Energy Metabolism of the Completely Isolated Mammalian Heart in Failure

Experimental cardiac failure was reinvestigated in the completely isolated mammalian heart using a simplified system in which only the left ventricle performs work and exhibits volume changes. An effort was made to assess the importance of such experimental artefacts as acapnia, altered or depleted substrate, and controlled (constant) diastolic volume. None of these factors appeared to play a determining role in the mechanism of experimental failure, which was characterized by a decline in mechanical efficiency, with little or no impairment of total energy liberation.