Table of variation

Question

I am trying to make a table of function variation with tkz-tab package, like

Problem is that I don't know how I could obtain arrows like in the image. My code is:

\documentclass[11pt,b5paper]{article}
%-Greek, Palatino Linotype Font and language related packages------------------------------------------------------------------
\usepackage{xltxtra}   
\usepackage{xgreek}   
\usepackage{amsfonts}   
\usepackage{amsmath}   
\usepackage{amsthm}   
\usepackage{amssymb}   
\usepackage{tkz-tab}   
\usetikzlibrary{matrix,arrows,decorations.pathmorphing}   
\usetikzlibrary{arrows,backgrounds}   
\usetikzlibrary{scopes,svg.path,shapes.geometric,shadows}   
\usetikzlibrary{decorations.pathreplacing}    
\begin{document} 
\setmainfont[Mapping=tex-text]{Palatino Linotype}
\tkzTabInit[lgt=1,deltacl=0.4]   
{$x$ / 1,   
$f'$ / 1,   
$f''$ /1 ,   
$f$ /2}  ty$}
\tkzTabLine{d,- ,d,- ,z,+ ,t }   
\tkzTabVar{+ / \ $0$ , -D+/ $-\infty$/ $+\infty$, -/ $e$,+/ \ $\dfrac{e^2}{2}$,+/\ $+\infty$ }   
\end{tikzpicture}   
\end{document}