Linear and nonlinear dynamics of heart rate variability after acute myocardial infarction with normal and reduced left ventricular ejection fraction.
We analyzed heart rate variability (HRV) in 2 groups of patients after acute myocardial infarction with normal and reduced ejection fraction (EF) by considering both the power of the 2 major harmonic components at low and high frequency and 2 indexes of nonlinear dynamics, namely the 1/f slope and the correlation dimension D2. HRV of patients with a reduced EF was characterized by a diminished RR variance as well as a different distribution of the residual power in all frequency ranges, with lower values of the low-frequency component expressed in both absolute and normalized units, and of the low- to high-frequency ratio. In these patients we also observed a steeper slope of the negative regression line between power and frequency in the very low frequency range. The presence of a smaller fractal dimension was suggested by a lower D2. Thus, in patients after acute myocardial infarction with a reduced EF, the reduction in HRV is associated with a different distribution of the residual power in the entire frequency range, which suggests a diminished responsiveness of sinus node to neural modulatory inputs.
Lombardi
F
F
Centro Ricerche Cardiovascolari, CNR; Milan, Italy.
Sandrone
G
G
Mortara
A
A
Torzillo
D
D
La Rovere
M T
MT
Signorini
M G
MG
Cerutti
S
S
Malliani
A
A
D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000502:physiology; D015716:Electrocardiography, Ambulatory / Q000379:methods*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted; D013318:Stroke Volume / Q000502:physiology*; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000503:physiopathology*; D016277:Ventricular Function, Left / Q000502:physiology*