Session P84.7

Measuring Implantable Cardioverter Defibrillators (ICD) during Implantation Surgery for Simulation Verification

JT Tate*, JG Stinstra, TA Pilcher, RS MacLeod

University of Utah
Salt Lake City, UT, USA

Implantable cardioverter defibrillators (ICDs) are increasing in use, as is the need of new methods for implantation, especially in pediatric cases. We have developed a patient specific simulation model to predict efficacy of the defibrillation shock. To date the simulation has predicted defibrillation thresholds similar to literature values and indicated more efficient possible placements of the device, yet further verification is required. A method of obtaining clinical measurements is needed to verify the potential distribution of the simulation against actual ICD discharges. Our goal was to develop a method of measuring the ICD surface potentials as the devices are tested during implantation surgery. Specifically, we applied a lead selection algorithm to develop a system of body surface potential mapping that will allow recording from sites that do not interfere with implantation surgery and testing.
In order to develop a measurement system, we used a simulation database of ICD potential distributions to perform the lead selection algorithm. Restrictions were applied to determine the optimal 32 lead locations and a transformation matrix relating the subset of lead to the total torso surface potential. We then analyzed the reconstructions of such measurements to determine the accuracy by finding the percentage error.
When using the optimal lead set to reconstruct surface potentials, the metrics showed an average of.5 % percent error. However, comparing the reconstructions and original potentials, there are regions of high differences only near the location of the ICD.
The optimal lead locations chosen by the algorithm were generally located close to the ICD. Additional important locations included the shoulders, the midaxillary line, and across the intercostal margin. We are currently using this lead set to obtain clinical ICD measurements that we will use for verification of the simulation model.

(Abstract Control Number: 119)