Dr. Fass raises several issues. The first is that local anesthesia should be avoided. We agree, in reality, that it is not possible to place a manometric probe through the mouth without pharyngeal anesthesia. However, we took precautions to avoid dispersion of local anesthetic downstream and did graded balloon distentions 30 to 45 minutes after probe placement, negating any possible influence of anesthetic on esophageal perception. The second issue is whether incremental distention using variable volumes is better than variable pressure. As discussed previously [1, 2], balloon distention with varying volume has a poor predictive value. Esophageal sensation is induced by the stretching of tension receptors. This effect is independent of the elasticity or length of the balloon. In contrast, the balloon characteristics could influence intraluminal volume and, as a result, visceral sensory responses. Third, Dr. Fass believes that pressure and not volume influences esophageal contraction. However, esophageal contractions are induced at a threshold level of esophageal-wall tension [1], regardless of volume or pressure. The fourth issue raised is whether a tracking paradigm is more appropriate. Although a tracking paradigm is useful, it is unclear whether it is superior to intermittent graded distention. Moreover, the tracking paradigm uses first sensation or moderate discomfort as the end point. Because pain was the end point of our study, a tracking paradigm was not suitable.

Dr. Jones has correctly observed that our controls were younger than our patients, but the difference in age was not significant. We previously showed that the esophagus is less sensitive and more compliant in older persons than in younger persons [3]. Therefore, if anything, the older patient group should have had a less sensitive and more compliant esophagus, but this was not the case. Our data show little overlap between controls and patients for sensory thresholds and for the relation between tension and strain. Unlike previous studies, we could define the differences between the two groups because of this new technology. Although patients had lower sensory thresholds, approximately 20% had values in the normal range. This suggests that these patients are a heterogenous group. Our interpretation of Dr. Goyal's editorial [4] is that simple esophageal distention, unlike impedance planimetry, may provide overlap of results and inadequate information. With impedence planimetry, however, it is possible to separate differences between controls and patients.

The case report by Drs. Reisner and Mason reaffirms our belief that patients with unexplained chest pain are a heterogenous group. Some of these patients may have panic disorder, and others may have hypersensitivity of cardiovascular structures [5]. Each patient requires careful evaluation.

Dr. Castrina raises the issue of misdiagnosis of coronary artery disease. We agree that patients who have persistent chest pain should first be tested for coronary artery disease. The gastrointestinal cocktail is commonly used in the emergency department but has never been investigated. We discourage its use. In addition, patients who have unexplained chest pain should not be labeled neurotic. As many as 80% of these patients may have an esophageal source of their pain. In a patient with persistent chest pain, coronary disease should therefore be excluded unequivocally; this should be followed by esophageal evaluation. Empirical therapies should be avoided.