Electrical stimulation of lower esophageal sphincter in patients with gastroesophageal reflux disease

Abstract

Introduction Effective treatment of gastro-esophageal reflux disease (GERD) can be achieved by direct modulation of the lower esophageal sphincter (LES) pressure. Recently the possibility of LES tonus increasing by the means of implantable electrical stimulator was described. Although this method is already used in clinical practice, optimal parameters of LES electrical stimulation are still unknown. Study Aims To obtain clinical data regarding effects of different modes of electrical stimulation of LES tonus. Methods LES electrical stimulation using external pulse generator was assessed in 9 patients with severe GERD and decreased LES tonus. These patients underwent standard laparoscopic antireflux intervention with additional insertion of 2 temporary electrodes at the level of gastroesophageal junction. Three sets of parameters were studied: 1) low- frequency, long pulse (375 ms pulses, 6 mA at 6 pulse/min); 2) highfrequency stimulation (0.3 ms, 6 mA at 40 Hz); 3) high-frequency, high-amplitude (0.3 ms, 10 mA at 40 Hz, 5 min intervals). High resolution esophageal manometry was used to assess changes in LES tonus. Each set of parameters was used in three patients. Duration of postoperative LES electrical stimulation session was 20 min. Esophageal manometry data during the stimulation were compared with postoperative baseline (20 min), poststimulation period (20 min) and with preoperative manometric values as well. Results The low-frequency, long pulse stimulation produces moderate increase in LES pressure, which is maintained in poststimulation period. The second set of parameters (used in commercially available implantable stimulators) generates moderate relaxation of LES during the stimulation period and significant increase of sphincter tonus in the poststimulation period. Patients stimulated with the third set of parameters did not demonstrated modification of LES tonus during the stimulation with moderate increase of the LES pressured in poststimulation period. Conclusions Electrical stimulation of LES produces changes in its tonus. Modifications in LES pressure during the stimulation and after the stimulation period depend on many factors, including frequency, pulse amplitude, waveform and duration of the stimulation. Further clinical studies are necessary for selection of optimal stimulation parameters, which can be applied in the treatment of GERD.