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Selective site pacing in paediatric patients—technology or function?

Michael Gammage
DOI: http://dx.doi.org/10.1093/europace/eup073 542-543 First published online: 4 April 2009

While the debate about the role of selective site pacing in adults with structurally normal hearts continues, many in the paediatric pacing fraternity have adopted the new technologies available with open arms as a means to address some of the long-standing difficulties associated with pacing infants, children, and young adults. The challenges for endocardial pacing in the paediatric population are many, but include unusual anatomy, smaller access vessels, need for active fixation, need for good manoeuvrability of the lead/delivery system, ability to deal with growth and leads with very high expectations of longevity and reliability. In many ways, a new catheter-delivered lead system as discussed by Cantù et al.1 in this issue seems to address the needs of the paediatric population quite closely.

The lumen-less lead itself is 4.1 French (Fr) (but requiring an 8.6 Fr catheter for delivery), has an active fixation mechanism and is designed (in theory) to be as robust as current technology allows through use of cable technology and redundant insulation. The delivery system is steerable in one plane, protects the lead screw until fixation is required and allows for pressure monitoring through the catheter.2 The implant technique is, however, different from that used for ‘traditional’, stylet-delivered leads (although similar to that used for coronary sinus leads); there is an undoubted learning curve, the system is more costly than a stylet-delivered lead and the procedure may be (at least in the early stages of experience) more prolonged. Although the lead diameter is only 4.1 Fr, concern has been expressed from paediatric implanters over the need of using an 8.6 Fr catheter with greater potential for size-related vessel damage or difficulty of access in very small children. Reports using the lead with smaller (5 Fr) delivery systems have demonstrated that this lead can be used in very small children ( <20 kg) with reduced risk of subclavian injury; this approach, however, precludes the steerable, site-selective opportunities offered by the delivery system designed to accompany the lead and leaves the fixed helix exposed during lead manipulation.3 Hansky et al.4 have described their use of this lead in the proximal coronary sinus with a 6 Fr guiding catheter; this catheter is longer than the lead allowing helix protection but requiring trimming of the catheter and slitting with scissors following fixation. The same group also showed the benefits of using this catheter-delivery/lumen-less lead system in patients who have undergone the Fontan procedure.5

In paediatric (and adult congenital) practice, however, many of these concerns fade into insignificance compared with the ability to place the lead in the most functionally effective site, minimize the risk of vessel occlusion, and to ensure reliable, long-term pacing (where long-term may be defined as more than 50 years!). Cantù et al. detail their experience using the Medtronic SelectSecure™ system in 30 patients between the ages of 2 and 16 years with specific emphasis on targeting right ventricular (RV) pacing sites using the Karpawich definitions.6 Whether the sites chosen by the authors for lead placement are functionally correct remains a topic for future discussion; perhaps, more important is the fact that the implanters should be able to place the lead at the site that they feel most appropriate—underlining the use of the word ‘selective’ rather than ‘alternative’ site pacing in this context.

Cantù et al. have shown that this approach can be used to successfully place leads on the mid-septum, low-septum, in the outflow tract and in the LEVO-RV-apex in children between the ages of 2 and 16 years. Although follow-up is relatively short (11 ± 10 months), the electrical performance of the leads appears entirely satisfactory in comparison with other modern active fixation, steroid-eluting leads, and data appear stable. The numbers are relatively small, but the demonstration of the ability to target these sites effectively and without complication is in line with reports from other groups using this system in paediatric and adult congenital practice. The authors recognize that there are currently few studies supporting the benefits of selective-site pacing in children,7 although data to demonstrate the detrimental long-term effects of RV apical pacing over the periods encountered as a result of pacing children are convincing.8,9 It is of note, however, that no medium- or long-term study has demonstrated any detrimental effects of selective site ventricular pacing when compared with RV apical pacing in any patient group.

There is little doubt that endocardial pacing offers significant reliability benefits over epicardial pacing10 in paediatric practice; if this can be associated with reduced vessel occlusion/damage and improved long-term cardiac function, the use of small, catheter-delivered leads should become the standard approach. Unfortunately, lead reliability can only be proven by exhaustive long-term follow-up over many years and demonstration of functional benefit requires large randomized studies of prolonged duration. These processes are underway in the adult population; many of the data obtained may be transferable to younger patients but in the meantime the proven benefits of a small, selectively placed pacemaker lead would appear to justify the increased cost of the system as there is nothing to suggest that this approach is not at least as good as a stylet-delivered lead placed in the RV apex or an epicardial approach.

Conflict of interest: Dr Gammage has acted as a Consultant for Medtronic Inc. and was involved in the development and evaluation process for the SelectSecure™ lead system.

Footnotes

  • The opinions expressed in this article are not necessarily those of the Editors of Europace or of the European Society of Cardiology.

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