Are the Jarvik artificial ventricles limited by inflow resistance?

The pneumatic total artificial heart has been assumed to be inflow limited. Mock circulation studies on the Jarvik-5 and Jarvik-7 artificial ventricles seemed to support this assumption because a Starling's response comparable to the natural heart was not achieved. Unfortunately, mock circulation studies do not separate the effects of valvular regurgitation from inflow resistance. By using a simple filling tank, filling times were determined for the Jarvik ventricles that were a function of inflow resistance alone. Theoretical maximum cardiac outputs based on these inflow resistance-dependent filling times were then calculated. For filling pressures around 5 mmHg and under modest diastolic vacuum of 5 cm H2O, the Jarvik ventricles yield a theoretical cardiac output as good as the natural heart's. Thus, inflow resistance is not a limiting factor and valvular regurgitation is left as the most likely cause of a less than optimal Starling's response on mock circulation and in vivo.

[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.

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.

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.

[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.

[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.

Evolution of the solenoid-actuated left ventricular assist system: integration with a pusher-plate pump for intra-abdominal implantation in the calf.

The performance of an implantable left ventricular assist system (LVAS) utilizing a pulsed solenoid energy converter and a pusher-plate blood pump has been characterized in vitro and in vivo. A microprocessor-based electronic control system makes the LVAS completely self-regulating over the range of operating conditions and provides considerable flexibility in various assist modalities. Over forty thousand hours of in vitro and in vivo operating experience has been accumulated with current systems, and significant progress has been acheived in system durability and reliability. A new toggle latch has provided nearly a year of failure-free operation on the bench, without measurable wear. Energy converter efficiencies of 50% have been demonstrated. In vivo evaluation has been highlighted by an animal experiment still in progress after nearly four months of fault-free, continuous synchronous pumping.

[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.

Prolonged, transapical left ventricular bypass (TALVB) in sheep and man.

Transapical left ventricular bypass has been demonstrated in normal sheep and one lamb. Recently, TALVB was applied in 3 clinical cases of cardiac failure, with recovery of myocardial function in one patient after 9 days of bypass (6 days total TALVB). These studies suggest that LV apical cannula-roller pump bypass with low dose heparin anticoagulation and secondary surgery to remove the cannula may salvage some patients now dying of temporary cardiac failure.