Download Permanent cardiac pacemaker: an emergency perspective

Hong Kong Journal of Emergency Medicine
Permanent cardiac pacemaker: an emergency perspective
CW Lam
The number of patients with permanent pacemaker are increasing and may present into the emergency
department with a variety of complications and malfunctions. The presence of a pacemaker may also affect
management of unrelated medical issues. This article review the complications of the implant procedure,
the causes, diagnosis and management of pacemaker malfunction, the pacemaker syndrome, Twiddler's
syndrome. Interaction of permanent pacemaker with other medical condition and its implication in
Emergency Department environment are also discussed. (Hong Kong j.emerg.med. 2001;8:169-175)
Keywords: Complication, electrocardiogram, haemodynamic stability, malfunction, pacemaker
Introduction
Pacemaker therapy has transformed the lives of many
bradyarrhythmic patients both in terms of quality and
long term survival.1 The pacemaker implantation rate
in Hong Kong is not as high as western countries (UK
20,000, USA 115,000 cases) annually. 1 Nevertheless
it is increasing due to expanded indications of pacing
and aging of the population. 2 The progressively
increased number of patients with permanent
pacemaker has considerable impact on emergency
medicine practices as they will attend emergency
department for various pacemaker complications and
malfunction. Most of them are elderly, the average
age being 60. 3 Co-morbidities among them are not
uncommon. In addition, the presenting symptoms of
pacemaker malfunction and complications occasionally
are subtle, non-specific and mimic other medical diseases.
Emergency physicians need to have high index of
suspicion to diagnose pacemaker related problems.
The presence of pacemaker may complicate
management of unrelated medical problems such as
trauma, acute coronary syndrome and the institution
of advanced cardiac life support. On the other hand,
Correspondence to:
Lam Chi Wang, MBChB, FRCS(Edin)
Prince of Wales Hospital , Accident and Emergency
Department, Shatin, N.T., Hong Kong
Email: [email protected]
the emergency department envir onment may
pose potential hazard by interfering with the
functioning of pacemaker.4
Early complications
Complications arising within 6 weeks after implantation
are regarded as early.5 Although this differentiation is
arbitrary, the duration after implantation provide
useful clues to the underlying causes of pacemaker
malfunction. This will be further discussed in the
pacemaker malfunction and diagnosis.
Early complications of permanent pacemaker
implantation relate mainly to surgical procedures,
venous access, lead positioning or displacement. 5
The incidence is about 6.7%. The most important
determinant of complication is the experience of the
operators.5 Whether single or dual chamber
systems are more likely to cause problems remains
unclear.5
Permanent pacemakers are generally implanted under
local anaesthesia. The electrical leads are placed
transvenously (either via cephalic cut down or
subclavian vein puncture) into right atrial appendage,
right ventricular apex or both. The pacing and sensing
thresholds are assessed and the pacemaker is programmed
accordingly. After the leads are secured, the generator
is attached and implanted in a subcutaneous pectoral
170
pocket. The surgical procedures carry the risks of
haemopneumothorax, bleeding, venous thrombosis
and air embolism.
Pneumohaemothorax
The subclavian approach is most commonly associated
with pneumothorax. 5 The overall incidence is
approximately 2%. Initially both the clinical and
radiographic features may be normal but will become
apparent 48 hours following implantation. Any
unexplained dyspnoea in patients with recent
pacemaker insertion should be assessed by chest x-ray
in deep expiration to exclude this complication
Respiratory distress, haemothorax or pneumothorax
greater than 10% are indications for internention.
Venous thrombosis
Venous thrombosis induced by transvenous permanent
pacemakers is common, although many of them are
subclinical.6 It may be early or late. Pain, swelling with
venous engorgement in ipsilateral extremities should
be investigated by venography or isotope studies.
Thrombosis should be treated by anticoagulation,
thrombolytic treatment or angioplasty. Rarely the
superior vena cava may be involved. 7 It is a medical
emergency and presents with plethora of face, swelling
of face, neck and upper trunk together with distended
veins of neck and upper chest. Severe dyspnoea and
shock may be developed. Immediate anticoagulation
by intravenous heparin should be started in emergency
department after confirming the diagnosis by duplex
ultrasound. Low molecular weight heparin is a new
alternative.8 In addition to thrombolytic treatment and
angioplasty, surgical bypass may be required for severe
cases of superior vena cava obstruction.
Haematoma
Early complication involving the pocket commonly
include haematoma, infection or wound dehiscence.
