Temporary Pacemaker Troubleshooting
8/11/10
PY Mindmaps
Will Young Tutorial on Pacing
GENERAL MANAGEMENT
- review rhythm strip and 12 lead ECG
- check integrity of circuit (start at patient -> pacing box): lead placement, polarity, integrity,
connected to right port of pacing box – atrial/ventricular, battery, settings
- check mode
- check rate
- check capture threshold (find threshold and double it for safety)
- check sensitivity (normal = 2-5mV) – changes with position
- backup plans = transcutaneous or tranvenous pacing, atropine, adrenaline, isoprenaline,
ephedrine, electrolyte replacement
Failure to Pace
= no electrical output at the pacing wire tips
- causes: lead malfunction, unstable connection, insufficient power, cross-talk inhibition,
oversensing (see below), apparent failure to pace.
 check power, battery and connections
 increase output to maximum (20mA atrial and 25mA ventricular)
 switch to an asynchronous mode to prevent oversensing (AOO, VOO)
 connect the pacemaker directly to the pacing lead (occasionally the connecting wires may
be faulty)
 prepare for transcutaneous pacing
 prepare for CPR and chronotropic drugs
Failure to Capture
= no electrical out at the pacemaker tips (visible pacing spikes on ECG but no cardiac
contraction seen in arterial line or SpO2 waveform)
- causes: fibrosis at wire-myocardium interface, MI, electrolyte imbalance, post-defibrillation,
drugs (flecanide, sotalol, betablockers, lignocaine, verapamil)
 correct exacerbating causes
 reverse polarity of both unipolar and bipolar systems may help
 in bipolar leads, the negative electrodes develop fibrosis first -> use other electrode and
plug into negative terminal and insert return electrode in the subcutaneous tissue (create
unipolar circuit)
 may need temporary transvenous wire
Failure to Sense
- produces atrial pacing when not appropriate
- due to specific setting of sensitivity (including AOO mode)
 same mechanisms as failure to capture and pace
 decrease absolute value of sensitivity (making it easier to inhibit)
Jeremy Fernando (2011)
Cross talk
- in dual chamber pacing it is possible that the atrial pacemaker spike will be sensed by the
ventricular wire and is misinterpreted as a ventricular depolarisation -> inhibits ventricular
pacemaker output (ventricular standstill).
- the opposite can happen as well.
 reduce sensitivity in atrial or ventricular channel
 reduce mA delivered to the ventricular or pacing wire
Pacemaker mediated tachycardia
- VDD or DDD pacing problem
- can switch to VVI or DVI (but may loose AV synchrony)
(1) atrial sensing of a ventricular spike -> interpreted as an endogenous atrial depolarisation
-> another ventricular impulse
 use an atrial blanking period (now preset into box)
(2) retrograde conduction between ventricle and atrium through AV node or accessory
pathway -> ‘endless’ loop of periodicity
 adjustable post ventricular (pacing spike) atrial refractory period (PVARP)
Oversensing
- in DDD external electrical impulses can also be misinterpreted as atrial activity ->
pacemaker mediated tachycardia
 increase sensitivity threshold or switch to an asynchronous mode (AOO, VOO)
Jeremy Fernando (2011)