Local capture of atrial fibrillation (AF) was shown in animal experiments for a wide range of pacing rates thus demonstrating the existence of an excitable gap. The aim of this study was to assess the existence of an excitable gap in human atrial fibrillation, by studying the mechanism of local control and acceleration of atrial fibrillation over a wide range of pacing rates and by evaluating the time window of capture. Recording and stimulation of electrical activity in the right atrium during AF was performed by a monophasic action potential (MAP) contact electrode catheter in 17 patients with lone atrial fibrillation during electrophysiological study. Stimulation was started at pacing intervals close to the mean atrial fibrillation interval and the time window of capture was estimated by lengthening or shortening the pacing interval until capture was lost. Pacing intervals shorter than the minimum cycle length for capture were also tested. Beat-to-beat measurements of AF intervals during pacing was performed. Atrial MAP signal showed rapid irregular activity with an average atrial fibrillation interval of 151.3±16.1 ms and standard deviation of 21.3±5.2 ms. Rapid pacing with a cycle length slightly shorter or longer than the mean atrial fibrillation interval resulted in local capture of atrial fibrillation. The width of time window of capture ranged from 22 to 36 ms with a mean value of 28.8 ± 4.9 ms. The average minimum pacing interval of stable capture was 129.2±19.5 ms while the maximum was 158.1±18.7 ms corresponding to 85% and 104% of mean AF cycle length respectively. Pacing too rapid resulted in a transient acceleration of atrial fibrillation with an average shortening of fibrillation interval from 149.8±16.6 to 123.2±15.1 ms (p<0.01). Local capture is feasible during AF in humans over a wide range of pacing rates indicating the possibility of regional control of the fibrillatory process. This result demonstrates the presence of an excitable gap during atrial fibrillation in human atria
Capture window in human atrial fibrillation: evidence of an excitable gap
Ravelli, Flavia;Nollo, Giandomenico;
1999-01-01
Abstract
Local capture of atrial fibrillation (AF) was shown in animal experiments for a wide range of pacing rates thus demonstrating the existence of an excitable gap. The aim of this study was to assess the existence of an excitable gap in human atrial fibrillation, by studying the mechanism of local control and acceleration of atrial fibrillation over a wide range of pacing rates and by evaluating the time window of capture. Recording and stimulation of electrical activity in the right atrium during AF was performed by a monophasic action potential (MAP) contact electrode catheter in 17 patients with lone atrial fibrillation during electrophysiological study. Stimulation was started at pacing intervals close to the mean atrial fibrillation interval and the time window of capture was estimated by lengthening or shortening the pacing interval until capture was lost. Pacing intervals shorter than the minimum cycle length for capture were also tested. Beat-to-beat measurements of AF intervals during pacing was performed. Atrial MAP signal showed rapid irregular activity with an average atrial fibrillation interval of 151.3±16.1 ms and standard deviation of 21.3±5.2 ms. Rapid pacing with a cycle length slightly shorter or longer than the mean atrial fibrillation interval resulted in local capture of atrial fibrillation. The width of time window of capture ranged from 22 to 36 ms with a mean value of 28.8 ± 4.9 ms. The average minimum pacing interval of stable capture was 129.2±19.5 ms while the maximum was 158.1±18.7 ms corresponding to 85% and 104% of mean AF cycle length respectively. Pacing too rapid resulted in a transient acceleration of atrial fibrillation with an average shortening of fibrillation interval from 149.8±16.6 to 123.2±15.1 ms (p<0.01). Local capture is feasible during AF in humans over a wide range of pacing rates indicating the possibility of regional control of the fibrillatory process. This result demonstrates the presence of an excitable gap during atrial fibrillation in human atriaI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