Haematoma of the pocket was a common problem 9
due to residual bleeding from the dissection of the
fascial plane when creating pocket, leakage of venous
blood along the pocket leads or arterial bleeding may
also cause the haematoma. A small haematoma does
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not require treatment but if it is large enough to be
palpated, surgical exploration is required to treat the
underlying causes. Simple aspiration is not effective
and electrocautery should be avoided to prevent
damaging the pacemaker.
Infection
Infectious complication is not common but may
occasionally be severe and life threatening. Patients
with diabetes, malignancy, on steroid or anticoagulant
therapy are at higher risk. It is also more common in
longer procedures, reoperation and in patients with a
temporary pacing lead in situ.10 Infection of pacemaker
may occur at any part of the pacing system but
generator pockets are most commonly involved.9 They
are mainly due to local contamination during insertion
and can occur as early or late complications. Early
infection is more aggressive and may present as
septicaemia. Rarely it can cause endocarditis,
pneumonia or pyrexia of unknown origin.1 It is usually
due to staphylococcus aureus whereas staphylococcus
epidermidis is associated with more indolent late
infection.
Electrode lead infection is unusual but have a high
mortality.11 It frequently cause vegetation or thrombus
along the lead. The spectrum of casual organisms is
similar to pocket infection. 10 Clinically it usually
present as fever, chills and may progress to septicemia.
Chest involvement both clinically and radiologically
is also common. The diagnosis by conventional imaging
methods is difficult.11 However along with the blood
culture, transoesophageal ultrasound can facilitate the
diagnosis by visualisation of the vegetation.11 Generally
antibiotic together with complete removal of the
infected system is needed. Emergency physicians should
consider pacing systems as a potential source of infection
and promptly recognise it.
Lead problems
Lead displacement is the commonest cause of early
revision of implant, especially in system requiring
atrial lead.1 Nevertheless the frequency is very low due
to improved fixation. It may occur in the first 4-6
weeks after implantation. Clinical suspicion should
Lam/Permanent cardiac pacemarker: an emergency perspective
be raised when there is recurrence of bradycardia with
its associated symptoms. ECG may reveal failure to
capture or sense. Alternatively, it may be complicated
by thromboembolism, cardiac perforation or electrode
lead induced arrhythmia. Diaphragmatic twitching
will occur if displaced lead lie close to diaphragm. A
change in axis of ECG (from left axis deviation to
right axis deviation), suggest dislodgement and
migration of lead. 12
A rare but life threatening complication is cardiac
tamponade resulting from inadvertent puncture
t h r o u g h ve n t r i c u l a r w a l l b y t h e l e a d d u r i n g
implantation. Generally most perforation are benign
and self limiting but rarely it may progress to
tamponade and haemodynamic compromise.13
Post cardiotomy like syndrome secondar y to
pacemaker insertion was first described in 1975. This
is characterised by fever, pleuropericarditis and
pericardial effusion. It usually present 1-4 weeks after
implantation. The diagnosis is by exclusion of other
systemic infection and inflammation. Overall prognosis
is good and respond well to non steroidal anti
inflammatory drugs with or without pericardiocenteis.14
Although ventricular perforation was not recognised,
inadvertent cardiac perforation as an aetiology is
postulated. Such syndrome rarely occur but it should
be considered in the differential causes of fever and
lethargy after implantation.
Lead malposition is a rare complication but may
occasionally be missed. They may present incidentally
or be complicated by thromboembolism. Diagnosis
is suggested by a RBBB pattern of the QRS complex
(normally it is a LBBB like pattern) in ECG and
atypical lead position in chest x-ray. Echocardiogram
will confirm the diagnosis. Revision of lead placement
is needed. 12
Late complications
The overall incidence is low and compares favourably
with early complication rates. Lead fracture is the most
common late complication. Others include erosion
and infection. 15
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Lead insulation break is not usually associated with
severe failure of the pacing system. However the
current leak may induce pectoral or diaphragmatic
twitching, oversensing and failure to capture. It is
characterised by ver y low lead impedance and
replacement of lead is required.
Lead fracture is much more serious and present with
pacemaker failure. It often result from blunt trauma,
from sport injuries, road traffic accidents and domestic
falls 1 Occasionally, damage to a pacemaker is self
inflicted by patient who repeatedly manipulate the
pacemaker. This is called "Twiddler's Syndrome". 16
Fracture may result in oversense, undersense or failure
to capture due to the electrical noise.
Thin elderly are particularly vulnerable to mechanical
erosion. Patients who participate in strenuous sport
activities may displace pacemaker from its implant site
and accelerate erosion. Repositioning of generator may
be necessary.
Sudden battery depletion and generator failure are
uncommon as the pacing system is regularly assessed
and it is possible to check battery life with accuracy.
