A high-temporal resolution algorithm for quantifying organization during atrial fibrillation

Abstract

Atrial fibrillation (AF) has been described as a "random" or "chaotic" rhythm. Evidence suggests that AF may have transient episodes of temporal and spatial organization. We introduce a new algorithm that quantifies AF organization by the mean-squared error (MSE) in the linear prediction between two cardiac electrograms. This algorithm calculates organization at a finer temporal resolution. (approximately 300 ms) than previously published algorithms. Using canine atrial epicardial mapping data, we verified that the MSE algorithm showed nonfibrillatory rhythms to be significantly more organized than fibrillatory rhythms (p < .00001). Further, we compared the sensitivity of MSE to that of two previously published algorithms by analyzing AF with simulated noise and AF manipulated with vagal stimulation or by adenosine administration to alter the character of the AF. MSE performed favorably in the presence of noise. While all three algorithms distinguished between low and high vagal AF, MSE was the most sensitive in its discrimination. Only MSE could distinguish baseline AF from AF with adenosine. We conclude that our algorithm can distinguish different levels of organization during AF with a greater temporal resolution and sensitivity than previously described algorithms. This algorithm could lead to new ways of analyzing and understanding AF as well as improved techniques in AF therapy.

A new method to assess sinus rhythm maintenance likelihood before electrical cardioversion of persistent atrial fibrillation

“…This observation agrees with findings reported in other works, such as: (i) the higher the AA organization, the higher the success rates in AF cardioversion [24,11], (ii) the higher the level of AA organization, the lower the energy required for successful cardioversion [12] and (iii) paroxysmal AF requires less energy for cardioversion than persistent AF [25]. These previous observations highlight the fact that, when a higher number of reentries are wandering throughout the atrial tissue, a lower probability of successful electrical cardioversion is obtained.…”

“…This observation also agrees with the outcomes reported with invasive recordings [24,11] and, thereby, the obtained results consistency is increased.…”

“…In this respect, the atrial activity (AA) organization was estimated noninvasively, because it can be hypothesized that NSR maintenance would be more likelihood in patients who present a highly organized AA. This hypothesis is based on the observation that the more disorganized the AA, the higher the number of propagating wavelets [11], and the larger the atrial volume that could support reentries propagation after the shock [12].…”

“…In this respect, the atrial activity (AA) organization was estimated noninvasively, because it can be hypothesized that NSR maintenance would be more likelihood in patients who present a highly organized AA. This hypothesis is based on the observation that the more disorganized the AA, the higher the number of propagating wavelets [11], and the larger the atrial volume that could support reentries propagation after the shock [12].In order to estimate the AA organization obtained from surface electrocardiographic (ECG) recordings, Sample Entropy (SampEn), which is a non-linear index for quantifying time series regularity [13], was selected because nonlinearity, as necessary condition for a chaotic behavior, is present in the diseased heart with AF at cellular level, and the electrical remodeling in AF is a far-from-linear process [14]. This phenomenon can be described as the progressive shortening of effective atrial refractory periods, thus increasing the number of simultaneous reentries and, as a consequence, the perpetuation of AF [2].…”

Presence of Left-to-Right Atrial Frequency Gradient in Paroxysmal but Not Persistent Atrial Fibrillation in Humans

“…Although previously thought to be a "random" arrhythmia, animal and human studies have shown various degrees of spatiotemporal organization during sustained AF. [1][2][3][4][5][6] In humans, Haissaguerre and colleagues 7 showed that the onset of AF is frequently triggered by atrial premature beats that originate from sleeves of atrial muscle that extend into the pulmonary veins (PVs). Others have reported focal firing within the PVs during sustained AF.…”