Europace Advance Access originally published online on May 19, 2008
Europace 2008 10(7):888-889; doi:10.1093/europace/eun126
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CASE REPORTS
Unusual electrocardiographic presentation of pacemaker battery depletion with lead failure: pacing spike, artefact or native QRS? A short communication
luDivision of Pacing and Electrophysiology, Department of Cardiology, Institute of Cardiology, Istanbul University, Haseki-Fatih, Istanbul, Turkey
Manuscript submitted 20 February 2008. Accepted after revision 21 April 2008.
* Corresponding author. Tel: +90 505 389 63 91; fax: +90 212 570 40 98. E-mail address: drfaridaliyev{at}yahoo.com.tr
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Abstract |
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Herein we report an unusual electrocardiographic presentation of a patient with pacemaker battery depletion and lead insulation failure.
Key Words: Lead fracture, Insulation, Pacemaker battery depletion, Electrical current, Leakage
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Introduction |
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A 63-year-old male patient presented to emergency department of our institute, with sudden onset dizziness, lightheadedness, and syncope. His medical history revealed implantation of permanent pacemaker (pacemaker: Neway VDR, Sorin; lead: St Jude, AVPlus DX 1368) for third-degree atrioventricular block 10 years ago and loss of pacemaker follow-up for the last 3 years.
During monitorization and electrocardiographic examination, we observed regular electrical activity at a rate of 75 bpm mimicking unusual QRS pattern (Figure 1). But physical examination revealed a heart rate of 30 bpm and blood pressure of 70/30 mmHg. Pacemaker could not be interrogated due to the depletion of battery, and temporary transvenous pacemaker was introduced with subsequent stabilization of the haemodynamic condition of the patient. No fracture or insulation break was detected on fluoroscopic examination of the visible lead segments and replacement of battery was planned. During replacement procedure, we observed a very thick capsule surrounding the battery and explantation of the device revealed insulation break in the segment of lead underlying the battery (Figure 2). Pacing threshold was 2.5 V with bipolar and 2.2 V with unipolar stimulation and pacing impedance was 230 
. Unipolar pacing resembled high amplitude spikes, which are its well-known features. Possibility of intermittent ventricular capture was excluded, because of the different morphology of ventricular escape rhythm and paced QRS complexes, which was best seen in precordial leads (data not shown). There was no pocket stimulation at pacing output of 5 V. Above mentioned electrical activity was noted even with pacing at 0.5 V. The older lead could not be extracted and we introduced second lead from the same right subclavian vein and replaced a battery. This unusual electrocardiographic pattern disappeared after implantation of new pacing system. Patient had uneventful recovery and was discharged on the fifth post-procedural day.
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Discussion |
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We suggest that internal insulation failure of the lead resulted in low impedance and increased battery current, which led to acceleration of battery depletion during the 3 years period, when the patient did not come for follow-up. And onset of symptoms in our patient was a consequence of sudden drop in pacing output due to the critically depleted pacing battery. These factors, all together led to unusual electrocardiographic pattern of regular electrical activity, mimicking unusual QRS.
Close examination of Figure 1 shows regular and narrow electrical activity at a rate of 75 bpm and native ventricular escape rhythm at a rate of 30 bpm. Differential diagnosis at this stage includes loss of capture if this electrical activity is assumed to represent a unipolar pacing spike, electrical artifact of unknown origin, or accelerated nodal rhythm, but the last was excluded based on the finding that patient heart rate was 30 bpm. Loss of capture can occur due to the battery depletion, lead fracture or dislodgement, and increase in pacing threshold. The presence of unipolar pacing spike is unlikely, taking into account the fact that pacing lead was bipolar one and unipolar pacing resembled spikes, with well-appreciated unipolar morphology, different from that we observed. There were no signs of myocardial ischaemia or history of recent drug intake as a potential factor leading to increase in pacing thresholds. Dislodgement of pacing lead was unlikely, because this lead was implanted 10 years ago.
Recurrence of pre-implantation symptoms and demonstration of sensing or pacing malfunction are signs of lead fracture or battery depletion. And fracture of the lead is generally accompanied by decrease in pacing impedance, which itself prevents sufficient energy delivery to the myocardium and this is especially important in patients with depleted pacemaker battery.
Various electrical artefacts can be recorded from failing bipolar leads, as a result of current flow from one conductor to another.1
But these artefacts are recorded directly from the lead as a chaotic electrical activity and are not expected to appear on surface ECG.
Electrical activity recorded in our patient is suggested to represent regular pacemaker discharge at a rate of 75 bpm, but the marked decrease in pacing output as a result of battery depletion and leakage of current from the lead insulation defect site prevents delivery of sufficient energy required for myocardial stimulation. Electrocardiographic devices and monitors recorded this electrical activity, resulting from the rhythmic leakage of current through the defect in the lead. Two important points, which we would like to mention here, are the fact that internal lead insulation failure results in low impedance, which leads to increased battery drainage with subsequent premature battery depletion, and short circuit between the proximal and distal conductors may prevent delivery of the sufficient current to the tip of the lead.
Conflict of interest: none declared.
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[1] Rosenheck S, Sharon Z, Leibowitz D. Artifacts recorded through failing bipolar polyurethane insulated permanent pacing leads. Europace (2000) 2:60–5.
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