my @ftpFiles =$ftp->ls ();                                                                                                   
my $i = 0;

while ($i < $#ftpFiles) {                                                                                                   
    if ($ftpFiles[$i] =~ m/andv/) {
        $ftp->get ($ftpFiles[$i]);
        $myfile = $ftp;
        }
    $i++;
    }
$ftp->quit ();

=>

foreach my $file (grep m/andv/ => $ftp->ls ()) {
    $ftp->get ($file);
    $myfile = $file; # <= your original code probably does not do what you want
    }
$ftp->quit ();