LT-HRV

   

Nevrokard® LT-aHRV is a software package designed to perform analysis of segmented ECG data (from 1 min. up to 120 hrs (5 days)) in the time and frequency domains. It is complementary to Nevrokard® aHRV Analysis software which works on files of the same length, but performs somewhat different types of analysis with more emphasis on the time domain and does not use file segments.

It consists of two software modules:

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

  • The Nevrokard LT-aHRV Analysis software can also analyze RRI data series in several different compatible formats (see Data Formats).

Nevrokard™ SA-LTaHRV is a software package for Long-Term advanced Heart Rate Variability 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-LTaHRV File Preparation software. The maximum allowed recording length for SA-LTHRV Analysis is 26 hrs.
   

 


   
An ECG file recorded by any acquisition system or an ASCII RR interval table 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:



ECG and RRI files may be edited:


 
All time-domain displays and calculations will be done either in the RR or HR mode
 
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
 
Either whole recordings or zoomed segments of recordings can be analyzed both in time and frequency domains. Segments may be either adjacent (continuous) or overlapping; the user selects the segment length (in time units) and the number of FFT data points for spectral analysis. If overlapping of segments is enabled, any percentage of overlapping between 1 and 100 percent can be selected in steps of 1 percent.



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.


 

Poincare Analysis: SD1 (ms), SD2 (ms), SD1 (n.u.), SD2 (n.u.), SD1/SD2, CSI (Cardiac Sympathetic Index), CVI (Cardiac Vagal Index) (mean ± S.D.) in consecutive time segments


 
  FREQUENCY DOMAIN ANALYSIS

Waterfall Graph: Waterfall graph is a
3D graph displaying individual FFT
spectra in successive time segments in 3D
units.
X-axis: frequency, Y-axis: spectral density,
Z-axis: time.

Surface Graph: Surface graph is a 3D
graph displaying individual FFT spectra
in successive time segments in 3D units.
It creates an illusion of a 3D surface by
connecting spectral lines between two
adjacent time segments.
X-axis: frequency, Y-axis: spectral
density, Z-axis: time.

Contour Graph: a 3D graph displaying
individual FFT spectra in successive
time segments in 2D units. This is
essentially a Surface Graph viewed from
'above'.
X-axis: frequency, Y-axis: time.

FSDmax Graph: displays changes of
frequencies at which spectral densities
within any of the individual frequency
bands selected (e.g. ULF, VLF, LF, HF and VHF) are maximal, in consecutive time segments.
X-axis: time, Y-axis: frequency.

Power Graph: displays changes of the
spectral power in individual frequency
bands (Total, ULF, VLF, LF, HF and VHF) in
consecutive time segments.
X-axis: frequency, Y-axis: power in
absolute units, normalized units or % scale.

Stacked Power Graph: displays changes
of spectral power in the form of stacks (i.e.,
ULF+VLF+LF+HF+VHF power) in individual frequency bands (Total, ULF, VLF, LF, HF and VHF) in consecutive time segments.
X-axis: frequency, Y-axis: power in absolute
units, normalized units or % scale.

Spectral Results Graph: displays changes of the LF/HF Power ratio, LF/(LF+HF) Power ratio, HF/(LF+HF) Power ratio,CCVLF (Coefficient of Component Variance for LF) and CCVHF (Coefficient of Component Variance for HF) in consecutive time segments.
X-axis: time, Y-axis: LF/HF ratio, LF/(LF+HF) ratio, HF/(LF+HF) ratio, CCVLF and CCVHF

Grouped Graphs: a group of four graphs
selected by the operator for comprehensive
presentation of graphic results in a single
screen.

RESULTS: a single table containing all the
numeric results of all the LT-HRV analyses
of the current file in both time and
frequency domains, as well as all the file
and settings information.

 

 

Chart Editor is available for all modes of analysis.

 
  OUTPUT OF ANALYSIS
 
  • All Graphs and Results of analysis can be exported, directly converted into graphic formats or presentation slides, transferred to clipboard etc.
  • Chart Editor is available for all modes of analysis.