Provocation testing in noncardiac chest pain

Noncardiac chest pain: diagnostic evaluation

Noncardiac chest pain (NCCP) is a common and challenging clinical problem. It is estimated that more than 70 million Americans (23% of the population) suffer from this condition yearly. Patients with NCCP represent a diagnostic dilemma. Their chest pain is often indistinguishable from cardiac pain leading to extensive and expensive evaluations. Once coronary artery disease and other cardiac and pulmonary sources of chest pain are excluded, patients are frequently referred to gastroenterologists to look primarily for esophageal sources of pain. A variety of diagnostic tests are available to the practicing clinician to identify the origin of pain, including ambulatory pH testing, esophageal motility, upper endoscopy, provocative testing and even therapeutic trials.

Patients with chest pain and occult gastroesophageal reflux demonstrate visceral pain hypersensitivity which may be partially responsive to acid suppression

OBJECTIVES

Mechanisms of chest pain in gastroesophageal reflux disease (GERD) are poorly understood. The recent demonstration in healthy subjects that lower esophageal acid exposure induces pain hypersensitivity within the non-acid-exposed upper esophagus (secondary allodynia) raises the possibility that an increase in spinal neuronal excitability (i.e., central sensitization) contributes to chest pain in GERD. The aim of this study was to determine whether in patients with unexplained chest pain, acid reflux contributes to esophageal pain hypersensitivity.

METHODS

In 14 patients with chest pain and GERD and 8 healthy volunteers, electrical pain thresholds (PT) were recorded from the upper esophagus before, and then repeatedly for 90 min after either hydrochloric acid (0.15 M) or saline (0.15 M) infusion into the lower esophagus. Six patients underwent a repeat study after 6 wk of high-dose proton pump inhibitor (PPI) therapy.

RESULTS

GERD patients had lower resting upper esophageal PT than in healthy subjects (40.8 +/- 9 mA and 70.4 +/- 11 mA, respectively; p= 0.018). Acid infusion reduced PT in the non-acid-exposed upper esophagus in healthy subjects, but not in the patients (area under curve [AUC] - 304 +/- 333 and 786 +/- 464; p= 0.03, respectively). Following PPI therapy, resting PT increased (34.65 +/- 13.4 to 40.5 +/- 12.5 mA; p= 0.03), and a reduction in PT now occurred in acid infusion (AUC - 369 +/- 321; p= 0.03).

CONCLUSIONS

Patients with unexplained chest pain and occult GERD have esophageal pain hypersensitivity that is PPI responsive. The increase in resting PT and secondary allodynia only following PPI therapy suggests that pain hypersensitivity in these GERD patients may partially be the result of central sensitization.

Treatment of chest pain in patients with noncardiac, nonreflux, nonachalasia spastic esophageal motor disorders using botulinum toxin injection into the gastroesophageal junction

OBJECTIVE

The aim of this study was to determine if botulinum toxin injection in the gastroesophageal junction improves symptoms in patients with noncardiac chest pain with a spastic esophageal motility disorder.

METHODS

Twenty-nine noncardiac chest pain patients with nonachalasia, nonreflux-related spastic esophageal motility disorders were enrolled in this open label trial of botulinum toxin injection at the gastroesophageal junction. Chest pain was the major complaint in all patients. Symptoms of chest pain, dysphagia, regurgitation, and heartburn were scored before and 1 month after botulinum toxin injection. A response to botulinum toxin was defined as at least a 50% reduction in the symptom score with a possible total chest pain score of 4. The duration of response was defined as the time period, between the time of injection and the point in time, at which the severity of the symptoms returned to the preinjection score.

RESULTS

Seventy-two percent of the patients responded with at least 50% reduction in chest pain. In these responders, there was a 79% reduction in the mean chest pain score from a preinjection score of 3.7 to a postinjection score of 0.78 (p < 0.0001). The mean duration of the response for chest pain in these patients was 7.3+/-4.1 months (range 1-18 months). There was also a significant reduction in the mean regurgitation score, dysphagia score, and total symptom score (p < 0.0001).

CONCLUSIONS

Botulinum toxin injection at the gastroesophageal junction leads to significant symptomatic improvement in patients with spastic esophageal motility disorders whose major complaint is chest pain.

