nevrokard

HRV

A system of Heart Rate Variability (aHRV, SA-aHRV) analysis giving a non-invasive estimate of the function of the sympathetic and parasympathetic autonomic nervous systems in patients and fulfilling the requirements of the Heart Rate Variability Standards*. The maximum allowed recording length is 120 hrs (5 days).

It consists of two software modules:

The input file for the Nevrokard Heart Rate Variability Analysis software module is a recorded (and edited if required) RR Interval (RRI) file prepared by means of the Nevrokard Heart Rate Variability File Preparation software module from ECG recordings of different compatible formats (see Data Formats).

The Nevrokard Heart Rate Variability Analysis software can also analyze RRI data series in several different compatible formats (see Data Formats).

Nevrokard™ SA-aHRV is a software package for Heart Rate Analysis in small animals. It features frequency domain analysis of up to 5Hz and a resampling rate of 10Hz. It is intended for use in animals having a considerably higher heart rate than human subjects. The complementary File Preparation software for small animals is Nevrokard™ SA-aHRV FP software. The maximum allowed recording length for SA-aHRV Analysis is 26 hrs.


	An ECG file recorded by any acquisition system or a RR interval file is required. The software is compatible with ECG and RRI files in several different formats (see Data Formats).

Detection of R waves, calculation of RR intervals, editing of the ECG record.

Either whole recordings or their parts can be analyzed both in time and frequency domains. The option to select by a single click either heart rate or RRI units (HR/RR) in all time domain-related types of analysis.

Premature heart beats can be edited out of RRI files manually...

... or automatically. The number of preceding beats on which correction is based, the parameters defining abnormal beats and the method of correction (deletion, interpolation) can be selected.


TIME DOMAIN ANALYSIS

All time-domain displays and calculations will be done either in the RR or HR mode.

Statistics: Max., Min., Max./Min., Range, Mean NN, Mean dNN (MSD), Median, 95% Conf. Interval, 99% Conf. Interval, lnHRV, Coef. of Variance, Variance, SDNN, SENN, SDSD, RMSSD, NN50 Count, pNN50, SDANN, SDNN Index, SDASD.

Segmented statistics: SDANN, SDNN Index, SDASD, t-test between segments; Mean, STD, SE, 95% and 99% Confidence Interval, RMSSD, pNNxx Index (pNN50, pNN27 or custom) for each segment.

Linear regression (trend): Coefficients A and B, R², SEE for each segment.

Histogram: Mean, SD, Median, Modus, Dispersion, Upper F(X), Uncertainty, Skeweness, Kurtosis and Variability Index (HRV Triangular Index with a freely adjustable Class Interval (bin value)).

Poincare Analysis: SD1, SD2 in both absolute and normalized units, SD1/SD2 Ratio, CSI (Cardiac Sympathetic Index), CVI (Cardiac Vagal Index), dRRt, dRRr in both absolute and normalized units, dRRt/dRRr, Centroid, Ellipse Area, R² and SEE.

FREQUENCY DOMAIN ANALYSIS

Based on non-linear analysis: CZF (Conte, Zbilut, Federici) analysis:

A non-linear method of HRV analysis.
Based on variogram analysis.
Can be applied in cases of non-linear and non-stationary time series.
Can be used to analyze the fractal variance function, the generalized fractal dimension and the relative probability density function of the data.
For more information about the CZF Analysis click here or visit the www.saistmp.com or www.societyforchaostheory.org/tutorials websites.

A robust PSD estimation method considered superior to the autoregressive and FFT spectra:

Produces robust PSD estimates in the presence of noise and ectopy.
Spectral density units: absolute, normalized.
Graphic presentation and calculation of integrals of up to 5 preset frequency bands (ULF, VLF, LF, HF, VHF) which represent the quantitative, numeric results of the procedure and give a non-invasive estimate of the function of the sympathetic and parasympathetic autonomic nervous systems in patients in absolute or normalized units (absolute power of given component/[sum of absolute powers of all components-F*] x 100, *F=adjustable low frequency limit for n.u. calculation).
On-screen determination of spectral density at any frequency.
LF/HF ratio, LF/(LF+HF) ratio, HF/(LF+HF) ratio, CCVLF (Coefficient of Component Variance for LF) and CCVHF (Coefficient of Component Variance for HF).

Based on the autoregressive model (parametric method):

Spectral density units: absolute, normalized.
Freely adjustable model order.
Graphic presentation and calculation of integrals of up to 5 preset frequency bands (ULF, VLF, LF, HF, VHF) which represent the quantitative, numeric results of spectral analysis and give a non-invasive estimate of the function of the sympathetic and parasympathetic autonomic nervous systems in patients in absolute or normalized units (absolute power of given component/[sum of absolute powers of all components-F*] x 100, *F=adjustable low frequency limit for n.u. calculation).
On-screen determination of spectral density at any frequency.
LF/HF ratio, LF/(LF+HF) ratio, HF/(LF+HF) ratio, CCVLF (Coefficient of Component Variance for LF) and CCVHF (Coefficient of Component Variance for HF).

Based on the FFT Algorithm (non-parametric method):

FFT spectra types: Amplitude (=Magnitude), RMS, Power.
FFT window types: Rectangular, Hanning, Hamming, Flat Top, Bartlet, Blackman, Exponent, Blackman Exact, Blackman Harris, Chebyshev, Cosine Tappered, Kaiser.
Spectral density units: absolute, normalized.
Absolute units: linear, logarithmic (absolute, relative).
Smoothing with triangular window (freely adjustable smooth index).
Graphic presentation and calculation of integrals of up to 5 preset frequency bands (ULF, VLF, LF, HF, VHF) which represent the quantitative, numeric results of spectral analysis and give a non-invasive estimate of the function of the sympathetic and parasympathetic autonomic nervous systems in patients in absolute or normalized units (absolute power of given component/[sum of absolute powers of all components-F*] x 100, *F=adjustable low frequency limit for n.u. calculation).
On-screen determination of spectral density at any frequency.
LF/HF ratio, LF/(LF+HF) ratio, HF/(LF+HF) ratio, CCVLF (Coefficient of Component Variance for LF) and CCVHF (Coefficient of Component Variance for HF).

RESULTS OF ANALYSIS

Results of analysis can be printed, exported, directly converted into graphic formats or presentation slides, transferred to clipboard etc.

Chart Editor is available for all modes of analysis.

The Export Results utility enables the operator to save the selected analysis results to an Excel (CSV) spreadsheet. The results are saved in groups and automatically and sequentially appended to (a) selected Excel Results file(s).

* Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology (Marek Malik, PhD, MD, Chairman of the Writing Committee): Heart Rate Variability: Standards of Measurement, Physiological Interpretation, and Clinical Use. Circulation. 1996; 93: 1043-1065.

** For more information about the CZF Analysis click here or visit a websites www.saistmp.com and http://www.societyforchaostheory.org/tutorials.