407-1 Cardio-Oesophageal Reflex: A Mechanism for “Linked Angina” in Patients with Angiographically Proven Coronary Artery Disease

Abstract

We have shown previously that oesophageal acid stimulation can reduce coronary blood flow in syndrome X patients suggesting the presence of a cardio-oesophageal reflex in humans. The presence of such a reflex in patients with coronary artery disease could explain the mechanism of “linked angina”. To investigate this hypothesis we studied the effect of oesophageal acid stimulation on coronary blood flow in 14 patients with angiographically documented significant (>50% stenosis) coronary artery disease (CAD) and 18 heart transplant patients (HT). A fine tube was introduced through the patient's nose in to the distal oesophagus. A 3.6F intracoronary Doppler catheter was positioned in the proximal left anterior descending coronary artery. Coronary blood flow was calculated from measurements of coronary flow velocities and arterial cross-sectional area from quantitative angiography. Oesophageal instillation of 0.1 M hydrochloric acid and 0.9% saline was performed in random, double-blind fashion (60 ml over 5 minutes) and the measurements were repeated after each infusion. Nine patients in the CAD group reported their usual chest pain on acid instillation but none experienced any pain after saline infusion. None of the patients in the HT group experienced any chest pain on acid or saline infusion. There were no significant difference in systemic haemodynamics after the infusions in both groups. The coronary blood flow (CBF) was significantly reduced by acid oesophageal stimulation in the CAD group [CBF pre-acid 70.4 ± 14.3, CBF post-acid 46.4 ± 19.1 ml/min (p < 0.01)]. However, there was no significant difference in the CBF on saline infusion [73.5 ± 15.3 versus 72.5 ± 14 ml/min]. CBF in the HT group was unaffected by acid or saline infusion. In the 9 CAD patients who experienced angina on oesophageal acid infusion there was a significant reduction in CBF from 73.4 ± 12.9 to 34.6 ± 4.7 ml/min. However, in the 5 CAD patients who did not have any chest pain the CBF was unaffected by acid infusion [65.1 ± 16.7 versus 67.5 ± 16.7 ml/min] . Oesophageal acid stimulation can produce angina and significantly reduce coronary blood flow. The lack of any significant effect in the HT group, in whom the heart is denervated, suggests a neural reflex. The presence of such a reflex may be a mechanism for “Linked Angina” in patients with coronary artery disease.