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F Brandstaetter

Publications and source records attributed to F Brandstaetter.

10 recordsLinked to original sources
PubMed2002

The seventh prototype of the mini-spindle-pump: does it fulfill the expectations of a short-term pump?

According to recent trends to develop implantable nonpulsatile blood pumps for different function modes and times, our intention was and still is to build a Mini-Spindle-Pump for a pumping duration of about 14 days. Initial conception for this plan was the premise that the device in a mock circuit should move 4 L of water/min at a speed of 12,000 to 15,000 rpm against a pressure difference of 90 mm Hg between pump inlet and outlet. Despite the development of 6 different prototypes, this project was not realized. Under the above-mentioned conditions, the main problem of this type of blood pump, the blood trauma, could not be reduced to an adequate level, i.e., the Mini-Spindle-Pump is not a high speed pump. Therefore, a revision of the conception was necessary. The device in a mock circuit should transport 5 L of water/min at a speed of about 9,000 rpm against a pressure difference of 90 mm Hg between its inlet and outlet. Considering the implantability of the blood pump, the following measurements for its components were arrived at. The U-shaped blockformed plexiglas housing was enlarged to 120 x 40 x 40 mm (length of blood chamber 86 mm, inner diameter 27 mm), and the rotor with 5 windings was redesigned at a length of 64 mm (outer diameter 25 mm, inner diameter 6.7 mm). In a mock circuit, this 7th prototype transported with a speed of 9,000 rpm about 10 L of water/min at an afterload of 80 mm Hg. In acute animal experiments with calves up to 15 h of pumping duration, the device showed the expected efficiency. Experiments with a longer pumping duration are necessary to confirm that this prototype will fulfill the criteria of a short-term pump according to Dr. Y. Nosé's advice.

Equipment Design↗
PubMed1995

Considerations and problems in the development of the mini-spindle pump.

The premise for the development of the mini-spindle pump, planned as an implantable device for assisted circulation, was to transport 4 L of water/min in mock circulation with a speed of 12-15,000 rpm against an afterload of 90 mm Hg. After calculations, the resulting first prototype had a spindle rotor with 3 threads (outer diameter, 18 mm; inner diameter, 6.2 mm; length, 45 mm) in a U-shaped housing, driven by an electric motor with a cooling system. In mock circulation, this pump moved 7.8 L of water/min at 18,000 rpm. To avoid animal experiments, its influence on the blood was tested in a Maxima oxygenator. The device circulated 4.2 L of blood/min with the same speed. Because of its high traumatic hemolysis rate (> 250 mg% of free hemoglobin after 7 h of pumping), the rotor was modified, first without effect at 2.5 threads and then at 4 threads. In addition, in this third prototype, the flow direction was reversed. This prototype was more effective (4.3 L of blood/min at 12,000 rpm in the oxygenator) and the hemolysis rate, after a pumping duration of 8 h, could only be reduced to 180 mg% of free hemoglobin. As a result, a fourth prototype was developed (i.e., the U-shape of the housing was abandoned). This device functioned better than the third prototype (4.5 L of blood/min at 12,000 rpm in the oxygenator), but the blood trauma increased (220 mg% of free hemoglobin after 7 h of pumping).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Light and electronmicroscopic examination of calf lung tissue after left ventricular assisted circulation with the spindle pump.

The influence of the spindle pump, a nonpulsatile blood pump, used as LVAD on calf lung tissue was examined by means of the actual 16th protoype which was applied in 3 "acute" tests up to 13 hours of pumping duration and 8 prolonged experiments with pumping periods up to 63 hours. Samples were taken during the operation and after exitus of the test animal and investigated by light and electronmicroscopy. Histological findings of tissue changes could be ascribed to mechanical manipulations and shock-like influences. Regardless of the time of nonpulsatile perfusion this tissue damage remained within an acceptable range, indicating the absence of a deleterious effect of nonpulsatile flow.

Animals↗
PubMed1988

Left heart assistance with the spindle pump.

The spindle pump--a new attempt at assisted circulation--was developed to prevent the main problems of nonpulsatile blood pumps, i.e. traumatic hemolysis, thrombus formation and sealing. It was essential to achieve adequate output with the lowest possible speed in order to minimize traumatic hemolysis. The result was a spindle pump with three windings in a U-shaped housing driven by an electric motor. Many tests were necessary to establish a prototype. The spindle was completely redesigned several times to reach an acceptable volume output and corresponding pressure output. In animal experiments this final prototype working as a LVAD, with a speed of 5400 RPM circulates 4 liters/min against BP of 110 mmHg. The hemolysis rate has been low in acute and survival experiments (27 hours up to now), and is between 25 and 30 mg/100 ml of free hemoglobin, thus within the normal range.

Animals↗
PubMed1985

The spindle pump--a new concept for a nonpulsatile bloodpump.

The spindle pump--a new nonpulsatile bloodpump--has been developed as paracorporeal ventricular assist pump. The experiments with calves clearly demonstrated, that this pump as LVAD empties the left ventricle completely, the aortic pressure curve showing the typical nonpulsatile profil. A problem is the traumatic hemolysis, the free hemoglobin was in all experiments slightly but always above our standard. To solve this problem we will optimize shapes of the spindle and of the housing and coate all parts of the pump with polyurethane.

Animals↗
PubMedDate not supplied

Functional heart replacement with the spindle pump: first results.

The spindle pump is a nonpulsatile blood pump with a double function, i.e., it works centrifugally and represses simultaneously. The first experiences with this type of pump used as a biventricular assist device in four short-term animal experiments (up to 13 hours) are described. It can be demonstrated that in cases of a normally beating heart, this BVAD decompresses both ventricles by 60-70%, while the aortic pressure is slightly increased; on the other hand, in case of ventricular fibrillation, the BVAD with two spindle pumps maintained the entire circulation, at an arterial pressure between 80 and 90 mmHg with a flow volume between 3.5 and 4 L/min.

Animals↗
PubMedDate not supplied

The spindle pump. Development of a nonpulsatile blood pump for assisted circulation.

The spindle pump is a combined working nonpulsatile blood pump, i.e., a centrifugally propelling device. This special concept was chosen to tackle the main problems of nonpulsatile pumps, such as thromboembolic complications, sealing difficulties, and traumatic hemolysis. The first two of these problems were relatively simple to solve compared with the third problem--traumatic hemolysis. Various modifications and constructive steps of the spindle pump were necessary to keep stress on blood components within adequate limits. The actual prototype--tested in three acute experiments and eight experiments with a longer pumping duration (the longest lasting 63 hours)--is described in extenso, and its development is discussed.

Animals↗