Europace Advance Access originally published online on January 20, 2008
Europace 2008 10(3):334-335; doi:10.1093/europace/eum299
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PACING
Efficacy of closed-loop stimulation with epicardial leads in an infant with congenital atrioventricular block
Paediatric Cardiology and Cardiac Surgery Unit, S. Vincenzo Hospital, Contrada Sirina, 98039 Taormina, Messina, Italy
Manuscript submitted 19 October 2007. Accepted after revision 19 December 2007.
* Corresponding author. Tel: +39 0942579550. E-mail address: dipinoa{at}yahoo.it
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Abstract |
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We present the case of an infant with a congenital atrioventricular block and sinus node dysfunction that was implanted with a pacemaker with physiological closed-loop stimulation (DDD-CLS) pacing mode with two epicardial leads. We have observed the response of DDD-CLS system with respect to conventional rate responsive accelerometer-based mode (DDDR): the atrial pacing percentage and the 24 h rate trend showed higher values during DDD-CLS compared with DDDR. In this patient, rate responsive feature seems preserved in DDD-CLS also using epicardial leads.
Key Words: Epicardial, Closed-loop stimulations, Infant
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Case presentation |
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TopAbstractCase presentationDiscussionAcknowledgements |
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Pacemaker implantation was performed in a 4-month-old infant for a congenital atrioventricular block (AV) block. The baby presented at birth with a complete AV block and a junctional escape rhythm with a mean heart rate of 50 bpm at the Holter monitoring. Permanent pacing was performed for failure in growth and evidence of progressive dilatation of the left ventricle. We decided to implant a rate responsive pacemaker for the presence of a sinus rate that was not adequate to his metabolic status. A DDD-closed-loop stimulation (CLS) PROTOS pacemaker (Biotronik, Berlin, Germany) was surgically implanted in the abdomen. The pacemaker pocket was tailored between the posterior aspect of the left rectus muscle and the anterior fascia. Inferior sternotomy was adopted for leads positioning. The pacemaker was then programmed in DDDR mode for 30 days and in DDD-CLS mode for the following 30 days. For both stimulation modes, the following parameters were programmed: lower rate at 80 bpm; upper CLS/accellerometer rate at 160 bpm; upper tracking rate at 185 bpm. After these periods, the two pacing modalities were compared on the basis of pacemaker diagnostics. In DDD-CLS mode, atrial pacing was 48% with respect to 16% of DDDR and keeping higher in all rate ranges (Figure 1). The 24 h rate trend showed a mean rate during DDD-CLS higher than in DDDR. An echocardiogram performed after 2 months documented a reduction of the left ventricle dilatation, and infant’s growing recovered.
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Discussion |
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TopAbstractCase presentationDiscussionAcknowledgements |
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Previous studies have demonstrated the efficacy of a CLS system to modulate the heart rate physiologically on the basis of the indirect measurement of the ventricular contractility, using an impedance signal. This signal is sampled by subthreshold unipolar pulse trains by an endocardial lead generally assumed to be placed in some region around the right ventricular apex within the right ventricle. No experience was ever documented, to our knowledge, of CLS pacing permanently used along with an epicardial lead, even if this may be theoretically possible. Actually, it is well known that the major component of the resultant impedance value is largely due to the tissue comprised in a small region of
1 cc around the lead tip. Therefore, the CLS performance should only slightly depend on whether the lead tip is placed inside or outside the myocardial wall. Once verified the efficacy of the CLS sensor, we were able to compare it with the accelerometer-based sensor in terms of heart rate modulation. Indeed, this kind of comparison is not truly appropriate because of the restricted movements of such a small infant but is the only actually available in this baby. Nevertheless, the comparison is justified because the accelerometer is not expected to correctly respond to every variation of autonomic tone balance, particularly in the non-movement neurovegetative stresses observed in such a small baby. During DDD-CLS mode, we obtained both an increase in the atrial pacing events rate in every single frequency range and a higher mean rate trend with respect to DDDR. In this setting, the high percentage of atrial pacing observed near the lower rate limit could be seen as a confirmation of the presence of an associated sinus node dysfunction. Thus, even with the limitations aforementioned, these data suggest that CLS is able to modulate heart rate to an extent considerably higher than DDDR. Anyway, we believe that the clinically short-term improvement was due mainly to the increase in the heart rate and not to the CLS heart rate modulation. We actually do not know whether, in this baby, this rate modulation responds physiologically to neurovegetative tone better than DDDR and this issue should be verified by specific tests performed at an older age. This would be a very desirable feature, especially in infants, who would benefit from a pacing driven by neurovegetative stimuli during important life experiences like nursing, weeping, fear, or other emotional states. In conclusion, this report, for the first time, shows a possible application of the CLS along with an epicardial lead, reasonably providing a physiological pacing in a very young patient. |
Acknowledgements |
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The authors thank Ezio Pizzimenti for the discussion and interpretation of the results.
Conflict of interest: none declared.
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