title: Anatomical vertebral artery hypoplasia and insufficiency impairs dynamic blood flow regulation.
abstract: Recent studies have suggested that vertebral artery (VA) hypoplasia is a predisposing factor for posterior cerebral stroke. We examined whether anatomical vertebrobasilar ischemia, i.e., unilateral VA hypoplasia and insufficiency, impairs dynamic blood flow regulation. Twenty-eight female subjects were divided into three groups by defined criteria: (i) unilateral VA hypoplasia (n = 8), (ii) VA insufficiency (n = 6), and (iii) control (n = 14). Hypoplastic VA criterion was VA blood flow of 40 ml min(-1) , whereas VA insufficiency criterion was net (left + right) VA blood flow of 100 ml min(-1) or less. We evaluated left, right, and net VA blood flows by ultrasonography during hypercapnia, normocapnia, and hypocapnia to evaluate VA CO2 reactivity. The unilateral VA hypoplasia group showed lower CO2 reactivity at hypoplastic VA than at non-hypoplastic VA (2.65 ± 0.58 versus 3.00 ± 0.48% per mmHg, P = 0.027) and net VA CO2 reactivity was preserved (Unilateral VA hypoplasia, 2.95 ± 0.48 versus Control, 2.93 ± 0.42% per mmHg, P = 0.992). However, the VA insufficiency group showed a lower net VA CO2 reactivity compared to the control (2.29 ± 0.55 versus 2.93 ± 0.42% per mmHg, P = 0.032) and the unilateral VA hypoplasia (P = 0.046). VA hypoplasia reduced CO2 reactivity, although non-hypoplastic VA may compensate this regulatory limitation. In subjects with VA insufficiency, lowered CO2 reactivity at the both VA could not preserve normal net VA CO2 reactivity. These findings provide a possible physiological mechanism for the increased risk of posterior cerebral stroke in subjects with VA hypoplasia and insufficiency.
authors: Research Institute of Physical Fitness, Japan Women's College of Physical Education, Tokyo, Japan.
authors: Kohei
authors: K
authors: Sato
authors: Research Institute of Physical Fitness, Japan Women's College of Physical Education, Tokyo, Japan.
authors: Marina
authors: M
authors: Yoneya
authors: Research Institute of Physical Fitness, Japan Women's College of Physical Education, Tokyo, Japan.
authors: Aki
authors: A
authors: Otsuki
authors: Research Institute of Physical Fitness, Japan Women's College of Physical Education, Tokyo, Japan.
authors: Tomoko
authors: T
authors: Sadamoto
authors: Research Institute of Physical Fitness, Japan Women's College of Physical Education, Tokyo, Japan.|Department of Biomedical Engineering, Toyo University, Saitama, Japan.
authors: Shigehiko
authors: S
authors: Ogoh
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation; D006487:Hemostasis; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods; D014711:Vertebral Artery / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014715:Vertebrobasilar Insufficiency / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D055815:Young Adult
keywords: cerebral blood flow; cerebrovascular CO2 reactivity; posterior cerebral stroke; ultrasonography; vertebral artery hypoplasia; vertebral artery insufficiency