Figure 4.

Guidance of lead placement with ECGI. Activation maps for 5 pacing regimes (Pre-CRT, CRT-OPT, CRT-NOM, ANT-P, POST-P) are shown in 2 views, anterior (left) and inferior (right). This patient is an 8-year-old male with hypoplastic left heart syndrome, mitral atresia, and double outlet right ventricle who had a DDD epicardial pacemaker implanted at the age of 3 months for postoperative complete heart block. The pacing lead was placed in a right posterior area (white asterisk, pre-CRT panel). At 4 years of age, he had a fenestrated extra-cardiac Fontan operation. Over the following several years he developed worsening HF. His pre-CRT activation map (top panel) showed a severely elevated electrical dyssynchrony (ED) index (ED = 50ms; text for ED definition), with severely delayed activation of the left anterior basal and inferior basal areas of the ventricle (dark blue, pre-CRT). These areas were designated as suitable sites for the resynchronization lead. The patient underwent surgical implant of an epicardial lead at the left anterior basal area. Repeated ECGI 3 months after implant showed a dramatically improved synchrony during optimal BiV pacing, with ED dropping to the normal range (ED = 27ms; CRT-OPT); improvement with nominal BiV pacing(without optimization of inter-ventricular pacing delay) was slightly less (ED = 29ms; CRT-NOM). LA, left atrium; RA, right atrium; ANT-P, anterior lead pacing only; POST-P, posterior lead pacing only. White asterisks denote sites of pacing leads. (From Silva JN, Ghosh S, Bowman TM, Rhee EK, Woodard PK, Rudy Y. Cardiac Resynchronization Therapy in Pediatric Congenital heart Disease: Insights from Noninvasive Electrocardiographic Imaging. Heart Rhythm 2009;6:1178–1185; with permission.)