Abstract
While no simple electrical descriptor provides a good measure of defibrillation efficacy, the waveform parameters that most directly influence defibrillation are voltage and duration. Voltage is a critical parameter for defibrillation because its spatial derivative defines the electrical field that interacts with the heart. Similarly, waveform duration is a critical parameter because the shock interacts with the heart for the duration of the waveform. Shock energy is the most often cited metric of shock strength and an ICD’s capacity to defibrillate, but it is not a direct measure of shock effectiveness. Despite the physiological complexities of defibrillation, a simple approach in which the heart is modeled as passive resistor–capacitor (RC) network has proved useful for predicting efficient defibrillation waveforms. The model makes two assumptions: (1) The goal of both a monophasic shock and the first phase of a biphasic shock is to maximize the voltage change in the membrane at the end of the shock for a given stored energy. (2) The goal of the second phase of a biphasic shock is to discharge the membrane back to the zero potential, removing the charge deposited by the first phase. This model predicts that the optimal waveform rises in an exponential upward curve, but such an ascending waveform is difficult to generate efficiently. ICDs use electronically efficient capacitive-discharge waveforms, which require truncation for effective defibrillation. Even with optimal truncation, capacitive-discharge waveforms require more voltage and energy to achieve the same membrane voltage than do square waves and ascending waveforms. In ICDs, the value of the shock output capacitance is a key intermediary in establishing the relationship between stored energy—the key determinant of ICD size—and waveform voltage as a function of time, the key determinant of defibrillation efficacy. The RC model predicts that, for capacitive-discharge waveforms, stored energy is minimized when the ICD’s system time constant τ s equals the cell membrane time constant τ m, where τ s is the product of the output capacitance and the resistance of the defibrillation pathway. Since the goal of phase two is to reverse the membrane charging effect of phase one, there is no advantage to additional waveform phases. The voltages and capacitances used in commercial ICDs vary widely, resulting in substantial disparities in waveform parameters. The development of present biphasic waveforms in the 1990s resulted in marked improvements in defibrillation efficacy. It is unlikely that substantial improvement in defibrillation efficacy will be achieved without radical changes in waveform design.
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Denman, R. A., Umesan, C., Martin, P. T., Forbes, R. N., Kroll, M. W., Anskey, E. J., et al. (2006). Benefit of millisecond waveform durations for patients with high defibrillation thresholds. Heart Rhythm, 3, 536–541.
White, J. B., Walcott, G. P., Wayland, J. L., Jr., Smith, W. M., & Ideker, R. E. (1999). Predicting the relative efficacy of shock waveforms for transthoracic defibrillation in dogs. Annals of Emergency Medicine, 34, 309–320.
Mehdirad, A. A., Love, C. J., Stanton, M. S., Strickberger, S. A., Duncan, J. L., & Kroll, M. W. (1999). Preliminary clinical results of a biphasic waveform and an RV lead system. Pacing and Clinical Electrophysiology, 22, 594–599.
Schauerte, P., Schondube, F. A., Grossmann, M., Dorge, H., Stein, F., Dohmen, B., et al. (1998). Influence of phase duration of biphasic waveforms on defibrillation energy requirements with a 70-microF capacitance. Circulation, 97, 2073–2078.
Walcott, G. P., Walker, R. G., Cates, A. W., Krassowska, W., Smith, W. M., & Ideker, R. E. (1995). Choosing the optimal monophasic and biphasic waveforms for ventricular defibrillation. Journal of Cardiovascular Electrophysiology, 6, 737–750.
Sharma, A. D., Fain, E., O’Neill, P. G., Skadsen, A., Damle, R., Baker, J., et al. (2004). Shock on T versus direct current voltage for induction of ventricular fibrillation: A randomized prospective comparison. Pacing and Clinical Electrophysiology, 27, 89–94.
Mehdirad, A. A., Stohr, E. C., Love, C. J., Nelson, S. D., & Schaal, S. F. (1999). Implantable defibrillators impedance measurement using pacing pulses versus shock delivery with intact and modified high voltage lead system. Pacing and Clinical Electrophysiology, 22, 437–441.
