Diurnal variations of the dominant cycle length of chronic atrial fibrillation

High-resolution digital Holter recording was carried out in 21 patients (15 men, 64 ± 12 yr) with chronic atrial fibrillation. Dominating atrial cycle length (DACL) was derived by frequency domain analysis of QRST-reduced electrocardiograms. Daytime mean DACL was 150 ± 17 ms, and nighttime mean was 157 ± 22 ms ( P = 0.0002). Diurnal fluctuation in DACL differed among patients: it tended to be virtually absent in those with a short mean DACL, but in those with longer DACL the night-day difference was as much as 23 ms ( R = 0.72, P < 0.001, correlation of mean DACL to night-day difference). Mean DACL also correlated with ventricular cycle length ( R = 0.40, P < 0.001), particularly at night ( r = 0.49). The shorter cycle lengths found in this study during the day are consistent with sympathetic and/or other physiological modulation, but since increased vagal tone shortens atrial refractoriness in most models, parasympathetic influences are not likely to play a major role. Alternatively, atrial effective refractory period may not be the sole determinant of atrial cycle length during atrial fibrillation.

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A Simple Porcine Model of Inducible Sustained Atrial Fibrillation

Innovations Technology and Techniques in Cardiothoracic and Vascular Surgery ◽

10.1097/imi.0000000000000230 ◽

2016 ◽

Vol 11 (1) ◽

pp. 76-78 ◽

Cited By ~ 1

Author(s):

Anson M. Lee ◽

Jacob R. Miller ◽

Rochus K. Voeller ◽

Andreas Zierer ◽

Shelly C. Lall ◽

...

Keyword(s):

Atrial Fibrillation ◽

Animal Model ◽

Cycle Length ◽

Porcine Model ◽

New Technologies ◽

Median Sternotomy ◽

Manual Stimulation ◽

History Of ◽

Cycle Lengths ◽

Rapid Pacing

The surgical management of atrial fibrillation (AF) is an evolving field with a history of testing various lesion sets and ablation technologies. Previous animal models of AF require a chronic intervention to make AF reliably inducible. Our objective was to create an acute, reliable, and reproducible porcine model of sustained AF. To accomplish this, 21 adult domestic pigs underwent median sternotomy. Methods to induce AF were then performed sequentially: manual stimulation, rapid pacing (200 beats per minute), and then rapid pacing of 8 beats with a cycle length of 300 milliseconds, followed by an extra stimulus at decreasing cycle lengths. If AF was not induced, burst pacing was performed at a cycle length of 90 milliseconds for 30 seconds. If AF was still not induced, intravenous neostigmine was administered, and the process was repeated. Atrial fibrillation was considered sustained after 1 minute. Attempts at AF induction were successful in 18 (86%) of 21. Atrial fibrillation was induced during manual stimulation in four (19%), during rapid pacing in five (24%), during burst pacing in five (24%), and after the administration of neostigmine in four (19%). Mean (SD) duration of AF was 3.6 (2.6) minutes. Of the 18, 14 (78%) reverted to sinus rhythm spontaneously and 4 (22%) required an antiarrhythmic. This technique of inducing AF can easily be used to evaluate new technologies and lesion sets without the need for creating a chronic animal model.

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Thoracic vein ablation terminates chronic atrial fibrillation in dogs

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00595.2003 ◽

2004 ◽

Vol 286 (6) ◽

pp. H2072-H2077 ◽

Cited By ~ 13

Author(s):

Angela M. Park ◽

Chung-Chuan Chou ◽

Paul C. Drury ◽

Yuji Okuyama ◽

Anish Peter ◽

...

Keyword(s):

Atrial Fibrillation ◽

Sinus Rhythm ◽

Superior Vena Cava ◽

Superior Vena ◽

Vena Cava ◽

Chronic Atrial Fibrillation ◽

Atrial Pacing ◽

Bipolar Electrodes ◽

Cycle Lengths ◽

Activation Cycle

The thoracic vein hypothesis of chronic atrial fibrillation (AF) posits that rapid, repetitive activations from muscle sleeves within thoracic veins underlie the mechanism of sustained AF. If this is so, thoracic vein ablation should terminate sustained AF and prevent its reinduction. Six female mongrel dogs underwent chronic pulmonary vein (PV) pacing at 20 Hz to induce sustained (>48 h) AF. Bipolar electrodes were used to record from the atria and thoracic veins, including the vein of Marshall, four PVs, and the superior vena cava. Radio frequency (RF) application was applied around the PVs and superior vena cava and along the vein of Marshall until electrical activity was eliminated. Computerized mapping (1,792 electrodes, 1 mm resolution) was also performed. Sustained AF was induced in 30.6 ± 6.5 days, and ablation was done 17.3 ± 8.5 days afterward. Before ablation, the PVs had shorter activation cycle lengths than the atria, and rapid, repetitive activations were observed in the PVs. All dogs converted to sinus rhythm during ( n = 4 dogs) or within 90 min of completion of RF ablation. Rapid atrial pacing afterward induced only nonsustained (<60 s) AF in all dogs. Average AF cycle lengths after reinduction were significantly ( P = 0.01) longer (183 ± 31.5 ms) than baseline (106 ± 16.2 ms). There were no activation cycle length gradients after RF application. We conclude that thoracic vein ablation converts canine sustained AF into sinus rhythm and prevents the reinduction of sustained AF. These findings suggest that thoracic veins are important in the maintenance of AF in dogs.

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