The Syncardia Temporary Cardiowest Total Artificial Heart

Executive Summary

The heart is one of the centerpieces of the body, pumping blood throughout it and keeping it functioning. However, when plagued by disease, it is perhaps one of the most difficult organs to treat. There are not enough human heart transplants at one time for people who are in dire need of one due to their failing hearts. The Syncardia Temporary CardioWest Total Artificial Heart (TAH-t) is able to provide circulatory support to hospitalized patients who are waiting for a donor heart, keeping them alive until one is available (See Fig. 1) (1). As a result of blood flow being restored, kidney and liver function is also restored, negating treatments for those organs. There is one other FDA approved artificial heart that can be used as an alternative treatment option. An advantage to the AbioCor Replacement Heart is that no wires or tubes penetrate the skin, resulting in a lower risk of infection (2).

Figure 1. CardioWest TAH-t (3).

The CardioWest TAH-t is designed to replicate the action of the natural heart ventricles. The device is sewn into the patient's remaining atria. A power-generating console operates and monitors the device through tubes connected to the heart, going through the chest wall. The two ventricles of the Cardiowest TAH-t are split by a diaphragm into two parts. As blood fills the ventricles, air pressure is applied to the opposite side of the diaphragm and ejects the blood from the ventricles. Once set, the patient's blood flow automatically adjusts as blood continues to flow into the ventricle and is ejected. As a result of the TAH-t, blood is able to circulate to both the lungs and the rest of the body (1).

The CardioWest TAH-t has been out on the market for several years after being approved by the FDA on October 15, 2004. During the 10 year clinical study prior to approval, 79 percent of patients that were implanted with the TAH-t received a donor heart. This shows that the artificial heart is able to successfully serve as a bridge to transplant. So far there have been more than 900 implants of the TAH-t, while its main competitor, the AbiorCor Replacement Heart, has only been implanted in 14 patients (2). It continues to have the highest bridge-to-transplant rate for any heart device in the world. The temporary CardioWest TAH-t should not be used in patients who are not eligible for a heart transplant, do not fit the device, cannot be adequately anticoagulated, or have left sided heart failure only.

Clinical Problem

Heart failure, or congestive heart failure, is one of the most deadly versions of heart disease. The result of a failing heart is that the heart is unable to supply enough blood flow to meet the needs of the body. Though not the mose prevalent disease to affect the heart, the amount of cases of heart failure has increased greatly over the years and is currently increasing at 550,000 new cases per year. The Americans who have heart failure, almost 5 million, generate about $38.1 billion in annual health care costs (3). Nearly 300,000 Americans die of heart failure every year. 15 to 25 percent of that number are those who are waiting for transplantation (3). Though cardiac transplantation has been seen as an effective and successful therapy, the deman for donor hearts has doubled while the supply of hearts available has decreased from about 2500 to 2000 (3). With an artificial heart serving as a bridge to transplantation though, the rate of survival of a patient waiting for transplantation can be greatly increased.

Alternative Treatment Options

The main competitor that the CardioWest TAH-t faces is the AbioCor Implantable Replacement Heart, the only other FDA approved artificial heart. Though both devices perform the same function of pumping blood throughout the bodym the advantage to the AbioCor is that it is a self-contained, internal artificial heart, unlike the CardioWest TAH-t which requires connection to an outside generator. Because of this design, there is a smaller chance of infection of the body due to the lack wires and tubes penetrating the skin. The internal battery powering the AbioCor is able to be recharged through transmission of power across the skin. As of November 2010, fourteen patients have veen successfully implanted with the AbioCor, including one patient who survived for 512 days with the device (2).

Advantages of the Device

Essentially, the advantage to the CardioWest TAH-t is that it is able to keep a patient alive long enough to receive a heart transplant. Serving as a bridge to transplant, the device is for patients who are nearing death due