Pendekanti, R., Henriquez, C., Tomassoni, G., Miner, W., Fain, E., Hoffmann, D., et al. (1997). Surface coverage effects on defibrillation impedance for transvenous electrodes. Annals of Biomedical Engineering, 25, 739–746.
Olsovsky, M. R., Shorofsky, S. R., & Gold, M. R. (1999). The effect of shock configuration and delivered energy on defibrillation impedance. Pacing and Clinical Electrophysiology, 22, 165–168.
Weiss, D. N., Shorofsky, S. R., Peters, R. W., & Gold, M. R. (1998). The effect of delivered energy on defibrillation shock impedance. Journal of Interventional Cardiac Electrophysiology, 2, 273–277.
Kontos, M. C., Ellenbogen, K. A., Wood, M. A., Damiano, Jr., R. J., Akosah, K. O., Nixon, J. V., et al. (1997). Factors associated with elevated impedance with a nonthoracotomy defibrillation lead system. American Journal of Cardiology, 79, 48–52.
Schwartzman, D., Hull, M. L., Callans, D. J., Gottlieb, C. D., & Marchlinski, F. E. (1996). Serial defibrillation lead impedance in patients with epicardial and nonthoracotomy lead systems. Journal of Cardiovascular Electrophysiology, 7, 697–703.
Iskos, D., Lock, K., Lurie, K. G., Fahy, G. J., Petersen-Stejskal, S., & Benditt, D. G. (1998). Submuscular versus subcutaneous pectoral implantation of cardioverter-defibrillators: Effect on high voltage pathway impedance and defibrillation efficacy. Journal of Interventional Cardiac Electrophysiology, 2, 47–52.
Swerdlow, C., Kass, R., Hwang, C., Gang, E., Chen, P., & Peter, C. (1994). Effect of voltage and respiration on impedance in nonthoracotomy defibrillation pathways. American Journal of Cardiology, 73, 688–692.
Prevost, J., & Batelli, F. (1900). Quelques effets des decharges electriques sur le coeur des mammiferes. Journal de Physiologie et de Pathologie Generale, 2, 40–52.
Peleska, B. (1957). Transthoracic & direct defibrillation. Rozhledy v Chirurgii, 36, 731–755.
Schuder, J. C., Stoeckle, H., West, J. A., & Keskar, P. Y. (1971). Transthoracic ventricular defibrillation in the dog with truncated exponential stimuli. IEEE Transactions on Biomedical Engineering BME, 18, 410–415.
Feeser, S. A., Tang, A. S., Kavanagh, K. M., Rollins, D. L., Smith, W. M., Wolf, P. D., et al. (1990). Strength–duration and probability of success curves for defibrillation with biphasic waveforms. Circulation, 82, 2128–2141.
Dixon, E. G., Tang, A. S., Wolf, P. D., Meador, J. T., Fine, M. J., Calfee, R. V., et al. (1987). Improved defibrillation thresholds with large contoured epicardial electrodes and biphasic waveforms. Circulation, 76, 1176–1184.
Tang, A., Yabe, S., Wharton, J., Dolker, M., Smith, W., & Ideker, R. (1989). Ventricular defibrillation using biphasic waveforms: The importance of phasic defibrillation. Journal of the American College of Cardiology, 13, 207–214.
Parler, S. (2007). Heating in aluminum electrolytic strobe and photoflash capacitors. Cornell Dubelier (Available online at http://www.cde.com).
Malkin, R. A., Guan, D., & Wikswo, J. P. (2006). Experimental evidence of improved transthoracic defibrillation with electroporation-enhancing pulses. IEEE Transactions on Biomedical Engineering, 53, 1901–1910.
Blair, H. (1932). On the intensity–time relations for stimulation by electric currents, I. Journal of General Physiology, 15, 709–729.
Blair, H. (1932). On the intensity–time relations for stimulation by electric currents, II. Journal of General Physiology, 15, 731–755.
Cleland, B. (1996). A conceptual basis for defibrillation waveforms. Pacing and Clinical Electrophysiology, 19, 1186–1195.
Fishler, M. G. (2000). Theoretical predictions of the optimal monophasic and biphasic defibrillation waveshapes. IEEE Transactions on Biomedical Engineering, 47, 59–67.
