Objectives Cardiac arrest after open surgery has an incidence of approximately 3%, of which more than 50% of the cases are due to ventricular fibrillation. Electrical defibrillation is the most effective therapy for terminating cardiac arrhythmias associated with unstable hemodynamics. The excitation threshold of myocardial microstructures is lower when external electrical fields are applied in the longitudinal direction with respect to the major axis of cells. However, in the heart, cell bundles are disposed in several directions. Improved myocardial excitation and defibrillation have been achieved by applying shocks in multiple directions via intracardiac leads, but the results are controversial when the electrodes are not located within the cardiac chambers. This study was designed to test whether rapidly switching shock delivery in 3 directions could increase the efficiency of direct defibrillation.© 2014 The American Association for Thoracic Surgery Methods A multidirectional defibrillator and paddles bearing 3 electrodes each were developed and used in vivo for the reversal of electrically induced ventricular fibrillation in an anesthetized open-chest swine model. Direct defibrillation was performed by unidirectional and multidirectional shocks applied in an alternating fashion. Survival analysis was used to estimate the relationship between the probability of defibrillation and the shock energy.Results Compared with shock delivery in a single direction in the same animal population, the shock energy required for multidirectional defibrillation was 20% to 30% lower (P <.05) within a wide range of success probabilities.Conclusions Rapidly switching multidirectional shock delivery required lower shock energy for ventricular fibrillation termination and may be a safer alternative for restoring cardiac sinus rhythm.148632133218Dunning, J., Fabbri, A., Kolh, P.H., Levine, A., Lockowandt, U., Mackay, J., Guideline for resuscitation in cardiac arrest after cardiac surgery (2009) Eur J Cardiothorac Surg, 36, pp. 3-28Vanden Hoek, T.L., Morrison, L.J., Shuster, M., Donnino, M., Sinz, E., Lavonas, E.J., Part 12: Cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care (2010) Circulation, 122, pp. 829-S861Walker, R.G., Koster, R.W., Sun, C., Moffat, G., Barger, J., Dodson, P.P., Defibrillation probability and impedance change between shocks during resuscitation from out-of-hospital cardiac arrest (2009) Resuscitation, 80, pp. 773-777Zipes, D.P., Fischer, J., King, R.M., Nicoll, A., Jolly, W.W., Termination of ventricular fibrillation in dogs by depolarizing a critical amount of myocardium (1975) Am J Cardiol, 36, pp. 37-44Chapman, P.D., Sagar, K.B., Wetherbee, J.N., Troup, P.J., Relationship of left ventricular mass to defibrillation threshold for the implantable defibrillator: A combined clinical and animal study (1987) Am Heart J, 114, pp. 274-278Yabe, S., Smith, W.M., Daubert, J.P., Wolf, P.D., Rollins, D.L., Ideker, R.E., Conduction disturbances caused by high current density electric fields (1990) Circ Res, 66, pp. 1190-1203Fedorov, V.V., Nikolski, V.P., Efimov, I.R., Effect of electroporation on cardiac electrophysiology (2008) Methods Mol Biol, 423, pp. 433-448Hendrikx, M., Jiang, H., Gutermann, H., Toelsie, J., Renard, D., Briers, A., Release of cardiac troponin i in antegrade crystalloid versus cold blood cardioplegia (1999) J Thorac Cardiovasc Surg, 118, pp. 452-459De Oliveira, P.X., Bassani, R.A., Bassani, J.W., Lethal effect of electric fields on isolated ventricular myocytes (2008) IEEE Trans Biomed Eng, 55, pp. 2635-2642Tsai, M.S., Tang, W., Sun, S., Wang, H., Freeman, G., Chen, W.J., Individual effect of components of defibrillation waveform on the contractile function and intracellular calcium dynamics of cardiomyocytes (2009) Crit Care Med, 37, pp. 2394-2401Tung, L., Sliz, N., Mulligan, M.R., Influence of electrical axis of stimulation on excitation of cardiac muscle cells (1991) Circ Res, 69, pp. 722-730Knisley, S.B., Baynham, T.C., Line stimulation parallel to myofibers enhances regional uniformity of transmembrane voltage changes in rabbit hearts (1997) Circ Res, 81, pp. 