Pulsatile interaction between the macro-vasculature and micro-vasculature: proof-of-concept among patients with type 2 diabetes
It is widely thought that excess pulsatile pressure from increased stiffness of large central arteries (macro-vasculature) is transmitted to capillary networks (micro-vasculature) and causes target organ damage. However, this hypothesis has never been tested. We sought to examine the association between macro- and micro-vasculature waveform features in patients with type 2 diabetes (i.e., those with elevated stiffness; T2D) compared with non-diabetic controls.
Among 13 T2D (68 ± 6 years, 39% male) and 15 controls (58 ± 11 years, 40% male) macro-vascular stiffness was determined via aortic pulse wave velocity (aPWV) and macro-vascular waveforms were measured using radial tonometry. Forearm micro-vascular waveforms were measured simultaneously with macro-vascular waveforms via low power laser Doppler fluxmetry. Augmentation index (AIx) was derived on macro- and micro-vascular waveforms. Target organ damage was assessed by estimated glomerular filtration rate (eGFR) and central retinal artery equivalent (CRAE).
aPWV was higher among T2D (9.3 ± 2.5 vs 7.5 ± 1.4 m/s, p = 0.046). There was an obvious pulsatile micro-vascular waveform with qualitative features similar to macro-vasculature pressure waveforms. In all subjects, macro- and micro-vasculature AIx were significantly related (r = 0.43, p = 0.005). In T2D alone, micro-vasculature AIx was associated with eGFR (r = − 0.63, p = 0.037), whereas in controls, macro-vasculature AIx and AP were associated with CRAE (r = − 0.58, p = 0.025 and r = − 0.61, p = 0.015).
Macro- and micro-vasculature waveform features are related; however, micro-vasculature features are more closely related to markers of target organ damage in T2D. These findings are suggestive of a possible interaction between the macro- and micro-circulation.
KeywordsBlood pressure Arterial stiffness Aorta Physiology
- 24 ABPM
24-h ambulatory BP monitoring
Aortic pulse wave velocity
Body mass index
Central retinal artery equivalent
Central retinal vein equivalent
Estimated glomerular filtration rate
Laser Doppler fluxmetry
Type 2 diabetes
This study was performed at the Blood Pressure Clinic at the Menzies Institute for Medical Research, Tasmania, Australia. REDC, DSP, AQ, SR and JES conceived the study, REDC, DSP, SB and SEK acquired and analyzed the data, REDC, DSP and JES interpreted the results, REDC drafted the manuscript and DSP, SB, SEK, AQ, SR and JES provided critical evaluation of the manuscript. All authors approved the final version of the manuscript and are accountable for all aspects of the work. All authors qualify for authorship.
Compliance with ethical standards
Conflict of interest
Ahmad Qasem is the principal scientist at AtCor medical, the manufacturer of non-invasive central pressure waveform analysis devices SphygmoCor and XCEL.
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