IJCS | Volume 31, Nº2, March / April 2018

195 1. Karpawich PP, Singh H, Zelin K. Optimizing paced ventricular function in patients with and without repaired congenital heart disease by contractility-guided lead implant. Pacing Clin Electrophysiol.2015;38(1):54-62. doi: 10.1111/pace.12521. 2. Shimony A, Eisenberg MJ, Filion KB, Amit G. Beneficial effects of right ventricular non - apical vs. apical pacing: a systematic review and meta - analysis of randomized - controlled trials. Europace. 2012;14(1):81-91. doi: 10.1093/europace/eur240. 3. Janousek J, van Geldorp IE, Krupicková S, Rosenthal E, Nuget K, Tomaske M, et al. Permanent cardiac pacing in children: choosing the optimal pacing site: a multicenter study. Circulation. 2013;127(5):613-23. doi: 10.1161/CIRCULATIONAHA.112.115428. 4. Thambo JB, Dos Santos P, De Guillebon M, Roubertie F, Labrousse L, Sacher F, et al. Biventricular stimulation improves right and left ventricular function after Tetralogy of Fallot repair: Acute animal and clinical studies. Heart Rhythm. 2010;7(3):344-50. doi: 10.1016/j. hrthm.2009.11.019. 5. Dubin AM, Feinstein JA, Reddy VM, Hanley FL, Van Hare GF, Rosenthal DN. Electrical resynchronization: a novel therapy for the failing right ventricle. Circulation. 2003;107(18):2287-9. doi: 10.1161/01. CIR.0000070930.33499.9F. 6. Tomaske M, Breithardt OA, Balmer C, Bauersfeld U. Successful cardiac resynchronization with single-site left ventricular pacing in children. Int J Cardiol. 2009;136(2):136-43. doi: 10.1016/j.ijcard.2008.04.048. 7. Vanagt WY, Prinzen FW, Delhaas T. Reversal of pacing induced heart failure by left ventricular apical pacing. NEngl JMed. 2007;357(25):2637-8. doi: 10.1056/NEJMc072317. References Guillen et al. RV resynchronization with septal lead inTOF Int J Cardiovasc Sci. 2018;31(2)193-195 Case Report This RBBB may actually respond better with pacing in the RV when compared with the LV. Placement of the pacing electrode in close proximity to the normal conduction system reestablishes the intraventricular synchrony and offers the potential to improve the ventricular function. Karpawich et al. 1 evaluated the physiological variables of contractility (dP/dt and dP/dt/p) at various sites in younger patients with and without CHD. 1 Their results demonstrated that themid-septal ventricular implantation site offers the best paced ventricular contractility. 1 In addition, the authors recommend that biventricular (Biv) pacing may not be necessary if the pacing site associated with the best contractility response can be established. 1 Moreover, two studies evidenced that both RV and Biv pacing improved RV dP/dt in patients with repaired TOF and clinical signs of RV failure. 4,5 These findings confirm the beneficial effects of RV stimulation in subjects with right heart dysfunction andRBBB, with a preference for Biv pacing when concomitant LV failure is present. We advocate the use of single-site pacing based on the advantage that a single ventricular lead in small children prolongs battery longevity and reduces vascular complications and lead-associated problems. Data in children with LV failure suggest that single-site pacing may be sufficient for resynchronization therapy. 6,7 Changing the site of pacing should be considered if routine echocardiographic tests demonstrate ventricular dilatation or dysfunction. Nevertheless, an individual approach may be best to identify the optimal pacing site in order to prevent future negative effects on electrical activation and cardiac performance. Stimulation fromamidseptal site is associatedwith the best hemodynamic responses and ventricular synchrony compared with other RV pacing sites. This explains the successful resynchronization observed in our patient and confirms that the ventricular pacing site is the major determinant of cardiac pump function. Author contributions Conception and design of the research: Guillen AG, Ortega MC. Acquisition of data: Ortega MC, Ramos DBB. Analysis and interpretation of the data: Ramos DBB, Ramírez FD. Writing of the manuscript: Guillen AG, OrtegaMC.Critical revisionof themanuscript for intellectual content: Guillen AG, Ortega MC, Ramírez FD, Ramos DBB. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding There were no external funding sources for this study. Study Association This study is not associated with any thesis or dissertation work.