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Mecanismos subyacentes a las oscilaciones del intervalo RR de muy baja frecuencia en humanos

J A Taylor¹, D L Carr, C W Myers

¹Department of Internal Medicine, Hunter Holmes McGuire Department of Veterans Affairs Medical Center, and Medical College of Virginia, Virginia Commonwealth University, Richmond, USA. ataylor@mail.hrca.harvard.edu

|August 26, 1998

Resumen

La variabilidad del ritmo cardíaco de muy baja frecuencia, crucial para la supervivencia después de un ataque cardíaco, es impulsada principalmente por el sistema nervioso parasimpático. El sistema renina-angiotensina-aldosterona también juega un papel, pero el tono vagal es clave para la salud cardiovascular.

Área de la Ciencia:

Fisiología cardiovascular fisiología cardiovascular.
Regulación del sistema nervioso autónomo.
Análisis de la variabilidad de la frecuencia cardíaca Análisis de la variabilidad de la frecuencia cardíaca

Sus antecedentes:

La reducción de la variabilidad del intervalo de RR de muy baja frecuencia (VLF) está relacionada con una menor supervivencia en pacientes después de un infarto de miocardio.
Los fundamentos fisiológicos de las oscilaciones del VLF siguen siendo incompletamente entendidos.
Este estudio investiga las funciones de los sistemas simpático, vagal y renina-angiotensina-aldosterona en la variabilidad de la FLV.

Objetivo del estudio:

Para aclarar las contribuciones autónomas y hormonales a la variabilidad del intervalo de RR de VLF.
Para diferenciar los efectos del bloqueo beta-adrenérgico, parasimpático y ACE en las oscilaciones del VLF.
Comprender las bases fisiológicas de la variabilidad del VLF en sujetos jóvenes sanos.

Principales métodos:

Los intervalos RR y las presiones arteriales se registraron en 10 sujetos sanos en posición supina e inclinada.
El bloqueo farmacológico incluyó solución salina (control), atenolol (bloqueo beta), atropina (bloqueo parasimpático), bloqueo combinado y enalaprilato (bloqueo ACE).
El análisis de la Transformación de Fourier Rápida cuantificó la potencia espectral en bandas de frecuencias muy bajas, bajas y respiratorias.

Principales resultados:

El bloqueo parasimpático con atropina redujo profundamente la variabilidad general del intervalo RR en un 92% en la banda VLF.
El bloqueo beta-adrenérgico no afectó significativamente el VLF o la potencia de baja frecuencia, pero aumentó la potencia de frecuencia respiratoria.
El bloqueo ACE aumentó modestamente la potencia VLF en posición supina (~21%) pero no durante la inclinación.

Conclusiones:

Los ritmos del intervalo RR del VLF dependen principalmente de la actividad del sistema nervioso parasimpático.
El sistema renina-angiotensina-aldosterona ejerce una influencia secundaria en la variabilidad del VLF.
La importancia pronóstica de las oscilaciones del VLF probablemente se deriva de su fuerte asociación con la función parasimpática y la salud cardiovascular.

Palabras clave:

Disciplina de la NASA en el área cardiopulmonar No perteneciente al Centro de la NASA.

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