Increased central arterial stiffness explains baroreflex dysfunction in spinal cord injury

Area of Science:

• Cardiovascular physiology
• Neuroscience
• Biomedical engineering

Background:

• Cervical spinal cord injury (SCI) frequently leads to orthostatic hypotension and intolerance.
• The cardiovagal baroreflex is crucial for blood pressure regulation and is impaired after SCI.
• Dysfunction may stem from arterial stiffening or downstream neural issues.

Purpose of the Study:

• To investigate the relationship between cardiovagal baroreflex sensitivity (BRS) and common carotid artery (CCA) stiffness in individuals with high-level SCI.
• To determine the role of arterial stiffening in mediating baroreflex dysfunction post-SCI.
• To assess the impact of blood pressure normalization on BRS and arterial stiffness.

Main Methods:

• Beat-by-beat blood pressure and heart rate recordings were analyzed.
• Common carotid artery diameter was measured to assess arterial stiffness (β-stiffness index).
• Participants included individuals with SCI and able-bodied controls, tested supine and upright, with and without midodrine.

Main Results:

• Arterial stiffness was significantly elevated in individuals with SCI when upright.
• Reduced BRS in SCI participants was negatively correlated with increased arterial stiffness.
• Blood pressure normalization with midodrine did not improve BRS or CCA stiffness.

Conclusions:

• Reduced baroreflex sensitivity after SCI is closely associated with increased arterial stiffness.
• Arterial stiffening appears to be a significant factor contributing to baroreflex dysfunction in SCI.
• Targeting arterial stiffness may offer a therapeutic avenue for managing orthostatic intolerance post-SCI.