Abstract 104: Assessment Of Brain Venous System In Hypertension

Abstract

With an increasing recognition of the contribution of venous collagenosis to cerebral small vessel disease there is a growing interest in the imaging of brain veins. Some studies showed increased prominence of cerebral veins in animal models of hypertension (HTN) and increased venous visibility in patients with white matter lesions using susceptibility weighted imaging (SWI). Since SWI uses deoxygenated blood as an intrinsic contrast agent, reduced cerebral blood flow (CBF) could result in increased oxygen extraction and thus greater vein prominence. However, others reported that fewer veins visible on SWI correlated with more brain atrophy. We examined whether the number of deep medullary veins (DMVs) was related to HTN and CBF, in a group of cognitively healthy subjects from a brain aging research center (n=351, 220 women, mean age 69.4 ± 7.1). DMVs were assessed by visual inspection on SWI on the level of lateral ventricles, and the number was defined as the average count of both hemispheres. CBF was assessed using arterial spin labeling. The number of DMVs did not differ (p=0.17 after adjusting for age, sex and acquisition type) between normotensive subjects (n=194, <140/90, and no antihypertensive treatment), subjects with controlled HTN (n=74, <140/90, and antihypertensive treatment), and subjects with uncontrolled blood pressure (n=72, ≥ 140/90). It was, however, numerically the lowest in the uncontrolled group (22.8 ± standard error (SE) 1.1, 25.6 ± 1.1 for controlled, and 24.4 ± 0.7 for normotensive individuals). In the entire group there was a negative correlation between CBF and DMVs: r=-0.23, p<0.001. The correlation became progressively stronger across HTN spectrum: r=-0.16, p=0.03 for normotensive subjects, r=-.23, p=0.03 for the controlled group and r=-.038, p=0.001 for the uncontrolled HTN group. At the same time there was a linear trend (p=0.06 after adjusting for age and sex) for CBF decrease from 59.5 ml/100mg/min ± SE 0.4 in normotensive subjects, 58.3±0.7 in controlled and 58.0±0.7 in the uncontrolled group. A greater reliance on oxygen extraction due diminishing perfusion across HTN spectrum may obscure structural changes in cerebral veins previously reported in subjects with vascular disease.