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Long-duration ventricular fibrillation exhibits 2 distinct organized states.

ABSTRACT: Previous studies showed that endocardial activation during long-duration ventricular fibrillation (VF) exhibits organized activity. We identified and quantified the different types of organized activity.Two 64-electrode basket catheters were inserted, respectively, into the left ventricle and right ventricle of dogs to record endocardial activation from the endocardium during 7 minutes of VF (controls, n=6). The study was repeated with the K(ATP) channel opener pinacidil (n=6) and the calcium channel blocker flunarizine (n=6). After 2 minutes of VF without drugs, 2 highly organized left ventricular endocardial activation patterns were observed: (1) ventricular electric synchrony pattern, in which endocardial activation arose focally and either had a propagation sequence similar to sinus rhythm or arose near papillary muscles, and (2) stable pattern, in which activation was regular and repeatable, sometimes forming a stable re-entrant circuit around the left ventricular apex. Between 3 and 7 minutes of VF, the percent of time ventricular electric synchrony was present was control=25%, flunarizine=24% (P=0.44), and pinacidil=0.1% (P<0.001) and the percent of time stable pattern was present was control=71%, flunarizine=48% (P<0.001), and pinacidil=56% (P<0.001). The remainder of the time, nonstable re-entrant activation with little repeatability was present.After 3 minutes, VF exhibits 2 highly organized endocardial activation patterns 96% of the time, one potentially arising focally in the Purkinje system that was prevented with a K(ATP) channel opener but not a calcium channel blocker and the other potentially arising from a stable re-entrant circuit near the apical left ventricular endocardium.

SUBMITTER: Li L

PROVIDER: S-EPMC3982786 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Long-duration ventricular fibrillation exhibits 2 distinct organized states.

Li Li L Zheng Xiangsheng X Dosdall Derek J DJ Huang Jian J Pogwizd Steven M SM Ideker Raymond E RE

Circulation. Arrhythmia and electrophysiology 20131115 6

<h4>Background</h4>Previous studies showed that endocardial activation during long-duration ventricular fibrillation (VF) exhibits organized activity. We identified and quantified the different types of organized activity.<h4>Methods and results</h4>Two 64-electrode basket catheters were inserted, respectively, into the left ventricle and right ventricle of dogs to record endocardial activation from the endocardium during 7 minutes of VF (controls, n=6). The study was repeated with the K(ATP) ch ...[more]

PMID: 24243784

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Project description:ObjectiveWe have observed consistent hemodynamic patterns after restoration of spontaneous circulation (ROSC) after ventricular fibrillation (VF) cardiac arrest. We sought to characterize the time-course of these patterns, and to determine whether these differed based on duration of the VF insult.MethodsWe performed a retrospective review of data from a randomized animal experiment that was conducted in an AAALAC-approved animal laboratory. We used mixed-breed domestic swine of either sex. Animals were anesthetized and instrumented for continuous recording of ECG and blood pressures. VF was induced electrically and allowed to progress for various times ranging from brief (22s) to moderate (less than 3 min) to prolonged (3-10 min). All animals were initially shocked (150J) up to three times. If ROSC was not achieved on the three initial shocks, a standardized treatment protocol was followed. We defined cardiovascular collapse as a SBP<90 mmHg sustained for 1 min. For statistical purposes, we classified animals as having VF of <3 min, or >3 min duration. Data were analyzed with Fisher's exact test and survival analysis.ResultsA hyperdynamic phase, consisting of very high-blood pressures and tachycardia, was seen in all animals immediately after ROSC. This lasts from 1 to 4 min. Post-resuscitation cardiovascular collapse occurred in 2/7 (29%) animals in the <3 min group and 13/14 in the >3 min group (93%) p=0.006. Onset of cardiovascular collapse was highly related to duration of VF (log-rank p=0.004).ConclusionsThere are two distinct phases of hemodynamic change after resuscitation of VF. The first phase is a brief hyperdynamic phase. The second phase is either stabilization or cardiovascular collapse. When VF is brief, blood pressures often return to normal without exogenous support. When VF was prolonged animals were rescued with exogenous pressor. Healthcare providers should be prepared to provide pressor support for patients having ROSC after prolonged VF.

Project description:BackgroundMeasures of the ventricular fibrillation (VF) waveform may enable better allocation of cardiac arrest treatment by discriminating which patients should receive immediate defibrillation versus alternate therapies such as CPR. We derive a new measure based on the 'roughness' of the VF waveform, the Logarithm of the Absolute Correlations (LAC), and assess and contrast how well the LAC and the previously published scaling exponent (ScE) predict the duration of VF and the likelihood of return of spontaneous circulation (ROSC) under both optimal experimental and commercial-defibrillator sampling conditions.Methods and resultsWe derived the LAC and ScE from two different populations--an animal study of 44 swine and a retrospective human sample of 158 out-of-hospital VF arrests treated with a commercial defibrillator. In the animal study, the LAC and ScE were calculated on 5s epochs of VF recorded at 1000 samples/s and then down sampled to 125 samples/s. In the human study, the LAC and ScE were calculated using 6s epochs recorded at 200 samples/s that occurred immediately prior to the initial shock. We compared the LAC and ScE measures using the Spearman correlation coefficients (CC) and areas under the receiver operating characteristic curve (AUC).ResultsIn the animal study, the LAC and ScE were highly correlated at 1000 sample/s (CC=0.93) but not at 125 samples/s (CC=-0.06). These correlations were reflected in how well the measures discriminated VF of < or =5 versus >5 min: AUC at 1000 samples/s was similar for LAC compared to ScE (0.71 versus 0.76). However AUC at 125 samples was greater for LAC compared to ScE (0.75 versus 0.62). In the human study, the LAC measure was a better predictor of ROSC following initial defibrillation as reflected by an AUC of 0.77 for LAC compared to 0.57 for ScE.ConclusionsThe LAC is an improvement over the ScE because the LAC retains its prognostic characteristics at lower ECG sampling rates typical of current clinical defibrillators. Hence, the LAC may have a role in better allocating treatment in resuscitation of VF cardiac arrest.

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Long-duration ventricular fibrillation exhibits 2 distinct organized states.

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Long-duration ventricular fibrillation exhibits 2 distinct organized states.

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