International Journal of Cardiology 177 (2014) e150–e152
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
Far-field ventricular sensing defects and syncope in a patient with right subclavian VDD pace-maker Natale Daniele Brunetti ⁎, Pier Luigi Pellegrino, Girolamo D'Arienzo, Francesco Santoro, Michele Correale, Andrea Guaricci, Matteo Di Biase University of Foggia, Foggia, Italy
a r t i c l e
i n f o
Article history: Received 22 August 2014 Accepted 16 September 2014 Available online 28 September 2014 Keywords: Sensing defect Double-counting Right subclavian pace-maker
Far field sensing defect may complicate the clinical course of patients implanted with a pacemaker (PM) [1,2]. It is still unknown whether right subclavian PM position may be associated with a higher incidence of sensing defects in the case of unipolar sensing modality. We report the case of an 82-year-old man, implanted with a PM more than 10 years earlier, referred to emergency room after an episode of orthostatic syncope followed by 15 min of impaired consciousness. Electrocardiogram at admission showed sinus rhythm (Fig. 1) and PM activity without any apparent sign of PM malfunction. At telemetry control, however, an apparent double-counting of ventricular activity
Fig. 1. Admission electrocardiogram showing sinus bradycardia exceeding programmed lower frequency pacing (50 bpm).
⁎ Corresponding author at: Viale Pinto 1 71100 Foggia, Italy. Tel.: +39 3389112358; fax: +39 0881745424. E-mail address: [email protected] (N.D. Brunetti).
http://dx.doi.org/10.1016/j.ijcard.2014.09.047 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
N.D. Brunetti et al. / International Journal of Cardiology 177 (2014) e150–e152
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Fig. 2. Telemetry pacemaker control showing double-counting ventricular over-sensing defects (red box and arrow), presumably responsible for syncope in the case of marked bradycardia.
caused by far-field sensing defect was found (Fig. 2). PM was programmed in VDD modality, a lower pacing rate of 50 bpm and unipolar sensing modality. PM sensing threshold was 2 mV while pacing threshold was 1.25 mV. PM was therefore reprogrammed in bipolar modality, with no more evidence of ventricular over-sensing. At following ambulatory electrocardiogram and telemetry control no episodes of PM malfunction were found. Six-month follow-up was uneventful. Signals responsible for PM over-sensing may arise from the pacing system itself, P or T wave, concealed ventricular extra-systoles, skeletal muscle potentials, and distant electromagnetic fields2. Oversensing is the most common cause of pacemaker pauses and a common clinical problem during follow-up of patients with implanted pulse generators. In a large registry, the overall incidence was 7.3%; double-counting over-sensing was observed in 0.8% [3].
We hypothesize that the episode of syncope could have been associated with marked orthostatic sinus bradycardia and far-field ventricular over-sensing. Given the double-counting over-sensing defect, PM stimulation may have been inhibited unless heart rate went below 25 bpm, thus justifying the onset of syncope and impaired consciousness. Sensing defects and far field sensing may have been probably facilitated by right subclavian position of PM. In the case of unipolar sensing modality, the interposition of right atrium between PM box and ventricular catheter tip may have induced an incorrect detection of atrial activity as ventricular activation (Fig. 3).
Conflict of interest Authors have no potential conflict of interest to disclose.
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N.D. Brunetti et al. / International Journal of Cardiology 177 (2014) e150–e152
Fig. 3. a) Right subclavian pacemaker position: in the case of unipolar sensing, atria are interposed between pulse generator and the tip of ventricular lead. b) Left subclavian pacemaker position: in the case of unipolar sensing, atria are not interposed between pulse generator and the tip of ventricular lead.
References [1] Johnson CD. Atrial synchronous ventricular inhibited (VDD) pacemaker-mediated arrhythmia due to atrial undersensing and atrial lead oversensing of far-field ventricular afterpotentials or paced beats: crosstalk. Pacing Clin Electrophysiol 1986;9: 710–9.
[2] Barold SS, Falkoff MD, Ong LS, Heinle RA. Oversensing by single-chamber pacemakers: mechanisms, diagnosis, and treatment. Cardiol Clin 1985;3:565–85. [3] Rauwolf T, Guenther M, Hass N, Schnabel A, Bock M, Braun MU. Ventricular oversensing in 518 patients with implanted cardiac defibrillators: incidence, complications, and solutions. Europace 2007;9:1041–7.
