This is a research program in the broad area of cardiopulmonary pathophysiology. Specific topics of investigation range from predominantly cardiovascular to predominantly pulmonary but are related through similar experimental and mathematical techniques. Sub-programs include: "Coronary Circulation in Normal and Abnormal States" focusing on the evaluation of heterogeneous myocardial perfusion, including assessment of regional perfusion. "Mechanisms of Arrhythmia Production" including studies on the effects of antiarrhythmic agents under different experimental conditions. "Kinetics of Gas Exchange in the Lungs and Tissues" investigating the mechanism and kinetics of the Haldane effect, as well as studying the speed of the Bohr shift in the intact erythrocyte. "Intrapulmonary Distribution of Ventilation and Perfusion in Normal and Abnormal States" having as its primary goal the determination of the distribution of ventilation-perfusion ratios from steady-state measurements of intrapulmonary elimination of several inert gas tracers. "Cardiopulmonary Flow Models" involving a detailed study of the fluid mechanical behavior of isolated coronary arterial lesions; also the development of numerical techniques for determining the ventilation-perfusion distribution in the lung using measured retentions of multiple inert gases "Methodological Techniques for the Evaluation of Cardiopulmonary Dysfunction" involving three projects: Improved technique for measurement of cardiac output, Kinetics of the reaction of Indocyanine green and Quantitation of adipose tissue content. BIBLIOGRAPHIC REFERENCES: Jaliwala, S.A., R.E. Mates and F.J. Klocke. An efficient optimization technique for recovering ventilation-perfusion distributions from inert gas data. Effects of random experimental error. J. Clin. Invest. 55:188-192, 1975; Klocke, F.J. Coronary blood flow in coronary artery disease. Bull. Erie Co. Med. Soc. 51:5, 1975.