Conventional clinical tests of the esophagus often fail to yield positive results when thoracic pain originates in the esophagus. Newer methods, including cineradiography, acid perfusion test, esophageal motility test, and intraluminal pH and pressure test, are more precise, in patients complaining of chest pain. The acid perfusion test has been particularly useful in identifying esophagitis. The esophageal motility test is the only means by which the hypertensive gastroesophageal sphincter and diffuse spasm can be diagnosed with certainty. The intraluminal pH and pressure test is the most sensitive means of detecting gastroesophageal reflux. Of 34 patients with chest pain of obscure origin tested by this method, 17 were found to have reflux.
Morgan EH, Hill LD. Objective Identification of Chest Pain of Esophageal Origin. JAMA. 1964;187(12):921-926. doi:10.1001/jama.1964.03060250039009