keys burst x4 and ramp ▼, to prevent
the high rates that can be reached in these modes of operation.
11.4. Protection against electro-magnetic interferences
The 4427 Easypace is provided of an embedded Patient's spontaneous heart activity
detection circuit calibrated on the ventricular impulse. However, owing to the high
sensitivity of the stimulator and to the interference which, in some cases, may reach a
remarkable level, the rare possibility exist that some electromagnetic interferences, with
morphological characteristics as those of cardiac signals, could be considered as
spontaneous heart activity, with consequent unwanted inhibition of the stimulation.
In order to reduce such eventuality when operating in the VVI mode, the stimulator is
provided with a program performing an automatic check of noise presence with a rate
higher than the device measurable maximum frequency. Therefore impulses with rate
higher than 300 ppm (impulses at intervals of less than 200 ms) are considered
interference.
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