1 Gastric myoelectrical activity compared to pyloric pressure in patients with gastroparesis

Background:  Gastric emptying is a function of gastric contraction, electrical activity, pyloric and duodenal resistance. Pylorospasm (basal pyloric pressures >10 mmHg; Mearin et al. Gastro 1986) has been implicated in gastroparesis. Currently, pyloric pressures can be measured invasively, using a Dent sleeve (Mui Scientific, Inc.) manometry catheter. Electrogastrography (EGG) is a noninvasive tool for measuring gastric myoelectrical activity. EGG has been shown to distinguish gastric outlet obstruction from idiopathic gastroparesis (Brzana et al. Amer J Gastro 1998). Aims:  The aims of this study were to 1) determine whether EGG can distinguish patients with gastroparesis who have pylorospasm and 2) correlate basal pyloric pressure with various EGG parameters. Methods and Results:  23 patients with gastroparesis (19 diabetics, mean age 40.4 ± 2.3, mean 4 hr gastric retention 43.0 ± 5.1%) had basal pyloric pressure measurements and EGG. Stationary basal pyloric pressures were measured using a Dent sleeve that was placed across the pyloric channel during endoscopy with fluoroscopic guidance. 60.9% (14/23) of patients had elevated pyloric pressures (21.8 ± 3.4 mmHg vs. 5.5 ± 0.8 mmHg). There was no difference in the postprandial power ratio and gastric emptying as measured by scintigraphy between the 2 groups. The fasting dominant slow wave frequency (SWF) in the elevated pyloric pressure group was significantly higher compared to the normal pyloric pressure group (3.1 ± 0.1 cpm vs. 2.4 ± 0.3 cpm; p = 0.013). There was significantly less dysrhythmia in the elevated pyloric pressure group (75.5 ± 6.0% normal rhythm vs. 54.8 ± 9.7% normal; p = 0.03). More patients in the elevated pyloric pressure group had normal fasting electrical rhythm (>70% normal electrical rhythm) compared to the normal pyloric pressure group (64.3% vs. 22.2%; p = 0.03). There was a correlation between pyloric pressure and fasting slow wave frequency (r = 0.53, p = 0.005) but no correlation with the percentage of dysrhythmia, postprandial power ratio or gastric emptying. Conclusion:  Patients with normal pyloric pressure and delayed gastric emptying have significantly more abnormalities in slow wave frequency and dysrhythmia compared to patients with abnormal pyloric pressure. This suggests that patients with delayed gastric emptying with normal pyloric pressures have abnormalities in gastric conduction as a cause of their gastroparesis.