Short- and Long-Term Blood Pressure Variability

Abstract

It has long been known that blood pressure (BP) is characterized by an array of spontaneous variations.1 That is, BP values vary markedly within the 24 hours because of day-night changes but also because of differences among hours, minutes, and even adjacent beats. They also show variations over more prolonged periods because of differences among days, months, and seasons, 2 also with a trend for systolic BP to increase over the years and for diastolic BP to display an age-related biphasic change. 3This article summarizes current knowledge on short-term (within the 24 hours) and long-term BP variability. Mention will be made of the following: (1) factors responsible for BP variations and mechanisms through which they occur; (2) the relationship of BP variability with BP mean values in absence and during antihypertensive treatment; and (3) the prognostic significance of BP variability. Current limitations of the studies on BP variability will be also discussed to emphasize what future studies should address. Twenty-Four Hour BP Variability Factors and MechanismsA large body of evidence shows that, over the 24 hours, BP undergoes marked variations in response to physical activity, sleep, and emotional stimuli of various nature and duration, thereby documenting the profound involvement of behavioral influences on BP variability. However, spontaneous BP variations also occur independently on behavior. For example, throughout the day and night, BP oscillates regularly at different frequencies, presumably because of influences originating within the brain. 4 Furthermore, BP varies more or less regularly in response to the mechanical forces generated by ventilation and also shows irregular nonbehaviorally and nonmechanically related changes with a possible origin from humoral influences and even local vasomotor phenomena. Finally, BP variations are opposed throughout the 24 hours by the baroreflex, which makes the magnitude of 24-hour BP variability in a given individual the net effect of prooscillatory and antioscillatory influences.1 Some of these influences operate via the sympathetic nervous system, 5 but nonneural mediators are also importantly involved, as shown by the complex effects of sympathectomy on BP variability in experimental animals, that is, the disappearance of some variability components with the persistence or even the increase of others. 6 The factors possibly responsible for 24-hour BP variability are illustrated in Figure 1. Relationship With 24-Hour BP MeanEarly studies with intra-arterial ambulatory BP monitoring have shown that 24-hour, daytime, and nighttime BP variabilities (quantified as the SD of the 24-hour, day, and night mean values) increase from normotensives to patients with a progressively more severe hypertension 7 (Figure 2, top left). They have further shown that an increase of BP variability when BP mean increases also occurs within individuals, because the BP SD becomes progressively greater from the half hours in which mean BP is lowest to the half hours in which it is maximal...

Short-term variability and nocturnal decline in ambulatory blood pressure in normotension, white-coat hypertension, masked hypertension and sustained hypertension: a population-based study of older individuals in Spain

“…Blood pressure measurement 5 BP was measured using standardized procedures and conditions, with validated automatic devices (Omron M6) and appropriate-sized cuffs. Trained observers measured each participant's BP during a home visit: three measurements were taken at two-minute intervals after resting for five minutes in a seated position.…”

“…3,4 BP not only exhibits large circadian variations in terms of changes between day and night but also changes from minute-to-minute and hour-to-hour in both hypertensive and normotensive patients. 5 Thus, non-invasive 24-hour ABPM is a robust method to assess short-term BP variability within 24 hours. 6 Most studies have found that high 24-hour BP variability is associated with organ damage and may contribute to cardiovascular risk prediction, over and beyond mean BP.…”

“…Alternatively, it may reflect a diffuse atherosclerotic process induced by aging and hypertension that leads to increased 9 stiffness of the large elastic arteries and/or depressed baroreflex functions causing impaired cardiovascular control mechanisms. 5 In addition, we postulate that mechanisms other than sympathetic activity are operating in white-coat hypertension, since this activity correlates with the level and standard deviation of BP, but not with the coefficient of variation, a measure of variability that is less dependent on the level of BP than the standard deviation. 40 It is noteworthy that in patients with antihypertensive treatment, we did not observe any differences in BP variability indexes.…”

Assessment of Short‐term Blood Pressure Variability in Patients With Ascending Aortic Dilatation

“…Twenty-four-hour ambulatory BP monitoring is a widely used method evaluating short-term BPV. 4 Hypertension has a well-known association with ascending aortic dilatation (AAD) and dissection. 5 But there are no data regarding association between BPV and AAD in the literature.…”

Wytyczne ESH/ESC dotyczące postępowania w nadciśnieniu tętniczym w 2013 roku

“…Na podstawie ABPM można uzyskać wiele dodatkowych pochodnych wskaźników [75--81]. Należą do nich: zmienność BP [75], poranny wzrost BP [76,77,81], ładunek BP [78] oraz ambulatoryjny wskaźnik sztywności tętnic (ambulatory arterial stiffness index) [79,80]. Jednak dotychczas nie wyjaśniono dodatkowej wartości predykcyjnej tych wskaźników i dlatego należy traktować je jako eksperymentalne, niemające jeszcze zastosowania w rutynowej praktyce klinicznej.…”