Close Relationship Between Media to Lumen Ratio of Subcutaneous Small Arteries and Wall to Lumen Ratio of Retinal Arterioles Evaluated Non Invasively By Scanning Laser Doppler Flowmetry

Structural alterations of subcutaneous small resistance arteries, as indicated
by an increased media to lumen (M/L) ratio, are frequently present in
hypertensive and/or diabetic patients, and may represent the earliest
alteration observed. In addition, M/L of small arteries evaluated by micromyography
has a strong prognostic significance; however its extensive
evaluation is limited by the invasivity of the assessment, since a biopsy of
subcutaneous fat is needed. Non-invasive measurement of wall to lumen
(W/L) of retinal arterioles using scanning laser doppler flowmetry (SLDF) has
been recently introduced (Harazny J et al, Hypertension 2007; 50:623-629).
However, this new technique was never compared with micromyographic
measurement, considered the gold standard approach.
Methods and Results: We have investigated 37 subjects and patients.
Twenty-three of them were hypertensives and 14 normotensives. Blood pressure
values were 139/8817/10 mmHg and 125/7117/12 mm Hg, respectively
(p<0.05). All patients underwent a biopsy of subcutaneous fat
during an elective surgical intervention. Subcutaneous small resistance
arteries were dissected and mounted on a wire myograph, and M/L was
measured. In addition, an evaluation of W/L of retinal arterioles by SLDF
was performed (Heidelberg Retina Flowmeter, Heidelberg Engineering). A
close correlation was observed between M/L of subcutaneous small arteries
and WL of retinal arterioles: rZ0.77, p<0.001 (see Figure).
Conclusion: A non invasive and easily repeatable procedure (intraobserver
and interobserver variation coefficient around 10%) such as an evaluation
of the arterioles in the fundus oculi by SDLF may provide similar information
regarding microvascular morphology compared in respect with an invasive,
accurate and prognostically relevant micromyographic measurement of M/L.