BACKGROUND AND AIMS: Perfused miniature manometric assemblies with lumina of 0.4-0.5 mm i.d. have been developed. Reduced luminal size offers the advantages of reduced assembly bulk and increased assembly complexity with greater numbers of lumina and lower manometric infusion volumes because of a slower perfusion rate. This study investigated the recording fidelity of miniature manometric assemblies in the measurement of esophageal peristalsis. METHODS: Four miniature manometric assemblies, each containing manometric lumina of either 0.4 or 0.5 mm i.d., were evaluated at 100 and 180 cm lengths. The fidelity of miniature manometric luminal recordings were evaluated in vivo during esophageal peristalsis by using a simultaneous comparison with the standard lumina and an intraluminal strain gauge. RESULTS: During esophageal peristalsis, miniature manometric lumina recorded the peak amplitude of pressure waves, with an accuracy at perfusion rates of 0.04 mL/min (0.4 mm, i.d.) and 0.15 mL/min (0.5 mm, i.d.). CONCLUSION: Miniature manometric assemblies of lengths that are practical for use in humans are suitable for recording esophageal peristalsis. ; Ganes Shanmuganathan, Marc A Ritz, Richard H Holloway, Addolorata C Di Matteo and Taher I Omari