Arterial tree asymmetry reduces cerebral pulsatility

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Neuroscience

Background:

• Pressure waves (PWs) propagate from the aorta to the periphery with each heartbeat.
• In cerebral circulation, four arteries converge at the circle of Willis (CW), leading to PW interference.
• Arterial pulsatility is linked to brain pathologies and protective mechanisms.

Purpose of the Study:

• To investigate the hypothesis that asymmetry in brain-supplying arteries creates phase differences in converging PWs.
• To determine if asynchronous PW arrival reduces downstream cerebral pulsatility.
• To explore the physiological significance of PW arrival timing in the CW.

Main Methods:

• Developed simple computational models of four converging arteries.
• Analyzed the impact of asynchronous versus synchronous PW arrival on pressure dynamics.
• Utilized probabilistic calculations to assess the likelihood of synchronous vs. asynchronous arrival.

Main Results:

• Asynchronous PW arrival resulted in lower maximum pressure and slower pressure amplification.
• Models showed reduced downstream pulsatility with asynchronous wave arrival.
• Probabilistic analysis indicated asynchronous arrival is more probable than synchronous.

Conclusions:

• Asynchronous arrival of PWs into the cerebral circulation influences hemodynamics.
• This asynchronous arrival decreases blood flow pulsatility and kinetic energy transmission.
• Asynchronous PW arrival is a physiological necessity for cerebral circulation.