(I) Almost everyone has experienced heartburn at one time or another, usually after a meal. (II) Heartburn is the painful sensation a person feels when the cardiac sphincter fails to prevent the stomach contents from refluxing into the esophagus. (III) As a matter of fact, anyone who has heart trouble should consult a doctor. (IV) This may happen if a person eats or drinks too much or both. (V) Tight clothing and even changes of position (lying down, bending over) can cause it, too, as can some medications and smoking.