229-241Bassani, R.A., Lima, K.A., Gomes, P.A., Oliveira, P.X., Bassani, J.W., Combining stimulus direction and waveform for optimization of threshold stimulation of isolated ventricular myocytes (2006) Physiol Meas, 27, pp. 851-863Fonseca, A.V., Bassani, R.A., Oliveira, P.X., Bassani, J.W., Greater cardiac cell excitation efficiency with rapidly switching multidirectional electrical stimulation (2013) IEEE Trans Biomed Eng, 60, pp. 28-34Bourland, J.D., Tacker, Jr.W.A., Wessale, J.L., Kallok, M.J., Graf, J.E., Geddes, L.A., Sequential pulse defibrillation for implantable defibrillators (1986) Med Instrum, 20, pp. 138-142Chang, M.S., Inoue, H., Kallok, M.J., Zipes, D.P., Double and triple sequential shocks reduce ventricular defibrillation threshold in dogs with and without myocardial infarction (1986) J Am Coll Cardiol, 8, pp. 1393-1405Jones, D.L., Klein, G.J., Guiraudon, G.M., Sharma, A.D., Kallok, M.J., Bourland, J.D., Internal cardiac defibrillation in man: Pronounced improvement with sequential pulse delivery to two different lead orientations (1986) Circulation, 73, pp. 484-491Exner, D., Yee, R., Jones, D.L., Klein, G.J., Mehra, R., Combination biphasic waveform plus sequential pulse defibrillation improves defibrillation efficacy of a nonthoracotomy lead system (1994) J Am Coll Cardiol, 23, pp. 317-322Kerber, R.E., Spencer, K.T., Kallok, M.J., Birkett, C., Smith, R., Yoerger, D., Overlapping sequential pulses. A new waveform for transthoracic defibrillation (1994) Circulation, 89, pp. 2369-2379Pagan-Carlo, L.A., Allan, J.J., Spencer, K.T., Birkett, C.L., Myers, R., Kerber, R.E., Encircling overlapping multipulse shock waveforms for transthoracic defibrillation (1998) J Am Coll Cardiol, 32, pp. 2065-2071Kerber, R.E., Bourland, J.D., Kallok, M.J., Hite, P., Pritchard, B., Charbonnier, F., Transthoracic defibrillation using sequential and simultaneous dual shock pathways: Experimental studies (1990) Pacing Clin Electrophysiol, 13, pp. 207-217Roscher, R., Arlock, P., Sjoberg, T., Steen, S., Effects of dopamine on porcine myocardial action potentials and contractions at 37 degrees C and 32 degrees C (2001) Acta Anaesthesiol Scand, 45, pp. 421-426Petrucci Junior, O., Oliveira, P.P., Carmo, M.R., Vieira, R.W., Braile, D.M., Standardization of an isolated pig heart preparation with parabiotic circulation: Methodological considerations (2003) Braz J Med Biol Res, 36, pp. 649-659Euler, D.E., Whitman, T.A., Roberts, P.R., Kallok, M.J., Low voltage direct current delivered through unipolar transvenous leads: An alternate method for the induction of ventricular fibrillation (1999) Pacing Clin Electrophysiol, 22, pp. 908-914Suzuki, Y., Yeung, A.C., Ikeno, F., The representative porcine model for human cardiovascular disease (2011) J Biomed Biotechnol, 2011, p. 195483Neunlist, M., Tung, L., Spatial distribution of cardiac transmembrane potentials around an extracellular electrode: Dependence on fiber orientation (1995) Biophys J, 68, pp. 2310-2322Gilbert, S.H., Benoist, D., Benson, A.P., White, E., Tanner, S.F., Holden, A.V., Visualization and quantification of whole rat heart laminar structure using high-spatial resolution contrast-enhanced MRI (2012) Am J Physiol Heart Circ Physiol, 302, pp. 287-H298Efimov, I., Ripplinger, C.M., Virtual electrode hypothesis of defibrillation (2006) Heart Rhythm, 3, pp. 1100-1102Koster, R.W., Baubin, M.A., Bossaert, L.L., Caballero, A., Cassan, P., Castren, M., European Resuscitation Council Guidelines for Resuscitation 2010 Section 2. Adult basic life support and use of automated external defibrillators (2010) Resuscitation, 81, pp. 1277-1292Shelton, R.J., Brown, B.D., Allinson, A., Johnson, T., Smales, C., Jolly, S., A comparison between monophasic and biphasic defibrillation for the cardioversion of persistent atrial fibrillation in patients with and without heart failure (2011) Int J Cardiol, 147, pp. 405-408Tanabe, S., Yasunaga, H., Ogawa, T., Koike, S., Akahane, M., Horiguchi, H., Comparison of outcomes after use of biphasic or monophasic defibrillators among out-of-hospital cardiac arrest patients: A nationwide population-based observational study (2012) Circ Cardiovasc Qual Outcomes, 5, pp. 689-696