Published Online
on May 6, 2002

A more recent version of this article appeared on May 28, 2002

This Article Full Text (PDF) All Versions of this Article: 105/21/2537    most recent 01.CIR.0000016702.86180.F6v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Qin, H. Articles by Ideker, R. E. Search for Related Content PubMed Articles by Qin, H. Articles by Ideker, R. E. Related Collections Electrophysiology CPR and emergency cardiac care

Submitted on September 7, 2001
Revised on March 6, 2002
Accepted on March 6, 2002

Impact of Myocardial Ischemia and Reperfusion on Ventricular Defibrillation Patterns, Energy Requirements, and Detection of Recovery

Hao Qin MD, Gregory P. Walcott MD, Cheryl R. Killingsworth DVM, PhD, Dennis L. Rollins MS, William M. Smith PhD, and Raymond E. Ideker MD, PhD^*

From the Departments of Physiology and Biophysics, Medicine, and Biomedical Engineering, University of Alabama at Birmingham.

^* To whom correspondence should be addressed. E-mail: rei{at}crml.uab.edu.

Background—Shocks that have defibrillated spontaneous ventricular fibrillation (VF) during acute ischemia or reperfusion may seem to have failed if VF recurs before the ECG amplifier recovers after shock. This could explain why the defibrillation threshold (DFT) for spontaneous VF appears markedly higher than for electrically induced VF.

Methods and Results—The DFT for electrically induced VF (E-DFT) was determined in 15 pigs before ischemia, followed by left anterior ascending or left circumflex artery occlusion. VF was electrically induced 20 minutes after occlusion, followed 5 minutes later by reperfusion. Whether spontaneous or electrically induced, VF during occlusion or reperfusion was treated with up to 3 shocks at 1.5xE-DFT. If all 3 shocks failed, shock strength was increased. Thirty minutes after reperfusion, the other artery was occluded and the protocol was repeated. Defibrillation was considered successful if postshock sinus/idioventricular rhythm was present for 30 seconds. VF recurring within 30 seconds after the shock was considered immediate or delayed if the first postshock activation complex in a rapidly restored ECG recording was VF or sinus/idioventricular rhythm, respectively. Defibrillation efficacy at 1.5xE-DFT was significantly higher for electrically induced ischemic VF (76%) than for spontaneous VF (31%). The incidence of delayed recurrence after electrically induced nonischemic (3%) or ischemic (20%) VF was significantly lower than after spontaneous VF (75%). Mean VF recurrence time after spontaneous VF was 4.6±5.3 seconds.

Conclusions—Spontaneous VF can be halted by a shock but then quickly restart before a standard ECG amplifier has recovered from postshock saturation, making it appear that the shock failed.

Key words: ischemia • fibrillation • defibrillation

This article has been cited by other articles:

				J.-q. Zhong, G. Laurent, P. P.-S. So, Xudong Hu, J. K. Hennan, and P. Dorian Effects of Rotigaptide, a Gap Junction Modifier, on Defibrillation Energy and Resuscitation From Cardiac Arrest in Rabbits Journal of Cardiovascular Pharmacology and Therapeutics, March 1, 2007; 12(1): 69 - 77. [Abstract] [PDF]

				P. J. Kudenchuk, L. A. Cobb, M. K. Copass, M. Olsufka, C. Maynard, and G. Nichol Transthoracic Incremental Monophasic Versus Biphasic Defibrillation by Emergency Responders (TIMBER): A Randomized Comparison of Monophasic With Biphasic Waveform Ascending Energy Defibrillation for the Resuscitation of Out-of-Hospital Cardiac Arrest due to Ventricular Fibrillation Circulation, November 7, 2006; 114(19): 2010 - 2018. [Abstract] [Full Text] [PDF]

				X. Fang, W. Tang, S. Sun, L. Huang, Y.-T. Chang, Z. Huang, and M. H. Weil Cardiopulmonary resuscitation in a rat model of chronic myocardial ischemia J Appl Physiol, October 1, 2006; 101(4): 1091 - 1096. [Abstract] [Full Text] [PDF]

				B. Rodriguez, B. M. Tice, J. C. Eason, F. Aguel, J. M. Ferrero Jr., and N. Trayanova Effect of acute global ischemia on the upper limit of vulnerability: a simulation study Am J Physiol Heart Circ Physiol, June 1, 2004; 286(6): H2078 - H2088. [Abstract] [Full Text] [PDF]

				J. R de Groot Why shocking might be not shocking enough Cardiovasc Res, January 1, 2004; 61(1): 9 - 10. [Full Text] [PDF]

				J. J. Sims, K. L. Schoff, J. M. Loeb, and N. A. Wiegert Regional gap junction inhibition increases defibrillation thresholds Am J Physiol Heart Circ Physiol, June 5, 2003; 285(1): H10 - H16. [Abstract] [Full Text] [PDF]