Effects of therapy with local anesthetics (TLA) on heart rate variability (HRV) over 24 hours

Therapy with local anesthetics (TLA) is known to provide long-lasting pain relief, raising the question of whether these effects are mediated by changes in autonomic nervous system (ANS) regulation. To address this, we examined alterations in 24-h heart rate variability (HRV) following TLA treatment. Twenty-four patients undergoing TLA and 11 controls were monitored with Holter-ECG over 24 h. HRV parameters including mean heart rate (HR), root mean square of successive differences (RMSSD), stress index (SI), low- and high-frequency power, and total power were calculated in 15-min epochs. Changes were analyzed separately for the day and subsequent night, and the standard deviation of change between consecutive 15-min intervals was introduced as an additional parameter. TLA was associated with significant shifts in HRV within 24 h: HR and SI decreased, whereas RMSSD and low-frequency power increased, with effects most pronounced during the night. Moreover, the variability of changes between epochs was reduced across several parameters, particularly HR, RMSSD, and SI, suggesting a "smoothing" effect in HRV dynamics. These findings indicate that 24-h HRV monitoring can capture autonomic effects of TLA beyond its immediate analgesic action. The reduction of variability in HRV changes introduces a novel metric for assessing ANS modulation, offering new insight into the mechanisms and therapeutic potential of TLA.