Microcirculatory compensation to progressive atherosclerotic disease

Area of Science:

• Vascular Physiology
• Microcirculation Research
• Peripheral Artery Disease

Background:

• The venoarterial reflex (VAR) normally increases precapillary resistance in foot skin upon standing, limiting capillary pressure.
• Atherosclerosis, a progressive disease, may impact this microcirculatory autoregulation.
• Understanding these adaptations is crucial for managing peripheral artery disease (PAD).

Purpose of the Study:

• To investigate microcirculatory compensation in response to increasing severity of atherosclerotic disease in the lower limb.
• To test the hypothesis that microcirculatory changes occur early in the progression of PAD.

Main Methods:

• Foot skin perfusion (FSP) was measured using laser Doppler in 100 limbs categorized by ankle-brachial index (ABI): normal (>=0.96), claudicants (0.5-0.86), and critical ischemia (<=0.49).
• FSP was assessed in supine and dependent positions to evaluate the VAR.
• Exclusion criteria included signs of chronic venous insufficiency.

Main Results:

• Normal limbs showed a significant decrease in FSP in the dependent position, indicating an intact VAR.
• The VAR was absent in 33% of claudicant limbs.
• Critically ischemic limbs exhibited increased FSP in the dependent position, suggesting a compensatory mechanism.

Conclusions:

• Microcirculatory compensation occurs early in atherosclerotic limbs.
• A significant percentage of claudicants show a loss of the VAR, indicating early microcirculatory alterations.
• Altered FSP in dependent positions in critically ischemic limbs may explain symptom relief and edema formation.