[Variation, variability of blood pressure. Study techniques].
Blood pressure (BP) is not a constant parameter, but exhibits variations, which involve a change in its value with time, and variability, which corresponds to the extent of this variation. A circadian pattern of BP, with higher values during the day than at night, is one expression of this variation in BP. This variation corresponding to the circadian pattern is dependent on both physical constraints and psychosensory factors. Investigation of variability implies consideration of both long-term and shorter term changes in BP. Long-term variability can be assessed by ambulatory determinations of BP, which can be carried out at intervals of 1/4 hour. This variability can be used to define the daytime/nighttime alteration of the circadian cycle, with the possible absence of the nocturnal reduction in BP or even a reversal of this circadian pattern. An abnormality of this type would be of prognostic importance, particularly in terms of impact on the left ventricle. Medium- or above all short-term variability can be assessed only from the change in beat/beat difference in BP and heart rate (HR) which depends on vagal tone and the orthosympathetic system. This variability can be detected by invasive methods and, more recently, using non-invasive methods (Finapres). It would seem that changes in this variability may reveal a defect in baroreceptor control which it is useful to identify for both diagnostic and therapeutic purposes.
Mallion
J M
JM
Service de Cardiologie, CHU de Grenoble.
Siché
J P
JP
Trémel
F
F
Chevallier
M
M
D000375:Aging; D000553:Ambulatory Care; D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000379:methods*; D002940:Circadian Rhythm; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D008955:Models, Cardiovascular; D011379:Prognosis; D013997:Time Factors
Variation, variabilité de la pression artérielle. Techniques d'explorations.