Discussion:
Suspicion should arise of lead malposition if there is a pacemaker
derived right bundle branch block pattern on a 12-lead electrocardiogram
instead of the typical left bundle branch block
morphology1. Utilisation of the posterolateral and
anterolateral projections can differentiate and provide further evidence
that LV malposition may have occurred. Various reports have recommended
or used TTE as an imaging modality if there is a suspicion of lead
malposition which offers the ability to see the lead using the
parasternal, apical and subcostal views2,1. A single
centre study by Ohlow and colleagues (2016) concluded that 0.34% of
device implants out of 2579 patients between 2007 and 2012 experienced
lead malposition of which the leading cause was unusual thoracic
anatomy, congenital heart disease and operator
inexperience3. Patients with LV lead malposition are
often asymptomatic until presenting with systemic thromboembolic related
complications such as ischemic stroke4.
The incidence of cerebral embolic events have been reported as high as
37% in patients with LV lead malposition3. The most
common cause of systemic emboli is thrombus or fibrosis formation on the
lead or at the site of implantation. At present there is no clear
recommendations on management of lead malposition with duration between
implant and discovery of lead malposition often influencing treatment.
Incidental findings of lead malposition are often managed with
anticoagulation and antiplatelet therapy in the first instance with the
consideration of percutaneous or surgical lead extraction if deemed
appropriate2,1. As life-long anticoagulation with
Warfarin with a target international nominal ratio of 2.5 – 3.5 has
been advised in this population5, some papers have not
supported the use of anticoagulation in isolation due to reports of
patients with lead malposition presenting with an ischemic stroke after
prophylactic anticoagulation6,7. Other serious
complications associated with LV lead malposition include mitral valve
leaflet perforation8, mitral
regurgitation7 and endocarditis9which must be taken into consideration when discussing the benefits and
risks of lead extraction. While lead repositioning is a potential
treatment option, caution must be taken to ensure percutaneous lead
extraction does not displace any material which has formed on the
lead10. One strategy recently reported by Contractor
and colleagues (2019) suggested that deploying an embolic protection
device in the brachiocephalic and left carotid artery can be used to
remove the risk of potential cerebral embolisation11.
It is beneficial that the patient undergo a TTE and TOE prior to the
procedure to identify the presence of mobile thrombus or fibrous
material as seen within our case study which may increase the risk of
embolisation during extraction12. The addition of
three dimensional views during a standard TOE views (3DTOE) has been
recognised as a useful technique to offer supplementary information of
thrombus characteristics and mobility. The advantage of 3DTOE in
addition to the already high spatial resolution and superior
visualisation of cardiac anatomy seen in standard two-dimensional TOE
offers high specificity and sensitivity when visualising presence of
intra-cardiac thrombus including left atrial thrombi. A recent
case-study recognised that the use of 3DTOE was beneficial when
assessing a large LV apical thrombus when magnetic resonance imaging and
computed tomography were not appropriate13. The
ability to use offline reconstructive techniques assists operators to
augment image quality while visualising any mobile components and its
attachments to the surrounding cardiac structures of a suspected
thrombus. Another advantage of using 3DTOE within this particular
case-study was the high quality images of mitral valve anatomy which
offers a better perspective than 2D imaging including good visualisation
and size of all scallops and mitral valve geometry. The benefits of
3DTOE in this case study was the ability to observe the exact position
of the lead crossing the mitral valve with the use of the ‘surgeons
view’, to see if the position of the pacing lead was negatively impeding
the behaviour and mobility of the mitral valve leaflets and the thrombus
attached to the lead in the left atrium. While some studies have
identified that right ventricular lead extraction is viable and safe
option of lead extraction, only few publicised cases have demonstrated
the safe removal of anomalous rhythm management leads seen in the
LV13, 14. Recommendations provided by the heart rhythm
society in 2009 discussing indications for lead extraction offered
caution when considering LV percutaneous lead extraction with the
heightened risk of thromboembolic stroke. Although, the review cautioned
that surgical removal of anomalous transvenous leads is a class III
indication and could be offered at the same time as other surgical
interventions requiring cardiopulmonary bypass15.
Based upon the results of the TEE our patient was offered
anticoagulation and antiplatelet therapy in the short-term with the goal
of percutaneous lead extraction. A TEE was repeated after six months of
medical therapy which showed no evidence of a mass and the patient was
consented for percutaneous lead extraction due to the patient’s
co-morbidities making him high risk for surgery.