Research Abstracts Online
2008 - March 2009
University of Minnesota Twin Cities
Department of Surgery
PI: Paul A. Iaizzo
Modeling Induced Electric Fields as a Function of Cardiac Anatomy and Pacing Lead Locations
The effects of cardiac anatomy and pacing lead electrode locations in left ventricular cardiac veins on resultant pacing thresholds are not well understood. In vitro thresholds measured in swine hearts were compared with electric fields simulated by a computational model (Ansoft Maxwell®, available through MSI) of left ventricular venous pacing with varying vein diameters, fat thicknesses, and electrode positions. Simulation pacing thresholds were defined as 1 V/cm and simulated materials were defined as isotropic. These results demonstrated higher thresholds when an electrode was oriented away from the myocardium or in free-floating positions requiring more myocardial tissue to have 1 V/cm than when it was oriented toward the myocardium. Modeled electric fields followed the same qualitative trends as in vitro experiments performed in our lab. While electrode position affected pacing thresholds, vein diameter and epicardial fat thickness also influenced thresholds. Electrostatic field simulations can provide insight as to how cardiac anatomy and electrode locations affect thresholds by providing visualization of the electric field propagating through cardiac tissues during a pacing pulse.
Sara Anderson, Graduate Student