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
Far-field ventricular sensing defects and syncope in a patient with right subclavian VDD pace-maker Natale Daniele Brunetti ⁎, Pier Luigi Pellegrino, Girolamo D'Arienzo, Francesco Santoro, Michele Correale, Andrea Guaricci, Matteo Di Biase University of Foggia, Foggia, Italy
a r t i c l e
i n f o
Article history: Received 22 August 2014 Accepted 16 September 2014 Available online 28 September 2014 Keywords: Sensing defect Double-counting Right subclavian pace-maker
Far field sensing defect may complicate the clinical course of patients implanted with a pacemaker (PM) [1,2]. It is still unknown whether right subclavian PM position may be associated with a higher incidence of sensing defects in the case of unipolar sensing modality. We report the case of an 82-year-old man, implanted with a PM more than 10 years earlier, referred to emergency room after an episode of orthostatic syncope followed by 15 min of impaired consciousness. Electrocardiogram at admission showed sinus rhythm (Fig. 1) and PM activity without any apparent sign of PM malfunction. At telemetry control, however, an apparent double-counting of ventricular activity
Fig. 1. Admission electrocardiogram showing sinus bradycardia exceeding programmed lower frequency pacing (50 bpm).
⁎ Corresponding author at: Viale Pinto 1 71100 Foggia, Italy. Tel.: +39 3389112358; fax: +39 0881745424. E-mail address: [email protected] (N.D. Brunetti).
http://dx.doi.org/10.1016/j.ijcard.2014.09.047 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
N.D. Brunetti et al. / International Journal of Cardiology 177 (2014) e150–e152
e151
Fig. 2. Telemetry pacemaker control showing double-counting ventricular over-sensing defects (red box and arrow), presumably responsible for syncope in the case of marked bradycardia.
caused by far-field sensing defect was found (Fig. 2). PM was programmed in VDD modality, a lower pacing rate of 50 bpm and unipolar sensing modality. PM sensing threshold was 2 mV while pacing threshold was 1.25 mV. PM was therefore reprogrammed in bipolar modality, with no more evidence of ventricular over-sensing. At following ambulatory electrocardiogram and telemetry control no episodes of PM malfunction were found. Six-month follow-up was uneventful. Signals responsible for PM over-sensing may arise from the pacing system itself, P or T wave, concealed ventricular extra-systoles, skeletal muscle potentials, and distant electromagnetic fields2. Oversensing is the most common cause of pacemaker pauses and a common clinical problem during follow-up of patients with implanted pulse generators. In a large registry, the overall incidence was 7.3%; double-counting over-sensing was observed in 0.8% [3].
We hypothesize that the episode of syncope could have been associated with marked orthostatic sinus bradycardia and far-field ventricular over-sensing. Given the double-counting over-sensing defect, PM stimulation may have been inhibited unless heart rate went below 25 bpm, thus justifying the onset of syncope and impaired consciousness. Sensing defects and far field sensing may have been probably facilitated by right subclavian position of PM. In the case of unipolar sensing modality, the interposition of right atrium between PM box and ventricular catheter tip may have induced an incorrect detection of atrial activity as ventricular activation (Fig. 3).
Conflict of interest Authors have no potential conflict of interest to disclose.
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N.D. Brunetti et al. / International Journal of Cardiology 177 (2014) e150–e152
Fig. 3. a) Right subclavian pacemaker position: in the case of unipolar sensing, atria are interposed between pulse generator and the tip of ventricular lead. b) Left subclavian pacemaker position: in the case of unipolar sensing, atria are not interposed between pulse generator and the tip of ventricular lead.
References [1] Johnson CD. Atrial synchronous ventricular inhibited (VDD) pacemaker-mediated arrhythmia due to atrial undersensing and atrial lead oversensing of far-field ventricular afterpotentials or paced beats: crosstalk. Pacing Clin Electrophysiol 1986;9: 710–9.
[2] Barold SS, Falkoff MD, Ong LS, Heinle RA. Oversensing by single-chamber pacemakers: mechanisms, diagnosis, and treatment. Cardiol Clin 1985;3:565–85. [3] Rauwolf T, Guenther M, Hass N, Schnabel A, Bock M, Braun MU. Ventricular oversensing in 518 patients with implanted cardiac defibrillators: incidence, complications, and solutions. Europace 2007;9:1041–7.
