An alpha-adrenergic coronary constriction during esophageal distention in the dog

Downstream effects of esophageal distention

This review focuses on primary peristalsis and the normal swallow and secondary peristalsis as it relates to esophageal distention. In addition, high-pressure zones in the esophageal sphincters and innervation in the esophageal body are discussed. Distention-induced protective reflexes for the pharynx and airway are described, as are extraesophageal effects of esophageal distention. Experimental and clinical research in these areas is summarized, along with its possible clinical applications.

Coronary spasm reflects inputs from adjacent esophageal system

Mechanisms underlying coronary spasm are still poorly understood. The aim of the study was to assess the hypothesis that fluctuations in the development of coronary spasm might reflect inputs from the adjacent esophageal system. We enrolled patients admitted to the coronary care unit for episodes of nocturnal angina. Seven patients with variant angina and five with coronary artery disease (CAD) had concurrent ECG and esophageal manometric monitoring. ECG monitoring documented 28 episodes of ST elevation in variant angina patients and 16 episodes of ST depression in CAD patients. Manometric analysis showed that esophageal spasms resulted remarkably more frequently in variant angina patients (143 total spasms; individual range 9–31) than in CAD patients (20 total spasms; individual range 0–9; P < 0.01). Time series analysis was used to assess fluctuations in the occurrence of abnormal esophageal waves and its relationship with spontaneous episodes of ST shift. Episodes of esophageal spasm in CAD were sporadic (<1 in 30 min) and not related to ECG-recorded ischemia. In the variant angina group, esophageal spasms were time related to ischemia (>1 into 5 min before ECG-recorded ischemia) ( P < 0.05). A bidirectional analysis of causal effects showed that the influence processes between esophageal and coronary spasms were mutual and reciprocal (transfer function model, P < 0.05) in variant angina. We concluded that in variant angina patients, episodes of esophageal spasms and myocardial ischemia influenced each other. Mechanisms that cause esophageal spasm can feed back to produce coronary spasm. Coronary spasm may feed forward to produce additional episodes of esophageal spasm.

Esophagocardiac convergence onto thoracic spinal neurons: comparison of cervical and thoracic esophagus

The aim of this study was to characterize thoracic spinal neurons receiving convergent inputs from the esophagus, heart and somatic receptive fields. Extracellular potentials of single T3-T4 spinal neurons were recorded in pentobarbital anesthetized male rats. Thoracic and cervical esophageal distensions (TED, CED) were produced by water inflation of a latex balloon. A catheter was placed in the pericardial sac to administer bradykinin or a mixture of algogenic chemicals. 96/311 (31%) neurons responded to both TED and intrapericardial chemicals (IC) and 48/177 (27%) neurons responded to both CED and IC. Long-lasting excitatory responses were more frequently encountered (P<0.05) in esophagocardiac spinal neurons responding to TED (T-ECSNs, 62/91) than in neurons responding to CED (C-ECSNs, 23/47). Ninety-one percent of T-ECSNs and 98% of C-ECSNs had somatic fields on chest, axilla and upper back areas. Esophagocardiac convergence on thoracic spinal neurons provided a spinal mechanism that might mediate viscerovisceral nociception and reflexes.

Cardioesophageal reflexes: an invasive human study

Neural reflex arcs from the esophagus and heart have been shown in both animals and man. The purpose of this study was to further investigate these pathways in individuals undergoing cardiac catheterization. A total of 298 patients undergoing cardiac catheterization were asked to participate in the protocol. Thirty patients were able to complete the study. Esophageal manometry and pH were monitored throughout the cardiac procedure. Afterwards, esophageal provocation with ice water, hydrochloric acid, and balloon inflation was performed with observation of cardiac rate and rhythm. Twelve patients with normal coronary arteries developed diffuse esophageal spasm on either esophageal or cardiac provocation. In one patient with abnormal coronary arteries, coronary angioplasty precipitated diffuse esophageal spasm. Esophageal acid sensitivity was increased in patients with normal coronaries as compared to those that were abnormal. The esophageal pain threshold was significantly lower in patients undergoing angioplasty versus those undergoing coronary angiography alone. There was no significant change in esophageal pH during invasive cardiac maneuvers and manipulations. In conclusion, cardiac manipulation can induce esophageal motility abnormalities, but not gastroesophageal reflux. Coronary angioplasty is associated with esophageal hyperalgesia.

Pain perception and brain evoked potentials in patients with angina despite normal coronary angiograms

OBJECTIVE

To evaluate the role of nociception in patients with angina despite normal coronary angiograms and to investigate whether any abnormality is confined to visceral or somatosensory perception.

METHODS

Perception, pain threshold, and brain evoked potentials to nociceptive electrical stimuli of the oesophageal mucosa and the sternal skin were investigated in 10 patients who had angina but normal coronary angiograms, no other signs of cardiac disease, and normal upper endoscopy. Controls were 10 healthy volunteers. The peaks of the evoked potential signal were designated N for negative deflections and P for positive. Numbers were given to the peaks in order of appearance after the stimulus. The peak to peak amplitudes (P1/N1, N1/P2) were measured in microV.

RESULTS

(1) Angina pectoris was provoked in seven patients following continuous oesophageal stimulation. (2) Distant projection of pain occurred after continuous electrical stimulation of the oesophagus in four patients and in no controls. (3) Patients had higher oesophageal pain thresholds (median 16.3 mA v 7.3 mA, P = 0.02) to repeated stimuli than controls, whereas the values did not differ with respect to the skin. There were no intergroup differences in thresholds to single stimuli. (4) Patients had substantially reduced brain evoked potential amplitudes after both single oesophageal (P1/N1, median values: 7.2 microV, controls: 29.0 microV; N1/P2: 16.5 microV, controls: 66.0 microV; P < 0.001 for both) and skin (N1/P2: 13.5 microV; controls: 76.0 microV; P < 0.001) stimuli despite the similar pain thresholds.

CONCLUSION

Central nervous system responses to visceral and somatosensory nociceptive input are altered in patients who have angina despite normal coronary angiograms.

Oesophageal sensation assessed by electrical stimuli and brain evoked potentials--a new model for visceral nociception

Sensory thresholds and brain evoked potentials were determined in 12 healthy volunteers using electrical stimulation of the oesophagus 28 and 38 cm from the nares. The peaks of the evoked potentials were designated N for negative deflections and P for positive. Continuous electrical stimulation (40 Hz) at the 38 cm position resembled heartburn (five of 12 subjects) while non-specific ('electrical') sensations were provoked at 28 cm (10 of 12). Thresholds of sensation and of pain were lower at the initial than the second determination, but did not differ with respect to stimulation site. The pain summation threshold to repeated stimuli (2 Hz, 5 stimuli) was determined for the first time in a viscus. This threshold was lower than the pain threshold to single stimuli at 38 cm (p < 0.02). Evoked potential latencies did not change significantly over a six month period while the N1/P2 amplitude was higher at the first measurement (p < 0.05). P1 and N1 latencies were significantly shorter 38 cm (medians 100 and 141 ms) than 28 cm from the nares (102 and 148 ms) (p = 0.04 and p = 0.008). Electrical stimulation of the oesophagus may serve as a human experimental model for visceral pain. Longer evoked potential latencies from the proximal compared with distal stimulations provide new information about the sensory pathways of the oesophagus.