Kroll, M. W. (1993). A minimal model of the monophasic defibrillation pulse. Pacing and Clinical Electrophysiology, 16, 769–777.
Kroll, M. W. (1994). A minimal model of the single capacitor biphasic defibrillation waveform. Pacing and Clinical Electrophysiology, 17, 1782–1792.
Swerdlow, C., Fan, W., & Brewer, J. (1996). Charge-burping theory correctly predicts optimal ratios of phase duration for biphasic defibrillation waveforms. Circulation, 94, 2278–2284.
Dillon, S. M., & Kwaku, K. F. (1998). Progressive depolarization: A unified hypothesis for defibrillation and fibrillation induction by shocks. Journal of Cardiovascular Electrophysiology, 9, 529–552.
Chen, P.-S., Wolf, P. D., & Ideker, R. E. (1991). The mechanism of cardiac defibrillation: A different point of view. Circulation, 84, 913–919.
Cheng, Y., Mowrey, K. A., Van Wagoner, D. R., Tchou, P. J., & Efimov, I. R. (1999). Virtual electrode-induced reexcitation: A mechanism of defibrillation. Circulation Research, 85, 1056–1066.
Efimov, I. R., Cheng, Y., Yamanouchi, Y., & Tchou, P. J. (2000). Direct evidence of the role of virtual electrode-induced phase singularity in success and failure of defibrillation. Journal of Cardiovascular Electrophysiology, 11, 861–868.
Hodgkin, A. (1938). The subthreshold potentials in a crustacean nerve fiber. Proceedings of the Royal Society of London. Series B, Biological Science, 126, 87–121.
Kao, C. Y., & Hoffman, B. F. (1958). Graded and decremental response in heart muscle fibers. American Journal of Physiology, 194, 187–196.
Krassowska, W., Cabo, C., Knisley, S. B., & Ideker, R. E. (1992). Propagation versus delayed activation during field stimulation of cardiac muscle. Pacing and Clinical Electrophysiology, 15, 197–210.
Tovar, O., & Tung, L. (1991). Electroporation of cardiac cell membranes with monophasic or biphasic rectangular pulses. Pacing and Clinical Electrophysiology, 14, 1887–1892.
Jones, J. L., & Jones, R. E. (1983). Improved defibrillator waveform safety factor with biphasic waveforms. American Journal of Physiology, 245, H60–H65.
Jones, J. L., & Jones, R. E. (1984). Decreased defibrillator-induced dysfunction with biphasic rectangular waveforms. American Journal of Physiology, 247, H792–H796.
Anderson, C., Trayanova, N., & Skouibine, K. (2000). Termination of spiral waves with biphasic shocks: Role of virtual electrode polarization. Journal of Cardiovascular Electrophysiology, 11, 1386–1396.
Behrens, S., Li, C., Kirchhof, P., Fabritz, F. L., & Franz, M. R. (1996). Reduced arrhythmogenicity of biphasic versus monophasic T-wave shocks. Implications for defibrillation efficacy. Circulation, 94, 1974–1980.
Efimov, I. R., Cheng, Y., Van Wagoner, D. R., Mazgalev, T., & Tchou, P. J. (1998). Virtual electrode-induced phase singularity: A basic mechanism of defibrillation failure. Circulation Research, 82, 918–925.
Efimov, I. R., Cheng, Y. N., Biermann, M., Van Wagoner, D. R., Mazgalev, T. N., & Tchou, P. J. (1997). Transmembrane voltage changes produced by real and virtual electrodes during monophasic defibrillation shock delivered by an implantable electrode. Journal of Cardiovascular Electrophysiology, 8, 1031–1045.
Schauerte, P. N., Ziegert, K., Waldmann, M., Schondube, F. A., Birkenhauer, F., Mischke, K., et al. (1999). Effect of biphasic shock duration on defibrillation threshold with different electrode configurations and phase 2 capacitances: Prediction by upper-limit-of-vulnerability determination. Circulation, 99, 1516–1522.
Mouchawar, G., Kroll, M., Val-Mejias, J. E., Schwartzman, D., McKenzie, J., Fitzgerald, D., et al. (2000). ICD waveform optimization: A randomized, prospective, pair-sampled multicenter study. Pacing and Clinical Electrophysiology, 23, 1992–1995.
