Why is it that trapped gas feels like you are having a heart attack? when i pass i feel fine.

Can't be too sure...: No one symptom definitively indicates a heart attack is or is not in progress (many people make the fatal mistake of waiting out atypical heart pain). In fact, "heart pain" is often indistinguishable from esophageal, pericardial, mediastinal, gastric, and chest wall distress. By the same token, where in your gut you retain "trapped gas" may give you very different sensations. See doctor to be sure.

Pressure: Gas buildup in the stomach or intestines can cause pressure leading to abdominal pain, shortness of breath, leading to a feeling of chest discomfort that can give the impression of a heart attack. When the pressure is released, the feeling stops.