Diagrammatic reasoning with interactive P-V curves

In this paper, we describe a case study that supports pathophysiological reasoning using a combination of diagrammatic and qualitative reasoning. Pressure-Volume (P-V) representations of the cardiac cycle have been traditionally used to represent clinical situations, from textbooks to research articles. This has led us to develop an interactive version of the P-V curve which supports diagrammatic inference, based on user-driven modification of essential parameters of the P-V curve. Because diagrammatic inference cannot account for temporal adaptation of the cardio-vascular system, we have extended the diagrammatic reasoning system to incorporate qualitative simulation of adaptive mechanisms. We discuss detailed examples of the system in operation, which produces results fully consistent with the medical literature on some typical pathological situations, for a continuous range of user-driven modification of the P-V curve.