The Angle of His as a Measurable Element of the Anti-reflux Mechanism

Gastroesophageal reflux disease (GERD) is a common condition, resulting from the loss of the anti-reflux barrier. Laparoscopic fundoplication is the surgical procedure of choice for treatment of GERD; however, there remains a debate on the exact mechanism through which it prevents reflux.

Our aim was to understand the relationship between reflux, fundoplication, and the angle of His on an experimental model.

The study was conducted on four groups of fresh explanted swine stomachs: control group, myotomy, myotomy with Nissen fundoplication, and myotomy with Toupet fundoplication. The stomachs were placed in a specially designated container on an inclinable platform which would increase the hydrostatic pressure on the esophago-gastric junction. Measurements of the angle of His using fluoroscopy and the esophago-gastric orifice area using endoscopy were performed, and the occurrence of reflux was documented.

Each group of the study contained nine swine stomachs. In the control and myotomy groups, the angle became wider as the incline level increased the pressure and was significantly different between the groups (p < .001). Both groups demonstrated an increase in the orifice area as the incline level increased the pressure. There was a significant correlation between the angle of His and the area of the esophago-gastric orifice (p < .001). In the control group, the reflux began at the 0°. In the myotomy group, it began at the + 15° incline (less pressure). Reflux rarely occurred in the Nissen and Toupet groups, with the breaking point being mostly defined as "beyond - 30°". A significant difference was noted in the occurrence of reflux between fundoplication and the non-fundoplication groups (p < 0.001), while there was no significant difference between the Toupet and Nissen groups (p = 0.134). Analysis showed a significant independent correlation between both the angle of His and the orifice area with the presence of reflux (p = .002 and p = .024 respectively).

In this study, we developed an experimental model to enable careful evaluation of the elements of the anti-reflux mechanism, of which, the angle of His has a measurable element. We demonstrated that as the angle of His becomes wider the esophago-gastric orifice area becomes larger. Additionally, a wider angle of His and a larger esophago-gastric orifice area were correlated independently with more reflux. This suggests that the fundoplication creates an acute angle of His which is correlated with a smaller area of the esophago-gastric orifice and eventually with a lower incidence of reflux.