Clinical Studies on the Mechanism of Ventricular Arrhythmias

Nau, Gerardo; Aldariz, Antonio E.; Acunzo, Rafael S.; Elizari, Marcelo V.; Rosenbaum, Mauricio B.

doi:10.1007/978-94-009-6781-6_12

Cited by 12 publications

(2 citation statements)

References 51 publications

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“…The relationship between the timing of ventricular extrasystoles during the cardiac cycle and the heart rate was also extensively described by Nau et al . [53] and although the participation of supernormal excitability was not considered in their paper, they stated that slowing of the heart rate suppressed the ectopic activity in all patients with coupled ventricular extrasystoles. Moreover, they describe some zones of silent ectopic activity at both ends of the range of cardiac rates.…”

Section: Ventricular Premature Beats and Supernormal Excitability Andmentioning

confidence: 99%

Clinical and Experimental Evidence of Supernormal Excitability and Conduction

Elizari¹,

Schmidberg²,

Atienza³

et al. 2014

CCR

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True supernormality of excitability and conduction has been demonstrated in normal Purkinje fibers in in vitro studies. In the clinical setting, supernormality of conduction is manifested better than expected. This phenomenon is much more common than previously thought, particularly in the presence of certain clinical conditions. If a careful scanning of the cardiac cycle is performed on all patients with intermittent bundle branch block and second degree or advanced infranodal AV block, accessory pathways and mulfunctioning pacemakers, it is anticipated that a much larger amount of supernormal excitability and conduction will be unmasked.

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Section: Ventricular Premature Beats and Supernormal Excitability Andmentioning

confidence: 99%

Clinical and Experimental Evidence of Supernormal Excitability and Conduction

Elizari¹,

Schmidberg²,

Atienza³

et al. 2014

CCR

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“…Studies which discuss clinical VEA mechanisms usually do so on an anecdotal or case-by-case basis (e.g. Nau 1983). …”

Section: Vea In Chronic Heart Diseasementioning

confidence: 99%

A stochastic characterization of chronic ventricular ectopic activity

Albrecht

Cohen

Mark

1988

IEEE Trans. Biomed. Eng.

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Ventricular ectopic beats are clinically important because of their association with the problem of sudden cardiac death. Ventricular ectopic activity (VEA) is most commonly evaluated using long-term ambulatory electrocardiographic (ECG) recordings. The results of these recordings are usually summarized in the form of hourly counts of VEA events.Although such hourly counts are useful, they are a nonspecific measure which, in effect, treats VEA generation as an unpredictable process.This thesis develops a new means for characterizing the activity of the VEA-generating mechanism using the beat type and timing information of the long-term ECG. The approach is founded on the hypothesis that the VEA mechanism is often stable over time, although its activity may be modulated by physiologic influences and by the timing of the sino-atrial node impulses.This hypothesis implies that there should be some relationship between the beat type and timing of preceding beats and the subsequent generation of ectopic beats.The VEA generation was characterized by a multi-dimensional conditional distribution which gives the probability that an ectopic beat will follow a specific conditioning sequence of beat types and intervals. Using this approach a three part study was performed. The first step examined the conditional distributions and tested the null hypothesis that the generation of ectopic beats is unpredictable.Using a database of half-hour ECG tapes from 66 patients, the null hypothesis was rejected at p=0.005 in 80% of the tapes.The second step developed a means of displaying the multidimensional distributions. By an appropriate transformation of the conditioning variables, the distributions could be represented as one-dimensional distributions. The resulting distributions were useful for. separating patients into groups and for finding characteristic, VEA-related events in the ECG data.The third step examined the reproducibility of the onedimensional distributions over time. Using ten-hour ECG tapes, it was found that in 7 of 10 patients the patient-specific distribution, although modulated in amplitude, maintained a similar shape over the ten hours.The VEA characterization which has been developed goes significantly beyond the simple counting of ectopic beats. The distributions can be considered a kind of "fingerprint" of the VEA-generating mechanism -a "fingerprint" which may be useful in the selection and evaluation of therapy.

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