Abstract
ABSTRACTObjectiveTo characterize heart rate (HR) changes during autonomic dysreflexia (AD) in daily life for individuals with chronic spinal cord injury (SCI).DesignData analysis of two prospective clinical studies and one cross-sectional study.SettingSingle-center study.ParticipantsForty-five individuals (including 8 females) with a chronic SCI at or above the sixth thoracic spinal segment with confirmed AD, and a median age and time since injury of 43 years (interquartile range [IQR] 36 – 50) and 17 years (IQR 6 – 23) respectively, were included for analysis.InterventionsNot applicable.Main outcome measureAny systolic blood pressure (SBP) increase ≥ 20mmHg from baseline from a 24-hour ambulatory surveillance period was identified and categorized as either confirmed (i.e. known AD trigger), unknown (i.e. no diary entry), and unlikely (i.e. potential physical activity driven SBP increase). SBP-associated HR changes were categorized as either unchanged, increased or decreased compared to baseline.ResultsA total of 797 episodes of SBP increase above AD threshold were identified and classified as confirmed (n = 250, 31.4%), unknown (n = 472, 59.2%) or unlikely (n = 75, 9.4%). Median SBP changes and median SBP-related HR changes were 37 mmHg and -8 bpm, 28 mmHg and -6 bpm, or 30 mmHg and -4 bpm for confirmed, unknown, or unlikely episodes, respectively. HR-decrease/increase ratio was 3:1 for confirmed and unknown, and 1.5:1 for unlikely episodes. HR changes resulting in brady-/tachycardia were 34.4% / 2.8% for confirmed, 39.6% / 3.4% unknown, and 26.7% / 9.3% for unlikely episodes, respectively.ConclusionsOur findings suggest that the majority of confirmed AD episodes are associated with a HR decrease. Further improvements, such as more precise participant diaries combined with the use of 24-hour Holter electrocardiogram and wearable-sensors-derived measures of physical activity could provide a better, more detailed characterization of HR changes during episodes of AD.
Publisher
Cold Spring Harbor Laboratory