The preload of the heart, also known as volume load, is essentially the volume of blood contained in the blood vessels of the entire body. This volume is to exclude the volume of blood contained in the heart and lung circulation. Excess volume in the body’s body circulation can lead to increased preload, and preload can interfere with the heart. In normal individuals, the increase in preload can be compensated for without significant uncomfortable symptoms. For patients with myocardial ischemia, especially those with myocardial infarction, increased preload will significantly increase the burden on the heart and cause a further increase in ischemia. Therefore, for people with coronary artery disease and heart failure, it is important to reduce the patient’s preload, or volume load, while treating them, mainly through diuresis. Diuresis is mainly done with intravenous or oral tachypnea preparations, together with spironolactone, a potassium-preserving diuretic, through a dual diuretic strategy that allows the patient to excrete more urine, thus reducing the blood volume in the entire blood vessel. Thus it also reduces the preload and reduces the volume burden on the heart.