Patients with heart disease may experience weakness in the legs. Heart disease is usually caused by insufficient blood and oxygen supply to the coronary arteries, resulting in insufficient perfusion to the corresponding target organs, and ischemia and hypoxia to the peripheral organs and peripheral tissues and organs. If a patient has weakness in both legs, it is usually due to heart disease. In addition, if a patient has heart failure due to heart disease, there is usually swelling in both lower extremities and weakness in both legs during right heart failure. For patients with heart disease who have weakness in the legs, it is also important to consider whether the weakness is caused by hypokalemia due to long-term use of diuretics, such as hydrochlorothiazide or furosemide.