Is blood flow in the middle cerebral artery determined by systemic arterial stiffness?

The relationship between systemic arterial stiffness and parameters of cerebral circulation is poorly understood. We aimed to assess the relation between pulsatility (PI) and resistance (RI) indexes of the middle cerebral artery (MCA) and aortic pulse wave velocity (PWV) and brachial pulse pressure (PP).

Bilateral transcranial Doppler ultrasound (TCD) examination of the MCAs was performed using the GE Vivid 3 Ultrasound, equipped with a 2.5-MHz probe and PI and RI were calculated. Aortic PWV was obtained with the Complior device (Colson France). Conventional blood pressures were measured at the time of TCD. Data regarding risk-profile constituents, habits and medication use were recorded. Subjects with occlusion or significant stenosis of carotid arteries or MCA, previous or acute stroke, temporary ischaemic attack, bilaterally absent transtemporal sonographic windows, dysrhythmia, haematocrit value <30% or >48% were excluded.

Of the 165 included subjects (mean age, 56.70+/-11.80 years, range 22-86 years), 50.3% were men, 20.9% smokers, 20.7% diabetic and 63.4% hypertensive. PWV correlated to both PI (r=0.45, p<0.001) and RI (r=0.36, p<0.001) of MCA. A similar relation was found for PP and PI (r=0.32, p<0.001) or RI (r=0.30, p<0.001). Age, diabetes and hypertension, but not chronic tobacco smoking, interfered with MCA flow parameters. In multivariate adjusted regression analysis, PP was related to both PI and RI of MCA (p<0.001). In similar models, increased PWV was related to PI (p=0.007), but not RI (p=0.08) of MCA.

Increased PI and RI of MCA are closely related to measures of increased aortic stiffness.