Oesophageal stimulation lowers exertional angina threshold.

The effect of oesophageal stimulation with acid on the exertional angina threshold was examined in 12 subjects. Each walked until the angina threshold was reached on four successive occasions; during two tests the oesophagus was instilled with 0.1 mol/l hydrochloric acid and during the other two with physiological saline. Oesophageal instillation was carried out for 20 min at rest before each walk. In 10 patients the angina point was reached after walking a significantly shorter distance on the treadmill when acid was instilled than when the saline was instilled. ST-segment changes and rate-pressure product were not significantly different during the acid and saline tests. The mechanism responsible for the reduction of angina threshold is not known. However, the effect was more pronounced in the 6 patients who had experienced regular oesophageal symptoms than in those who had not. Ischaemic heart disease and gastro-oesophageal reflux are both common, and the possibility that acid reflux may aggravate angina should be borne in mind, particularly when oesophageal symptoms are present.