“Irregular” ventricular parasystole: The influence of sinus rhythm on a parasystolic focus

Oreto, Giuseppe; Satullo, Gaetano; Luzza, Francesco; Donato, Antonino; Saccà, Carmelo; Arrigo, F; Consolo, F; Schamroth, L

doi:10.1016/0002-8703(88)90527-3

Cited by 26 publications

(11 citation statements)

References 27 publications

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“…Similar rhythms obeying the rules of pure parasystole were observed by Oreto et al (29). Their first and fourth case reports show triplets of allowed NIB values of 1, 2, 4 and 1,4,6, respectively.…”

Section: Discussionsupporting

confidence: 83%

“…Sinus beats at early phases either have little effect or cause a lengthening of the ectopic cycle; sinus beats at later phases trigger an ectopic discharge, i.e., cause a shortening of the cycle. The curves in this figure are typical of results found in model experimental systems (2, 10, 16) and clinical studies (15,25,(27)(28)(29)35).…”

supporting

confidence: 62%

“…They were also able to reproduce rhythms that are well known clinically, such as ventricular bigeminy and ventricular trigeminy, in which every second or third contraction of the heart is a VPC. Several groups of investigators subsequently identified modulated parasystole in clinical ECG recordings (4,25,(27)(28)(29)35). They determined the phase response curve, which gives the effect of a sinus depolarization on the period of the ectopic pacemaker as a function of its location within the ectopic cycle (see APPENDIX).…”

mentioning

confidence: 99%

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Beyond pure parasystole: promises and problems in modeling complex arrhythmias

Courtemanche

Glass

Rosengarten

et al. 1989

American Journal of Physiology-Heart and Circulatory Physiology

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The dynamics of pure parasystole, a cardiac arrhythmia in which two competing pacemakers fire independently, have recently been fully characterized. This model is now extended in an attempt to account for the more complex dynamics occurring with modulated parasystole, in which there exists nonlinear interaction between the sinus node and the ectopic ventricular focus. Theoretical analysis of modulated parasystole reveals three types of dynamics: entrainment, quasiperiodicity, and chaos. Rhythms associated with quasiperiodicity obey a set of rules derived from pure parasystole. This model is applied to the interpretation of continuous electrocardiographic data sets from three patients with complicated patterns of ventricular ectopic activity. We describe several new statistical properties of these records, related to the number of intervening sinus beats between ectopic events, that are essential in characterizing the dynamics and testing mathematical models. Detailed comparison between data and theory in these cases show substantial areas of agreement as well as potentially important discrepancies. These findings have implications for understanding the dynamics of the heartbeat in normal and pathological conditions.

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Section: Discussionsupporting

confidence: 83%

supporting

confidence: 62%

mentioning

confidence: 99%

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Beyond pure parasystole: promises and problems in modeling complex arrhythmias

Courtemanche

Glass

Rosengarten

et al. 1989

American Journal of Physiology-Heart and Circulatory Physiology

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“…between two premature beats (P'-P'), are irregular. (5) The intervals between the last P wave preceding the pause and the premature P' wave are quite regular (226, 227, 224, 226).…”

Section: Noncontinuous Recordings Of Lead Vl Numbers Above the Tracmentioning

confidence: 99%

Irregular Sinus Parasystole Due to Intermittency and Modulation of Parasystolic Activity

Satullo

Donato

Busà

et al. 1996

Cardiovasc electrophysiol

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A case of intermittent sinus parasystole in which the parasystolic focus is protected from the dominant sinus rhythm only during the second half of its intrinsic cycle is reported. In addition, a modulating (i.e., electronic) effect is often clearly exerted from the dominant rhythm upon the focus during the protected period. Coexistence of both modulation and intermittency in sinus parasystole, as well as a modulating effect limited to the second part of the parasystolic cycle, have not been previously reported.

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“…Several clinical resports [11,14,[18][19][20] have also noted the presence of distinctive numbers of sinoatrial beats between ectopic beats (NIB) which can be understood in the context of models like Eq. (2).…”

Section: (Dmentioning

confidence: 99%

Dynamics underlying the patterning of cardiac dysrhythmias

Wang

1993

Phys. Rev. Lett.

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We use nonlinear methods to predict changes in cardiac rhythms over periods of up to several hours. The patterns of measured premature heart beats which correspond to return cycles of a 1 D map are found to be organized into a devil's staircase when plotted against heart rate. Throughout the data collections, changes in patterns with heart rate agree with the computed dynamics. This result, typical of the majority of patients examined, demonstrates that (1) simple recursions can model complex biological rhythms and (2) mode locking can play a dominant role in the patterning of arrhythmias. PACS numbers: 87.45.Bp, 42.60.Fc Coupled modulated systems can exhibit distinct dynamical behaviors. For example, a solid with two components of different natural atomic spacing can form incommensurate, commensurate, or chaotic phases [1]. In a temporal oscillating system with two natural frequencies, the orbit can be quasiperiodic, periodic (mode locked), or chaotic. In general, if the coupling strength is insufficient to induce chaotic behavior, short period return cycles are more stable than long period or quasiperiodic motions. Thus simple motions tend to overwhelm their neighboring complex ones. This phenomenon gives rise to the distinctive, self-similar structure of the "devil's staircase" as in the standard circle map [2,3]. It is the dominance of simple return cycles that facilitates the treatment of biological dynamical systems which are typically in the presence of short-term fluctuations in underlying control parameters.Some cardiac arrhythmias are known to result from the interaction of two oscillators (i.e., pacemakers) giving rise to a condition clinically termed parasystole [4]. The timing of the normal heart beat is dictated by the concerted electrical discharge of a group of specialized cells called the sinoatrial node [5]. The transmission of the electrical pulses initiated by this pacemaker coordinates the contraction of the heart muscle. Subsequent pulses can be conducted only after a period of time necessary to recharge the conductive cardiac tissue. This period of time, the refractory period, typically ranges from 0.25 to 0.50 of the time between cardiac contractions. When a secondary, or ectopic, pacemaker is present heart beats are induced by the ectopic pacemaker only when it discharges outside the refractory period following the previous sinoatrial excitation. Because the electrical pulse originating at one pacemaker can alter the local electrical environment of the other and thus the timing of its subsequent discharge, the phase relationship of the two pacemakers can be reset upon discharge of either, thus giving rise to the recursion 0n=e"-l + n-f m (e n -] ,e n -2, ... % o n -m ). (DHere 0" is the phase within the ectopic cycle of the nth sinoatrial discharge, O is the ratio of natural periods of the sinoatrial and ectopic oscillators, and /" are the coupling terms which dictate the resetting of the nth ectopic cycle as a function of the phases of the previous mth sinoatrial discharges within the ec...

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“Irregular” ventricular parasystole: The influence of sinus rhythm on a parasystolic focus

Cited by 26 publications

References 27 publications

Beyond pure parasystole: promises and problems in modeling complex arrhythmias

Beyond pure parasystole: promises and problems in modeling complex arrhythmias

Irregular Sinus Parasystole Due to Intermittency and Modulation of Parasystolic Activity

Dynamics underlying the patterning of cardiac dysrhythmias

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