Key result
High large artery stiffness with low wave reflection was associated with significantly higher retinal artery resistance index (0.51 vs 0.37, P=0.004) and pulsatility ratio (2.2 vs 1.6, P=0.008).
Cross-Sectional (n=67)
Increased large artery stiffness is associated with microcirculatory damage, but increased wave reflections may exert a protective effect by reducing pulsatility transmitted to the microcirculation.
Suggests wave reflections may protect retinal microcirculation from arterial stiffness; hypothesis-generating for macro-microvascular interactions.
Objective: Increased arterial stiffness is associated with a reduced buffering capacity of the large arteries, therefore predisposing the microcirculation to increased flow and pressure pulsatility. However, increased wave reflection may be protective, by reducing the amount of pulsatility transmitted to the microcirculation. The aim of this study was to examine this hypothesis by exploring the relationship between large artery stiffness, wave reflections and pulsatility in the microvasculature. Design and Method: 67 volunteers, aged 64 ± 10 years, not taking any sympathomimetic compounds and free from any acute ocular symptoms participated. Aortic pulse wave velocity (aPWV) and augmentation index (AIx) were recorded using the SphygmoCor system as measures of large artery stiffness and wave reflection, respectively. Retinal artery resistance index (RI), a measure of early retinal organ damage and pulsatility ratio (PR), a measure of retinal artery pulsatility were recorded using doppler ultrasound (Aloca). Results: aPWV was significantly associated with RI (R = 0.43,P = 0.001) and PR (R = 0.54,P = < 0.001) whereas AIx was significantly and inversely related to RI (R = -0.26,P = 0.047) and PR (R = -0.33, P = 0.011, respectively). Stratifying individuals according to tertile of aPWV and AIx revealed that RI and PR were significantly higher in those individuals with high aPWV but low AIx, compared with individuals with low aPWV and high AIx (0.51 ± 0.13 vs 0.37 ± 0.06, P = 0.004,RI; and 2.2 ± 0.61vs1.6 ± 0.20; P = 0.008, PR). Conclusions: Increased large artery stiffness is implicated in microcirculatory damage. However, increased wave reflections may exert a protective effect. Future mechanistic studies linking the macro and micro-circulations may provide important insights into the management of conditions such as hypertension and diabetes.
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McDonnell et al. (2010) reported a cross-sectional. High aortic pulse wave velocity (aPWV) and low augmentation index (AIx) vs. Low aPWV and high AIx was evaluated on Retinal artery resistance index (RI) (p=0.004). High large artery stiffness with low wave reflection was associated with significantly higher retinal artery resistance index (0.51 vs 0.37, P=0.004) and pulsatility ratio (2.2 vs 1.6, P=0.008).
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