Abstract
A 72-year-old man presented for routine dual chamber pacemaker interrogation 13 years following insertion for sick sinus syndrome. Increased noise, impedance and threshold of the right ventricular (RV) lead were identified. RV capture was maintained with an overall RV pacing burden of 47%. A routine generator replacement was scheduled alongside RV lead replacement. Fluoroscopy at the start of the procedure revealed an unexpected striking fracture of the RV pacing lead with complete separation of the proximal and distal portions within the RV. The patient was asymptomatic and described no predisposing factors. He underwent implantation of a new ventricular lead and generator and has remained well. This case demonstrates clear RV lead fracture as a late complication of pacemaker implantation despite maintained capture. This emphasises the need for a chest X-ray when a change in device parameters is noted at device interrogation even in the absence of symptoms.
Keywords: cardiovascular medicine, pacing and electrophysiology
Background
Pacemaker implantation is a common procedure. Most complications occur acutely or in the first year following implantation. Prospective data report that the rate of early major complications is 4%, while the rate of minor complications is 7.4% in a cohort followed up for 6 months.1
Patients with a lead fracture may present with symptoms of loss of capture including dizziness, syncope, chest discomfort and palpitations or may be asymptomatic. Theoretically, impedance increases if a lead fractures and decreases if there is an insulation breach.2 However, clinical data suggest that impedance is within the normal range at >70% of implantable cardiac defibrillator lead insulation breaches or lead fractures.3 The causes of lead fracture are incompletely understood but blunt chest trauma, crush injuries between the clavicle and the first rib on excess slack on the pacemaker leads have been reported. Studies have shown that fracture rate of multifilar coil leads is less frequent than with single filar coil leads.4
Case presentation
A 72-year-old man presented for a routine annual pacemaker check. He had a history of hypertension, non-ST elevation myocardial infarction and sick sinus syndrome with subsequent pacemaker insertion in 2007 (Symphony DR SN:706WG109) with a passive right atrial (RA) lead (Aprox 60-BP SN:28221695) and a passive right ventricular (RV) lead (Isoflex 1646T/58 cm SN: 00UB154480). Routine follow-up device interrogation revealed an increase in noise, threshold and impedance in the RV lead since the previous check 14 months prior. The RV impedance had increased from 702 Ohms to 2900 Ohms and the R wave had dropped from 11 mV to 4 mV. Furthermore, the threshold had increased from 1.25 V to 2.25 V at 0.35 ms/2 V at 1.0 ms. The lead was, however, still capturing the RV (figure 1) with a device reported overall RV pacing percentage of 47%. The pacemaker had not been checked in the 14 months between routine appointments and the patient had remained asymptomatic. In view of the altered pacing parameters, RV output was programmed to 4.5 V at 0.35 ms and RV sensitivity increased to 1.5 mV. Due to battery depletion, he was listed for a routine generator replacement, and in view of the changing parameters of the RV lead he was also listed for this to be replaced.
Figure 1.
Surface ECG recorded immediately prior to the right ventricular (RV) lead replacement procedure demonstrating RV capture.
Prior to the RV lead replacement and generator replacement procedure, a surface ECG was obtained which clearly demonstrated RV capture by the broken RV lead (figure 1). Fluoroscopy at the start of the case demonstrated a striking and unexpected fracture of the RV lead with complete separation of the proximal and distal portions of the RV lead (figure 2). On questioning, the patient was asymptomatic with no history of syncope, presyncope, dyspnoea or chest discomfort and he reported no chest trauma.
Figure 2.
Left: Fluoroscopy at the start of the case demonstrated clear fracture of the proximal and distal portions of the right ventricular (RV) lead. Right: fluoroscopy at the end of the case indicating the position of the new RV alongside the pre-existing pacing leads.
Investigations
The patient had two chest X-rays in 2012 for investigation of atypical chest pain (figure 3). These did not reveal any abnormality in the pacing leads, other than a large loop of the RA lead within the right ventricle and generous slack on the RV lead. Following device interrogation demonstrating a significant change in RV lead parameters, he underwent insertion of a new RV lead alongside routine generator change where the complete separation of the proximal and distal portions of the RV lead was identified (figure 2).
Figure 3.
Chest X-ray demonstrating prominent loop in the right atrial (RA) lead and a generous slack of the right ventricular (RV) lead.
Treatment
At the start of the procedure, a venogram demonstrated a patent subclavian vein suitable for the insertion of a new RV lead. Checks of the pacing leads confirmed that both the RA and RV leads were capturing the myocardium (figure 4). In view of his age and time since original lead implantation, it was felt that the potential risk of extraction was significant. Therefore, the proximal end of the RV lead was disconnected from the generator, capped and buried. A new RV lead (Biotronik Solia S 60 active fix IS-1) was implanted via the axillary vein under fluoroscopic guidance alongside the existing leads. The new RV lead and existing RA lead were connected to a new generator and placed in the pre-existing pocket. This was uneventful and the patient was discharged later that day.
Figure 4.
Top panel: Pacing check at the start of the case demonstrated that the broken right ventricular (RV) lead was sensing an R wave between 3.6 mV and 4.1 mV. Lower panel: Pacing check at the start of the case demonstrated capture of the myocardium by the completely broken RV lead between 1.8 V and 2 V.
Outcome and follow-up
Device interrogation was performed remotely 1 week and 1 month after discharge from hospital. The patient has remained well and routine follow-up interrogation of the device has demonstrated satisfactory pacing parameters.
Discussion
Pacemaker lead fracture is a relatively common complication affecting pacemakers with an estimated prevalence of around 1%–4% per year.4 5 One study reporting long-term follow-up of RV pacing leads found that the vast majority of lead fractures occurred within the first 5 years following implantation. The majority of cases of pacing lead fracture have been attributed to points of stress along the trajectory of the wire and several cases have been reported of pacing lead fracture associated with trauma6 and shear stress.7 The most common sites of fracture reported were either within the pacemaker pocket or between the clavicle and the first rib.8
The likely cause for lead fracture in this case was the amount of slack on both the RA and RV pacing leads at the time of insertion leading to repeated trauma or stress and friction over time.
Lead fractures are usually symptomatic due to loss of capture or noise causing inhibition of pacing especially in pacing dependent patients. This case is unusual as the RV lead was still capturing the myocardium despite a complete fracture (figure 2). The patient presented in this case was entirely asymptomatic as he is unlikely to be pacing dependent. It is likely that the broken conductor in the proximal portion of the lead was in good contact with the myocardium, capturing it although at a higher threshold. This case underlines the importance of timely investigations including a chest X-ray when evaluating pacemaker leads with rising thresholds.
Patient’s perspective.
Since having a pacemaker inserted in 2007 things definitely improved. I had a heart attack in 2012 which I do not think was related. Getting old is a funny thing.
Learning points.
Patients may remain asymptomatic even in the presence of complete fracture of pacing leads.
Chest X-ray imaging is an important investigation if device interrogation shows a sudden change in lead parameters.
In this case, despite complete separation between the proximal and distal portions of the lead, the proximal portion of the right ventricular lead was still capturing the myocardium.
Footnotes
Twitter: @georgia_may_c
Contributors: TS created the initial draft of the manuscript. GMC edited the draft, created the figures and obtained consent from the patient. ES edited the draft and assisted with the creation of the figures. ID oversaw the entire process, edited the draft and granted final approval to the submitted manuscript.
Funding: The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests: None declared.
Provenance and peer review: Not commissioned; externally peer reviewed.
Ethics statements
Patient consent for publication
Obtained.
References
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