Impact of tetraplegia vs. paraplegia on venoarteriolar, myogenic and maximal cutaneous vasodilation responses of the microvasculature: Implications for cardiovascular disease

The Journal of Spinal Cord Medicine, 2022 · DOI: 10.1080/10790268.2020.1761173 · Published: January 1, 2022

Spinal Cord Injury Cardiovascular Science

Simple Explanation

Cardiovascular disease is a major health concern for individuals with spinal cord injuries (SCI). This study investigates how SCI affects the small blood vessels (microvasculature), which play a vital role in cardiovascular health. The study focuses on three key microvascular responses: venoarteriolar (VAR), myogenic (MYO), and maximal vasodilation. These responses are essential for maintaining blood pressure and overall cardiovascular function. The researchers compared these responses in able-bodied individuals versus those with tetraplegia (TP) and paraplegia (PP) to understand how the level of SCI impacts microvascular function and cardiovascular disease risk.

Study Duration

Not specified

Participants

8 able-bodied, 6 tetraplegic, and 8 paraplegic persons

Evidence Level

Observational

Key Findings

1
The study found that venoarteriolar (VAR) and myogenic (MYO) responses, which are important for blood pressure regulation during orthostatic stress, remain intact after spinal cord injury (SCI).
2
Maximal vasodilation, the ability of blood vessels to widen fully, was found to be higher in the lower extremities of individuals with SCI (both tetraplegia and paraplegia) compared to able-bodied individuals.
3
The increased maximal vasodilation in the lower extremities of SCI patients may be due to smooth muscle atrophy from denervation, neural remodeling, or an unidentified pathology.

Research Summary

This study investigated the impact of spinal cord injury (SCI) on microvascular responses, specifically venoarteriolar (VAR), myogenic (MYO), and maximal vasodilation, in individuals with tetraplegia (TP) and paraplegia (PP) compared to able-bodied (AB) controls. The results indicated that VAR and MYO responses remain intact after SCI, suggesting that these local reflexes are preserved despite limb paralysis. However, maximal vasodilation in the lower extremities was significantly higher in SCI patients compared to AB individuals. These findings suggest that the microvasculature in SCI patients undergoes remodeling that differs from the macrovasculature, and microvascular dysfunction may not be a major contributing factor to cardiovascular disease in this population.

Practical Implications

Preserved Blood Pressure Regulation

The intact VAR and MYO responses suggest that local reflexes contributing to blood pressure regulation during orthostatic challenges are maintained after SCI, which may have implications for managing orthostatic hypotension.

Altered Microvascular Structure

The increased maximal vasodilation in the lower extremities indicates that the microvascular structure is altered in SCI patients, potentially due to muscle atrophy. This finding warrants further investigation to understand the underlying mechanisms.

Targeted Interventions

Understanding the differences in microvascular function between TP, PP, and AB individuals can inform the development of targeted interventions to improve cardiovascular health in the SCI population.

Study Limitations

1
Lack of validated tests to quantify remaining autonomic function post-SCI.
2
Menstrual cycle was not controlled for in female participants, which can impact vascular responsiveness.
3
Venous pressure was assumed based on previous studies, not directly measured.

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