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February 29, 2012 // By Jessica Mikulski // Comments

iPod-like Advances Changing the Face of Cardiac-Assist Technology

Aging // Experts // Heart // Heart Month // Surgery // Transplant Share this article

To celebrate February as American Heart Month, the News Blog is highlighting some of the latest heart-centric news and stories from all parts of Penn Medicine.

VADThis month marks the five-year anniversary of Penn Medicine’s first implantation of a temporary total artificial heart (TAH) in a patient suffering from end-stage heart failure. See the full story here.  

In 2007, this device was viewed as a major breakthrough in cardiovascular surgery, used as a “bridge-to-transplant” for patients who were waiting for a donor human heart.  Originally designed as a permanent replacement heart, the TAH device is currently only being used as a bridge to human heart transplant for patients dying because both sides of their hearts are failing (irreversible end stage biventricular failure). 

The patient, a Philadelphia-area native, is still doing well.  While the device was only in place for less than a month (he went to receive a full heart transplant in March 2007) the technology proved to be a life-saving medical innovation. At the time, patients who received a TAH spent their days in the hospital, tethered to a rolling device weighing more than 400 pounds that required frequent monitoring, their artificial hearts ticking audibly in their chests. One HUP patient spent 310 days with the device implanted before receiving a transplant in 2009.

But in just the five short years since HUP’s first TAH procedure, cardiac-assist technology for heart failure has moved leaps and bounds. A separate class of devices, known as ventricular assist devices (VADs), have proven to be an invaluable tool in the ongoing search to replicate the very intricate and delicate functions of the human heart.

This technology is vital because there are far fewer hearts available for transplantation than there are patients who need them – more than 3,000 patients are currently waiting for a new heart in the United States, according to the Organ Procurement and Transplantation Network. These devices have become so critical that Penn performed more VAD implantations in 2011 than heart transplants.

Y. Joseph, Woo, MD, director, Cardiac Transplantation and Mechanical Circulatory Support Program at Penn, uses this analogy to describe the amazing technological advances that have been made in VAD technology since the first TAH procedure was performed at Penn:  “It’s almost like comparing a VHS cassette to an iPod in terms of the rapid evolution of cardiac assist devices. The newest devices are that much more amazing and useful to doctors and patients.”

VADs have been in use for over two decades and are used in several approaches to treat patients with ailing hearts - bridge-to-transplant, much like the TAH was first implemented for; destination therapy, where the device is left in the patient peremanently, in lieu of a heart transplant; and bridge-to-recovery, where the device is implanted for a short amount of time to let the heart heal from an illness. In those cases, when the patient recovers, the device is removed and the heart continues to pump on its own (more on this innovative approach in the video below). 

While the original assist devices emulated the pulsating heart, newer versions, provide continuous flow (which, by the way, leaves most recipients without a pulse because it pushes blood continuously instead of mimicking the heart's own pulsatile beat). These pumps are smaller and potentially more durable, lasting longer than the current generation of total heart replacement pumps.  Another major advantage of a VAD is that the patient keeps the natural heart, which may still function for temporary back-up support if the mechanical pump were to stop. For patients, this technology means vastly improved quality of life, allowing them to leave the hospital bed and move through life much as they did before the implantation.

Penn clinicians and surgeons have played a pivotal role in the development, testing and application of these devices through their various iterations.  Most recently, Penn clinicians and surgeons are involved in several ongoing studies looking at the new ways to use VADs. Some of the studies include:

  • ADVANCE: Evaluation of the HeartWare® Left Ventricular Assist Device for the Treatment of Advanced Heart Failure, evaluates the safety and effectiveness of the HeartWare® LVAD System as a bridge-to-transplantation in patients listed for cardiac transplantation with advanced heart failure who are otherwise at risk of death.
  • ENDURANCE: Evaluation of the HeartWare® Ventricular Assist System is investigating the safety and effectiveness of the HeartWare Ventricular Assist System in patients with chronic left ventricular failure who not responded to other treatments and are ineligible for cardiac transplantation.
  • REVIVE-IT: Randomized Evaluation of VAD InterVEntion before Inotropic Therapy aims to compare whether non-transplant-eligible patients whose heart failure is less advanced than that of current LVAD recipients fare better with implanted devices than with current medical therapy, which includes medication regimens using beta blockers, ACE inhibitors, and angiotensin-receptor blockers to improve function of the failing heart.

In the future, Dr. Woo says that the technology will move even further into the  “iPod-like” realm by allowing the devices to be charged wirelessly from outside the patient’s body.

“Right now, VADs are still powered through a cable through the skin, so patients have to carry a battery back with them at all times,” he says. “But in the near future, we should be able to implement a new way of charging the device, much like the cell phone charger pads, so the device can be powered via a transcutaneous method.”

Apart from the obvious cosmetic advantage, this reduces the risk of infection while using the devices, he says.

But even with the innovative advances in these devices, Mary Lou O'Hara, MSN, RN, Clinical Research and Mechanical Assist Device Coordinator at Penn, says the TAH will still have a role in the greater cardiac assist field, specifically for patients with biventricular failure, as was the case with the original Penn patient in 2007.

“The newer VAD devices are still limited to support of the left ventricle, so are not a substitute for the TAH.  Some of the newer, smaller devices may be utilized to assist the right ventricle but are not approved for that indication,” she says. “We’re also working with newer TAH technology that will potentially allow support outside the hospital with a smaller driver still under clinical investigation.” 

Regardless of the specific device, the ready availability of a variety of cardiac-assist devices, combined with the amazing innovations in the device technology, are a major  breakthrough for patients with these severe cardiac problems. As the iPod lead the way in a digital revolution, these cardiac assist devices lead the way for a new life for patients.

J. Eduardo Rame, MD, medical director, Ventricular Assist Device Program at Penn, discusses another new innovation, the potential for VADs to be used as a bridge-to-recovery.

  

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