Heart failure is not an independent disease; it can be caused by various factors, such as myocardial infarction, cardiomyopathy, and various myocarditis, which lead to changes in the heart structure and subsequent cardiac dysfunction. Heart failure is mainly due to a disturbance in the heart's contractile function or diastolic function, which prevents the heart from adequately ejecting the returning blood volume. This results in pulmonary congestion, systemic circulation congestion, and a series of syndromes caused by insufficient arterial perfusion.