The heart rate variability parameter is a value used to determine cardiovascular disease and has a range value of 102 to 180 milliseconds. A value greater than the range indicates that the patient is less likely to have ventricular fibrillation. If the value is less than the range, the patient is more likely to have ventricular fibrillation. Heart rate variability is the change in the difference between each heartbeat cycle and is used primarily to reflect sympathetic and parasympathetic tone and neural and humoral regulation of heart rate. Heart rate variability is a parameter used in clinical practice to determine the prevention of cardiovascular and other diseases and changes in condition, and the range of values should be between 102 and 180 milliseconds. If the patient’s HRV is greater than 180 milliseconds, this indicates an increase in parasympathetic tone and an increase in the threshold for ventricular fibrillation, which means that the patient’s likelihood of ventricular fibrillation is reduced. If the patient’s heart rate variability value is less than 102 milliseconds. This indicates that the patient’s sympathetic tone is increased and the threshold for the occurrence of ventricular fibrillation is decreased, indicating that the patient has an increased likelihood of ventricular fibrillation. When the patient’s HRV value is greater or less than the reference value, it is recommended that the patient go to the hospital in time for examination and diagnosis, and under the guidance of the doctor for treatment.