Developing A Fingertip-Sized Implantable Heart Pump

Originally Published MDDI October 2001

COMPUTER-AIDED DESIGN

At the École Polytechnique de Montréal, associate professor André Garon and other researchers have designed a tiny pump capable of being inserted directly into a cardiac patient's heart. The auxiliary pump, said to be the smallest of its kind in the world, is only 22 mm in diameter—about the size of a fingertip. While not intended to replace a heart, it will be inserted directly into the left ventricle of damaged hearts to serve as a temporary bridge to transplant and to prolong the life expectancy of children with congenital heart defects. Eventually a more permanent implant could be achieved, for up to 10 years or more. In addition, the device could be removed when a damaged heart heals and can function on its own.

The design and solid modeling of the pump was done by Garon using CATIA software. CATIA was also used to produce the numerical control commands that allowed the lab to machine prototypes of the very small parts that make up each pump. High-speed, five-axis tools were used to form precision titanium blades that are only 100 mm thick and rotate at 1–12 rpm.

Garon, who also teaches CATIA, is president of Cardianove Inc., which was formed to oversee the eventual production of the heart pump. The project was conceived at the Montreal Heart Institute, where a small pump was needed to assist failing hearts.

According to Conrad Pelletier, MD, Cardionove CEO, the device is likely to prove useful as more than just a bridge to transplant. "It's probably going to be the first application, but there will be other applications besides that one. One of the other applications we foresee is a bridge to recovery." Pelletier explains that "some of the acute illnesses of the heart can recover if sufficient time is allowed. And very often, these patients are so sick that they have to undergo transplantation if we want them to survive. Now if we could supplement or support the heart for awhile, it's possible that some hearts might recover completely. Then the device could be removed and the patient recover completely. So that would be another application. And the last one, which is a long-term application, would be a definitive implant. This would be for patients who have chronic heart failure but who, for any reason, can't go through heart transplantation, either because of an insufficient number of donors, or because they have a specific contraindication to heart transplantation. And we could probably use this device as a permanent implant."

Pelletier says the new pump provides a number of advantages when compared with conventional technologies. "The first one is improved efficiency of performance," he says. "We are looking at performance in the range of 40% to 50%, as compared to roughly 25% with current devices." He explains that a more efficiently performing pump requires less energy for activation. "Thus the energy source will last longer, with longer periods of autonomy for the patient, when he can rely exclusively upon his internal battery." He adds, "The second one is the miniaturization of our model. The actual size of the pump that we are developing is close to half the size of existing pumps. So we are looking for a pump that will probably be the only one that could be implanted inside the heart rather than in parallel to the heart."

Says Pelletier, "The major advantages interior implantation presents are that you avoid damage to the heart muscle from the pump inflow and there is no need for sutures to vessel walls for outflow from the pump. It will be inserted within the left ventricle and have the inflow directly from the left ventricle and the outflow directly into the aorta without any sutures or damage to the myocardium, contrary to existing pumps."

Pelletier explains that the device is powered by a conventional battery system. Describing the system, he says "it will work basically with two sets of batteries. One will be internal, giving the patient the opportunity for total autonomy for up to one hour daily. For instance, to take a bath or a shower, or to go swimming, for that matter. And the other set will be an external battery that will support the patient throughout the remainder of the day. The external battery will also act as a recharge source for the internal battery."

Copyright ©2001 Medical Device & Diagnostic Industry