How to independently adjust heatmap labels and cell sizes

I need to create a heatmap with long text labels (~ 40 - 50 characters parallel to the Y-axis), but I would prefer my cells to be small

squares (about 0.5 cm x 0.5 cm).  I have tried to adjust height and width of the graphical object, but this adjusts everthing and the heat map

cells become too large.

Is there some way to independently adjust heatmap labels and cell sizes?

Regards,

Jim Metz

James.Metz@AbbVie.com