Fibrosis around tip of electrode within the heart
sometimes causes elevation in pacing threshold and
result in failure to pace. This is referred to as "exit
block". More often the threshold is changed by
concurrent medication, myocardial ischaemia and
electrolyte disturbame.
The problems discussed above found in both single
and dual chamber systems. Other pacemaker related
conditions are discussed in the next section.
Pacemaker syndrome
It is a collection of signs and symptoms in patients
with otherwise normal functioning pacemaker systems
but with suboptional pacing modes. Pathologically it
is due to loss of AV synchrony and is commonly seen
in VVI patients. Clinically it is non specific and
presents with fatigue, weakness, headache and
syncope.16 They should be referred to cardiologist for
changing to a dual chamber system.
172
Paradoxically, pacemakers can be a source of
arrhythmia which may occasionally be potentially life
t h re a t e n i n g . It i n c l u d e p a c e m a k e r m e d i a t e d
tachycardia, runaway pacemaker, lead induced
arrhythmia, sensor induced arrhythmia.
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a focus for ventricular dysrhythmias. They should be
treated according to the ACLS protocol. Definitive
treatment involves repositioning or removal of the leads.
Sensor induced tachycardia
Pacemaker mediated tachycardia (PMT)
It is a re-entry arrhythmia that occur in dual chamber
pacemaker using the pacemaker itself as part of reentry circuit. PMT usually is precipitated by a
premature ventracular contraction but may also occur
spontaneously or after the removal of an applied
magnet.17 It is characterised by rapid, wide complex
tachycardia with each ventricular beat being initiated
by a pacing spike. It's rate is variable but below the
preset upper limit of programme.
Pacemaker capable of rate modulator may pace
inappropriately if the sensor that regulate the pacemaker
is stimulated by nonphysiologic parameters. They are
easily broken with the application of a magnet that
convert it to asynchronous pacing without sensing.
Helicopter aeromedical transport may activate these
sensor by loud noises and vibrations which result in
tachycardia during transport.
Pacing system malfunction and diagnosis
The simplest method to diagnosis and treat PMT in
emergency department is to apply a magnet to the
pacemaker. The magnet interrupts sensing and breaks
PMT. Alternatively intarevous ATP can block retrograde
as well as anterograde conduction through AV node.18
Other methods include carotid sinus message, chest
thump and transcutaneous pacing for refractory cases.17
Permanent cardiac pacemaker malfunction may be in
form of failure to pace, failure to sense or failure to
capture. They are usually due to lead problems or less
commonly generator defect and inappropriate
programming. 10 The importance of history and
physical examination cannot be overemphasised in
making the diagnosis. In addition, ECG can facilitate
the diagnosis of underlying problems.
Runaway pacemaker
A modified approach from Karkal & Syverud is
outlined for evaluating suspected pacemaker
malfunction in emergency department.19
This is a rare condition occurring in older type of
pacemaker. It is a medical emergency caused by
inappropriately rapid discharges exceeding the upper
limit of pacemaker. It can potentially induce
ventricular fibrillation. It cannot be controlled by
defibrillation or medication but may respond to
magnet application or overdrive pacing. Emergency
interrogation and reprogramming may also be
successful. If it fails, urgent surgical intervention to
cut the lead is necessary.
Dysrhythmia due to lead dislodgement
A lead tip may potentially bounce against the ventricular
wall as a result of dislodgement and migration can act as
1. Check 12 lead electrocardiogram. Is the patient in
their own rhythm or are paced beats evident? Paced
beat are identified by pacing spike. If pacing spikes
are present, do they capture? If it is absent, can it
b e a c c o u n t e d by h i g h e r i n t r i n s i c r a t e o r
inappropriate erratic variation in the timing of the
pacing spikes (oversense)?
2. Assess sensing function – do inappropriate pacing
spikes occur in the presence of intrinsic rhythm
(undersense).
3. Check magnet rate by applying a magnet
over generator – if the magnet rate is slower by
more than 10% of the expected rate, battery
depletion is likely.
Lam/Permanent cardiac pacemarker: an emergency perspective
Spike present: failure to capture
If it occur in first few days after implantation, lead
dislodgement or inadequate tightening of the set screw
on the generator head is likely. Problems with capture
weeks or months later are often due to elevated pacing
threshold above preset limit. They may due to exit block,
medication, electrolytic disturbance, metabolic acidosis,
myocardial infarction and defibrillator. Capture failure
that happened many months or years after implantation
is result of lead damage either due to insulation defect
or fracture. Pacing spike may fail to capture if they fall
in normal refractory period of native beat in which case
the problem is due to undersensing.
