Swelling of the legs is likely to be caused by cardiac and renal insufficiency. However, if one leg is swollen and the other is fine, it may be due to trauma to the leg or injury to the knee joint, or even varicose veins in one leg, leading to the pathology of one leg being swollen. In terms of renal function as well as cardiac insufficiency, if attention is paid to cardiac diuretic treatment, the treatment of drugs such as digoxin, sildenafil, furosemide, spironolactone, hydrochlorothiazide, etc., these can adjust the cardiac function as well as renal function diuretic effect, discharge and eliminate edema. Also need to do some tests, such as lower extremity venous ultrasound, to see whether varicose veins and lead to edema, or lower extremity veins if there is thrombosis, also need to carry out anti-thrombotic treatment.