signal processing – Why doesn’t HighpassFilter fully remove the DC component?

The high pass filter is not completely removing the DC component. See the picture. Blue is the signal before filtering, green is after. The really strange thing is that it removes part of the DC component, but it doesn’t finish the job. I’ve looked at the options for HighpassFilter, and I just can’t see anything to explain this.

As requested here is the code

RRData = RRDataCorrected;
 dumplot = 
 ListLinePlot[
  MapAt[# - Mean[RRDataCorrected[[All, 2]]] &, #, 2] & /@ 
   RRDataCorrected, PlotStyle -> {Blue}, 
  PlotMarkers -> Graphics@{Disk[{0, 0}, Scaled@0.008]}, 
  AspectRatio -> 1/10, ImageSize -> Full];

myInterpolation = Interpolation[RRData, InterpolationOrder -> 3];
filteredUniformRRData = 
  Table[{i*beatinterval, myInterpolation[i*beatinterval]}, {i, 0, 
    Length[RRData] - 1}];
filteredUniformRRData = 
  Transpose[{Table[i*beatinterval, {i, 0, Length[RRData] - 1}], 
    LowpassFilter[filteredUniformRRData[[All, 2]], 1.5000000]}];
filteredUniformRRData = 
  Transpose[{Table[i*beatinterval, {i, 0, Length[RRData] - 1}], 
    HighpassFilter[RRData[[All, 2]], 00.1]}];

Show[ListLinePlot[filteredUniformRRData, PlotStyle -> Green, 
  PlotRange -> {All, All}], dumplot, AspectRatio -> 1/10, 
 ImageSize -> Full, PlotRange -> {All, All}]