Cardiovascular control indexes in amyotrophic lateral sclerosis patients and their relation with clinical markers

We studied the autonomic response to an orthostatic challenge (i.e. head-up tilt) in 52 amyotrophic lateral sclerosis (ALS) patients and 16 healthy subjects by means of power spectral analysis of heart period (HP) and systolic arterial pressure (SAP) variability. In addition, we verified the correlation of spectral indexes with clinical features of the ALS patients. Results showed that cardiovascular control of the ALS patients was impaired and this impairment was more evident from SAP series. While the revised Functional Rating Scale score, its bulbar subscore, and disease duration were uncorrelated with spectral indexes, the rate of the disease progression was positively correlated with the absolute low frequency power of SAP variability at rest and negatively correlated with the normalized high frequency power of HP variability during head-up tilt. We conclude that: i) spectral analysis of HP and SAP variability provides indexes helpful to quantify the impairment of the cardiovascular neural control in ALS patients; ii) patients with a faster disease progression are characterized by a higher vascular sympathetic drive and/or a depressed vagal cardiac regulation.