This study evaluates a modified intraventricular balloon method for functional assessment of hearts from donation after circulatory death. By using a saline-filled balloon in the left atrium, the study measures left ventricular pressure during reperfusion in juvenile pigs. Results show significant correlations between contractility and relaxation parameters measured by the modified method and those in working mode. This technique offers a mitral valve-sparing option for early heart viability assessment during ex-vivo heart perfusion.