Comprehensive Study Of Heart Rate Variabilty In Heart Failure Patients

BackgroundIn recent years, with the increasing number of patients with coronary heart disease, heart failure incidence all over the world increased year by year. Heart failure is the serious stage for major cardiovascular diseases. Heart failure has the high mortality rate and it always leads to sudden cardiac death. At present, the clinical heart failure diagnosis is still based on the results of medical history, symptoms, signs, physical examination and necessary examinations. The clinical judgment index for heart failure should be convenient, fast, noninvasive and accurate.There are some relationships between heart failure and the damage of autonomic nervous system function. Abnormal activation of RAAS is caused by autonomic nervous system. The effects of the change are very important as the hemodynamic changes. Analysis of heart rate variability (HRV) is currently considered method to research autonomic nervous system functions. People use the linear index of heart rate variability to study the clinical cardiovascular disease which caused by autonomic nerve. At present, studies focus on hypertension, myocardial infarction, arrhythmia, coronary artery bypass grafting (CABG) and so on. Few of study focus on heart failure. Human body and the cardiovascular system are chaotic nonlinear systems. Although the linear indexes also can make the assessment of disease in part, but sometimes they are useless. Nonlinear indexes fit the chaotic characteristics of cardiovascular activity. They are the research hotspots in recently. But many subjects focus on theoretical study. Clinical studies are not enough. Comprehensive study which uses linear and nonlinear indexes of heart rate variability to evaluate heart failure patients we have not found.Objective1To study the characteristics of linear and nonlinear heart rate variability indexes in heart failure patients.2To analyze the linear and nonlinear heart rate variability indexes for different cardiac function levels patients.3To explore the clinical diagnostic indexes for heart failure and its classification method which are convenient, fast and noninvasive and accurate.MethodsForm Sep.2009to Dec.2010we completely randomly selected125eligible heart failure patients and healthy volunteers in Qilu Hospital of Shandong University. Their ages were in the range of22～77years. There were84heart failure patients in the heart failure group, including54males and30females. According to the NYHA classifications, the heart failure was divided into the classⅡ(30patients), the classⅢ(30patients) and the classⅣ group(24patients). According to the basic diseases the heart failure patients had, the heart failure group was divided into the coronary heart disease group(56patients), the myocardiosis group (22patients) and the rheumatic heart disease group(6patients). There were41persons in the healthy group, including18males18and23females. The informations were recorded which included general situations, histories, physical examinations, treatments, medications and so on. We used CVFD-I cardiac function status monitor to monitor HRV of research objects and GE Vivid7color Doppler ultrasonic diagnostic apparatus to collect the related indexes.Results1Comparison of the general situation There was no difference of age structures and sex ratios among the heart failure group, the healthy group and (P>0.05).The heart rate of the heart failure group was more than the healthy group (P<0.05). There was no difference of the heart rate among the classⅡ, Ⅲ and IVgroups (P>0.05)2Comparison of time-domain index SDNN, rMSSD and PNN50of the heart failure group were lower than the healthy group (P<0.05). There was no difference of SDNN, rMSSD and PNN50among the classⅡ, Ⅲ and Ⅳgroups (p>0.05).3Comparison of frequency-domain index HF, LF, LF/HF, HFn and LFn in the heart failure group were lower than in the healthy group (P<0.05). There was no difference of HF, LF, LF/HF, HFn and LFn among the classⅡ, Ⅲ and IVgroups (P>0.05).LFn, HFn and LF/HF in class Ⅱ,Ⅲ and IVgroups were lower than the healthy group (P<0.05).4Analysis of nonlinear indexes CER and CE of the heart failure group were higher than the healthy group (P<0.05). There was no difference of CER and CE among the classⅡ, Ⅲ and IVgroups (P>0.05). CER and CE of the Ⅱ, Ⅲ and IVgroups were higher than the healthy group(P<0.05). There was no difference of LLE between the heart failure group and the healthy group (P>0.05). MwEn of the heart failure group was lower than the healthy group (p<0.05). MwEn of the classⅡ, Ⅲ and Ⅳgroups were lower than the healthy group (P<.0.05). MwEn of the classIII and IV groups were lower than the class Ⅱ (p<0.05).There was no difference of MwEn between the classIII group and IV group(P>0.05).5Influencing factors of nonlinear indexes Among heart rate, age and LVEF, the LVEF was the only influencing factor of the nonlinear indexes (CER, CE and MwEn)(P<0.05). There were no evidence to prove that heart rate or age was the influencing factor of the nonlinear indexes (p>0.05)6analysis of heart failure patients with different basic pathological changes There was no difference of LFn, HFn, LF/HF, CE, LLE and MwEn between the coronary heart disease group and the myocardiosis group (P>0.05). CER in the myocardiosis group was lower than the coronary heart disease group (P<0.05).Conclusions1Time-domain indexes SDNN, rMSSD and PNN5O in heart failure patients are lower than healthy persons.2Frequency-domain indexes LF, HF, LFn, HFn and LF/HF in heart failure patients are lower than healthy persons.3MwEn in heart failure patients are lower than healthy persons. MwEn in the heart function classⅢ or Ⅳ patients is lower than the heart function class II patients.4CER and CE in heart failure patients are higher than healthy persons.5CER in heart failure patients with the myocardiosis was lower than with the coronary. 6Heart rate or age is not the influencing factor of MwEn, CER and CE. MwEn, CER and CE may be affected by LVEF.