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Variación circadiana en la refractividad ventricular humana.

T Q Kong1, J J Goldberger, M Parker

  • 1Department of Internal Medicine, Northwestern University Medical School, Chicago, Ill., USA.

Circulation
|September 15, 1995
PubMed
Resumen

El riesgo de muerte cardíaca súbita es más alto por la mañana. Este estudio encontró que los períodos refractarios ventriculares, cruciales para el ritmo cardíaco, muestran una variación diaria, con un pico en la madrugada. Los betabloqueantes normalizan estos períodos.

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Área de la Ciencia:

  • Cardiología Cardiología.
  • Biología circadiana Biología circadiana.
  • Electrofisiología y electrofisiología.

Sus antecedentes:

  • La incidencia de muerte cardíaca súbita alcanza su pico en la mañana.
  • La variación circadiana en la isquemia miocárdica es un factor potencial.
  • El papel de la variación circadiana en la refractividad ventricular sigue sin estar claro.

Objetivo del estudio:

  • Para investigar la existencia de una variación circadiana en la refractividad ventricular.
  • Para determinar si esta variación se correlaciona con el aumento de la incidencia matutina de muerte súbita cardíaca.

Principales métodos:

  • Los períodos refractarios efectivos ventriculares se midieron cada hora durante 24 horas en nueve sujetos con enfermedad del sistema de conducción.
  • Se evaluó la función del sistema nervioso autónomo.
  • Las mediciones se repitieron durante el bloqueo beta en un subconjunto de sujetos.

Principales resultados:

  • Se observó una variación circadiana significativa en la refractividad ventricular.
  • Los períodos refractarios más cortos ocurrieron dentro de las 2 horas de despertar.
  • El bloqueo beta abolió esta variación circadiana.
  • La hora del día, no los niveles de catecolaminas, fue el predictor independiente de los períodos refractarios.

Conclusiones:

  • Existe una variación circadiana significativa en los períodos refractarios ventriculares.
  • Los períodos refractarios más cortos y el acortamiento máximo ocurren en la madrugada.
  • Las fluctuaciones del tono beta-adrenérgico impulsan en gran medida este fenómeno.