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PubMed1991

Biventricular bypass: alternative to univentricular bypass and total artificial heart-bridge.

Left ventricular and biventricular bypasses (LVBs, BVBs) were performed in 102 experiments in sheep, goats, and donkeys. Biventricular bypass was performed in the assisted circulation mode or in the paracorporeal artificial heart bridge (PCAHB) mode when the natural heart fibrillates. During implantation of artificial ventricles instead of a heart-lung bypass, counterpulsation was used. Several types of connective conduits were developed and tested in experiments. The conduits included bifurcational connective pipes that permit "intake" of blood into artificial ventricles from atria and ventricles of the natural heart simultaneously and consequently provide effective blood flow through shunts not depending on the state of the natural heart (acute cardiac weakness or asystole). Monitoring gas content (PO2, PCO2, and pH) in the myocardium of both ventricles suggested development of right ventricular failure under conditions of LVB before hemodynamic changes occurred and confirmed the preferability of BVB over other methods of assisted circulation, as it is most effective and capable of normalizing short-term cardiac disturbances in the course of the 1st 2 days. Survival time of experimental animals (2-3 days for dogs, 5-12 days for sheep, goats, and donkeys) is sufficient to overcome acute cardiac insufficiency. This suggests that BVB in the assisted circulation mode or PCAHB mode can serve as a bridge for cardiac transplantation for the time of search for the available organ.

Animals↗
PubMed1983

Organization of treatment of patients with cardiac insufficiency of different origin.

Assisted circulation is now used in the treatment of severe forms of heart failure which complicate the course of many diseases. Application of one method of assisted circulation--intra-aortic counterpulsation by a balloon pump in cardiogenic shock--was successful: prolonged survival (over 1 year) was obtained in 18% of the patients. A further decrease in the mortality rate is dependent on the rational organization of treatment for these patients. This poses two major problems: the organization of treatment of patients in cardiogenic shock and postoperative heart failure in large cardiologic and heart surgery centers, and treatment of heart failure in patients in whom it has occurred secondarily. We developed a method of organizing the treatment of these patients beginning in the prehospital stage and continuing in a specialized hospital. In addition to methods of assisted circulation, various intensive care methods and hemosorption (in poisoning by liver toxins), hemodialysis (in anuria), etc., are used. Although this type of organization complicates therapy, the results are significantly improved.

Heart Failure↗
PubMedDate not supplied

[Mechanical assistance of circulation. 42 cases].

OBJECTIVES: Mechanical circulatory support was proposed in patients in cardiogenic shock, as a bridge to cardiac transplantation or weaning. The aim of the present study is an analysis of the first 42 cases. METHODS: The 42 cases included 31 patients in cardiogenic shock unresponsive to medical therapy, good cardiac transplant candidates, and 11 patients unweanable off ventricular assist, or in shock in the intensive care unit. Results are evaluated in terms of transplantability and hospital survival. RESULTS: Overall success rate is 67%, ranging from 25% in previously transplanted patients to 46% following acute myocardial infarction and 57% in cardiomyopathy. Age and learning curve played a significative role. CONCLUSION: These data suggest that mechanical support improves survival in patients in cardiogenic shock. Earlier implantation should improve the patient outcome.

Adult↗
PubMedDate not supplied

[Intrapulmonary venous admixture during open heart surgery].

Monitor-computer study of changes in the ventilatory parameters, hemodynamics, gas exchange has shown that assisted circulation in patients operated on for acquired heart valve defects causes in the postperfusion period a 2-fold increase in intrapulmonary venous admixture (Qs/Qt), which accompanied an increase in alveolar-arterial difference (pO2) and a fall in arterial blood pO2. An increase in Qs/Qt upon assisted circulation is associated with a decrease in ventilation/perfusion pulmonary ratio and possible deterioration of diffuse processes due to hemodilution-induced water balance disturbances. Controlled lung ventilation with positive end respiratory pressure (5-8 cm H2O) partially decreases intrapulmonary shunting and improves arterial blood oxygenation. Positive effect, i. e. improved oxygenating lung capacity and decreased intrapulmonary shunting is achieved with water balance normalization due to early administration of diuretics upon assisted circulation.

