Characterization of Atrial Fibrillation in Man: Studies Following Open Heart Surgery*

Abstract

The nature of localized atrial activation during atrial fibrillation was characterized in 34 patients following open heart surgery. Bipolar atrial electrograms (AEG) recorded in each patient with atrial fibrillation exhibited a myriad of sizes, shapes, polarities, amplitudes, and beat-to-beat intervals. On the basis of the AEG morphology and the nature of its baseline, we have classified the recordings into four Types. Type I was characterized by discrete AEG complexes separated by an isoelectric baseline free of perturbation, Type II by discrete AEG complexes but with perturbations of the baseline between complexes, Type III by AEGs which failed to demonstrate either discrete complexes or isoelectric intervals, and Type IV in which AEGs of Type III alternated with periods characteristic of Type I and/or Type II. In 22 patients, the AEGs were recorded a second time, and in 11 of these patients the type of atrial fibrillation changed between the first and second recording period. An atrial flutter-fibrillation pattern in the ECG was associated with a relatively ordered atrial activation pattern and a relatively slow atrial rate. Human atrial fibrillation is not an electrophysiologically homogeneous process when compared among different patients or ad seriatim in the same patient.

Role of Fibrillation Cycle Length in Spontaneous and Drug-Induced Termination of Human Atrial Fibrillation-Spectral Analysis of Fibrillation Waves From Surface Electrocardiogram-

“…5 Slocum et al reported that the power spectrum of human intracardiac fibrillation waves has a discrete peak in the 4-9 Hz band, 6 and in our previous study, we found that the specific spectral characteristics of intracardiac fibrillation waves depended on the duration of AF in patients without organic heart disease. 7 A new method for noninvasive assessment of the human AF cycle length using surface ECG with spectral analysis has been reported.…”

Exponential Distribution of Long Heart Beat Intervals During Atrial Fibrillation and Their Relevance for White Noise Behaviour in Power Spectrum

“…The size of the left atrium is to date the main parameter to support diagnosis and decisions for treatment options [5,6], although its role in predicting outcome after a cardioversion is discussed controversially [7,8]. Further classifications are based on the averaging of P waves [9,10], on the amplitude of the fibrillatory waves in the surface electrocardiogram (ECG) [11], or on the morphology of the intra-atrial ECG [12]. The number and degree of spatial uniformity of wave fronts was used for a classification into three different AF types [13].…”

Lengthening of Intraatrial Conduction Time in Atrial Fibrillation and Its Relation with Early Recurrence of Atrial Fibrillation.

“…7,8) The hypothesis of Moe could be confirmed in the 1980s both in experimental models and humans by mapping of the atrial activation pattern of AF. 9,10) Multiple wandering wavelets in the atria are the basis of AF. The wavelength of these wavelet is the distance traveled by the depolarization wave during the duration of its refractory period (wavelength=effective refractory period x conduction velocity).…”

“…6) Shortening of the effective refractory period or lengthening of intraatrial conduction time result in wavelength shortening which would cause AF to perpetuate, since at least 4-6 wavelets, at the same time, are thought to be essential for AF to be persistent. [7][8][9][10] In both AF and rapid atrial arrhythmias, changes in AERP have been demonstrated both in humans and experimental models. 5,[11][12][13] However, in what way does AF affect intraatrial conduction is controversial.…”