Congestion under the chest may be caused by coronary heart disease, chronic obstructive pulmonary disease, stomach cancer and other factors. 1. Coronary heart disease: If atherosclerosis occurs in the coronary arteries, it may lead to the obstruction of blood passage, thus causing myocardial ischemia and symptoms such as chest pain, chest tightness, and dyspnea. 2. Chronic Obstructive Pulmonary Disease (COPD): If you have the habit of smoking, or often inhale second-hand smoke, it may cause long-term lung damage, which may lead to long-term chronic cough, sputum, shortness of breath, chest tightness and other symptoms. 3. Stomach cancer: if cancerous lesions occur in stomach tissues, with the continuous development of the disease, abdominal pain, abdominal distension and ascites may occur, leading to the weakening or disappearance of abdominal respiration, which will lead to the manifestation of chest tightness and shortness of breath. If there is congestion under the chest, one should consult a doctor in time to avoid delaying the condition.