Download Pacemaker Malfunction

PACEMAKER PROBLEMS
Jeff Ball and Hla Chaw
The common complications after pacemaker insertion (temporary or
permanent) are interpreted by the features on 12 lead ECG, monitoring, or
CXR.
1 – COMPLICATIONS OF CENTRAL VENOUS CANNULATION (e.g.;
pneumothorax, bleeding)
2 – PERFORATION OF HEART by the electrode tip leading to pericardial
effusion, cardiac tamponade
3 – ELECTRODE DISPLACEMENT (microscopic or macroscopic) leading to:
4 - FAILURE TO CAPTURE
CAUSES
• Elevated Capture Threshold
- After electrode implantation, oedema and inflammation around the tip
result in a steady rise in the threshold over the first few weeks. The
process is mild and self-limiting.
- Electrolyte disturbance (e.g., hyperkalemia, acidemia), antiarrhythmic drugs
(class 1c such as Flecainide)
- Myocardial fibrosis (e.g., cardiomyopathy, myocardial infarction) can
increase threshold.
•
•
•
Lead malfunction
Lead fracture
Lead dislodgement or perforation
DIAGNOSIS - by 12 leads ECG shows the pacing spike with following QRS
(fig .a –The fourth stimulus fails to capture the ventricle)
TREATMENT – treat the underlying causes.
5 - FAILURE TO SENSE
CAUSES
• Lead dislodgement. Usually accompanied by failure to capture.
• Lead insulation failure.
• Inadequate endocardial signal.
• Change in ECG. Transient changes in electrolyte or acid-base
disturbance, permanent changes in myocardial infarction or
cardiomyopathy.
• Ectopic beats.
•
•
Pulse generator failure.
Functional under-sensing. If the intracardiac signal is of insufficient
amplitude the pacing stimulus will not be suppressed, resulting in
inappropriate pacemaker firing.
DIAGNOSIS - 12 leads ECG. The atrial pacemaker has failed to sense the
preceding atrial activity and therefore delivered the second stimulus. This has
captured the atrium, with the P-wave in the ST segment, and subsequent
conduction to the ventricle. (Fig b)
- pacemaker check
TREATMENT – Treat the causes.
Fig.a – Failure to capture
Fig.b – Failure to sense
Fig.c - Oversensing
6 – INFECTION AROUND THE GENERATOR
Once infection is established, or the skin is breached, it is almost never
possible to eradicate infection with antibiotics: removal and replacement of the
pacing system is required.
7 - INAPPROPRIATE INHIBITION (OVERSENSING)
CAUSES
• Local skeletal muscle stimulation
• Damage to the conductor or insulation of the pacing electrode due to
trauma at the site of ligation or compression between the clavicle and first
rib.
DIAGNOSIS – 12 lead ECG (fig c). The dual chamber pacemaker has sensed
an electrical artefact throughout the ventricular lead and as a result has
suppressed ventricular pacing, with the absence of ventricular activation
following the third P-wave.
TREATMENT – treat the causes.
8 – PACEMAKER SYNDROME
Symptoms of fatigue, dizziness, or hypotension, which are associated with the
presence of atrial cannon waves occurring as a result of simultaneous atrial
and ventricular contraction.
TREATMENT – If symptoms are troublesome, upgrade of the system to a
dual-chamber unit is necessary.
9 – PACEMAKER MEDIATED TACHYCARDIA – A paced tachycardia that is
sustained by the continued active participation of the pacemaker in the
rhythm.
DIAGNOSIS – pacemaker check
TREATMENT - Reprogram
10 – PSEUDOMAL FUNCTION. Artefact with small spikes on the surface
ECG. Pseudo malfunction when recording and digital artefacts are
misinterpreted.
DIAGNOSIS
Obtain a 12-lead ECG and evaluate the following:
Determine whether pacing stimulus artefacts are present and whether
a.
The appropriate chambers are captured.
b.
If no pacing stimulus can be seen, native depolarisation should be
adequate.
c.
Evaluate whether native beats are appropriately sensed in relation to
paced complexes.
FOLLOW-UP
Patients with permanent pacemakers require follow-up by a pacemaker clinic
(CTC)
To detect the complications
To assess the status of the pulse generator battery
To maximize the battery life
Patients should be assessed at least annually by the clinic.
Many patients who have long-standing heart block treated by permanent
pacing have no underlying cardiac rhythm, and that failure of pacing system
for whatever reason may be fatal.
PACEMAKER CHECK, REPROGRAMME, CLINIC etc
Temporary pacemaker may be checked by the ECG department
Permanent pacemakers, refer to CTC.