Mechanical Properties of the Gastro-esophageal Junction in Health, Achalasia, and Scleroderma

Abstract

Background: Manometric assessment of the gastro-esophageal junction (GEJ) is deceptive in that ignores key dynamic properties of the junction, such as resistance to flow and compliance. Our aim was to investigate the mechanical properties of the GEJ comprising intraluminal pressure (measured by manometry), resistance to flow and compliance (measured by resistometry). Methods: We studied 8 healthy subjects, 11 patients with achalasia and 11 patients with scleroderma. We used a pneumatic resistometer, previously developed and validated in our laboratory. The resistometer consists of a flaccid polyurethane 5-cm cylinder connected to an electronically regulated nitrogen-injection system; the instrument records nitrogen flow through the cylinder while maintaining a constant pressure gradient between its proximal and distal ends. By placing the cylinder successively in the proximal stomach and along the GEJ we measured the GEJ-gastric resistance gradient (GEJ resistance minus gastric resistance) and were able to calculate the cumulative resistance (sum of resistance exerted at each pressure level), peak resistance (at any injection pressure), nil resistance point (injection pressure in mmHg at which GEJ resistance equals gastric resistance), and compliance slope (flow/pressure relationship). Results: We found that GEJ resistance to flow (cumulative resistance, peak resistance, and nil resistance point) is significantly increased in achalasia and decreased in scleroderma (P < 0.05 versus health) while GEJ compliance is diminished in achalasia (P < 0.05 versus health) and normal in scleroderma. Conclusion: Achalasia is a disease characterized by increased GEJ resistance and rigidity. By contrast, although scleroderma is characterized by decreased GEJ resistance, GEJ compliance may be normal.