A device adapted for determining cardiac viability, wherein said device includes: a cannula having a hollow body and at least a distal end adapted for insertion into a heart and operator end for adapted for an operator to position the catheter in the ventricular apex and adapted for connection to a plumbing system; an inflatable balloon positioned near to the distal end in fluid communication with the hollow body to allow for selected inflation of the balloon, a controller adapted to calculate the viability of the heart from pressure data detected within cannula or balloon which is inflated to various degrees with an incompressible fluid.