Shorofsky, S. R., Rashba, E., Havel, W., Belk, P., Degroot, P., Swerdlow, C., et al. (2005). Improved defibrillation efficacy with an ascending ramp waveform in humans. Heart Rhythm, 2, 388–394.
Kroll, M., Lehmann, M., & Tchou, P. (1996). Defining the defibrillation dosage. In M. Kroll & M. Lehmann (Eds.), Implantable cardioverter-defibrillator therapy: The engineering-clinical interface (pp. 63–88). Norwell, MA: Kluwer.
Hillsley, R., Walker, R., Swanson, D., Rollins, D., Wolf, P., & Ideker, R. (1993). Is the second phase of a biphasic waveform the defibrillating phase? Pacing and Clinical Electrophysiology, 16, 1402–1411.
Hoorweg, J. (1892). Condensatorentladung und Auseinanderetzung mit du Bois–Reymond. Pfuger’s Archiv fur Gesamte Physiologie, 52, 87–108.
Weiss, G. (1901). Sur la possibilite’ de rendre comparable entre eux les appareils survant a l’excitation electrique. Archives Italiennes de Biologie, 35, 413–446.
Bourland, J. D., Tacker, W. A., & Geddes, L. A. (1978). Strength duration curves for trapezoidal waveforms of various tilts for transchest defibrillation in animals. Medical Instrumentation, 12, 38–41.
Gold, J., Schuder, J., Stoeckle, H., Granberg, T., Hamdani, S., & Rychlewski, J. (1977). Transthoracic ventricular defibrillation in the 100 kg calf with unidirectional rectangular pulses. Circulation, 56, 745.
Wessale, J., Bourland, J., Tacker, W., & Geddes, L. (1980). Bipolar catheter defibrillation in dogs using trapezoidal waveforms of various tilts. Journal of Electrocardiology, 13, 359–366.
Geddes, L. A., Niebauer, M. J., Babbs, C. F., & Bourland, J. D. (1985). Fundamental criteria underlying the efficacy and safety of defibrillating current waveforms. Medical & Biological Engineering & Computing, 23, 122–130.
Niebauer, M. J., Babbs, C. F., Geddes, L. A., & Bourland, J. D. (1983). Efficacy and safety of defibrillation with rectangular waves of 2- to 20-milliseconds duration. Critical Care Medicine, 11, 95–98.
Swerdlow, C. D., Brewer, J. E., Kass, R. M., & Kroll, M. W. (1997). Application of models of defibrillation to human defibrillation data: Implications for optimizing implantable defibrillator capacitance. Circulation, 96, 2813–2822.
Shorofsky, S., Rashba, E., DeGroot, P., Havel, W., Mugglin, A., & Gold, M. (2002). Is the membrane time constant for defibrillation independent of the waveform? Pacing and Clinical Electrophysiology, 24, 620 (abstract).
Gold, M. R., & Shorofsky, S. R. (1997). Strength–duration relationship for human transvenous defibrillation. Circulation, 96, 3517–3520.
Hahn, S., Heil, J., Lin, Y., Derfus, D., & Lang, D. (1994). Improved defibrillation with small capacitance and optimized biphasic waveforms. Circulation, 90, I–175.
Jung, W., Moosdorf, R., Korte, T., Wolpert, C., Spehl, S., Bauer, T., et al. (1994). Effect of capacitance on the defibrillation threshold in patients using a new unipolar defibrillation system. Circulation, 90(4), I–229.
Rist, K., Tchou, P. J., Mowrey, K., Kroll, M. W., & Brewer, J. E. (1994). Smaller capacitors improve the biphasic waveform. Journal of Cardiovascular Electrophysiology, 5, 771–776.
Leonelli, F. M., Kroll, M. W., & Brewer, J. E. (1995). Defibrillation thresholds are lower with smaller storage capacitors. Pacing and Clinical Electrophysiology, 18, 1661–1665.
Swerdlow, C. D., Brewer, J. E., Kass, R. M., & Kroll, M. (1997). Estimation of optimal ICD capacitance from human strength–duration data. Journal of the American College of Cardiology.
