The sternum as an electrical shield

Introduction - The TASER® conducted electrical weapon (CEW) delivers electrical pulses that can temporarily incapacitate subjects. We analyzed the distribution of TASER CEW currents in tissues posterior to the sternum to understand the likelihood of triggering cardiac arrhythmias. We also assessed the electrical `shielding' effects of the sternum. Methods and Results - Finite element modeling (FEM) was used to approximate the current density and electric field strength in tissues around the sternum. We analyzed 2 CEW dart deployment scenarios: (a) both darts over the anterior aspect of the sternum; and (b) a CEW dart anterior to the sternum and the other over the abdomen. In both scenarios, the sternum provided significant attenuation of CEW currents. Particularly, both FEMs predicted that the residual electrical current or charge from CEWs would be insufficient to cause either cardiac capture or induction of ventricular fibrillation at locations where cardiac tissue would reside relative to the posterior aspect of the sternum. Conclusion - The sternum offers significant `shielding' effect and protects the tissues posterior to it against effects of electrical current flow from anteriorly-placed CEW electrodes.

[1]  J Koebke,et al.  [Clinical morphology of the sternum]. , 1991, Biomedizinische Technik. Biomedical engineering.

[2]  S Saha,et al.  Electrical properties of bone. A review. , 1984, Clinical orthopaedics and related research.

[3]  G. Chatellier,et al.  Maximal thickness of the normal human pericardium assessed by electron-beam computed tomography , 1999, European Radiology.

[4]  H.A.M. Mahinda,et al.  Variability in Thickness of Human Skull Bones and Sternum – an Autopsy Experience , 2009 .

[5]  Mark W Kroll,et al.  Electrical Characteristics of an Electronic Control Device Under a Physiologic Load: A Brief Report , 2010, Pacing and clinical electrophysiology : PACE.

[6]  Dorin Panescu,et al.  Theoretical possibility of ventricular fibrillation during use of TASER neuromuscular incapacitation devices , 2008, 2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[7]  J. Webster,et al.  Optimisation of transcutaneous cardiac pacing by three-dimensional finite element modelling of the human thorax , 1995, Medical and Biological Engineering and Computing.

[8]  W. M. Smith,et al.  Effect of field stimulation on cellular repolarization in rabbit myocardium. Implications for reentry induction. , 1992, Circulation research.

[9]  John H. Busser,et al.  Principles of Applied Biomedical Instrumentation , 1968 .

[10]  D. Panescu,et al.  Optimization of cardiac defibrillation by three-dimensional finite element modeling of the human thorax , 1995, IEEE Transactions on Biomedical Engineering.

[11]  G. Mall,et al.  Klinische Morphologie des Brustbeins - Clinical Morphology of the Sternum , 1991 .

[12]  John G. Webster,et al.  ELECTROMUSCULAR INCAPACITATING DEVICE SAFETY , 2005 .

[13]  Dorin Panescu,et al.  Medical safety of TASER conducted energy weapon in a hybrid 3-point deployment mode , 2009, 2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[14]  Harold Bien,et al.  Calcium instabilities in mammalian cardiomyocyte networks. , 2006, Biophysical journal.

[15]  W M Smith,et al.  Prolongation and shortening of action potentials by electrical shocks in frog ventricular muscle. , 1994, The American journal of physiology.