Abnormal cerebral processing of oesophageal stimuli in patients with noncardiac chest pain (NCCP)

In noncardiac chest pain (NCCP), altered visceral perception may result from abnormal cerebral processing of sensory input rather than abnormalities of afferent pathways. However, the interactions between symptoms, autonomic function and oesophageal stimuli are poorly studied. Oesophageal stimulation elicits reproducible cortical evoked potentials [CEP] and modulates heart rate variability via vagal pathways, as visible on power spectrum analysis of heart rate variability [PS-HRV]. These methods are increasingly used to study the function of visceral afferent neural pathways in human. The aim of this study was to compare EP and PS-HRV during oesophageal stimuli in NCCP and controls. Twelve healthy volunteers (one female, 11 male; aged 24-51 years; mean 32 +/- 8 years), and eight NCCP patients (three female, five male; age range 26-58, mean 40.5 +/- 10 years) were studied. Electrical oesophageal stimulation (EOS; 200 microseconds, 0.2 Hz, 25 stimuli) was applied to the oesophageal wall 5 cm above the lower oesophageal sphincter (LOS), and perception thresholds (measured in mA) determined. EP responses were recorded using 22 standard electroencephalogram scalp electrodes. Autonomic activity was assessed using PS-HRV, before, during, and after oesophageal stimulation. Measured PS-HRV indices included high frequency (HF; 0. 15-0.5 Hz) and low frequency (LF; 0.06-0.15 Hz) power, respectively, assessing vagal and sympathetic activity, and the LF/HF ratio. EOS perception occurred at lower thresholds in NCCP than in controls (3. 6 +/- 1 vs. 7.8 +/- 2 mA, P < 0.05). EP amplitude was greater (13 +/- 2 vs. 6 +/- 1 microV, P < 0.0001), and latency longer in controls vs. NCCP (191 +/- 7 ms vs. 219 +/- 6 ms, P < 0.001). In NCCP, EOS decreased sympathetic outflow (low frequency peak on PS-HRV) and increased cardiovagal activity (high frequency peak, P < 0.02) to a significantly higher degree in comparison with controls. During EOS, heart rate decreased in NCCP from 68 vs. 62 beats min-1 (P < 0.003) but not in controls. In NCCP patients, EOS was perceived at lower intensities and was associated with a greater cardiovagal reflex response. EP responses associated with EOS were smaller in NCCP than in controls, suggesting that an increased perception of oesophageal stimuli results from an enhanced cerebral processing of visceral sensory input in NCCP, rather than from hyperalgesic responses in visceral afferent pathways.

Overview of diagnostic testing for chest pain of unknown origin

Identifying the cause of recurrent chest pain may be difficult. Significant coronary artery disease must be excluded before patients can be assured that their symptoms are truly "noncardiac." A normal coronary angiogram is the most definitive test but this may not preclude the presence of a new "fly in the ointment," i.e., microvascular angina. Musculoskeletal pain syndromes, psychological problems, and esophageal disorders, including both esophageal motility disorders and gastroesophageal reflux disease, are the most common causes of noncardiac chest pain. Nearly 30% of these patients will have an esophageal motility disorder, although its clinical relevance in the asymptomatic patient is controversial. Simple, inexpensive, provocation tests (most commonly edrophonium, bethanechol, and/or balloon distention) have been developed to recreate motility-related chest pain in the laboratory. These tests can identify the esophagus as the source of pain, but in most cases they do not direct therapy. Other disadvantages of provocation tests include the lack of a gold standard reference point, side effects, and the need for placebo because of a subjective end point. Recently, ambulatory esophageal pH and pressure monitoring have been used to define precisely the cause of esophageal chest pain. These systems can record multiple episodes of pain for up to 24 hours in an outpatient setting and have shown that gastroesophageal reflux (rather than motility disorders) is the most common esophageal cause of pain. However, these studies also suggest that many episodes of chest pain do not have an identifiable esophageal cause. Furthermore, this equipment is expensive, uncomfortable, may alter normal activity, and is not useful in patients having infrequent pain episodes. Psychological disturbances should be carefully sought in any patient with noncardiac chest pain: Many patients have anxiety, depression, or panic attacks that may complicate or contribute to their reported symptoms. It is questionable if these patients need additional testing. Rather, the challenge of the future is to prove that the multitude of tests aid in the overall treatment and outcome of patients with noncardiac chest pain.