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Remodelación en células de diferentes regiones del circuito de reentrada durante la taquicardia ventricular
Shigeo Baba1, Wen Dun, Candido Cabo
1Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, New York, NY, USA.
Circulation
|October 6, 2005
Resumen
Las diferencias regionales en las corrientes de sodio (INa) y calcio (ICaL) en la zona fronteriza epicárdica estabilizan la excitación reentrante después del ataque cardíaco. Estos cambios de corriente iónica crean líneas funcionales de bloqueo, promoviendo taquicardias ventriculares sostenidas en los corazones con infarto.
Área de la Ciencia:
- Fisiología cardiovascular fisiología cardiovascular.
- Electrofisiología Cardíaca Electrofisiología cardíaca.
- Mecanismos de las arritmias.
Sus antecedentes:
- Se observa una excitación reentrante anisotrópica en la zona de frontera epicárdica (EBZ) de los corazones caninos infartados.
- La estabilización de reingreso está vinculada a la formación de líneas funcionales de bloqueo.
- Se supone que las diferencias regionales de corriente iónica en las células EBZ causan estas líneas de bloqueo.
Objetivo del estudio:
- Mapear los circuitos de reentrada en la EBZ de los corazones infartados.
- Para investigar las diferencias regionales en las corrientes iónicas entre las células de la vía central (IZc) y la externa (IZo) de los circuitos reentrantes.
- Para determinar si estas diferencias de corriente iónica contribuyen a la estabilidad de la reentrada.
Principales métodos:
- Mapeo de circuitos reentrantes durante taquicardias ventriculares sostenidas en 17 corazones caninos con infarto.
- Dispersión de células desde las vías centrales (IZc) y externas (IZo) de los circuitos de reentrada para estudio electrofisiológico.
- Simulaciones por computadora de la EBZ 2D que incorporan las diferencias de corriente iónica medidas.
Principales resultados:
- Reducción de la densidad de INa y cinética alterada tanto en las células IZc como en las IZo, con marcadas diferencias cinéticas entre ellas.
- Remodelación estructural de los canales de sodio Nav1.5 observada en las células de la zona de infarto.
- ICaL reducido similar en IZc e IZo, pero con cinética alterada en IZc.
- Las simulaciones mostraron que las diferencias INa o ICaL por sí solas no estabilizaron la reentrada, pero las diferencias combinadas estabilizaron el circuito y formaron líneas de bloqueo.
Conclusiones:
- Existen diferencias en las propiedades de INa e ICaL entre las células de la vía central y externa en el circuito de reentrada.
- Estas diferencias de corriente iónica, especialmente cuando se combinan, estabilizan la reentrada en el sustrato EBZ remodelado.
- El estudio aclara la base iónica de las líneas funcionales de bloqueo que contribuyen a las arritmias post-infarto sostenidas.
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