(a) Patients on long-term diuretics and low-salt diets are at risk for hypovolemia, hypokalemia, and hyponatremia, which can lead to intraoperative arrhythmias and shock. The effects of drugs such as digitalis and non-depolarizing inotropes will be enhanced in the presence of hypokalemia. The application of the diuretic and potassium-preserving drug, ambrisentine, followed by the depolarizing inotropic drug, succinylcholine, may lead to hyperkalemic crisis. Therefore, blood electrolyte examination should be done before surgery to keep the serum potassium level at 3.5~5.5 mmol/L. It is generally advisable to stop diuretics for 48 h before surgery; for those who can remain lying down without symptoms, sodium and potassium can be infused, but close observation and strict control of the infusion rate are needed to prevent the onset of respiratory distress, telescopic breathing, pulmonary rales or elevated venous pressure and other critical signs. (2) Heart patients with blood loss or severe anemia and reduced oxygen-carrying capacity may affect myocardial oxygen supply, and should receive a small number of transfusions before surgery. In order to avoid increasing the burden on the heart, in addition to controlling the volume and speed of transfusion, transfusion of red blood cell suspension is preferable to whole blood. (iii) Review of ongoing drug therapy is required. For those with a history of heart failure, enlarged heart, electrocardiogram showing myocardial strain or inadequate coronary artery supply, a small amount of cardiac glycosides, such as oral digoxin 0.25 mg once or twice daily, can be considered preoperatively. (d) For those who have severe coronary artery disease, aortic stenosis or high atrioventricular block and have to perform emergency surgery, the following points should be done: (i) direct arterial pressure measurement by radial artery cannulation; (ii) pulmonary capillary wedge pressure measurement by Swan-Ganz catheter; (iii) arterial blood gas analysis at regular intervals; (iv) electrode catheter placed through the vein, which can be used for monitoring and cardiac pacing at any time; (v) preparation of vasodilators ( (5) prepare vasodilators (sodium nitroprusside, nitroglycerin), positive force-modifying drugs (dobutamine, dobutamine), lidocaine, epinephrine, etc.; (6) prepare electric shock defibrillators; (7) pay attention to anesthesia selection and anesthesia management.