CARDIAC ISCHEMIA INDUCES VAGALLY MEDIATED LOWER ESOPHAGEAL SPHINCTER RELAXATION

Gastro-oesophageal reflux and coronary artery disease frequently coexi st. Direct stimulation of myocardial vagal receptors impairs lower oes ophageal sphincter (LOS) function but the effect of cardiac ischaemia has not been examined. Eight adult mongrel dogs were studied under gen eral anaesthesia. Each underwent occlusion of the left circumflex coro nary artery before and after bilateral cervical vagotomy. Blood pressu re, heart rate and LOS responses were measured. Median (range) LOS ton e was significantly reduced by coronary artery occlusion, from 9 (6-14 ) to 6 (3-8) sphinctometer units (P<0.01). This was accompanied by a r eduction in heart rate (P<0.05) and blood pressure (P<0.01). After bil ateral cervical vagotomy the same ischaemic insult produced no signifi cant alteration in LOS tone or heart rate. These data suggest a direct vagal reflex to explain the high incidence of gastro-oesophageal refl ux in patients with coronary artery disease.