Cardiac Surgical Procedures↗
PubMed1977

[Emergency treatment of mechanical complications of acute myocardial infarction. Septum perforations and mitral insufficiency].

Over the last three years, thanks on the one hand to improvements in surgical techniques and ressuscitation, and on the other to assisted circulation using the intra-aortic balloon, which allows improved preoperative preparation of the patients, urgent medicosurgical treatment of the mechanical complications of infarction has improved the prognosis by comparison with the recent past. During the above period, our figures for operative intervention during the first two weeks after an acute infarction have been as follows: 1. Twenty nine cases of septal perforation (17 of which had previously had assisted circulation by balloon): there were 8 immediate deaths and 8 successful cases (no secondary deaths over a follow-up period of from 2 to 41 months). In all these cases, the surgeon approached the perforation by way of the left ventricle. No patient required an additional bypass procedure. Where indicated, assisted circulation by means of a balloon should not be continued for more than a few days. If there is no improvement with its use, it seems unreasonable to proceed to surgery regardless. 2. Ten cases of acute mitral incompetence; 8 were due to ruptured papillary muscle and two to mal function. 5 patients out of the 10 had required circulatory assistance by balloon preoperatively. There were 2 immediate deaths and 8 successful cases, with one secondary death (follow-up period of between 2 and 37 months).

Acute Disease↗
PubMed2003

Experimental evaluation of the influence of complete artificial circulation on renal circulation and tissue metabolism -comparative study of pulsatile vs nonpulsatile circulation.

In this study, pulsatile and nonpulsatile assisted circulation were compared to evaluate renal circulation under complete artificial circulation. In addition, differences were also compared between animals supported by high (assist rate 80%)- and low (assist rate 60%)-level artificial circulation. Using 20 pigs, ventricular fibrillation was induced after cardiogenic shock, assist by mechanical support by pulsatile and nonpulsatile artificial circulation. Hemodynamics and renal circulation were evaluated by measuring renal arterial blood flow, renal cortical blood flow, renal medullar blood flow, cortical/medullar flow ratio, serum urea nitrogen levels, blood creatinine levels, urinary beta(2)-microglobulin (MG) levels, and serum beta(2)-MG levels. Tissue metabolism was evaluated by comparing arterial ketone body ratios and lactic acid/pyruvic acid ratios. During the acute stage of cardiogenic shock, redistribution of renal blood flow and tissue metabolism were improved in the pigs with pulsatile artificial circulation, suggesting the usefulness of pulse pressure. In nonpulsatile artificial circulation, the possibility of irreversible renal dysfunction was suggested. Although changes in renal blood flow were smaller in high-level artificial circulation than in low-level artificial circulation, physiological maintenance of renal circulation was better in pulsatile artificial circulation than in nonpulsatile artificial circulation. These results suggest that this effect of pulsatile assisted circulation may become more marked when evaluated in the early state after cardiogenic shock.

Analysis of Variance↗
PubMed1982

Control system for circulatory assist devices: determination of suitable control variables.

This paper studies the problem of identification of suitable biological variables for optimal effectiveness of a CAD. To identify suitable error signals, a closed loop simulation and analysis of the assisted circulation was carried out. Results show that the combination of heart rate and left atrial pressure is very effective as an input error signal for either series or parallel assisted circulation when simulated heart failure is severe (greater than 50% decrease in left ventricular elastance). During simulated exercise (50% reduction in peripheral resistance) such a combination is even more effective. In addition, simulation results show that aortic pressure and cardiac output are not suitable control variables for CAD.

Assisted Circulation↗
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↗
PubMed1979

Intraaortic balloon pumping in the treatment of cardiogenic shock complicating acute myocardial infarction.

