\begin{tikzpicture}[]

    \pgfmathsetmacro{\pointnumber}{0};
    \pgfmathsetmacro{\pointnumberoffset}{\pointnumber*3};
    \pgfmathsetmacro{\offsetx}{2.9};
    \pgfmathsetmacro{\offsetxx}{2.0};
    \pgfmathsetmacro{\offsety}{-2.9};
    \pgfmathsetmacro{\meshnumbera}{0};
    \pgfmathsetmacro{\meshnumberb}{1};
    \pgfmathsetmacro{\meshnumberc}{2};
    \pgfmathsetmacro{\meshnumberd}{3};
    \pgfmathsetmacro{\imagewidth}{0.17};
    \pgfmathsetmacro{\leftshift}{-1.8};



    \foreach \i in {0,1,2,3,4}{
        \pgfmathsetmacro{\ii}{int(2*\i)};
        \pgfmathsetmacro{\iii}{int(2*\i+1)};
        \node[inner sep=0pt] (im\i) at (\offsetx*0,\offsety*\i) {\fbox{\includegraphics[width=\imagewidth\textwidth,trim={35 12 42 25},clip]{source/sampling/endo_\ii.png}}}; 
        \node[inner sep=0pt] (im\i) at (\offsetx*1,\offsety*\i) {\fbox{\includegraphics[width=\imagewidth\textwidth,trim={35 12 42 25},clip]{source/sampling/epi_\ii.png}}}; 
        \node[inner sep=0pt, rotate=90] (text1) at (\leftshift,\offsety*\i) {\small Sample \iii};
        }

    \foreach \i in {0,1,2,3,4}{
        \pgfmathsetmacro{\ii}{int(2*\i+1)};
        \pgfmathsetmacro{\iii}{int(2*\i+2)};
        \node[inner sep=0pt] (im\i) at (\offsetx*2+\offsetxx,\offsety*\i) {\fbox{\includegraphics[width=\imagewidth\textwidth,trim={35 12 42 25},clip]{source/sampling/endo_\ii.png}}}; 
        \node[inner sep=0pt] (im\i) at (\offsetx*3+\offsetxx,\offsety*\i) {\fbox{\includegraphics[width=\imagewidth\textwidth,trim={35 12 42 25},clip]{source/sampling/epi_\ii.png}}}; 
        \node[inner sep=0pt, rotate=90] (text1) at (\leftshift+\offsetx*2+\offsetxx,\offsety*\i) {\small Sample \iii};
        }

    \node[inner sep=0pt,anchor=north] (im) at (0,1.8) {\small Endocardium}; 
    \node[inner sep=0pt,anchor=north] (im) at (\offsetx,1.8) {\small Epicardium}; 
    \node[inner sep=0pt,anchor=north] (im) at (\offsetx*2+\offsetxx,1.8) {\small Endocardium}; 
    \node[inner sep=0pt,anchor=north] (im) at (\offsetx*3+\offsetxx,1.8) {\small Epicardium}; 

\end{tikzpicture}