Bradycardia

The central autonomic input (both sympathetic and parasympathetic) is crucial for cardiovascular control; therefore, spinal cord injuries can interfere with its function (Henrich, 1982; Lehmann et al. 1987). Bradycardia, defined as a heart rate of less than 60 bpm, is a common cardiovascular complication that is often lesion-dependent and unique to each SCI. Generally, higher-level injuries result in greater degrees of cardiovascular impairment; investigators have also reported a higher incidence of bradycardia in persons with tetraplegia than in persons with paraplegia (Mirkowski et al. 2018; Dixit, 1995; Biering-Sørensen et al. 2017). The relationship between injury completeness and the resulting cardiovascular dysregulation is less well-understood, no clear association has yet been established even though researchers have reported ECG abnormalities in the SCI population compared with the non-SCI population (West et al. 2013; Prakash et al. 2002).

It should be emphasized that bradycardia and other dysrhythmias, particularly atrial fibrillation, could also occur during episodes of AD in individuals with high-level SCI and may require immediate pharmacological intervention (Pine et al. 1991; Forrest, 1991). Current pharmacological management of bradycardia in individuals with SCI involves the use of different agents including phosphodiesterase inhibitors (e.g., aminophylline, theophylline) and chronotropic agents (e.g., atropine, epinephrine, and norepinephrine) (Mirkowski et al. 2018). Further, for those who do not respond to pharmacologic treatment, cardiac pacemakers for bradycardia may be implanted (Evans et al. 2014; Franga et al. 2006; Ruiz-Arango et al. 2006; Sadaka et al. 2010; Wood et al. 2014).