A 5.1% incidence of cardiogenic shock was found in consecutive series of 680 patients with acute myocardial infarction (AMI) during a five-year period. The hospital mortality was 94%. Shock was treated according to a stepwise policy including assisted circulation with intraaortic balloon pumping (IABP). During the five-year period, only five patients, 14% of the shock patients, had shock for more than three hours (the minimal time for attempting medical therapy and preparing for assisted circulation), were below 75 years of age and without terminal diseases. Together with ten AMI patients in shock referred from or treated in other hospitals, altogether 15 patients were given IABP during 1--318 hours (mean 58). Shock was reversed in 12 (80%) of these patients and five (33%) could be weaned off IABP and discharged from the CCU. However, only two patients (13%) were long-term survivors.

Acute Disease↗
PubMed1975

[Treatment of cardiogenic shock complicating myocardial infarct by the methods of counterpulsation].

The results of treatment of myocardial infarction complicated by cardiogenic shock by-means of arterial counterpulsation and that with an intra-arterial ballon are presented. In order to determine the indications for counterpulsation the authors introduce a classification of cardiogenic shock that takes into account the reactivity of the patient and the speed of decompensation of the systemic circulation. Both methods of counterpulsation permitted to reverse the cardiogenic shock in 81.8% of the cases. In 18.2% the shock appeared to be areactive in nature, 15.9% of the patients died due to a recurrence of the cardiogenic shock after it had been reversed by means of assisted circulation. Other complications of myocardial infarction caused the death of 43.3% of the rest. Hospital mortality comprised 77.4%. The main factors that determine the stable positive countershock effect of counterpulsation in myocardial infarction cases complicated by cardiogenic shock include early introduction of counterpulsation into the set of therapeutic and resuscitation measures, high capacity of assisted circulation devices (up to 31/min.), long duration of continuous counterpulsation (not less than 12 hours).

Assisted Circulation↗
PubMed1979

[The ellipsoid heart. Construction and animal experimental findings of a new kind of artificial heart].

In order to avoid thrombi generation within artificial ventricles the Ellipsoid heart is built with a one-piece membran in enddiastolic position. This allows to have an optimal washout of all inside surfaces during the cardiac cycles, in enddiastolic position the cross sectional veiw of the membran is circle-shaped. 82% of the filling volume can be used for the maximal stroke volume, which is 120 ml. The maximal cardiac output is 16 l/min. The Ellipsoid heart is evaluated as design for total heart replacement and assisted circulation. As total artificial heart the survival times were in calves experiments up to 40 days, in assisted circulation in parakorporeal position up to 83 days. The cardiac assistance with the Ellipsoid heart (E-LVAD) is performed due to implanted canula in the left ventricle via the left atrium and a connection to the ascending aorta. This technique was applied in 14 clinical cases with cardiac failure after open surgery. The E-LVAD could support the failing heart; it could be removed in 4 patients. The aim to avoid thrombiformation within artificial ventricles could be achieved with the Ellipsoid heart in calve experiments as well as clinically--the membrane was constantly clean and free of any thrombidepositions.

Animals↗
PubMed1989

[The clinical application and the problems in future for the ventricular assist device].

In an attempt to save patients with severe cardiac pump failure to which no emergency methods of treatment show effect even with various medications or machinery assisted circulation, the ventricular assisted device (VAD) has come more and more in need today as it provides patients with a temporary cardiac function and serves as a life-prolongation means, eventually aiming at patients' return to normal daily life. In Japan, basic researches for development of VAD have been proceeding since 1960. We have been pursuing researches in the related scientific field since 1980 with the theme of clinical application of VAD and have completed the total system of VAD in August, 1982. In October 1982, we succeeded for the first time in Japan in weaning a patient from the VAD. Until April, 1988 we had managed clinical applications of VAD in 121 cases. Based on this experience, I have presented here a result of our clinical analysis of these cases and have come up with the problems surrounding the clinical application of VAD.

