Epicardial Sock Mapping Following Monophasic and Biphasic Shocks of Equal Voltage with an Endocardial Lead System

Usui, Masahiro; Rl, Callihan; Walker, Robert G.; Gp, Walcott; Dl, Rollins; Wolf, P; Smith, Woollcott; Re, Ideker

doi:10.1111/j.1540-8167.1996.tb00533.x

Cited by 47 publications

(28 citation statements)

References 33 publications

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“…Similar results with regard to the isoelectric window and first activation location and patterns have been reported with plunge needles, 11 epicardial electrical mapping, 14,15,44 and optical mapping. 12,13 A study conduced in pigs with fiberglass plunge needles and an epicardial plaque demonstrated that a row of closely spaced fiberglass plunge needles did not substantially disrupt short duration fibrillation patterns.…”

Section: Study Limitationssupporting

confidence: 71%

Transmural and endocardial Purkinje activation in pigs before local myocardial activation after defibrillation shocks

et al. 2007

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Section: Study Limitationssupporting

confidence: 71%

Transmural and endocardial Purkinje activation in pigs before local myocardial activation after defibrillation shocks

et al. 2007

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“…Using plunge electrodes to map postshock activity in dogs, Chen et al (6) determined that the location and pathway of activation fronts are markedly different from those before the shock. Additional mapping studies (3)(4)(5)26) demonstrated that the first delayed postshock activation propagates focally away from the breakthrough site. Our results are consistent with these findings.…”

Section: Summary Of Findingsmentioning

confidence: 99%

Mechanistic inquiry into decrease in probability of defibrillation success with increase in complexity of preshock reentrant activity

Hillebrenner

Eason

Trayanova

2004

American Journal of Physiology-Heart and Circulatory Physiology

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Hillebrenner, Matthew G., James C. Eason, and Natalia A. Trayanova. Mechanistic inquiry into decrease in probability of defibrillation success with increase in complexity of preshock reentrant activity. Am J Physiol Heart Circ Physiol 286: H909-H917, 2004. First published November 6, 2003 10.1152/ajpheart.00492.2003Energy requirements for successful antiarrhythmia shocks are arrhythmia specific. However, it remains unclear why the probability of shock success decreases with increasing arrhythmia complexity. The goal of this research was to determine whether a diminished probability of shock success results from an increased number of functional reentrant circuits in the myocardium, and if so, to identify the responsible mechanisms. To achieve this goal, we assessed shock efficacy in a bidomain defibrillation model of a 4-mm-thick slice of canine ventricles. Shocks were applied between a right ventricular cathode and a distant anode to terminate either a single scroll wave (SSW) or multiple scroll waves (MSWs). From the 160 simulations conducted, dose-response curves were constructed for shocks given to SSWs and MSWs. The shock strength that yielded a 50% probability of success (ED 50) for SSWs was found to be 13% less than that for MSWs, which indicates that a larger number of functional reentries results in an increased defibrillation threshold. The results also demonstrate that an isoelectric window exists after both failed and successful shocks; however, shocks of strength near the ED 50 value that were given to SSWs resulted in 16.3% longer isoelectric window durations than the same shocks delivered to MSWs. Mechanistic inquiry into these findings reveals that the two main factors underlying the observed relationships are 1) smaller virtual electrode polarizations in the tissue depth, and 2) differences in preshock tissue state. As a result of these factors, intramural excitable pathways leading to delayed breakthrough on the surface were formed earlier after shocks given to MSWs compared with SSWs and thus resulted in a lower defibrillation threshold for shocks given to SSWs. scroll waves; isoelectric window; postshock activation; bidomain model ENERGY REQUIREMENTS FOR SUCCESSFUL antiarrhythmia shocks are arrhythmia specific. Cardioversion of a monomorphic ventricular tachycardia (VT) typically requires less energy than termination of ventricular fibrillation (VF). The American Heart Association recommends using lower currents and energies for termination of VT (1); these recommendations are supported by clinical studies (16,28). The study by Kerber et al. (16) demonstrated that the degree of organization of ventricular tachyarrhythmia determines the energy and current requirements for successful transthoracic cardioversion and defibrillation. Similar were the conclusions by Winkle et al. (28), which were derived from their internal defibrillation studies. However, the mechanisms by which the organization of the arrhythmia affects the probability of success for a given shock strength remain unclear. The...

