Studies are being done to improve the diagnostic and prognostic utility of the electrocardiogram by characterizing ventricular recovery properties in dogs under control conditions and in abnormal states such as coronary occlusion and manipulation of sympathetic tone. These findings are related to scalar T waveform, and isopotential distribution of the T. T waveform and patterns of distribution of T potentials are also being analyzed in terms of the degree of inhomogeneity of ventricular recovery to develop indices of cardiac states vulnerable to arrhythmias. BIBLIOGRAPHIC REFERENCES: Burgess, M.J., Blatt, S. and Abildskov, J.A.: Observations pertinent to the prolonged QT syndromes. Amer. J. Cardiol. 37:125, 1976. Burgess, M.J.: Sequence of normal ventricular recovery and its relation to T waveform. Vectorcardiography 3, I. Hoffman and R.I. Hamby, eds. Amsterdam, North-Holland Publishing Co., 1976, pp. 61-65.