The relationship between heart rate variability and left ventricular diastolic function

Objective To explore the relationship between heart rate variability(HRV)and left ventricular diastolic function in a population of middle age. Methods Using the simple random sampling method,138individuals from the Physical Examination Center of our hospital were recruited between June 2010and December 2010with mean age of(48.1±8.2)years and without organic heart disease. All subjects received the same questionnaires on medical history,smoking,alcohol intake and use of medications. Blood pressure and biochemical parameters were recorded. Enzyme-linked immunosorbent assay(ELISA)was used to detect the plasma concetration of N-terminal probrain natriuretic peptide(NT-proBNP). 2-dimensional echocardiography was used to measure the indexes of left ventricular diastolic function including transmitral diastolic early peak inflow velocity(E),transmitral diastolic late peak inflow velocity(A),early diastolic velocities of mitral annulus(E')and the deceleration time of peak E(EDT). Based on the classification standard of diastolic function,the subjects were divided into 3groups:normal diastolic function(n=74),impaired diastolic function(n=36)and pseudonormal(n=28). The indexes of time and frequency domain on heart rate variability were detected by 24-hour ambulatory electrocardiogram. Results With an impaired diastolic function,logNT-proBNP level was increased[(1.8±0.2),(1.9±0.2),(2.0±0.2)ng/L,P0.01]and low frequency power(LF)decreased[(21.0±5.2),(8.5±5.4),(17.8±6.3)ms2,P0.05]. After adjusted for age,sex,heart rate and medication,partial correlation analysis showed that the root mean square of time differ- ence of adjacent RR interval(rMSSD),the percentage of adjacent RR interval with time difference50ms among all RR intervals(pNN50%)and high frequency power(HF)were all negatively correlated with A (r=-0.210, -0.194,-0.212,P0.05),and positively correlated with the ratio of E to A (E/A)(r=0.189,0.189,0.175, P0.05);very low frequency power(VLF)and LF were positively correlated with EDT(r=0.265,0.194,P0.05),negatively correlated with the ratio of E to E'(E/E')(r=-0.174,-0.173,P0.05),and logNT-proBNP level (r=-0.315,-0.345,P0.01). Stepwise multiple regression analysis showed that A was an independent influencing factor for pNN50% (β=-0.200,P=0.012),E/E'and logNT-proBNP level were independent influencing factors for LF(β=-0.178,P=0.023;β=-0.165,P=0.019). E/E'and EDT were independent influencing factors for VLF(β=-0.170,P=0.021;β=0.177,P=0.015). Conclusions In the population of middle age,abnormal left ventricular diastolic function was correlated with the impaired autonomic nervous system.