Mapping-guided characterization of mechanical and electrical activation patterns in patients with normal systolic function using a sensor-based tracking technology.

AIMS: In times of evolving cardiac resynchronization therapy, intra-procedural characterization of left ventricular (LV) mechanical activation patterns is desired but technically challenging with currently available technologies. In patients with normal systolic function, we evaluated the feasibility of characterizing LV wall motion using a novel sensor-based, real-time tracking technology. METHODS AND RESULTS: Ten patients underwent simultaneous motion and electrical mapping of the LV endocardium during sinus rhythm using electroanatomical mapping and navigational systems (EnSite™ NavX™ and MediGuide™, SJM). Epicardial motion data were also collected simultaneously at corresponding locations from accessible coronary sinus branches. Displacements at each mapping point and times of electrical and mechanical activation were combined over each of the six standard LV wall segments. Mechanical activation timing was compared with that from electrical activation and preoperative 2D speckle tracking echocardiography (echo). MediGuide-based displacement data were further analysed to estimate LV chamber volumes that were compared with echo and magnetic resonance imaging (MRI). The lateral and septal walls exhibited the largest (12.5 [11.6-15.0] mm) and smallest (10.2 [9.0-11.3] mm) displacement, respectively. Radial displacement was significantly larger endocardially than epicardially (endo: 6.7 [5.0-9.1] mm; epi: 3.8 [2.4-5.6] mm), while longitudinal displacement was significantly larger epicardially (endo: 8.0 [5.0-10.6] mm; epi: 10.3 [7.4-13.8] mm). Most often, the anteroseptal/anterior and lateral walls showed the earliest and latest mechanical activations, respectively. 9/10 patients had concordant or adjacent wall segments of latest mechanical and electrical activation, and 6/10 patients had concordant or adjacent wall segments of latest mechanical activation as measured by MediGuide and echo. MediGuide's LV chamber volumes were significantly correlated with MRI (R2= 0.73, P < 0.01) and echo (R2= 0.75, P < 0.001). CONCLUSION: The feasibility of mapping-guided intra-procedural characterization of LV wall motion was established. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov; Unique identifier: CT01629160.

Intraoperative characterization of interventricular mechanical dyssynchrony using electroanatomic mapping system--a feasibility study.

BACKGROUND: Interventricular mechanical dyssynchrony (VVMD) is a strong predictor of cardiac resynchronization therapy (CRT) response. However, no simple and reliable clinical method of measuring VVMD during CRT implant is currently available. We tested the hypothesis that the EnSite™ NavX™ system (St. Jude Medical, St. Paul, MN, USA) can be used intraoperatively to determine VVMD, thereby facilitating CRT optimization. METHODS: During CRT implant, the leads in the right atrium (RA), right ventricle (RV), and left ventricle (LV) were connected to the EnSite™ NavX™ system to record the real-time 3D motion of the lead electrodes. The distances from RA to RV lead electrodes (RA-RV) and RA to LV lead electrodes (RA-LV) were computed over ten cardiac cycles during each of RV pacing and biventricular (BiV) pacing, respectively. The degree of synchrony was computed from the distance waveforms between RA-RV and RA-LV by a cross-covariance method to characterize VVMD. Septal-to-posterior wall motion delay (SPWMD) from M-mode echocardiography (echo) was measured for reference at each pacing intervention. VVMD was present in all five patients undergoing CRT implant. RESULTS: Four of the five patients demonstrated clear improvement in EnSite™ NavX™-derived VVMD during BiV versus RV pacing, which corresponded to the SPWMD results by echo. CONCLUSIONS: It is feasible to characterize VVMD and resynchronization in CRT patients with the EnSite™ NavX™ system during implant, demonstrating its potential as a tool for intraoperative CRT optimization.