Adolescent↗
PubMed1989

[A successful biventricular assist for postoperative patient with severe heart failure and hepatorenal dysfunction after mitral and tricuspid valve surgery].

We report a case of successful biventricular assist for severe heart failure after open heart surgery. A 62-year-old man suffering from advanced valvular disease accompanied with hepatorenal dysfunction underwent mitral valve replacement and tricuspid annuloplasty on September 22, 1988. Because of inability of weaning from cardiopulmonary bypass, left heart assisted circulation using a roller pump with heparin-coated tubing system was inserted. Following the left heart assist, an right ventricular assist device (RVAD) was subsequently applied to intractable right ventricular failure. He was successfully weaned from an RVAD after 24 hours, and from left heart assisted circulation after 46 hours. At present, he is doing well without significant complications. Earlier application of biventricular assist might be effective for biventricular failure with hepatorenal dysfunction.

Cardiac Output, Low↗
PubMed1989

[Clinical evaluation of low cardiac output syndrome following adult open heart surgery].

Between April, 1984 and December, 1988, 450 adult patients underwent open heart surgery for the valvular heart disease (VHD) and ischemic heart disease (IHD) in our institution. As the postoperative complication, LOS was observed in 33 patients with VHD (14.2%), and in 27 patients with IHD (12.4%) with no significant difference between the two groups. Treatment for LOS employed in this series consisted of pharmacological therapy in 11 patients, IABP in 42, IABP+veno-arterial bypass (VAB) in 5, right heart bypass (RHB)+IABP in 1 and left ventricular assist device (LVAD)+IABP in 1. All patients who were treated by the pharmacological therapy were alive and were discharged. Eighty-one % of the patients who were assisted with IABP were able to weaned off IABP, and 57% of the patients were alive and were discharged. All patients who were assisted with IABP+VAB died of LOS within 3 days after the operation. One patients who was assisted with RHB+IABP for pulmonary hypertension after emergency re-MVR and the other patient with LVAD+IABP for LOS after emergency CABG were able to be weaned off the assisted circulation and were discharged from the hospital. The salvage rate of patients with IHD by mechanical assisted circulation was generally higher than that of patients with VHD. Because of the limitation of IABP or VAB effect on the hemodynamic, LVAD directly assisted cardiac function would be indicated for severe LOS following open heart surgery without delay.

Adult↗
PubMedDate not supplied

[Means of improving the operational safety of balloon-pump counter-pulsation apparatus].

The apparatus of assisted circulation, in particular those intended for counter-pulsation with the pump-balloon, as concerns their reliability and safety to units whose failure presents immediate danger for the patient's life. An analysis of modern batch manufactured apparatus revealed a tendency toward widening the scope and complicating the signallization means of automatic protection and preventing failures. It is shown that the reliability of the units for counter-pulsation with the pump-balloon is not only a technical, but also a biomedicocybernetic problem. Substance is given to the need for introduction into the system of the apparatus for assisted circulation of sand-by actuating mechanisms for secure a purposeful influence on the physiological parameters of the organism.

Assisted Circulation↗
PubMedDate not supplied

[The use of ultra-high doses of insulin for the treatment of severe heart failure during cardiosurgical interventions].

The experience is reviewed on the use of superhigh insulin doses 1200 to 3800 U (31.4 +/- 5.3 U/kg) for the treatment of acute heart failure in 17 patients subjected to open heart surgery. Symptoms of heart failure refractory to catecholamines and vasodilators were accompanied by marked hyperglycemia (23.1 +/- 4.3 mmol/l). It was impossible to discontinue assisted circulation. In 82.3% of patients myocardial contractility upon insulin administration improved considerably, which led to discontinuation of assisted circulation with moderate inotropic support. Possible mechanisms ensuring the efficacy of massive insulin therapy in patients with acute heart failure are discussed.

Adolescent↗