Use of artificial heart for basic cardiovascular research.

Improved technology in artificial heart development and implantation studies in unanesthetized calves have stimulated a new model for cardiovascular research. Independent control of the left and right ventricles, replacement of the natural right atrium with an artificial atrium (with a compliant inner diaphragm) are illustrated as examples of new methods to study the cardiovascular system. Preliminary results in three calves suggest that synchronous ventricular pumping is not required for total circulatory maintenance. In four calves a passive artificial right atrium was shown to decrease outflow obstruction to the right ventricle. A compliant inner deiapragm demonstrated a reduction in the amplitude of the atrial C and V waves. The effects of volume and drug infusion on peripheral vascular response in the presence of controlled artificial heart pumping (which does not respond to direct neural or hormonal influences) further illustrate the efficacy of this preparation as a new model for cardiovascular research.

Successful use of a left ventricular assist device in cardiogenic shock from massive postoperative myocardial infarction.

A 41-year-old man underwent an uneventful aorta-coronary bypass for unstable angina pectoris. Four hours later, a massive anterior wall myocardial infarction resulted in cardiac arrest. Conventional resuscitative means were not effective. A left ventricular assist device (LVAD) was successfully employed for 94 hours. The patient is alive and well 8 months postoperatively.

Survival for 18 days with a Jarvik-type artificial heart.

This is a report of an experiment wherein a calf had its natural heart replaced with an artificial heart and survived for 18 days and 20 hours. All measured physiologic parameters remained normal until the fourteenth day. Thereafter a gradual persistent rise in venous pressure and signs of a decreased cardiac output occurred. However, the animal outwardly appeared normal until the eighteenth day. During the nineteenth day it became comatose and was killed. At autopsy large thrombi were found in both atria, impairing ventricular filling, resulting in venous congestion and diminished cardiac output. This extended survival time and our ability to understand and eliminate the problems associated with artificial heart implantation give support to our hope that artificial hearts for man will be possible in the not too distant future.

The artificial heart. Progress and promise.

A multidisciplinary group has designed, fabricated, and evaluated an artificial heart. The heart consists of two smooth-surfaced sac-type pumps, two pneumatic power units, and an electronic control system. The artificial heart has been employed in 22 calves. A variety of problems have been encountered and overcome and a significant improvement in pump design has been made. As a result, a gradual increase in survival times has occurred. The last two calves in which the heart was tested lived for 60 and 42 days respectively. These animals ate well and gained weight. The ability of the control system to balance the output of the two pumps over long periods of time and to automatically increase cardiac output with treadmill exercise has been confirmed. No insurmountable problems in the development of the artificial heart have been identified. The date that an artificial heart will be available for clinical use depends on the availability of funds and on the tenacity of the investigators.

An intracorporeal (abdominal) left ventricular assist device. Initial clinical trials.

We have initiated clinical trials with an intracorporeal (abdominal) partial artificial heart and ten preterminal postcardiotomy patients have been studied. During profound left ventricular failure, the device captures the entire cardiac output from the apex of the left ventricle at low pressures (20 to 40 mm Hg) and ejects (at 80 to 150 mm Hg) into the infrarenal abdominal aorta; the biological aortic valve opens only intermittently and the entire systemic circulation is pump generated. The device is six to ten times more effective than intra-aortic balloon pumping in man and has maintained systemic perfusion during clinical asystole and ventricular fibrillation. We have documented that the profoundly depressed postcardiotomy left ventricle, initially incapable of ejection, can recover during total left ventricular unloading with the abdominal left ventricular assist device support over a seven-day period.

A new right ventricular cardiac assist device.

At present no good method of assisting the right ventricle of the heart exists. This paper presents a new and effective approach to assisting the right ventricle of the heart which can be utilized independently or during cardiac surgery. Through implementation of this method, and timed inflation and deflation of several types of balloon catheters in the pulmonary artery, distal pulmonary arterial flow is augmented with subsequent unloading of the right side of the heart. This approach will be of great benefit in the treatment of atherosclerotic and congenital heart disease as well as in many cases of pulmonary hypertension.

[The research programme "Artificial Heart" at the 2nd Department of Surgery, University of Vienna: a ten year review (author's transl)]. / Das Forschungsprojekt "Künstliches Herz" an der II. Chirurgischen Universitätsklinik Wien. Ein 10-Jahres-Bericht.

