International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
RESTORE.network, Departments of Physiology and Pharmacology, Cardiac Sciences and Clinical Neurosciences, Biomedical Engineering, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
Am J Physiol Heart Circ Physiol. 2022 Dec 1;323(6):H1311-H1322. doi: 10.1152/ajpheart.00261.2022. Epub 2022 Nov 11.
Cervical spinal cord injury (SCI) leads to autonomic cardiovascular dysfunction that underlies the three- to fourfold elevated risk of cardiovascular disease in this population. Reduced common carotid artery (CCA) dilatory responsiveness during the cold-pressor test (CPT) is associated with greater cardiovascular disease risk and progression. The cardiovascular and CCA responses to the CPT may provide insight into cardiovascular autonomic dysfunction and cardiovascular disease risk in individuals with cervical SCI. Here, we used CPT to perturb the autonomic nervous system in 14 individuals with cervical SCI and 12 uninjured controls, while measuring cardiovascular responses and CCA diameter. The CCA diameter responses were 55% impaired in those with SCI compared with uninjured controls ( = 0.019). The CCA flow, velocity, and shear response to CPT were reduced in SCI by 100% ( < 0.001), 113% ( = 0.001), and 125% ( = 0.002), respectively. The association between mean arterial pressure and CCA dilation observed in uninjured individuals ( = 0.54, = 0.004) was absent in the SCI group ( = 0.22, = 0.217). Steady-state systolic blood pressure ( = 0.020), heart rate ( = 0.003), and cardiac contractility ( < 0.001) were reduced in those with cervical SCI, whereas total peripheral resistance was increased compared with uninjured controls ( = 0.042). Relative cerebral blood velocity responses to CPT were increased in the SCI group and reduced in controls (middle cerebral artery, = 0.010; posterior cerebral artery, = 0.026). The CCA and cardiovascular responsiveness to CPT are impaired in those with cervical SCI. This is the first study demonstrating that CCA responses during CPT are suppressed in SCI. Specifically, CCA diameter, flow, velocity, and shear rate were reduced. The relationship between changes in MAP and CCA dilatation in response to CPT was absent in individuals with SCI, despite similar cardiovascular activation between SCI and uninjured controls. These findings support the notion of elevated cardiovascular disease risk in SCI and that the cardiovascular responses to environmental stimuli are impaired.
颈椎脊髓损伤 (SCI) 可导致自主心血管功能障碍，这是该人群患心血管疾病风险增加三到四倍的基础。冷加压试验 (CPT) 时颈总动脉 (CCA) 扩张反应性降低与心血管疾病风险增加和进展相关。CPT 时的心血管和 CCA 反应可提供有关颈椎 SCI 个体自主神经功能障碍和心血管疾病风险的信息。在这里，我们使用 CPT 扰乱了 14 名颈椎 SCI 患者和 12 名未受伤对照者的自主神经系统，同时测量了心血管反应和 CCA 直径。与未受伤的对照组相比，SCI 患者的 CCA 直径反应降低了 55%（ = 0.019）。SCI 患者的 CCA 流量、速度和剪切对 CPT 的反应分别降低了 100%（ < 0.001）、113%（ = 0.001）和 125%（ = 0.002）。在未受伤的个体中观察到的平均动脉压与 CCA 扩张之间的关联（ = 0.54， = 0.004）在 SCI 组中不存在（ = 0.22， = 0.217）。在颈椎 SCI 患者中，稳态收缩压（ = 0.020）、心率（ = 0.003）和心肌收缩力（ < 0.001）降低，而与未受伤的对照组相比，总外周阻力增加（ = 0.042）。CPT 时相对大脑中动脉血流速度的反应在 SCI 组中增加，而在对照组中降低（大脑中动脉， = 0.010；大脑后动脉， = 0.026）。CPT 时 CCA 和心血管反应在颈椎 SCI 患者中受损。这是第一项表明 CPT 期间 CCA 反应受到 SCI 抑制的研究。具体来说，CCA 直径、流量、速度和剪切率降低。尽管 SCI 和未受伤的对照组之间存在类似的心血管激活，但 SCI 个体中 MAP 变化与 CCA 扩张反应之间的关系不存在。这些发现支持 SCI 中心血管疾病风险增加的观点，并且对环境刺激的心血管反应受损。
