*3.2.2 The autonomic nervous system as a mechanism for the link between mood and cardiomyopathy*

The autonomic nervous system has an important regulatory mechanism for the cardiovascular system, including the sympathetic nervous system and the parasympathetic nervous system (**Figure 1**) [52]. Heart rate variability (HRV) is a commonly used index for evaluating autonomic nerve function and the risk of sudden cardiac death. HRV analysis can effectively evaluate the state of cardiac autonomic nerve function. It is a relatively independent index for predicting the short- and long-term prognosis of various CVDs and sudden cardiac death [53]. Liu [54] found that when healthy individuals were exposed to negative emotional stress, the production of cardiac autonomic nerve function was significantly different. Similar changes in the pathological state of coronary heart disease suggest that long-term negative emotions may be one of the reasons for individual parasympathetic nerve damage.