The experimental and clinical results are presented of the research programme "Artificial Heart" carried out by the 2nd Department of Surgery, University of Vienna. In particular, an assessment of the clinical experience in 177 patients with the intra-aortic balloon pump is documented and it is concluded that only limited cardiac support is possible by this pump. In view of this fact more efficient methods of mechanical circulatory support, such as the interaortic auxilliary ventricle, the aortic "Windkessel" ventricle with guiding balloon, and two types of ventriculo-aortic bypass ventricle were tested with regard to their haemodynamic and long-time efficacy. The transatrio-aortic auxilliary ventricle (E-LVAD) was also clinically tested in 11 patients. In conclusion the problems of total mechanical heart replacement are discussed.

[Partial mechanical cardiac replacement in experimental cardiogenic shock]. / Mechanischer Teilherzersatz beim experimentellen kardiogenen Schock.

The importance to evaluate artificial ventricles for left heart assist under cardiogenic shock conditions is emphasized. The main cardiogenic shock models currently used for assisted circulation research are mentioned. Our own method called selective peripheral coronary embolization is presented in detail with its anatomic, pathologic-histologic and electrocardiographic pattern. Polyester fibrils are embolized selectively to the posterior wall of the heart by direct puncture of the circumflex branch of the left coronary artery. Shock hemodynamics and the effects of circulatory assist by the pneumatically driven ellipsoid ventricle (ELVAD) are demonstrated in 20 acute calf experiments. The artificial ventricle was inserted to the circulation between the natural left ventricle and the thoracic aorta in a paracorporeal and intrathoracic position. ELVAD activation was followed by a significant decrease of left ventricular pressure (-65%) and left atrial pressure (-35%). Cardiac index was increased by 10% and mean aortic pressure by 28% from their shock levels. Hemodynamics in irreversible ventricular fibrillation are analyzed in a calf experiment with a 40 hours survival only with ELVAD assist.

[Artificial left ventricle in paracardiac position between the apex of the heart and the ascending aorta (author's transl)]. / Ventricule gauche artificiel en position paracardiaque entre la pointe du coeur et l'aorte ascendante (I).

A device for assistance of the left side of the heart in acute failure is placed in the paracardiac position. The blood is drained into the apparatus through the apex of the heart and is reinjected into the ascending aorta by an artificial pump. The flow of blood within the prosthesis and at the level of the inlet and outlet values is studied by a system of lighting in thin layers. Several types of original valve have been tested but the most satisfactory results were obtained with a classical bead valve.

Surface-modified acrylic polymers in artificial heart pumps.

Blood chambers of counterpulsation heart pumps were subjected to a special hydrophilization process in order to reduce the coagulation activity of the surface of poly(methyl methacrylate) (PMMA). The chemical treatment of the surface was carried out in three variants, namely A (ethylenglycol), B (diethylenglycol), C (glycerine) by using concentrated sulphuric acid with subsequent neutralization [12]. Controls were performed with the same pumps made of PMMA but without surface treatment. 30 dogs were used in the experiments.

[Automatic control of an artificial heart with an autonomous energy source]. / Avtomaticheskoe upravlenie iskusstvennym serdtsem s avtonomnym istochnikom énergii.

Specific features and particularities in the design of the artificial heart control systems are considered, operated by various engines with a radioisotope energy source. The operation results showed the need in a complex approach to the problem solution. It should be based on optimized constructions, methods and principles of functioning for all ingradients of the artificial heart from the viewpoint of automatic control.

[Artificial heart control system]. / Sistema upravleniia iskusstvennym serdtsem.

To develop a system for the artificial heart control the algorhythm of the latter, with the blood pressure in the aorta acting as a regulation parameter, was analyzed on its mathematical model. The results of the algorhythm operation in three model situation describing transitional processes under physical efforts, stress and resuscitation are reported. The technical implemetation of the described algorhythm is set forth and a comparison of the obtained experimental data versus the design curves is made.

[Blood heat exchangers for the artificial heart using a radioisotope power source]. / Issledovanie teploobmennikov krovi iskusstvennogo serdtsa s radioizotopnym istochnikom pitaniia.

A design of a vascular heat exchanger enabling it to establish in experiments with animals the degree of the possible specific-capacity thermal loads has been devised. The performance results may be taken account of in designing implantable appliances of assistive circulation and artificial heart.

[Components of an implanted artificial heart and the medico-technical requirements]. / Sostavnye elementy implantiruemogo iskusstvennogo serdtsa i pred'iavliaemye k nim mediko-tekhnicheskie trebovaniia

The task of designing and providing power supply for an implanted artificial heart (AH) is a many-sided complex problem that includes a number of medico-biological, technical, physical, power-supply and other factors. The analysis of the AH components and the mentioned basic medico-technical requirements permits it to outline the ways and means for a rational solution of this complicated problem. The greatest attention is paid to the analysis of and future prospects for the use of different power sources and methods of power conversion.