Clinic Study Of Perioperative Cardiac Risk Events In Patients Undergoing Noncardiac Surgery

[Background and Objective] Cardiac risk events(CRE) accounts for the greatest number of deaths after anesthesia and surgery,especially in senile patients with coronary artery disease. CRE that occur most often are high risk ventricular ectopic beats (HRVEB) and myocardial ischemia. Many studies showed that symptomatic ventricular arrhythmias(VA),5 ventricular ectopic beats (VEB)/min,preoperative preexisting VA and myocardial ischemia in the first 48 hours after major noncardiac surgery were positively associated with patient's prognosis. In addition,the occurrence of CRE,such as arrhythemia,myocardial ischemia and myocardial infarction,were often preceded and/or accompanied by autonomic nervous dysfunction. Therefore,it is essential to know the relationship between the autonomic nervous dysfunction and the occurrences of HRVEB and myocardia ischemia so as to enhance the predictablity of them and to ensure perioperative safe of patients. The purpose of this study is to observe the changes of perioperative CRE and to identify its' independent predictors as well as to evaluate the roles of heart rate variability(HRV) in predicting CRE.[Methods] One hundred and fifty patients scheduled for elective surgery were monitered with dynamic electrocardiogram(DCG) for at least 12h within 24h before surgery and for 48h after surgery. The parameters of HRV including total power(TP),high frequency(HF),low frequency(LF),very low frequency(VLF),LF/HF,mean RR intervals(meanRR) and standard deviation of all normal to normalRR intervals(SDNN) were recorded and computed prior to the surgery,the first and second day after surgery. Cardiac risk events,such as HRVEB,myocardial ischemia,angina and myocardial infarction,were noted at the same time. So did other factors that could affect perioperative CRE,including age,sex,weight,ASA class,cardiac history,cardiac risk factors,cardiac medication,anesthesia,surgery,laboratory and other physiological data. Potential univariate predictors of CRE were identified using the jc2 or / Test,and then all variables that were significant at a nominal two-tailed P value of 0.1 or less than 0.1 were entered into multivariate logistic models. According to the presence or not of HRVEB including 10VEB/h,ventricular couplets (VC),ventricular tachycardia (VT) or higher Lown grade VA,all patients were assigned into the HRVEB group (I group) or no HRVEB group( II group). According to the presence or not of myocardial ischemia episodes,all patients were assigned into the myocardial ischemic group (A group) or no myocardial ischemic group (B group). The relationships of HRVEB or myocardial ischemia and HRV between the two groups were analyzed. [Results] HRVEB occurred in 29.3% of our patients:12.0% preoperatively and 26.0% postoperatively. Incidence of the HRVEB in 0-12h and 12-24h post of surgery(POS) was lower than that prior to anesthesia(PTA),and then increased significantly in 24-36h and 36-48h POS. Independent predictors of preoperative HRVEB were(RR value:big to small):VEB occurred in preoperative ECG,history of hypertension,ischemia in preoperative ECG,ASA III,history of cigarette smoking,myocardial ischemia in preoperative DCG. Independent predictors of postoperative HRVEB were(RR value:big to small):VEB occurred in preoperative ECG,HRVEB in preoperative DCG,myocardial ischemia in postoperative DCG,history of hypertension,AS A III,hemoglobin(Hb)(RR