|
Although heart failure cannot be cured, many treatments exist
for early-stage heart failure patients, including lifestyle changes, medications,
and surgery. However, for patients with end-stage heart disease, such treatments
are inadequate and device therapy or full heart replacement are the only viable
courses of action.
Heart Transplants
For several decades, heart transplants have been the gold standard of treatment
for end-stage Congestive Heart Failure (CHF) and certain types of Coronary Artery Disease (CAD). A heart transplant is the replacement
of a diseased heart with a healthy one from an organ donor.
As of December 2006, 40,363 heart transplants have been performed
in the United States. Nearly 85% of transplant recipients survive over one year
following the procedure, and 70% survive for over 5 years.
Approximately 228 medical centers perform heart transplants,
including 127 in the U.S. On average, over 3,000 transplants are performed worldwide
each year, including 2,125 in the U.S. in 2005.
Candidates for transplant have irreparably damaged hearts,
are facing imminent death, and have otherwise viable vital organs. Even under
these strict criteria, the National Heart, Lung, and Blood Institute estimates
that as many as 100,000 Americans would benefit from a transplant each year. Of
these, fewer than 8,000 are ever placed on the national transplant waiting list,
and only 2,000 to 2,500 hearts become available for transplantation. Most patients
spend months or years waiting for a suitable donor heart and die before one becomes
available.
Furthermore, transplanted hearts generally fail 9.5 years (on
average) after implantation. Most patients will not be re-listed on the national
heart transplant list, since they would compete with people waiting for their
first transplant.
Ventricular Assist Devices (VADs)
VADs are implants designed to help the weakened heart pump blood. Most VADs are
designed to help the left ventricle (Left Ventricular Assist Devices or LVADs) pump oxygen-rich blood
throughout the body (typically by pulling blood from the left ventricle and pumping
it into the aorta). Some are designed to support the right ventricle (Right Ventricular Assist Devices or RVADs),
and a few are biventricular (BVADs).
In general, VADs fulfill one of the following functions:
- Bridge-to-recovery: Support the heart during a recovery
process in less severely ill patients under circumstances such as:
- - Weaning from a heart-lung machine following heart surgery;
- - Following severe cardiac arrest; or
- - Combating severe viral infections of the heart muscle.
- Bridge-to-transplant: Sustaining life until a suitable donor
heart is identified for a transplant procedure.
In addition to our total artificial heart, SynCardia is developing
temporary and permanent partial heart assist devices to address the needs of patients
who would otherwise require a VAD.
Total Artificial Hearts (TAHs)
The goal of the CardioWest™ temporary Total Artificial Heart (TAH‑t) is to completely replace a diseased
heart with a mechanical device as a bridge-to-transplant. Ideally, the TAH‑t
will provide for normal hemodynamics (blood flow) and restore the patients' quality
of life with high survival rates.
In the first human application, the Liotta TAH kept a patient
alive for 64 hours as a bridge to transplant in 1969. In 1981, the Akutsu TAH
kept a patient alive for 2 days as a bridge to transplant.
In 1982, the Jarvik-7 TAH was implanted in Dr. Barney Clark,
with the goal of permanently sustaining life in a human. Dr. Clark survived for
112 days. The Jarvik-7 was implanted in four more patients on a permanent basis,
the longest surviving 620 days. Since 1985, the Jarvik-7 and the Penn State TAHs
were successfully used in a number of bridge-to-transplant applications.
In the 1990s, CardioWest™ Technologies was formed as
a non-profit entity to continue the development and study of the CardioWest TAH‑t.
During this period, a number of improvements were made to the heart's design and
manufacturing processes. In 2001, SynCardia acquired CardioWest TAH‑t system
assets and in 2004 the company received FDA approval for the CardioWest TAH‑t.
|
