AN INTERACTIVE QUALITATIVE MODEL IN CARDIOLOGY

Qualitative modeling is a generic term that involves explicit and qual itative representations of the physical world. It can extend the realm of pure mathematical modeling in the sense that qualitative descripti ons can, on one hand, simulate complex physical systems and processes and, on the other, produce linguistic descriptions and summaries of si mulated system behavior. These summaries should be an essential elemen t of the human/machine interface if truly interactive computational en vironments are to be developed. In the context of cardiac arrhythmias, a thorough understanding of the underlying processes that lead to the different pathological states is a first step toward optimizing diagn osis and therapy. The CARDIOLAB project is dedicated to cardiology and is aimed at providing a theoretical framework composed of computation al models of different grain size and based on different formalisms. O ne of the intended roles of the framework is to assist researchers, cl inicians, and pharmacologists in their quest for a better understandin g of rhythmic disorders and ischemic events. In this paper, we present the first element of the framework. It is a cardiac simulator concept ualized in terms of a research field known as qualitative physics. As a simulator, the model's role is to produce fairly detailed descriptio ns, at different levels of abstraction, of cardiac electrical events w hen initial tissue-state conditions are given. A crude simulated ECG i s also produced as a visual aid. At the end of each simulation session , and upon user request, the system can memorize the initial condition s and the descriptions into an arrhythmia knowledge base. As such, the model can be used as an interactive tool, to grossly delineate the re gions in parameter space that correspond to causing or predisposing st ates leading to specific rhythmic disorders. More refined analysis can thereafter be performed using finer-grained models, the initial condi tions of which will have been suggested by the qualitative model. (C) 1995 Academic Press, Inc.