Biomedical Engineering Reference
In-Depth Information
S1 pulse or burst are synchronized by the coupling interval
with the last sensed or paced event. If the permanent mode is
dual-chamber, the initial interval is synchronized with a ven-
tricular event.
EP tests consume extensive amounts of energy. Triggering
a burst at a lower battery capacity may lead to a considerable
temporary decrease in battery voltage, which is why it is not
recommended to set pacing pulses at the maximum ampli-
tude. When applying the EP protocol, the telemetry wand
must always be kept above the patient's pacemaker. Provided
that the telemetry wand is removed, the EP test may be ter-
minated prematurely, and the permanently programmed
mode can be restored. The EP functions usually are not avail-
able immediately after implantation or if an adaptive-rate
mode is the main pacing mode.
The application of a pacing pulse or a burst is secured,
and triggering must be reconfirmed. This function may be
used only by people trained in carrying out EP testing. Pacing
options of this function may be applied only if the patient is
monitored carefully and an external defibrillator is prepared
for immediate use.
Per the standard [ 17 ] , integrated protection against an
excessive output pacing rate (runaway) is required in all
pacemakers; the maximum permissible pacing rate must be
stated. This protection is devised to eliminate pacing accel-
eration resulting from most failures caused by the breakdown
of one component. This internal function is not programma-
ble and works independently from the pacemaker's main
timing circuit securing the pacing. Protective circuits must
eliminate the pacing acceleration over a certain value (e.g.,
210 pulses/min), depending on the type of device and manu-
facturer. During EP testing provided by the device and related
temporary pacing at a high rate, the runaway protection is
temporarily deactivated.
 
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