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failure, the priority is to restore haemodynamic status
before evaluating the pacemaker. Methods of choice
include :
1. Temporary pacing by transcutaneous means
especially those with 3rd degree AV block and
Mobitz II block.
2. Medication – atropine may be effective in patient
with bradycardia especially those with high vagal
tone and narrow QRS complex.
3. Application of magnet can treat arrhythmia due
to PMT, sensor induced tachycardia, runaway
pacemaker.
4. Cardioversion and defibrillation can be performed
when indicated but some precaution should be
taken.
Inappropriate presence of stimuli: undersensing
The native intracardiac signal may change over
time, during exercise or because of myocardial
ischaemia, drug treatment, or electolyte imbalance.
Lead fracture and insulation defect will attenuate the
signal reaching the generator but it may also be caused
by inappropriate programming.
Inappropriate absence of stimuli: oversensing
Pseudomalfunction must first be excluded as small
bipolar spike may not be well seen.
Either there no stimuli are sent from the generator or
when sent, they fail to reach the heart. The former
condition is oversensing which may be due to
interference from skeletal myo-potentials, normal
cardiac potentials, make-break signals from lead
fracture or insulation defects. Lead fracture or
dislodgement may block pacing stimuli from reaching
the heart. Oversensing are readily corrected by magnet
application but this is not the case with the latter.
Management of unstable patient in
emergency departments
For patients who are pacemaker dependent, in heart
failure and haemodynamically unstable as a pacemaker
Special consideration in patients with pacemaker
presenting to emergency departments
Resuscitation
There is no contraindication to perform cardiopulmonary resuscitation and institute advanced
cardiac life support for pacemaker patients in cardiac
arrest. However, the new semi-automatic defibrillation
used by paramedics may fail to discharge in the
presence of ventricular fibrillation as it oversense the
pacing spike as acceptable rhythm.20 Defibrillation or
cardioversion can be done under standard indication.
But the current may damage pacing and sensing
circuit. The incidence of failure to capture in patients
with permanent pacemaker was as high as 50%.21 To
minimise this, the defibrillator paddle should be
placed as far away as possible from the generator. As
there is risk of pacemaker malfunction after
defibrillator or cardioversion, external pacing should
be readily available. After successful defibrillation and
stabilisation, the pacemaker should be interrogated
and reprogrammed if necessary. Many antiarrhythmic
drug – pacemaker interactions will elevate pacing
threshold and result in failure to capture. But only
class IC drugs (Flecainide – like) are of clinical
significance at therapeutic drug concentration. It can
be reversed with isoproterenol which lowers the
pacing threshold. Alternatively the patients can be
Hong Kong j. emerg. med.
174
temporarily paced with transcutaneous pacing. Finally
the decision to terminate resuscitation should not be
influenced by the presence or absence of pacing
stimuli.
Acute coronary syndrome
Pacemaker patients are generally elderly and have a high
prevalence of ischaemic heart disease. ECG diagnosis of
AMI in the presence of ventricular pacing can be very
difficult because of pacing artifact and changes in
depolarisation rector (widened and LBBB like QRS
complex) that obscure the classic ECG finding of
AMI.22 In addition ST and T wave abnormalities can be
misleading because ischaemic injuries cannot be
differentiated reliably from ECG changes secondary to
cardiac pacing. Sgarbossa et al23 developed 3 criteria from
GUSTO-trail which may have some value in diagnosis
of AMI in ventricular paced rhythms.
1. ST elevation 5 mm discordant with QRS
2. ST elevation 1 mm concordant with QRS
3. ST depression 1 mm in lead V1 V2 V3
Other useful methods include comparing current
ECG to a previous ECG or looking for ST-T waves
abnormalities in serial electrocardiograms.
Trauma
Trauma may rarely have adverse effect on pacemakers
function which are commonly due to road traffic
accidents, sporting injuries and domestic falls. It can
cause generator failure, lead fracture, lead migration
and pocket erosion. In managing trauma in such
patient at emergency department, pacemaker pocket
and its function must be fully assessed.
Emergency departments
The procedures and investigation carried out in
emergency department may pose as electromagnetic
interference, affecting pacemaker function.
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Electrocautery can cause pacemaker inhibition and
damage the lead.4 So the ground plate and diathermy
should be placed as far as possible and away from the
pacemaker. The strength should be kept low and
continuous burst avoided. Standard radiography, CT
and isotope scanning procedure carry no risk but MRI
may be hazardous.
Conclusion
This review has discussed the complications,
malfunction of pacemakers and its treatment in
emergency departments. The special conditions that
are related to pacemakers’ presence have been
highlighted.
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