Miniature drives in ventricular assist device from Berlin Heart

A pair of human heart works in 24/7 operation and must not fail. Therefore, the Berlin Heart the highest quality requirements for your Cardiac support systems. In the mobile versions of the "Excor" series, the external Artificial heart from a miniatureBall Screws from NSK driven. Stroke volume and cycle frequency in Excor exactly reproduce the way the patient's human heart works.

Three to four and a half l delivery volume / min in idle state, adaptive control with cycle rates of 50 to 200 cycles / min and above 100.000 work cycles per day: The human heart is a remarkable “machine”. Unfortunately, there are people whose hearts do not fulfill their task or do so only insufficiently. Berlin Heart GmbH has developed heart support systems or VADs (Ventricular Assist Devices) for them.

Founded in 1996, Berlin Heart is the only European manufacturer of VAD systems and the only one who offers this sophisticated technology in addition to adults for children and infants. The youngest patient who was successfully supported until heart transplant was only eight days old when he received a VAD system.

How the artificial hearts at Berlin Heart work

In the mobile excor VADs from Berlin Heart are connected in the therapy of blood circulation by the patient via cannulas with compressed air membrane pumps, which are located outside the body. A miniature ball screw drives a stroke of up to 60 mm 130 to 55,5 times / min and thus presses a defined amount of air against the membrane, on the other side of which are the cannulas and with them the patient's bloodstream. When choosing the drive system, the service life was the decisive criterion. Nedim Arslan, Head of Design at Berlin Heart: "In our benchmark test, the NSK drives achieved a service life of around 120 million cycles - this was by far the best value."

Miniature connectors for safe signal transmission 

For maximum operational safety, the patient has to do one every three months - after around ten million cycles Maintenance of the drive units be carried out, during which the spindle is cleaned and greased, among other things. Service is made easier by modifications made to the geometry of the ball screw drive by the manufacturer. The selection of the grease was also taken into account when projecting the drive. Despite the low performance of servomotors the miniature spindle with a diameter of 8 mm reaches temperatures of 70° to 80 °C during operation. The fat was adjusted to this high temperature level.

Base of the spindle system is a ball screw with a ground finish with accuracy class C3. The spindles are manufactured according to customer needs, so that they can be considered as "tailor-made". The drive is supplied as a ready to install module with appropriately constructed bearing unit.