Swerdlow, C., Kass, R., Hwang, C., Chen, P.-S., & Raissi, S. (1994). Effect of capacitor size and pathway resistance on defibrillation threshold for implantable defibrillators. Circulation, 90, 1840–1846.
Sticherling, C., Klingenheben, T., Cameron, D., & Hohnloser, S. H. (1998). Worldwide clinical experience with a down-sized active can implantable cardioverter defibrillator in 162 consecutive patients. Worldwide 7221 ICD investigators. Pacing and Clinical Electrophysiology, 21, 1778–1783.
Thammanomai, A., Sweeney, M., & Eisenberg, S. (2006). A comparison of the output characteristics of several implantable cardioverter defibrillators. Heart Rhythm, 3(9), 1053–1059.
Yamanouchi, Y., Brewer, J. E., Mowrey, K. A., Donohoo, A. M., Wilkoff, B. L., & Tchou, P. J. (1998). Optimal small-capacitor biphasic waveform for external defibrillation: Influence of phase-1 tilt and phase-2 voltage. Circulation, 98, 2487–2493.
Malkin, R. A. (2002). Large sample test of defibrillation waveform sensitivity. Journal of Cardiovascular Electrophysiology, 13, 361–370.
Keane, D., Aweh, N., Hynes, B., Sheahan, R., Cripps, T., Bashir, Y., et al. (2007). Achieving sufficient safety margins with fixed duration waveforms and the use of multiple time constants. Pacing and Clinical Electrophysiology, 2007 May;30(5): 596–602.
Cheng, Y., Mowrey, K. A., Nikolski, V., Tchou, P. J., & Efimov, I. R. (2002). Mechanisms of shock-induced arrhythmogenesis during acute global ischemia. American Journal of Physiology. Heart and Circulatory Physiology, 282, H2141–H2151.
Natarajan, S., Henthorn, R., Burroughs, J., Esberg, D., Zweibel, S., Ross, T., et al. (2007). Fixed duration “tuned” defibrillation waveforms outperform fixed 50/50% tilt defibrillation waveforms: A randomized, prospective, pair-sampled multicenter study. Pacing and Clinical Electrophysiology (in press).
Sweeney, M. O., Natale, A., Volosin, K. J., Swerdlow, C. D., Baker, J. H., & Degroot, P. (2001). Prospective randomized comparison of 50%/50% versus 65%/65% tilt biphasic waveform on defibrillation in humans. Pacing and Clinical Electrophysiology, 24, 60–65.
Kroll, M. W., Efimov, I. R., & Tchou, P. J. (2006). Present understanding of shock polarity for internal defibrillation: The obvious and non-obvious clinical implications. Pacing and Clinical Electrophysiology, 29, 885–891.
Swerdlow, C., Ahern, T., & Chen, P.-S. (1996). Comparative reproducibility of defibrillation threshold and upper limit of vulnerability. Pacing and Clinical Electrophysiology, 19, 2103–2111.
Yamanouchi, Y., Cheng, Y., Tchou, P. J., & Efimov, I. R. (2001). The mechanisms of the vulnerable window: The role of virtual electrodes and shock polarity. Canadian Journal of Physiology and Pharmacology, 79, 25–33.
Strickberger, S. A., Daoud, E., Goyal, R., Chan, K. K., Bogun, F., Castellani, M., et al. (1996). Prospective randomized comparison of anodal monophasic shocks versus biphasic cathodal shocks on defibrillation energy requirements. American Heart Journal, 131, 961–965.
Strickberger, S. A., Hummel, J. D., Horwood, L. E., Jentzer, J., Daoud, E., Niebauer, M., et al. (1994). Effect of shock polarity on ventricular defibrillation threshold using a transvenous lead system. Journal of the American College of Cardiology, 24, 1069–1072.
Mowrey, K. A., Cheng, Y., Tchou, P. J., & Efimov, R. (2002). Kinetics of defibrillation shock-induced response: Design implications for the optimal defibrillation waveform. Europace, 4, 27–39.
Tomassoni, G., Newby, K., Deshpande, S., Axtell, K., Sra, J., Akhtar, M., et al. (1997). Defibrillation efficacy of commercially available biphasic impulses in humans. Importance of negative-phase peak voltage. Circulation, 95, 1822–1826.
