Single foot swelling is usually associated with local factors such as local trauma, mosquito bites or local exposure to medications. Therefore, swelling of the left foot should be localized to find the cause of the disease, and if necessary, can be referred to orthopedics or dermatology and other departments. Swollen feet include single foot swelling and double foot swelling. If it is caused by the heart, the swelling is usually bilateral, so single foot swelling is not considered to be related to the heart. Cardiac patients with double foot swelling, the body shows excessive fluid, that is, fluid retention, suggesting that patients with heart failure or aggravation of the disease. At this time, the diuretic dosage should be adjusted in a timely manner, increase the diuretic dosage to eliminate bilateral foot edema, to further stabilize the condition. Bilateral edema can also be seen in other systemic diseases, such as malnutrition leading to hypoproteinemia or lower extremity venous system diseases.