Interventional Endoscopic Ultrasound for Hiatus Hernia and the Diaphragm Annette Fritscher-Ravens, Sandy Mosse, Keiichi Ikeda, Paul Swain Background: Diaphragmatic structures adjacent to the esophageal hiatus can be imaged, measured and are accessible to needle puncture for diagnostic and therapeutic intervention. Current flexible endoscopic treatments of GERD do not influence hiatus hernias or structures beyond the wall of the stomach or lower esophageal sphincter. Aim: (1) To test the feasibility of measuring the dimensions and thickness of components of the diaphragm in the pig and humans, (2) to take needle biopsies of diaphragmatic muscle, (3) measure electrical potentials from the diaphragm at EUS puncture, (4) to place stitches to tighten the hiatus, (5) to use radiofrequency current to alter the compliance of the diaphragm at the cardia, (6) to pace the diaphragm. Methods/Results: Using linear array echo-endoscopes and 19 G needles diaphgramatic structures including right and left crus, median and medial arcuate ligaments were measured and identified. Using 22 and 19 G needles, biopsy specimens were taken from the diaphragm and examined at histology. Stitches were placed to tighten the diaphragmatic pinchcock effect on the esophagus using different patterns of stitches placed into the diaphragm (right crus and median arcuate ligament) through the upper stomach and lower esophagus. Needle and T shaped electrodes were placed in the diaphragm and used to record electrical activity. Using a Grass stimulator it was possible to pace the diaphragm. By selective electrode positioning it proved possible to stimulate the right crus and the median arcuate ligament without interfering with respiration. Using an Erbe generator and a needle electrode passed through a 21 G needle, it was possible to administer RF current to cause focal diaphragmatic scarring adjacent to the lower esophageal sphincter reducing compliance and inducing adhesion formation between the diaphragm and the esophagus. Conclusions: This feasibility study showed that it was possible (1) to acquire measurements of the dimensions and thickness of some components of the diaphragm in the pig and humans, (2) to take needle biopsies of diaphragmatic muscle, (3) measure electrical potentials from the diaphragm at EUS puncture, (4) to place stitches to tighten the esophageal hiatus (5) to use radiofrequency current to alter the compliance of the diaphragm at the cardia, (6) to pace the diaphragm selectively. Some of these possibilities might be of value in the management of reflux or diseases of the diaphragm.