Estimating defibrillation efficacy using combined upper limit of vulnerability and defibrillation testing

Malkin, R.A.; Pilkington, T.C.; Ideker, Raymond E.

doi:10.1109/10.477702

Cited by 11 publications

(2 citation statements)

References 29 publications

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“…Initially, the lower limit of vulnerability, upper limit of vulnerability, and the defibrillation threshold (DFT) were determined using an up-down protocol. 39 Determination of the lower limit of vulnerability was limited by the minimum output of the defibrillator, which was 50 V. Two shocks were applied 100 ms after the action potential upstroke. The first "preconditioning" strong shock was applied from the pair of coil electrodes.…”

Section: Antiarrhythmic Preconditioning With High-energy Shocksmentioning

confidence: 99%

The Role of Electroporation in Defibrillation

Al‐Khadra

Nikolski

Efimov

2000

Circulation Research

143

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Electric shock is the only effective therapy against ventricular fibrillation. However, shocks are also known to cause electroporation of cell membranes. We sought to determine the impact of electroporation on ventricular conduction and defibrillation. We optically mapped electrical activity in coronary-perfused rabbit hearts during electric shocks (50 to 500 V). Electroporation was evident from transient depolarization, reduction of action potential amplitude, and upstroke dV/dt. Electroporation was voltage dependent and significantly more pronounced at the endocardium versus the epicardium, with thresholds of 229+/-81 versus 318+/-84 V, respectively (P=0.01, n=10), both being above the defibrillation threshold of 181.3+/-45.8 V. Epicardial electroporation was localized to a small area near the electrode, whereas endocardial electroporation was observed at the bundles and trabeculas throughout the entire endocardium. Higher-resolution imaging revealed that papillary muscles (n=10) were most affected. Electroporation and conduction block thresholds in papillary muscles were 281+/-64 V and 380+/-79 V, respectively. We observed no arrhythmia in association with electroporation. Further, preconditioning with high-energy shocks prevented reinduction of fibrillation by 50-V shocks, which were otherwise proarrhythmic. Endocardial bundles are the most susceptible to electroporation and the resulting conduction impairment. Electroporation is not associated with proarrhythmic effects and is associated with a reduction of vulnerability.

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Section: Antiarrhythmic Preconditioning With High-energy Shocksmentioning

confidence: 99%

The Role of Electroporation in Defibrillation

Al‐Khadra

Nikolski

Efimov

2000

Circulation Research

143

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“…Determination of the ULV (as opposed to a vulnerability safety margin) requires initiation of a single episode of VF. If the strength of the defibrillation shock is selected in relation to the strength of the inducing T‐wave shock, the outcome of the defibrillation shock (success or failure) can—in principle—be analyzed with data from the ULV determination to provide a more accurate estimate of the shock strength required for reliable defibrillation 70 . In practice, optimal clinical methods for maximizing the information content of a given number of T‐wave shocks and inductions of VF have not been established.…”

Section: Introductionmentioning

confidence: 99%

Using the Upper Limit of Vulnerability to Assess Defibrillation Efficacy at Implantation of ICDs

Swerdlow

Shehata

Chen

2007

Pacing Clinical Electrophis

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The upper limit of vulnerability (ULV) is the weakest shock strength at or above which ventricular fibrillation (VF) is not induced when the shock is delivered during the vulnerable period. The ULV, a measurement made in regular rhythm, provides an estimate of the minimum shock strength required for reliable defibrillation that is as accurate or more accurate than the defibrillation threshold (DFT). The ULV hypothesis of defibrillation postulates a mechanistic relationship between the ULV-measured during regular rhythm-and the minimum shock strength that defibrillates reliably. Vulnerability testing can be applied at implantable cardioverter defibrillator (ICD) implant to confirm a clinically adequate defibrillation safety margin without inducing VF in 75%-95% of ICD recipients. Alternatively, the ULV provides an accurate patient-specific safety margin with a single fibrillation-defibrillation episode. Programming first ICD shocks based on patient-specific measurements of ULV rather than programming routinely to maximum output shortens charge time and may reduce the probability of syncope as ICDs age and charge times increase. Because the ULV is more reproducible than the DFT, it provides greater statistical power for clinical research with fewer episodes of VF. Limited evidence suggests that vulnerability testing is safer than conventional defibrillation testing.

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Defibrillation

Curry

Malkin

2006

Wiley Encyclopedia of Biomedical Engineering

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One leading cause of death in the United States is sudden cardiac death, often called cardiac arrest or a massive heart attack. Death results when the normally carefully choreographed electrical impulses of the heart become uncoordinated, a condition called ventricular fibrillation. Reversion of fibrillation to any other, more organized, electrical pattern is called defibrillation. Although electrical defibrillation is now widely practiced, the mechanism by which a strong electrical shock can stop fibrillation is still not understood. Defibrillation may fail because it does not extinguish fibrillation or because it creates a new fibrillation. It is not even clear how an electrical stimulus can affect tissue several centimeters away. Another mystery is why there is such a strong dependence on the temporal pattern, or waveform, of energy delivery for defibrillation. For example, it is more effective to withhold some available energy from certain defibrillators. The most recent data on these unknown aspects of defibrillation are discussed.

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Estimating defibrillation efficacy using combined upper limit of vulnerability and defibrillation testing

Cited by 11 publications

References 29 publications

The Role of Electroporation in Defibrillation

The Role of Electroporation in Defibrillation

Using the Upper Limit of Vulnerability to Assess Defibrillation Efficacy at Implantation of ICDs

Defibrillation

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