[The heart pumping function and the systemic regulation of blood circulation in groups of heart surgery patients]. / Nasosna funktsiia sertsia ta systemna rehuliatsiia krovoobihu v hrupakh kardiokhirurhichnykh khvorykh.

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.

[Theoretical analysis of the efficacy of G suits during exposure to continuously increasing gravitational overloads]. / Teoreticheskii analiz éffektivnosti protivoperegruzochnykh sredstv pri nepreryvno narastaiushchikh gravitatsionnykh peregruzakh.

A mathematical model of human circulation was employed to examine circulation responses to +GZ acceleration the value of which increased linearly at the rate 0.1 G/sec, using subjects having an anti-G suit on and sitting in a relaxed posture. It has been calculated that the anti-G suit can compensate as much as 83% of the increment of hydrostatic pressure in leg vessels and as much as 57% in abdominal vessels. The suit effect on resistance and capacity vessel properties makes an approximately equal contribution to an increase of the acceleration tolerance threshold. However the occlusion effect of the anti-G suit causes a significant increase of afterload.

[Mathematical model of baroreflex regulation of hemodynamics in the dog]. / Matematicheskaia model' baroreflektornoi reguliatsii gemodinamiki sobaki.

A non-linear mathematical model of dog hemodynamics regulation was developed including descriptions of the cardiovascular system, the arterial baroreflex and the Beinbridge reflex. Model calculated arterial and venous pressure, blood flow, and heart rate are in good agreement with experimental data.

["Tracking" the magnitude of arterial pressure in the circulatory system]. / "Slezhenie" za velichinoi arterial'nogo davleniia v sisteme krovoobrashcheniia

Steady--state characteristics of arterial and venous pressure, cardiac output, total peripheral resistance, heart rate, and pumping heart capacity depending on blood volume change were studied in dogs under conditons of rest, exercises, light and deep narcosis. The tracking mean arterial pressure was found to be the main principle of hemodynamic regulation. In unanesthetized animals the tracking is based on heart regulation component mainly, while under light narcosis it is the vascular component. In deep narcosis it is the suppressed tracking principle: arterial pressure change is proportional to blood volume changes.