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“…Earliest repolarization of cycle 2 also began at apex (arrow) before repolarization of cycle 1 was complete. in vivo porcine electrical mapping studies using the same shocking electrode configuration, 4,5 activation of the first postshock cycle arose focally at the LV apex after a 78Ϯ32-ms postshock interval (65Ϯ10 ms in an electrical mapping study, 5 PϭNS) and propagated toward the base in both SDF and FDF episodes ( Figure 5). Epicardial reentry was never observed during the first postshock cycle, unlike in optical mapping studies using rabbit hearts.…”

Section: Postshock Activation Cycles and Defibrillation Outcomementioning

confidence: 99%

“…[1][2][3] Whole-heart electrical mapping of defibrillation in dogs and pigs has shown that after shocks near the defibrillation threshold (DFT) in strength, the immediate postshock activation pattern is mainly focal and is similar for both successful (SDF) and failed (FDF) defibrillation episodes. 4,5 Epicardial reentry is infrequently observed. 6 The similarity of the first postshock activations suggests that the immediate myocardial responses to the shock alone may not determine defibrillation success but rather that the first several postshock cycles may influence shock outcome.…”

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Mechanism of Ventricular Defibrillation for Near-Defibrillation Threshold Shocks

et al. 2001

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Background-To study the mechanism by which shocks succeed (SDF) or fail (FDF) to defibrillate, global cardiac activation and recovery and their relationship to defibrillation outcome were investigated for shock strengths with approximately equal SDF and FDF outcomes (DFT 50 ). Methods and Results-In 6 isolated pig hearts, dual-camera video imaging was used to record optically from Ϸ8000 sites on the anterior and posterior ventricular surfaces before and after 10 DFT 50 biphasic shocks. The interval between the shock and the last ventricular fibrillation activation preceding the shock (coupling interval, CI) and the time from shock onset to 90% repolarization of the immediate postshock action potential (RT 90 ) were determined at all sites. Of 60 shocks, 31 were SDF. The CI (59Ϯ7 versus 52Ϯ6 ms) and RT 90 (108Ϯ19 versus 88Ϯ8 ms) were significantly longer for SDF than FDF episodes. Spatial dispersions of CI (36Ϯ5 versus 34Ϯ3 ms) and RT 90 (40Ϯ16 versus 40Ϯ8 ms) were not significantly different for SDF versus FDF episodes. The first global activation cycle appeared focally on the left ventricular apical epicardium 78Ϯ32 ms after the shock. Conclusions-For near-threshold shocks, defibrillation outcome correlates with the electrical state of the heart at the time of the shock and on RT. Global dispersion of RT was similar in both SDF and FDF episodes, suggesting that it is not crucial in determining defibrillation outcome after DFT 50 shocks.

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Epicardial Sock Mapping Following Monophasic and Biphasic Shocks of Equal Voltage with an Endocardial Lead System

Abstract: The decreased number of activation fronts and the longer delay following the shock for the earliest epicardial appearance of those activation fronts that do occur may be responsible for the increased defibrillation efficacy for biphasic shocks.

Cited by 47 publications

References 33 publications

Transmural and endocardial Purkinje activation in pigs before local myocardial activation after defibrillation shocks

Transmural and endocardial Purkinje activation in pigs before local myocardial activation after defibrillation shocks

Mechanistic inquiry into decrease in probability of defibrillation success with increase in complexity of preshock reentrant activity

Mechanism of Ventricular Defibrillation for Near-Defibrillation Threshold Shocks

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