Small Cardiac Pumps Save Lives
"This experience has changed my life,” reports Michelle Kellim, 33 years old from Florida. "I have always led a healthy life. I had never once considered that I could suffer from heart disease at my age." The mother of two children used to run five miles every day and had always had a healthy diet. But one night her husband, Erik, woke up next to her and noticed that Michelle had stopped breathing. It was a minimally invasive cardiac pump called Impella® 2.5 that saved Michelle’s life.
Whether in an acute emergency or during a planned operation, so-called haemodynamic instability ("haemodynamic" relates to the movement of blood) is a feared and serious complication which can occur when occluded coronary arteries are opened. Because of this, the pumps are used both in cardiac surgery during or following operations as well as during procedures in cardiac catheter laboratories. Depending on the Impella® model, the pump can support the heart for up to ten days which gives the heart time to regenerate.
Five liters of blood per minute
"Our Impella® pumps have already been used over 16,000 times worldwide,” explains Ronald Lutz, Marketing Manager of ABIOMED Europe GmbH (Aachen, Germany) which produces these remarkable miniature blood pumps. Basically, the Impella® pump mimics the natural cardiovascular system which transports oxygenated blood from the left ventricle through the aortic valve and into the ascending aorta, from where the blood enters the coronary vessels and the systemic circulation. The heart can recover because the Impella® pump actively relieves the strain on the left ventricle. The pump can deliver up to five liters of blood per minute.
Diameter of just a few millimeters
Using a guide wire inserted via the femoral artery, the Impella® pump is positioned in the left ventricle and ascending aorta. There the blood is transported through the inlet area via the cannula towards the outlet, following the natural flow direction of the blood. The diameter of just four millimeters in the Impella® 2.5 model means that the aortic valve leaflets can fully close around the cannula. The Impella® pump is controlled using an external console which is also used to optimize settings and to monitor the effect of the pump. The preparation time required before the pump can be put into action has in the meantime been reduced to less than three minutes. "Patients can be treated without delay, even in acute emergencies,” says Lutz.
Drive from FAULHABER
From a technical viewpoint, the pump drive consists of a brushless, electronically commutated DC-motor with a diameter of just 4 millimeters in the case of the smallest pump (Impella® 2.5) and 6.4 mm in the case of the larger pump (Impella® 5.0) and a stator length of 12 and 18 millimeters respectively. The pumping performance of the heart is supported with a speed of up to 51,000 revolutions per minute. The drive is based on a self-contained coil and essentially consists of a three-phase winding and a bipolar permanent magnet. The position of the rotor is detected by measuring and evaluating the retroactive generator voltage, making Hall sensors unnecessary.
An impressive feature of the motors is their high level of efficiency. The pressure sensors on the larger pump, which are required in the case of positioning inside the ventricles, have a thickness of 300 µm and are positioned in a flat area on the outside of the motor housing. Apart from the compact dimensions and the high reliability, the comparatively favorable cost/performance ratio is another important factor because each Impella® pump can be used only once.
Reliable and flexible partner
"With the Impella® pump, we are working at the very limits of the possible,” stresses Ronald Lutz, ABIOMED Marketing Manager. The demands placed on a medical product used in life-critical situations are extremely high. "There were no "off-the-shelf" motors that we could have used,” explains Lutz. "FAULHABER was flexible and prepared to pursue this path with us and, working as a team, developed the components exactly as we need them. We are extremely happy with the outstanding level of cooperation."
To this day, relentless further development continues to shape the collaboration between ABIOMED and FAULHABER. "This is one of our great strengths,” says Jan-Christopher Mohr from FAULHABER who provides support for ABIOMED from the company headquarters in Schönaich, Germany. The development, modification and enhancement of products precisely according to the needs of the customer are all part of the service that FAULHABER offers. "A process such as this can only be successful if there is continuous dialogue,” says Mohr. The continuous exchange of information with the customer allows specific requirements to be understood and optimum solutions to be found.
"The situation was very serious"
Two simultaneously used Impella® pumps saved Eduard Böhler’s life.
It was a pleasant winter evening on January 10, 2012 when, suddenly the 54-year-old felt sharp pains in his chest. Suspecting a heart attack, he was transported to the hospital. "The situation was very serious,” he recalls. "Because the doctors had to perform resuscitation measures, at first it seemed uncertain whether or not I would survive the night."
The physicians decided to move the patient to a nearby special clinic that is part of the University of Basel hospital in Switzerland. There, the Impella® 2.5 pump was immediately implanted in him for left ventricular support. However, all other life-essential organs failed - the lungs, kidneys and liver. Because of this, the attending specialist Professor Hunziker decided to use an additional Impella® RP for right ventricular support. This was a first in Europe, as no one before this had implanted two Impella® pumps at the same time. Additionally, this exception needed the approval by Swiss authorities.
Thanks to the biventricular support the patient’s heart was able to recover. After eight days, both Impella® pumps were removed. After six months he was released from the post-operative treatment in Freiburg to go home.
To this day he must still undergo physiotherapy and ergo therapy. Yet, Mr. Böhler is not the least bit discouraged as, "Thanks to Impella® my heart has fully recovered. I was given a second chance and happy to be with my family again.”
To learn more about medical and lab automation applicationsand the micro motors that power them, please contact one of our application engineers, or explore the MICROMO Motion System Selector to view our products and motor configuration options.