Advances & Insights: Heart Health
January 15, 2008
What the news means for you
Chand Ramaiah, MD
Shortage of donor hearts pushes technology ahead
We’re seeing a constant change in cardiac technology because there just aren’t enough donor hearts for patients needing a transplant. The numbers have been flat for a decade, so the situation probably isn’t going to change. In addition, there is a lot of competition among the larger transplant centers around the country for donor organs.
“Being on an LVAD] categorizes the recipient as high priority for a transplant because they're usually sicker.”
The average waiting time for patients in the University of Kentucky heart transplant program to find a donor heart is a year. Success in locating a heart depends on the person’s size and blood group as well as on how sick they are. While LVADs won’t increase the number of available organs, being on a device categorizes the recipient as high priority for a transplant because they’re usually sicker.
Congestive heart failure
There are four stages of congestive heart failure (CHF). We do cardiac transplantation only in stages three and four. On average, half the patients with CHF die within five years. Patients in stages three and four have a 50 percent mortality rate within just two years, even with the best medical management.
The LVADs with the longest successful track records in this country are Novacor and HeartMate. We use the HeartMate at UK. These units are completely implantable and the patient is constantly connected to an external machine. However, they are battery-powered as well, allowing the person some mobility. Most of our patients with these LVADs are able to remain in their homes.
Another bridge-to-transplant VAD we use is a biventricular system made by Thoratec. This highly mobile system has an external pump that sits outside the body. It is particularly well-suited to smaller patients. They are not designed to last for longer than a year or two, but one of UK’s patients lived for three years with this VAD - the longest to date on record.
Selective use of bridge to transplant
Bridge-to-transplant therapy is actually considered permanent since the patient will either get a transplant or die with the device. For patients who aren’t eligible for a transplant or who have a good chance for recovery, we have temporary support systems that can be attached to the heart for a week or two. The Abiomed BVS 5000 is typically used for such short-term therapy.
We’ve become more selective about which patients we put on a device as a bridge to transplant. We want to make sure they can do well on it while waiting for the best donor heart. Generally, we prefer not to use the devices at all because the transplant surgery becomes more difficult. The surgeon has to go through the patient’s chest twice - once to implant the VAD, then again to remove it and perform the transplant surgery.
Additionally, these devices are not benign. Patients may have complications much like with a wound. The machines can also fail. Blood clots are another risk. To help prevent clotting, we put our patients on aspirin and dipyramidole.
Mechanical circulatory support systems are also very expensive. The HeartMate is $60,000 to $100,000, and it can be used only once. Insurance usually pays for this therapy, but it just adds to the overall cost of health care.
Market of the future
There is certainly a need for a device like the total artificial heart (TAH), simply because there are not enough donor hearts. Technology is moving toward TAHs that last longer and are smaller and easily implantable. I believe this is the market of the future. It’s also an alternative for some patients who, although they qualify for a transplant, do not want to have one. The medical costs of cardiac transplantation are staggering - as high as $100,000 the first year following transplantation for drug therapy and follow-up care.
However, cardiac transplantation has a proven track record of success. Thirty days following surgery, 90 to 95 percent of the recipients are still alive, and the overall survival rate after one year is 80 to 85 percent. A major reason for this success is the careful selection of transplant recipients. We have an elaborate evaluation process, and final decisions are made democratically by a team that includes surgeons, physicians, nurses, social workers and dietitians.
Dr. Ramaiah is surgical director of the UK Heart Transplant Program within the UK Transplant Center. He is also director of minimally invasive cardiac surgery and an assistant professor of surgery in the UK College of Medicine.
Mechanical devices can prolong life for those awaiting transplant
Congestive heart failure (CHF) is rapidly reaching epidemic proportions in this country and around the world. According to the American Heart Association, 5 million people in the United States are living with CHF and 550,000 develop the condition annually. With better drug and medical therapy, many people are surviving heart attacks only to develop CHF later in life because of a damaged heart muscle.
Heart transplantation is the treatment of choice for the sickest of patients with CHF, yet fewer than 2,000 a year are fortunate enough to get a transplant because of the continued shortage of donor hearts. Of those who are placed on the waiting list for a heart, 10 to 20 percent will die before a suitable organ is found. As a result, more efforts have focused in recent years on improved mechanical circulatory support systems to keep patients with severe CHF alive until they can receive a transplant.
“Many people are surviving heart attacks only to develop congestive heart failure later in life because of a damaged heart muscle.”
Ventricular assist devices
Primary among these is the left ventricular assist device (LVAD), first developed more than 20 years ago as a bridge to transplant. More recently, ventricular assist devices (VADs) have also been used successfully as the main therapy in patients with end-stage heart failure who are ineligible for transplantation. In some cases, patients on VADs even recover and are weaned from the machine. But by far, the majority on these systems are targeted for bridge-to-transplant therapy.
Most systems are for support of the left ventricle-the heart’s most critical pumping chamber. These LVADs consist of an electric pump, an electronic control system and a power supply. The pump is implanted into the upper part of the abdominal wall and connected to the heart. A tube carries blood from the left ventricle to the pump.
The early LVADs were big and noisy, but newer, much smaller mechanical circulatory support systems have been developed during the past two years. At least 30 are currently in clinical trials, most in Europe.
LVADs are being used more and more often to support cardiac patients awaiting a transplant.”
According to a 2006 study by University of Alabama researchers, LVADs are being used more and more often to support cardiac patients awaiting a transplant. The researchers found that in 1990, only 3 percent of transplant patients had been supported by LVADs. In 2004, that number had risen to 28 percent.
A host of new devices
A variety of biventricular and left ventricular devices have received approval from the U.S. Food and Drug Administration. Some are intended to be used in the hospital setting alone and others can be used on an outpatient basis.
Devices that can be used in an outpatient setting while the patient awaits a donor heart include the HeartMate Vented Electric Left Ventricular Assist System and the Novacor LVAD. In these two systems, the device is surgically placed entirely within the thoracic and abdominal cavity and connected to the power source by a drive line inserted through the skin.
New devices in clinical trials in the United States are the Micromed Debakey LVAD, the HeartMate II LVAD and the Jarvik 2000 LVAD. All are designed not only as a bridge to transplant but to help reverse heart failure in certain patients and provide final support to those whose conditions are terminal. Because of their smaller size, they are suitable for adolescents or women, who typically have smaller builds than men.
Besides devices to assist failing ventricles, implantable mechanical hearts can replace the entire heart. The total artificial heart has been used much less often than VADs, but it is an alternative to severe failure of both ventricles. The first such device to receive FDA approval for bridge-to-transplant therapy was the Cardiowest total artificial heart in 2004.
Mechanical circulatory support therapy as a bridge to transplant or recovery, Current Opinion in Cardiology , v. 21, no. 2, March 2006
First use of TandemHeart ® percutaneous left ventricular assist device as a short-term bridge to cardiac transplantation, Texas Heart Institute Journal , v. 33, no. 4, 2006
Current status of the total artificial heart, American Heart Journal , v. 152, issue 1, July 2006
Heart failure, Health Information, UK HealthCare
Heart transplantation, Health Information, UK HealthCare
Left ventricular assist device , American Heart Association
Heart transplant, UK Transplant Center, UK HealthCare
UK HealthCare cardiac resources - UK Gill Heart Institute
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