Simultaneous separate assessment of the cardiac and LVAD output.

The electroimpedance indicators' dilution (EIID) technique was used to study the possibility of a simultaneous separate assessment of the biological heart and LVAD performance in the position of LVB. The experimental part of the research was performed on 5 dogs; an artificial ventricle of the pulsing type (USA) with cusps was used as a pump. The clinical part of the work was conducted on 5 patients after open-heart surgery who had the clinical picture of postcardiotomy cardiogenic shock; a centrifugal pump "Biopump" (Medtronic, USA) was used. The authors have shown a principally important possibility of applying the EIID, technique for studying the performance curves which are the integral derivatives of the work of a specific hybrid system--"the biological heart-assist device". From the practical viewpoint the EIID technique permits in the read time mode to control continuously the part of the pumping function which is assumed by the patient's own heart. This information can serve as the basis for making the prognosis and determining the further tactics of treatment; the restoration of the heart performance or its replacement by transplantation.

Small soft left ventricular assist device powered by intraaortic balloon pump console for infants: a less expensive option.

We have developed a pneumatically driven 20 cc soft ventricle for temporary right, left, or biventricular assist. The ventricle consists of a vacuum-formed soft housing, diaphragm, tricuspid outflow valve, and biflap inflow valve. All components including inflow and outflow valves were made with Pellethane. The advantages of this blood pump are as follows: it eliminates use of the quick connect system and therefore is less thrombogenic; the biflap inflow valve provides low inflow resistance; the soft ventricle is easy to implant; the polyurethane valves eliminate blood damage and thromboembolism and are low in cost compared with mechanical valves; and the vacuum-forming technique is reliable, fast, capable of mass production, and therefore inexpensive. We have already demonstrated in both in vitro and in vivo experiments that this ventricle has excellent hemodynamic performance with less blood damage and thrombogenesis. In this study, we evaluated the possible application of a well-defined and widely distributed intraaortic balloon pump (IABP) console to the 20 cc left ventricular assist device (LVAD) driver. The pump was tested in 6 mongrel dogs (6 to 10 kg) using an IABP console. The pump was connected between the left atrium and the ascending aorta, placed paracorporeally on the chest wall, and driven at a synchronous or fixed rate mode without using vacuum. The 20 cc ventricle could maintain the same output as the control output of the natural heart at filling pressures of 5 to 10 mm Hg during the entire observation time of 5 h. Thus, this 20 cc soft ventricle has the potential to be widely used for the treatment of severe heart failure in infants because of its excellent hemodynamic performance, simplicity, and low cost.

Hemodynamic and energetic assessment of calves implanted with a left ventricular assist device (LVAD).

Hemodynamic and ventricular energetic parameters were measured in calves implanted with the air driven Utah Ventricular Assist Device (UVAD). Uptake site was varied to determine the effect of control mode and vacuum augmentation of filing. Uptake was drawn solely from the left atrium or combined with a left ventricular apical vent. LVAD outflow returned to the descending, thoracic aorta. Control modes examined included asynchronous pumping as well as 1:1 and 1:2 synchronous diastolic counterpulsation. The 85cc LVAD, vacuum formed from PELLETHANE, was implanted acutely in four animals and chronically in six (7, 49 and 116 days paracorporeally, 1, 28 and 32 days intrathoracically). Instantaneous blood pressures, intramyocardial pressure, aortic outflow, oxygen consumption, LVAD output and drive parameters were recorded. LVAD output was independent of control mode when the natural heart rate was greater than or equal to 80 beats per minute. Intrathoracically positioned LVADs pumped a mean flow of approximately equal to 5 liters/min without vacuum augmentation of filling. Paracorporeally positioned LVADs pumped approximately equal to 3 liters/min mean flow without vacuum augmentation and up to approximately equal to 6 liters/min with 38 mm Hg of vacuum augmentation of filling. Instantaneous ascending aortic pressure and flow showed distinct beat-to-beat variation depending on LVAD control mode. Lower average ventricular afterload was observed when pumping the LVAD asynchronously or 1:2 synchronously. In one acute preparation, left ventricular myocardial oxygen consumption was reduced from the unassisted average control level by 37% for the asynchronous and 1:1 synchronous control modes with left atrial uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Cost of home dialysis versus institutional dialysis.

An actual cost analysis in the summer of 1975 showed that under the most costly of circumstances possible, home dialysis is always much less costly than institutional dialysis. During the first year of dialysis, when a patient must go through the expensive part of being trained for home dialysis in the center and of having the equipment installed, home dialysis even then is between $5,000 and $10,000 less costly than center dialysis. In subsequent years, after the initial outlay, home dialysis will be between $8,000 and $13,000 less costly than center dialysis.