General properties of cardiovascular system functioning in the groups of postoperative patients in the cardiac surgery clinic were studied using the information technology (IT), combined the methods of cluster and nonlinear regression analysis and computer simulation. It was shown, that in all five separated groups of observations (clusters) the direct dependency of cardiac (CI) and stroke (SI) indexes on central venous pressure (CVP) was determined by the variations of total peripheral resistance and reactions of venous tone (u), contractility (E) and heart rate (HR), oriented on the stabilisation of mean aortic pressure (AP) on approximately the same level. Significant differences between the characteristics CI(CVP), SI(CVP) in the groups were determined by the level of E (especially of the right ventricle) and diastolic tone of the heart. Correlation of the cardiac (E,HR) and vascular (u) components of Ap regulation changed correspondingly the heart functional state. Proposed approach and IT may be used in such clinical and experimental research where considerable volume of observations is combined with the great variation of data and, correspondingly, a poor definition level of system behavior.