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PubMedDate not supplied

[Power units of implanted artificial heart and assisted circulation system].

The existing and presently planned systems of power supply for an artificially implanted heart and assisted circulation devices are reviewed. A comparative analysis as to their conformability to biological, functional and technical demands placed on the implanted systems is given. In an implanted artificial heart and assisted circulation systems most promising is shown to be the use of nuclear fuel as a source of power and as converters -- that of thermal engines with gas and steam cycle.

Assisted Circulation↗
PubMed1979

[Trauma to the blood during assisted circulation].

Trauma inflicted to blood in different method of assisted circulation was studied in experiments and in the clinic. Morphological disturbances of red blood cells and changes in their aggregation properties were revealed. Left ventricular shunt and aorto-aortic counter-pulsation are attended with increased aggregation properties of blood platelets. Aorta-aortic counter-pulsation causes a greater damaging effect than shunting of the left ventricle. Counter-pulsation by means of a balloon pump is attended with least hemolysis.

Animals↗
PubMed1972

Assisted circulation following myocardial infarction: a review of 25 patients treated before 1971.

Twenty-five patients with impending death from myocardial infarction were treated with assisted circulation. Of these, 19 had suffered cardiac arrest from which they could not be resuscitated and six were in severe, intractable and expectedly terminal cardiogenic shock.All patients were treated by venoarterial bypass employing a bubble oxygenator. Assistance was continued for an average duration of one hour and 45 minutes at a flow rate between two and four litres per minute. The patients all showed improved cerebral, pulmonary and renal function and acid-base values returned to normal.Five patients survived for at least one month and two were improved; hence 28% of these otherwise terminal patients were helped by this technique of assisted circulation.

Adult↗
PubMedDate not supplied

[Hydrodynamic stands for testing assisted circulation and artificial heart apparatus].

Problems arising in devising the assisted circulation apparatus and artificial heart can be solved only with investigations conducted on hydrodynamic models of the circulation system--the stands. An analysis of literature sources dealing with test stands justifies their classification according to the purpose, the types of tests, the specific structure and basic characteristics. It is necessary to proceed with further improvement of the stand equipment in the direction of creating a sufficiently accurate imitation of the anatomic structure and resilient properties of major arteries and veins, of constructing a geometrical and elastic model of the aorta, of pressure and flow control instruments at different points of the vessels, of the ones regulating the energy parameters, as well as of working out criteria for effectiveness of the devices to be used.

Assisted Circulation↗
PubMed1988

[Assisted circulation for volume relief of the right heart ventricle].

The model of the failure of the right ventricle was formed in dog experiments. The animals were connected with the right mechanically assisted circulation. The blood was pumped synchronously with the heart action from the right atrium directly to the pulmonary artery by temporary bypass of the right ventricle. The right volume relief improved (p less than 0.03) the decisive hemodynamic parameters. The value of assisted circulation in case of the hitherto only difficulty to controlled failure of the right ventricle is proved with that.

Animals↗
PubMed1991

Assisted circulation for myocardial recovery after repair of congenital heart disease.

Between January 1987 and May 1990, six children underwent ventricular assisted circulation for recovery of myocardial function after cardiac surgery. Their ages ranged from 9 months to 12 years. Three patients had tetralogy of Fallot and one had atrioventricular discordance with ventriculoarterial concordance, ventricular septal defect, and under-over ventricles. Double outlet left ventricle and a large ventricular septal defect with pulmonary hypertension was present in the remaining two. The duration of circulatory support averaged 126 +/- 57 h. An extracorporeal membrane oxygenator (ECMO) was used in four patients, biventricular assistance with centrifugal pumps in one, and left ventricular assistance followed by ECMO in the last patient. Circulatory support was begun in the operating room in two patients who could not be weaned from cardiopulmonary bypass. Both these patients are long-term survivors. Assisted circulation was implanted in four patients in the intensive care unit because of low cardiac output refractory to any pharmacological treatment. Only one of these patients could be weaned from circulatory support but he died 20 days later because of multiorgan failure due to persistent poor myocardial function. The causes of death in the remaining three patients were intracranial hemorrhage, untreatable bleeding, and failure of myocardial recovery, respectively. We believe that early postoperative use of circulatory support can be a major determinant for recovery of myocardial function in patients who have severe low cardiac output following repair of congenital cardiac lesions. Our initial experience with the use of biventricular assistance in small children is encouraging. Nevertheless, further observations are clearly necessary to establish the role of postoperative circulatory support in children with congenital cardiac lesions.

