Can shocks timed to action potentials in low-gradient regions improve both internal and out-of-hospital defibrillation?

Jones, Janice L.; Noe, W.A.; Tovar, Oscar H.; Lin, Yong; Hsu, William

doi:10.1016/s0022-0736(98)90282-5

Cited by 11 publications

(12 citation statements)

References 5 publications

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“…Although it is not clear why some postshock activations that originate in the low potential gradient regions degenerate into VF while others do not, a possibility is that the organization of the activation pattern within those regions prior to the shock, which would influence the extension of refractoriness produced by the shock and subsequently the dispersion of refractoriness after the shock, may influence shock outcome. This hypothesized mechanism also explains the observations of Tovar et al 7 and Jones et al 8 that, in the areas of low potential gradients, those shocks that extended refractoriness were more likely to be successful than others. It is possible, therefore, that for shocks with strengths that produce close to 50% probability of success, it is the degree of organization in activations before the shock within the areas of low potential gradient regions that influences shock outcome.…”

Section: Coherence Between Ecgs and Defibrillation Outcomementioning

confidence: 53%

“…5 Extension of refractoriness and uniformity of activation or degree of organization during VF have been hypothesized to play a role in the outcome of defibrillation shock. [6][7][8] These results suggest that the spatial similarity in rates of activation can be used as an indicator of uniformity of activation 9 or as a global index of degree of organization during VF. Together with the evidence from studies that suggest that uniformity of activations during VF may influence shock outcome, the authors hypothesized that coherence between ECGs recorded during VF may be correlated with shock outcome.…”

Section: Introductionmentioning

confidence: 87%

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Correlation Between Defibrillation Shock Outcome and Coherence in Electrocardiograms

Patwardhan¹,

Moghe²,

Wang³

et al. 2001

Pacing Clinical Electrophis

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Cycle periods in ECG during VF are correlated with periods of reentrant activation. The ECGs recorded from different locations on the thorax were contributed to from electrical activations within the heart in approximately inverse proportion of their distance from the recording sites. Similarity in cycle periods between ECGs recorded from two locations, therefore, can be used as an index of spatiotemporal similarity in the rate of activation. In the present study coherence was used, which is a mathematical function that measures the degree of similarity that two signals exhibit at specific cycle periods, to test if spatiotemporal similarity in cycle periods between pairs of orthogonal ECGs was correlated with defibrillation shock outcome. The authors estimated time-varying coherence from orthogonal ECGs during 10 seconds of electrically induced VF, which was terminated with a defibrillation shock with a 50% probability of successful outcome. Defibrillation shocks were delivered between a coil electrode placed at the right ventricular apex and a subdermal patch electrode. Time-varying coherencies between pairs of ECGs were estimated using an adaptive least mean square algorithm. Time-coherence surfaces were integrated within a frequency region centered at the dominant frequency. Data were collected from ten dogs during 206 (48%) successful and 221 (52%) unsuccessful trials. The results showed that coherencies between the sagittal-transverse pair were 10%-15% higher (P < 0.05) for successful than unsuccessful trials. The correlation between coherence and defibrillation outcome suggests that more defibrillation shocks occurred when the degree of spatial similarity in the rate of activations was higher terminated VF, than those that occurred at other times. These results are consistent with a hypothesis, recently proposed by others, that more uniform activation within regions of the heart that receive low potential gradients during shock may increase the probability of successful defibrillation.

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Section: Coherence Between Ecgs and Defibrillation Outcomementioning

confidence: 53%

Section: Introductionmentioning

confidence: 87%

Correlation Between Defibrillation Shock Outcome and Coherence in Electrocardiograms

Patwardhan¹,

Moghe²,

Wang³

et al. 2001

Pacing Clinical Electrophis

View full text Add to dashboard Cite

show abstract

“…The wavefront captured a large area of tissue in the mapped region by delivering a properly timed stimulus. This area of synchronized activation may lead to a change in the timing and direction of VF propagation that are important for VF termination 17–19 . The entire mapped region in anterior LV was activated in 40 ms.…”

Section: Resultsmentioning

confidence: 99%

Post‐Shock Synchronized Pacing in Isolated Rabbit Left Ventricle: Evaluation of a Novel Defibrillation Strategy

Tang

Hwang

Song

et al. 2007

Cardiovasc electrophysiol

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“…Consequently, in the meantime, a firing of 5-mA electric stimulus was performed at the post-shock pacing site, creating a functional block area. This area of synchronized activation may lead to a change in the timing of VF propagation, which is important for VF termination [4,14,15]. This result shows that the feasible post-shock SyncP technique can be an effective strategy for manipulation of timing during VF propagation.…”

Section: A Feasibility Of Post-shock Syncpmentioning

confidence: 87%

“…Substantial efforts have been devoted to improve the defibrillation efficacy [3][4][5]. Recently, use of low-energy electrical pulses to pace the myocardium during the arrhythmia has attracted great interest [6,7].…”

Section: Introductionmentioning

confidence: 99%

Method of Post-Shock Synchronized Pacing in the Excitable Gaps

Tang¹,

Hwang²,

Yang³

et al. 2006

2006 International Conference of the IEEE Engineering in Medicine and Biology Society

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Ventricular fibrillation (VF) can be synchronized with a novel synchronized pacing technique (SyncP) using lowenergy pacing pulses, which causes pace termination of VF. Synchronized pacing (SyncP) is defined as optical recording guided real-time detection and stimulation of spatiotemporal excitable gaps. In this paper, we investigate the effect of postshock SyncP strategy on improvement of defibrillation efficacy. After a near-threshold defibrillation shock, when the reference site detected the earliest activation of the reinitiated VF, a 5-mA electric stimulus was delivered from the post-shock pacing electrode to depolarize the excitable gap. This area of wavefront synchronization may lead to a change in the timing of VF propagation, which is important for VF termination. Here, we implemented the concept of post-shock synchronized pacing by a real-time feedback mechanism and demonstrated a successful VF termination by the post-shock SyncP strategy. Further optimization of this technique may prove effective in improving the defibrillation efficacy for low-energy ventricular defibrillation.

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Can shocks timed to action potentials in low-gradient regions improve both internal and out-of-hospital defibrillation?

Cited by 11 publications

References 5 publications

Correlation Between Defibrillation Shock Outcome and Coherence in Electrocardiograms

Correlation Between Defibrillation Shock Outcome and Coherence in Electrocardiograms

Post‐Shock Synchronized Pacing in Isolated Rabbit Left Ventricle: Evaluation of a Novel Defibrillation Strategy

Method of Post-Shock Synchronized Pacing in the Excitable Gaps

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