Criteria for human total artificial heart implantation based on steady state animal data.
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Animals↗
Biomedical subjects
R K Jarvik
Publications and source records attributed to R K Jarvik.
Surgical positioning of the Jarvik-7 artificial heart.
The Jarvik-7 total artificial heart has been implanted in 18 patients at the time of this writing. Eleven patients received the 100 ml heart, and the remaining seven were treated with the 70 ml device. To date, five patients have been implanted for permanent use with an average survival in excess of 9 months, and the longest survival is more than 1 1/2 years following implantation of the heart. Complications related to positioning were a contributing factor in the death of one patient. Thirteen patients have received the Jarvik-7 heart as a bridge to transplant. Three died before transplant, and the remaining ten have been transplanted. To date, all are alive, several are home and in excellent condition, and several are still hospitalized but are expected to be released shortly. Three patients have experienced serious complications after transplantation. One patient rejected her heart transplant, was reimplanted with the artificial heart, and now has been sustained for more than 3 months. At this time she is in good condition awaiting a second donor. Selection of the appropriate size Jarvik-7 artificial heart for the individual patient can best be made based on measurements of thoracic dimensions obtained from a computed tomography scan and calculation of body surface area. The appropriate medial or lateral positioning can be determined and decisions concerning the lengths of the grafts and cuffs, excision or nonexcision of the left pericardium, and air drive line position can be made. The Jarvik-7 heart can be successfully used in patients from 50 kg. However, at the lower size limit in patients from approximately 50 to 65 kg, the risk of fit complications is the greatest and availability of an even smaller model heart would be desirable.
Adult↗
Mechanical unloading with a miniature in-line axial flow pump as an alternative to cardiopulmonary bypass.
Cardiopulmonary bypass (CPB) causes a well described systemic inflammatory response. To avoid these potential detrimental effects, coronary artery bypass grafting (CABG) has been attempted off CPB on the beating heart. With the use of a left ventricular (LV) assist device during CABG, the heart can be made flaccid with beta-blockade, and the systemic circulation can continue to be supported. The hemodynamic and hematologic consequences of left heart bypass with a miniature axial flow pump were studied in a sheep CABG model. The pump weighs 45 g and was connected to standard venous and arterial cannulas. Left sided inflow and brachiocephalic outflow were employed. A pump speed of 14,000 rpm resulted in a flow of 5.63 +/- 0.18 L/min and provided 75% of the LV output during a 2 hr pump run. This resulted in complete capture of the aortic pressure tracing (mean 56.3 mmHg) with a 15.5 mmHg augmentation in the esmolol depressed ventricle. Reductions in LV end diastolic pressure and LV end systolic pressure resulted in a 66% reduction in LV external work under baseline conditions and an 83% reduction in the beta-blocked ventricle. Myocardial oxygen demand was reduced 16% after axial flow unloading in the esmolol depressed condition. Right ventricular pressures, pulmonary artery flow, LV filling, and oxygenation were adequate in the esmolol depressed animal and remained unchanged throughout the experiment. No changes in hematocrit, total bilirubin, lactate dehydrogenase, or plasma free hemoglobin were detected after 2 hr of assist. Axial flow left heart bypass results in acceptable hemodynamics with no hemolysis and may provide an alternative to CPB during CABG.
Animals↗
Progress in the development of a transcutaneously powered axial flow blood pump ventricular assist system.
Development of the Jarvik 2000 intraventricular assist system for long-term support is ongoing. The system integrates the Jarvik 2000 axial flow blood pump with a microprocessor based automatic motor controller to provide response to physiologic demands. Nine devices have been evaluated in vivo (six completed, three ongoing) with durations in excess of 26 weeks. Instrumented experiments include implanted transit-time ultrasonic flow probes and dual micromanometer LV/AoP catheters. Treadmill exercise and heart pacing studies are performed to evaluate control system response to increased heart rates. Pharmacologically induced cardiac dysfunction studies are performed in awake and anesthetized calves to demonstrate control response to simulated heart failure conditions. No deleterious effects or events were encountered during any physiologic studies. No hematologic, renal, hepatic, or pulmonary complications have been encountered in any study. Plasma free hemoglobin levels of 7.0 +/- 5.1 mg/dl demonstrate no device related hemolysis throughout the duration of all studies. Pathologic analysis at explant showed no evidence of thromboembolic events. All pump surfaces were free of thrombus except for a minimal ring of fibrin, (approximately 1 mm) on the inflow bearing. Future developments for permanent implantation will include implanted physiologic control systems, implanted batteries, and transcutaneous energy and data transmission systems.
Animals↗