14th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 2000

Jan. 29 - Feb. 5, 2000
Marilleva, Trento, Italy

RT-191

Electrical remodeling in humans

Claudio Pandozi, Filippo Lamberti, Antonio Castro, Leonardo Calo, Massimo Santini.
Division of Cardiology, San Filippo Neri Hospital, Rome, Italy

Electrical remodeling

The multiple wavelets hypothesis postulates that persistence of AF depends on the average number of wavelets being present in the atria. If the number is high the statistical probability that they will all extinguish at same time will be small and the A will persist; on the contrary AF will self-terminate when the number of reentrant wavelets is small and the chance that they will die out simultaneously is higher³. This hypothesis suggested by Moe in the 60s has been more recently demonstrated in animals and human studies. Mapping studies have shown that the critical number of wavelets required to sustain AF is between four and six. The number of wavelets that can coexist in the atria is determined both by the atrial tissue mass and the wavelength of atrial impulse⁴. The wavelength is defined as the distance travelled by the depolarisation wave during the duration of its refractory period (RP) (wavelenght=conduction velocity x RP) so that the smaller the wavelength of circulating wavelets the more easily AF is induced. A slower conduction velocity or a shorter RP can reduce the wavelength.

It has recently been demonstrated in experimental studies that prolonged episodes of AF induced shortening of the atrial RP and loss of the physiological rate-related shortening of RPs in the absence of changes in conduction velocity. These modifications induced by AF itself have been named as “electrical remodeling” (ER) and it is supposed that this may be the mechanism by which AF can promote its perpetuation and worsening with time (AF begets AF)⁵.