Characteristics and frequency of transient relaxations of the lower esophageal sphincter in patients with reflux esophagitis.

Electromyogram of the submental muscles, esophageal manometry, and pH studies were simultaneously performed in an unselected group of 12 patients with subjective and objective evidence of gastroesophageal reflux (GER) disease to determine the frequency of transient relaxation of the lower esophageal sphincter (LES) and mechanisms of GER. Findings from these patients were compared with data from 10 asymptomatic healthy volunteers. Recordings were obtained for 1 h in the fasting state and 3 h after a standard 850-kcal meal. Transient relaxation of the LES was the only mechanism of acid reflux in normal subjects and accounted for 73.0% of the episodes of acid reflux in patients with GER disease. In both normal subjects and patients with GER, a large number of transient relaxations were associated at their onset with an attenuated submental EMG complex, a small pharyngeal contraction, and an esophageal contraction. The incidences of these associated events were similar in the two study populations. The frequency of transient relaxation of the LES in patients with GER was identical to that of controls. The frequency did not differ even in 9 patients with GER disease who had endoscopic esophagitis. Thirty-six percent of transient relaxations in the normal subjects were accompanied by pH evidence of reflux, but in the GER patients with endoscopic esophagitis 65% of the transient LES relaxations resulted in a reflux event. Acid reflux at the moment of deep inspiration was the second most common mechanism of GER in our patients. Four patients who demonstrated this mechanism had hiatal hernias and more severe esophagitis than the rest of the group. Our findings confirm that transient relaxation of the LES is the major mechanism of GER in patients with reflux esophagitis. However, the similar frequency of this relaxation in GER patients and in healthy asymptomatic subjects suggests that factors other than transient LES relaxation play an important role in the pathogenesis of GER disease.