Table 2 The statistical time-domain features based on RR-interval [41]
From: An improved electrocardiogram arrhythmia classification performance with feature optimization
Statistical time-domain features | Description | Formula |
|---|---|---|
mean_RR | The mean of normal-to-normal RR-intervals | \(\frac1N{\textstyle\sum_{i=1}^N}RR_i\) |
std_RR | Standard deviation of RR-intervals | \(\sqrt{\frac1N}\sum\left(RR_i-{\mathrm m\mathrm e\mathrm a\mathrm n}\_\mathrm{RR}\right)^2\) |
nn_50 | Number of adjacent RR-intervals | \(\mathrm{Num}(\mathrm{abs}({\mathrm{RR}}_{\mathrm n+1}-{\mathrm{RR}}_{\mathrm n}))\geq50\mathrm{ms}\) |
rms_RR | Root mean square of successive RR-intervals differences | \(\sqrt{\frac1{\mathrm N}}\sum{({\mathrm{RR}}_{\mathrm i+1}-{\mathrm{RR}}_{\mathrm i}})^2\) |
pnn50 | Percentage of NN50 | \((\frac{NN50}{N})\times{100}{\%}\) |
cv_RR | Coefficient of Variation of RR-interval | \(\frac{\mathrm s\mathrm{td}\_RR}{\mathrm m\mathrm e\mathrm a\mathrm{n}\_RR}\) |
min_RR | Minimum RR-interval | \(\min(\mathrm{RR}-\mathrm{interval})\) |
max_RR | Maximum RR-interval | \(\max(\mathrm{RR}-\mathrm{interval})\) |