Objective To explore the mechanism of effects of cardiac sympathetic anesthesia on left ventricular ejection fraction(LVEF) and left cardiac cavity size of patients with dilated cardiomyopathy.Method 121 consecutive patients with dilated cardiomyopathy were divided into cardiac sympathetic nerve blockade group(TEA group) and control group(c group).In TEA group,5％ lidocaine was injected into thoracic epidural cavity for about 4 to 8 weeks in addition with routine therapy.In c group,only routine therapy was used.We observe the changes of LVEF and left cardiac cavity size before and after treatment in both groups. Result In TEA group,after anesthesia,LVEF was increased from(31.3± 12.8) to(47.3± 21.3),P<0.001;left ventricular end－ diastolic diameter was reduced from(69.1± 7.1)to (65.1± 8.0),P<0.001;left atrial diameter was decreased from(44.0± 6.2)to(39.4± 7.2),P< 0.001. Conclusion Cardiac sympathetic anesthesia can effectively improve the ejection performance of dilated cardiomyopathy and make the dilated cardiac cavity turn to normal level.