September 24, 2009
Dear Friend of the Texas Heart Institute,
Salina Gonzales came to the Texas Heart Institute at St. Luke's Episcopal Hospital with congestive heart failure. Without treatment, this 27-year-old mother and school teacher had only months to live. The best therapy would have been a transplant, but as with thousands of other patients each year, the shortage of donor hearts foreclosed that option for Salina.
So Dr. O.H. Frazier did what he has done 1100 times, more than any other surgeon in the world. He implanted a ventricular assist device (VAD), a small pump to help Salina's failing heart. (Dr. Frazier is Chief of Cardiopulmonary Transplantation, Chief of the Center for Cardiac Support, and Director of Surgical Research at THI.)
The operation saved Salina's life.
Why do hearts fail? Usually because the left ventricle—the heart's main pumping chamber—is injured by a heart attack, a virus, aging, excessive alcohol consumption, or a faulty heart valve. The weakened ventricle cannot pump enough blood to support the body's needs. The heart then progressively enlarges and, if untreated, fails.
In the early stages, medications and other therapies are helpful. As the heart continues to weaken, however, the best hope for many patients—assuming a donor heart is unavailable—is implantation of a VAD. (Stem-cell therapy, either alone or in combination with a VAD, is being studied as another promising option.) The VAD is a small mechanical pump implanted in the heart. It helps the left ventricle pump blood. This eases the heart's workload and allows many patients with severe heart failure to survive and lead normal lives. Some patients need a VAD for the rest of their lives. Some patients have had the device removed after the heart has had time to rest and recover.
VADs have been under development for more than four decades, and THI has been deeply involved at every stage. Under Dr. Frazier's direction, our physician scientists have the world's most extensive experience in developing VADs, then using breakthroughs from the lab to save lives. He and his colleagues have had a hand in every major development for every model of VADs in use today.
First-generation VADs were large and pumped blood in pulses, like the natural heart. Second- and third-generation VADs are less complicated. They pump blood in a continuous flow, like a fan pushes air. Because they have only one moving part, they are less likely to break or wear out. And because they are only about the size of a flashlight battery, they can be implanted in children and small adult patients.
The next challenge is whether these continuous-flow pumps, which work so well at assisting the heart, can be used for total heart replacement. This has never been done before, but—thanks to grants totaling $6.9 million from the National Institutes for Health—THI researchers are now studying the possibility of using two continuous-flow pumps to replace the heart. One would circulate blood through the body; the other would move blood to and from the lungs.
The challenges are immense. Can the devices be designed to simulate the natural heart by pumping more or less blood, depending on how much is in the heart? Or can the device respond to exercise by increasing the blood flow and to rest by reducing it? Our researchers believe they can meet these design goals. They are also studying how continuous blood flow, as opposed to the pulsed flow of a natural heart, affects the major organs.
This is just one example of what we do at THI. In Houston, we serve patients directly, but our research also helps improve patient care around the nation and throughout the world.
This takes financial resources. Government grants are not enough. Much of our initial work on VADs and total artificial hearts was supported by generous grants from the Cullen Foundation, the John S. Dunn Research Foundation, and the John M. O'Quinn Foundation.
To learn more about the Institute's research and education programs—and to see how you can help—please contact Marc Mattsson, our chief executive officer (832-355-3792 or mmattson@heart.thi.tmc.edu) or Irene Helsinger, chief operating officer (832-355-9510 or ihelsinger@heart.thi.tmc.edu).
Oh, and how is Salina Gonzales doing today? Well, her heart recovered and after 17 months the VAD was removed. Now, she is back in the classroom, and her young son has a healthy mother.
Respectfully yours,
James T. Willerson, MD
President and Medical Director
Contact Dr. Willerson
Learn more about the development and application of heart assist devices.
Follow the Salina Gonzales story in our multimedia room.
Read the previous issue of Heart to Heart about the promise of therapies that use adult stem cells.
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