Abstract 13241: Effect of Left Ventricular Assist Devices on Defibrillation Thresholds a Computational Simulation
Introduction: Patients (pts) who receive left ventricular assist devices (LVADs) often have implantable cardioverter defibrillators (ICDs). LVADs provide a conductor substrate for electric field distortions during cardiac defibrillation (DEFIB). We used full torso finite element models (FEMs) computer simulation to calculate these distortions and evaluate clinical impact.
Methods: Seven MRIs and 1 CT of 4 pediatric and 4 adult pts were formulated into FEMs. DEFIB simulations were compared with and without LVADs. The RV shocking coils of single (SC) and dual coil (DC) leads were positioned in 13 locations from base to apex. The ICD generator was placed in right (R) and left (L) pre-pectoral positions. LVADs were positioned with an insertion into the LV apex and coursing below the diaphragm in the abdomen. DEFIB thresholds (DFTs) were calculated for 832 FEMs and compared.
Results: LVADs resulted in a substantial change in DFTs, especially in a subset of standard L ICD placements (see Chart 1). LVADs had disparate effects on DFTs depending on RV coil location. The change in DFT with LVAD for R ICDs ranged from 72.2 to -25.6 J, mean 7.6 ± 16.5 J (p<0.001) for SC and 21.4 to -9.5 J, mean 0.9 ± 5.4 J (p=0.1) for DC leads. The change in DFT for L ICDs ranged from 31.8 to -0.4 J, mean 4.7 ± 6.7 J (p<0.001) for SC and 13.3 to -1.4 J, mean 1.0 ± 2.7 J (p<0.001) for DC leads. SC leads in the RVOT showed the greatest increase in DFT for both R and L ICDs. LVADs improved DFTs for ICDs with DC leads in the RV apex. Pediatric pts had a larger change in DFT than adults for L but not R ICDs.
Conclusions: FEMs predict that LVADs change DFTs. Changes vary with the location of ICD generator and RV coil and the number of coils. Computer simulation provides non-shock evaluation of ICD effectiveness in presence of LVADs and shows utility of simulation to optimize ICD implants. Patients with L SC ICDs, RVOT coil positions or prior high DFT should undergo repeat DFT testing after LVAD placement.
- © 2013 by American Heart Association, Inc.