Peleska, B. (1963). Cardiac arrhythmias following condenser discharges and their dependence upon strength of current and phase of cardiac cycle. Circulation Research, 13, 21–32.
Nikolski, V. P., & Efimov, I. R. (2005). Electroporation of the heart. Europace, 7(Suppl 2), 146–154.
Jones, D. L., Klein, G. J., Guiraudon, G. M., Sharma, A. D., Kallok, M. J., Bourland, J. D., et al. (1986). Internal cardiac defibrillation in man: Pronounced improvement with sequential pulse delivery to two different lead orientations. Circulation, 73, 484–491.
Russo, A. M., Sauer, W., Gerstenfeld, E. P., Hsia, H. H., Lin, D., Cooper, J. M., et al. (2005). Defibrillation threshold testing: Is it really necessary at the time of implantable cardioverter-defibrillator insertion? Heart Rhythm, 2, 456–461.
Shukla, H. H., Flaker, G. C., Jayam, V., & Roberts, D. (2003). High defibrillation thresholds in transvenous biphasic implantable defibrillators: Clinical predictors and prognostic implications. Pacing and Clinical Electrophysiology, 26, 44–48.
Anderson, K. P. (2005). Sudden cardiac death unresponsive to implantable defibrillator therapy: An urgent target for clinicians, industry and government. Journal of Interventional Cardiac Electrophysiology, 14, 71–78.
Mitchell, L. B., Pineda, E. A., Titus, J. L., Bartosch, P. M., & Benditt, D. G. (2002). Sudden death in patients with implantable cardioverter defibrillators: The importance of post-shock electromechanical dissociation. Journal of the American College of Cardiology, 39, 1323–1328.
Poole, J., Johnson, G., Callans, D., Raitt, M., Yee, R., Reddy, R., et al. (2004). Analysis of implantable defibrillator shock electrograms in the sudden cardiac death-heart failure trial. Heart Rhythm, 1, S178 (abstract).
Tokano, T., Bach, D., Chang, J., Davis, J., Souza, J. J., Zivin, A., et al. (1998). Effect of ventricular shock strength on cardiac hemodynamics. Journal of Cardiovascular Electrophysiology, 9, 791–797.
Holmes, H., Bourland, J., Tacker, Jr., W., & Geddes, L. (1980). Hemodynamic responses to two defibrillating trapezoidal waveforms. Medical Instrumentation, 14, 47–50.
Boriani, G., Biffi, M., Silvestri, P., Martignani, C., Valzania, C., Diemberger, I., et al. (2005). Mechanisms of pain associated with internal defibrillation shocks: Results of a randomized study of shock waveform. Heart Rhythm, 2, 708–713.
Boriani, G., Kroll, M., Biffi, M., Silvestri, P., Martignani, C., Valzania, C., et al. (2007). Plateau waveform shape allows a higher patient shock energy tolerance. Journal of Cardiovascular Electrophysiology, 18 (in press).
Seidl, K., Denman, R. A., Moulder, J. C., Mouchawar, G., Stoeppler, C., Becker, T., et al. (2006). Stepped defibrillation waveform is substantially more efficient than the 50/50% tilt biphasic. Heart Rhythm, 3, 1406–1411.
Sweeney, M. O., Wathen, M. S., Volosin, K., Abdalla, I., DeGroot, P. J., Otterness, M. F., et al. (2005). Appropriate and inappropriate ventricular therapies, quality of life, and mortality among primary and secondary prevention implantable cardioverter defibrillator patients: Results from the Pacing Fast VT REduces Shock ThErapies (PainFREE Rx II) trial. Circulation, 111, 2898–2905.
Swerdlow, C. D. (2006). ICD waveforms: What really matters? Heart Rhythm, 3, 1060–1062.
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Kroll, M.W., Swerdlow, C.D. Optimizing defibrillation waveforms for ICDs. J Interv Card Electrophysiol 18, 247–263 (2007). https://doi.org/10.1007/s10840-007-9095-z
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DOI: https://doi.org/10.1007/s10840-007-9095-z