Acute effect of spinal cord stimulation on autonomic nervous system function in patients with heart failure.

AIMS: To test the hypothesis that spinal cord stimulation (SCS) acutely improves heart rate variability (HRV) and baroreceptor sensitivity (BRS) in patients with heart failure (HF). METHODS: SCS (15 minutes) was delivered in four different settings: 90% of maximal tolerated stimulation amplitude (MTA) targeting the T1-T4 spinal cord segments (SCS90T1-4), 60% of MTA (SCS60T1-4), 90% of MTA with cranial (SCS90CR) and caudal (SCS90CA) electrode configuration. HRV and BRS were recorded continuously and stimulation was compared to device off. RESULTS: Fifteen HF patients were included. SCS90T1-4 did not change the standard deviation of intervals between normal beats (SDNN, p = 0.90), BRS (p = 0.55) or other HRV parameters. In patients with baseline SDNN <50 ms, SCS90T1-4 significantly increased SDNN (p = 0.004). CONCLUSIONS: Acute SCS at 60-90% of MTA targeting upper thoracic spinal cord segments does not improve autonomic balance or baroreceptor sensitivity in unselected patients with heart failure but may improve HRV in patients with low SDNN.