Sleep-Wakefulness Variations in Arterial Stiffness: Assessment Using Ambulatory Recording of Arterial Pulse Transit Time

Introduction and objectivesThe incidence of cardiovascular events is related to the sleep–wakefulness cycle. In particular, the magnitude and speed of the changes in hemodynamic variables that occur during transitions between wakefulness and sleep and between sleep and wakefulness are regarded as factors that either predict or determine target organ damage and cardiovascular risk. Although increased arterial stiffness (AS) is associated with the development of cardiovascular abnormalities, it is not known whether there exist any changes in AS that are associated with circadian variations in the incidence of cardiovascular events. The aims of this study were to assess AS in healthy subjects over a 24-hour period, to characterize any differences that occur between sleep and wakefulness, and to investigate any changes in AS that occur during the transition from wakefulness to sleep or from sleep to wakefulness.MethodsTwenty healthy volunteers with a dipper circadian blood pressure pattern underwent 24-hour ambulatory monitoring of blood pressure, heart rate and AS. In practice, AS was determined using the aorta-brachial pulse transit time and fractional pulsatility indices. Myocardial oxygen consumption was quantified using the double product (DP). An average was calculated for all variables for periods of sleep (23:00 to 06:00) and wakefulness (8:00 to 21:00) and for transitions from wakefulness to sleep (20:00 vs 02:00), and from sleep to wakefulness (06:00 vs. 10:00 hours).ResultsIn complete contrast to DP, AS was greater during sleep than wakefulness (P<.05). Moreover, the changes in AS that occurred during transitions from wakefulness to sleep and from sleep to wakefulness were the opposite of those observed in DP (P<.05).ConclusionsArterial stiffness was greater during sleep than wakefulness, increased during the transition from wakefulness to sleep, and decreased during the transition from sleep to wakefulness.

Introducción y objetivosLa incidencia de complica-ciones cardiovasculares guarda relación con el ciclo sue-ño-vigilia. Particularmente, la magnitud y la velocidad de cambio de variables hemodinámicas durante los períodos de transición entre vigilia y sueño se consideran factores pronósticos y/o determinantes de daño de órgano diana y riesgo cardiovascular. Si bien los aumentos en la rigidez arterial (RA) se asocian a desarrollo de alteraciones car-diovasculares, se desconoce si existen variaciones en la RA con relación al patrón circadiano de incidencia de eventos cardiovasculares. El objetivo fue analizar la RA en sujetos sanos durante 24 h y caracterizar las potencia-les diferencias entre sueño y vigilia y los cambios en la RA durante la transición de vigilia a sueño y de sueño a vigilia.MétodosEn 20 voluntarios sanos con patrón dipper, se realizó durante 24 h monitorización ambulatoria de presión arterial, frecuencia cardiaca y RA. La RA se eva-luó mediante el tiempo de tránsito de la onda de pulso aortobraquial e índices de pulsatilidad fraccional. Se cuantificó el consumo miocárdico de oxígeno mediante el doble producto (DP). Se promediaron las variables para el sueño (de las 23.00 a las 6.00), la vigilia (de las 8.00 a las 21.00) y las transiciones vigilia-sueño (a las 20.00 frente a las 2.00) y sueño-vigilia (a las 6.00 frente a las 10.00).ResultadosContrariamente al DP, la RA fue mayor durante el sueño que en la vigilia (p < 0,05). La RA varió en forma opuesta al DP durante las transiciones vigilia-sueño y sueño-vigilia (p < 0,05).ConclusionesLa RA fue mayor durante el sueño que en la vigilia, aumentó durante la transición vigilia-sueño y disminuyó durante la transición sueño-vigilia.