Heart rate variability and functional severity of XXXX secondary to @entity453 .

@entity1 @entity453 @entity712
To investigate the behaviour of heart rate variability (HRV) with the advancing severity of @entity712 (CHF) we studied 20 normal subjects and 80 @entity453 ( @entity453 ) @entity1 in sinus rhythm. @entity453 @entity1 were selected consecutively in order to form four equal groups of 20 subjects with different degrees of CHF according to the New York Heart Association (NYHA) functional classification. In each subject a 24 h ECG Holter tape was recorded and subsequently analysed to obtain measures of heart rate and HRV. We used several measures of HR and both spectral and non-spectral measures of HRV. Among these we employed the width of the R-R interval distribution over 24 h at three different heights (TV, 10%Var, 50%Var). The @entity453 group showed significantly lower HRV counts and smaller spectral components than controls. However, these differences were due to the presence of CHF rather than to @entity453 . Indeed, a progressive and significant increase in heart rate and a contemporary decrease in HRV was observed with the advancing severity of CHF. Class IV @entity1 had the smallest HR variation; the spectral composition in this group was barely detectable. The decrease in time domain measures of HRV followed the increase in NYHA Class in a progressive and regular pattern, while the low frequency and high frequency spectral power showed the largest reduction from NYHA Class I to NYHA Class II @entity1 . No significant change was demonstrated in NYHA Class I @entity1 as compared to Controls.(ABSTRACT TRUNCATED AT 250 WORDS)
