Objectives: The purpose of this study was to investigate the presence of a cardioesophageal reflex in patients with coronary artery disease that may explain the mechanism of "linked angina."
Background: It has been previously shown that esophageal acid stimulation can reduce coronary blood flow in patients with syndrome X, suggesting the presence of a cardioesophageal reflex in humans.
Methods: We studied the effect of esophageal acid stimulation on coronary blood flow in 14 patients with angiographically documented significant coronary artery disease and in 18 heart transplant recipients. Hydrochloric acid (0.1 mol/liter) and 0.9% saline solution were infused in random, double-blind manner (60 ml over 5 min) through a fine-bore tube positioned in the patient's distal esophagus, and coronary blood flow measurements were obtained after each infusion by use of a 3.6F intracoronary Doppler catheter positioned in the proximal left anterior descending coronary artery.
Results: Coronary blood flow was reduced significantly by esophageal acid stimulation in the coronary artery disease group (before acid 70.4 +/- 14.3 ml/min, after acid stimulation 46.4 +/- 19.1 ml/min [mean +/- SD], p < 0.01). However, there was no significant difference in coronary blood flow during saline infusion (73.5 +/- 15.3 vs. 72.5 +/- 14 ml/min). Coronary blood flow in the heart transplant group was not affected by acid or saline infusion.
Conclusions: Esophageal acid stimulation can cause animal attacks and significantly reduce coronary blood flow in patients with coronary artery disease. The lack of any significant effect in heart transplant recipients with heart denervation suggests a neural reflex.