PubMed Health⌕ Search

Biomedical subjects

G P Itkin

Publications and source records attributed to G P Itkin.

At least 19 recordsLinked to original sources
PubMed1995

Comparative hemolysis tests of rotary blood pumps.

At present, hemolysis is one of the most important characteristics used to evaluate rotary blood pumps. However, the conditions of testing procedures in various research centers differ considerably. We proposed to conduct the experiments under conditions similar to those from clinical applications of arterial pumps in extracorporeal perfusion. Proceeding from these considerations, the following parameters of Hemolysis (H) testing were adopted: output, 6 L/min; difference of pressure, 300 mm Hg; initial hematocrit, 30 mg%; and initial hemolysis (PHbo) < 5 mg%. The channel pump IBP80 designed on the basis of the BP80 was tested using fresh human blood. The experimental results indicate that the H level due to the use of the IBP80 is 2-3 times less than H for the BP80. H dependence on the difference of pressure in the range between 200 and 300 mm Hg was noted for the BP80, which can be accounted for by the transition of the laminar conditions of flow to turbulence. According to the results of the hydrodynamic efficiency evaluation, the IBP80 is twice as efficient as the BP80.

Blood Flow Velocity↗
PubMed1991

Present and future of the artificial heart driving system.

The totally artificial heart (TAH) is now in development in two trends. First, there is the development of a bridge system for temporary support of cardiac function. The TAH with the extracorporeal pneumatic driving system Sinus-IS is more efficient and safer. Parallel with this, a portable pneumatic driving system has been developed. That can be considered a stage in the development of the second trend: a totally implantable TAH. This article reviews problems of building of the Micron energy system to be used in implantable TAH designs.

Animals↗
PubMed1991

Centrifugal blood pumps--a brief analysis: development of new designs.

Analysis of 350 different sources of information from leading countries of the world enabled us to determine the availability of 20 different designs of centrifugal and rotary blood pumps. Most of them are for extracorporeal applications with radial pumping wheels of disc or vane type. The prospect of improving these designs was suggested by a combination of these two types. Five new designs based on the Biomedicus have been produced. Basic calculations are given for one of these with respect to limitations for shear stresses. It is proposed that the suggested designs will allow reductions in thrombosis and haemolysis which are the main problems for these pump designs.

Animals↗
PubMed1991

[The first clinical experience with orthotopic transplantation of the liver].

The article deals with material concerning the performance of 4 operations for orthotopic liver transplantation (OLT). The operations were carried out on 2 males and 2 females whose ages ranged from 20 to 52 years. The indications for OLT were as follows: ++hemangioendothelioma of the liver, hepatocellular carcinoma, cirrhosis-carcinoma of the liver, and metastatic affection of the liver. One male patient died immediately after the end of the operation, another patient died 3 days after the operation due to nonfunctioning of the transplant. In 2 female patients the operations were carried out successfully. One of them was discharged from the clinic in 62 days in a satisfactory conditions and a well functioning transplant. The other patient died from a complication which was not connected with the operation--perforation of the small intestine 69 days after OLT. The technical aspects of and the provision for the operation and the postoperative management of patients are discussed. The encountered complications are analysed.

Adult↗
PubMed1987

Use of an ellipsoid artificial heart.

Experiments with the Poisk model of an ellipsoid artificial heart are reported. With a modified model of the diaphragm type made from polyurethane, calves survived for a mean of 55 days, with a maximum survival of 3 months. With adequate anticoagulation therapy, no thrombogenesis was observed in the blood chamber (except for the inlet valves); a low level of plasma hemolysis was observed postoperatively. Good correlation was demonstrated between the stroke volume and left and right atrial pressures. Changes in the blood coagulation indices are reported. Implantation of a clinical variant of this prosthesis into human cadavers demonstrated no difficulties in placing the heart in the pericardial cavity. Developmental efforts are continuing.

Animals↗
PubMed1983

[Experimental study of the output characteristics of the left heart ventricle].

A method is suggested of evaluating the cardiac internal hydraulic resistance R0 and maximal blood flow at zero post load Q0. R0 in intact dogs is 11.9 mm/Hg/l/min and Q0 is 27.1 l/min. In the condition of acute cardiac insufficiency and under the effect of large adrenaline doses these parameters were, respectively, 8.8 mm Hg/l/min, 7.0 mm Hg/l/min and 36.9 l/min, 38.8 l/min. The reducing of of R0 reflect the reduction of rigidity of the myocardial wall, and the increase of Q0 reflects the increase of the cardiac muscle inotropism connected with the compensatory increase of the catecholamines level in blood.

Animals↗
PubMed1982

In vitro evaluation of U.S. and U.S.S.R. artificial hearts.

This report summarizes the results of the in vitro evaluation of Soviet and American artificial hearts. The devices were tested at the All-Union Institute of Transplantation and Artificial Organs, Moscow, U.S.S.R., and Baylor College of Medicine, Houston, Texas, U.S.A. These studies were designed to standardize procedures to allow comparison of artificial ventricles of different designs. Also, these studies might provide a means for evaluation of other characteristics such as hemolysis, durability, and reliability. Static and dynamic tests were performed, varying preload, afterload, rate, and systolic and diastolic time intervals. All designs demonstrated comparable function curves with capability of taking over the pressure and volume work of the natural heart.

Blood Flow Velocity↗
PubMed1982

[Use of left cardiac shunting in severe acute heart failure].

The efficiency of assisted circulation by means of an artificial ventricle joined in through left atrial-aortal shunt in severe cases of acute heart failure was assessed in an experimental study on calves. Myocardial insufficiency was produced by coronary ligation. Assisted circulation was conducted for 2-6 hours. The recovery of cardiac pumping function was noted in 56.3% of observations, an evidence of high efficiency of the method. The experimental results showed the efficiency of an asynchronous operation regimen of the artificial ventricule in the presence of acute arrhythmias and hypotension.

Acute Disease↗
PubMed1977

[Effect of adrenaline on the contractility of different portions of the myocardium of homeotherms].

The contractility of myocardial strips from the atrium and ventricle of rabbit heart had some differences in the parameters of single contraction, interval--tension relationship, and transitional process. These differences were eliminated by increasing the concentration of epinephrine in bath solution. Epinephrine changed the mode of time--force relation of contraction and induced appearance of extremum in all the parts of the heart. The linear relation between the force of atrium contraction and that of ventricle contraction (homochromity) during change of contraction frequency in normal solution, was shown. The homochromity of atrium and ventricle was broken by high epinphrine concentrations. The level of endogenous catecholamines which modulate the excitation--contraction relations, is believed to determine the differences in the physiological reactions of atrial and ventricular strips. The use of atrium of the heart as a transducer for management of artificial heart is proposed.

Animals↗