TY - JOUR
T1 - Impact of age and blood pressure on the lower arterial pressure limit for maintenance of consciousness during passive upright posture in healthy vasovagal fainters
T2 - Preliminary observations
AU - Giese, Ann E.
AU - Li, Vuy
AU - McKnite, Scott
AU - Sakaguchi, Scott
AU - Ermis, Cengiz
AU - Samniah, Nemer
AU - Benditt, David G.
PY - 2004/9
Y1 - 2004/9
N2 - Maintenance of consciousness importantly depends on systemic arterial blood pressure (BP) remaining above the lower pressure limit for cerebrovascular autoregulation. This study evaluated the impact of age and baseline arterial blood pressure (BP) on the BP recorded at onset of syncope in otherwise healthy individuals undergoing passive head-up tilt (HUT) testing for suspected vasovagal syncope. Since hypertension is thought to shift the lower autoregulation point to higher values, and since older healthy patients tend to have higher BP than younger individuals, we hypothesized that even among healthy individuals HUT-induced syncope would occur at higher BP in older compared with younger subjects. Three groups of otherwise healthy individuals who had positive HUT were identified: Group 1: <25 years, n=17; Group 2: 25-59 years, n=18; and Group 3: ≥60 years, n=7. As expected, baseline arterial systolic blood pressure of patients ≥60 years (162±37 mmHg) was significantly higher than in the other two groups (Group 1: <25 years, 116±15 mmHg; Group 2: 25-59 years, 128±12 mmHg). Further, the ≥60 age group tolerated upright posture for a longer period before syncope than did younger patients. However, despite a trend for BP at syncope to increase with age, differences were small (Group 3: ≥60 years, 61±15 mmHg, Group 2: 25-59 years, 58±6 mmHg, and Group 1: 54±16 mmHg) and were not statistically significant. Thus, in generally healthy individuals, age and baseline BP has only a minor effect on the lower limit of BP necessary for maintenance of consciousness. On the other hand, higher baseline BP provides older individuals a greater blood pressure 'reserve' for maintenance of consciousness compared with younger subjects.
AB - Maintenance of consciousness importantly depends on systemic arterial blood pressure (BP) remaining above the lower pressure limit for cerebrovascular autoregulation. This study evaluated the impact of age and baseline arterial blood pressure (BP) on the BP recorded at onset of syncope in otherwise healthy individuals undergoing passive head-up tilt (HUT) testing for suspected vasovagal syncope. Since hypertension is thought to shift the lower autoregulation point to higher values, and since older healthy patients tend to have higher BP than younger individuals, we hypothesized that even among healthy individuals HUT-induced syncope would occur at higher BP in older compared with younger subjects. Three groups of otherwise healthy individuals who had positive HUT were identified: Group 1: <25 years, n=17; Group 2: 25-59 years, n=18; and Group 3: ≥60 years, n=7. As expected, baseline arterial systolic blood pressure of patients ≥60 years (162±37 mmHg) was significantly higher than in the other two groups (Group 1: <25 years, 116±15 mmHg; Group 2: 25-59 years, 128±12 mmHg). Further, the ≥60 age group tolerated upright posture for a longer period before syncope than did younger patients. However, despite a trend for BP at syncope to increase with age, differences were small (Group 3: ≥60 years, 61±15 mmHg, Group 2: 25-59 years, 58±6 mmHg, and Group 1: 54±16 mmHg) and were not statistically significant. Thus, in generally healthy individuals, age and baseline BP has only a minor effect on the lower limit of BP necessary for maintenance of consciousness. On the other hand, higher baseline BP provides older individuals a greater blood pressure 'reserve' for maintenance of consciousness compared with younger subjects.
KW - Cerebral autoregulation
KW - Head-up tilt testing
KW - Syncope
UR - http://www.scopus.com/inward/record.url?scp=4344674191&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=4344674191&partnerID=8YFLogxK
U2 - 10.1016/j.eupc.2004.04.003
DO - 10.1016/j.eupc.2004.04.003
M3 - Article
C2 - 15294273
AN - SCOPUS:4344674191
SN - 1099-5129
VL - 6
SP - 457
EP - 462
JO - Europace
JF - Europace
IS - 5
ER -