Cardiac Output, Low↗
PubMedDate not supplied

[Gas volume stabilization in the pneumatic transmission unit of the assisted circulation apparatus].

A compensator connected to the section consisting of the pump-main line-operating member and including a pneumatic resistance and a flaxid non-elastic container enables it in combination with the feedback to maintain through the volumetric displacement of the gas, or changing the pump diaphragm position, the stability of the gas volume in the pneumatic transmission element of the assisted circulation apparatus. The stabilization of the gas volume in the pneumatic transmission element creates favourable conditions of exploitation and heightens the effect of the cardiac insufficiency treatment, expecially in cases of protracted assisted circulation.

Assisted Circulation↗
PubMed1966

Clinical experiences with assisted circulation.

Of primary importance in the clinical application of mechanical support for the failing circulation are the selection of patients and definition of criteria for assessing the therapeutic results. Experimental and clinical observations suggest that serial measurements of arteriovenous oxygen difference are a reliable rough measurement of the adequacy of the existing cardiac output to meet the oxygen requirements of the tissues. Patients with a decreasing cardiac output may profit from assisted circulation. Thirteen such patients are presented, all of whom were in intractable heart failure. Seven "medical" patients underwent common femoral vein-to-artery perfusion with an oxygenator for an average of 135 minutes. Of these, one patient who had already had two cardiac arrests died, six patients showed striking clinical and biochemical improvement for hours to days, and two patients were discharged from the hospital. Of particular interest were five in whom the indication for assisted circulation was irreversible cardiac arrest. Three patients were resuscitated, and one, who had neurological signs usually accepted as those of anoxic cerebral damage for 45 minutes, recovered completely.

Adult↗
PubMedDate not supplied

Transesophageal color Doppler echocardiography during mechanical assist circulation.

Information available to determine the optimal timing for separation of patients (pts) from mechanical assist circulation (MAC) is usually limited, due to the difficulty of transfer of patients with heavy MAC systems. To evaluate the clinical efficacy of transesophageal color Doppler echocardiography (TEE) in management of patients during MAC, we examined 37 pts (32, intra-aortic balloon pumping = IABP; 4, left ventricular assist device = LVAD; 1, right VAD = RVAD) by TEE. In the other 3 pts, thoracic aneurysms (AN) (2, dissecting An; 1, true AN) were detected by TEE, which were contraindications to safe introduction of IABPs. In 29 pts on IABPs, 2 pts with LVADs, and in 1 pt with a RVAD, patients were safely weaned from MACs with confirmation of full recovery of cardiac function by TEE. However, repeat introduction of IABP support was needed in 2 pts due to severe residual mitral regurgitation, even after initial success; these became the cause of late multiple organ failure. In one pt with a LVAD, a detrimental right to left shunt through the patent foramen ovale, which resulted in severe desaturation of the arterial blood oxygenation, was detected by TEE. Left main coronary flow was measured by TEE and found to increase by 55% on IABP and by 67% on a LVAD. In conclusion, TEE is the only currently available diagnostic tool for total evaluation of cardiac function in an intensive care unit, which can provide very important information for management of patients on MACs.

Adult↗
PubMed1978

[Changes in the myocardial catecholamines in experimental stress and during assisted circulation].

After two hours of immobilization stress in rats, the authors observed significantly decreased noradrenalin values in the myocardium, returning to normal values later. The concentration of adrenalin in the myocardium of rats showed a contrary behavior under stress conditions. Myocardiac catecholamin shifts in dogs with experimental stress induced by coronary occlusion were registered. After 120 minutes of mechanical circulatory support for the left-sided bypass system the catecholamin level in the left atrium decreased. On the other hand, catecholamin levels in the left ventricular myocardium, injured by experimental infarction, were unchanged after 120 minutes of assisted circulation. In correspondence with hemodynamic and metabolic findings, these results could support the method of assisted leftside bypass. Myocardial catecholamines seem to be another possible parameter for the assisted circulation.

Animals↗
PubMed1976

[Myocardial ultrastructure in the presence of assisted circulation].

Experiments were conducted on dogs; a study was made of the influence of a method of assisted circulation--contrapulsation, on the myocardial ultrastructure. A sharp glycogen accumulation in the muscle cells of the heart, the presence of mitochondria with a marked osmophilic microgranular matrix, and also a high pinocytic activity of the capillary endothelial cells were revealed by electron microscopy. The data obtained pointed to the metabolic reconstruction in the myocardium, and primarily to the reduction of the energy level of the myocardial muscle cell function. The changes in the myocardial ultrastructure revealed apparently provided the positive therapeutic effect.

Animals↗