Hypertension affects approximately one fourth of the world population and therefore
contributes substantially to the worldwide burden of cardiovascular (CV) disease and
Changes in small artery structure characterized by an increased wall-to-lumen ratio (WLR) are
characteristic feature of target organ damage in hypertension. Of clinical importance,
structural arteries of small subcutaneous arteries have been shown to be of prognostic
significance, with adverse prognosis in subjects with higher WLR. However, the assessment of
arteriolar structure from biopsies of subcutaneous tissue is invasive and impractical in
clinical practice. A new approach focuses on retinal arteriolar structural parameters by
using scanning laser Doppler flowmetry (SLDF) with automatic full-field perfusion imaging
analyses (9). This approach allows the non-invasive assessment of both the outer diameter
(OD) and inner diameter (ID) of retinal arterioles in vivo and, thus, analyses vascular
remodeling of retinal arterioles by calculating WLR = (OD - ID) / ID).
A crucial role in the efforts of prevention of end-organ damage plays the renin angiotensin
system (RAS). The increased mechanical strain on the vasculature at a higher BP can cause
injury to the endothelial wall. Activation of the RAS increases BP and stimulates a local
inflammatory response to repair the injury. Long-term or repeated response to injury leads to
endothelial dysfunction and microvascular damage, and hence end-organ damage.
Combining RAS inhibitors may provide greater end-organ protection than use of either class
alone. However, ONTARGET has failed to show superiority of the dual RAS blockade (ACE-I and
ARB) in patients at high cardiovascular risk. The combination of ARBs and direct renin
inhibitors (DRIs) emerged as the only available, valid and innovative option for blocking the
RAS at two different sites (sequential blockade). Indeed, AVOID study and ALLAY study
demonstrated that the DRI aliskiren has additional and to some extent blood pressure
independent effects on albuminuria and left ventricular hypertrophy, both signs of
subclinical organ damage in hypertension, respectively.
However, no data are available with respect to the effects of ARBs and DRIs on vascular
properties in the short and long term To close this gab we focus in this study on vascular
structural and functional changes since vascular adaptation to high blood pressure occurs in
the early phase of hypertensive disease.