Advanced liver failure affects many organs in addition to the liver. For example, when the liver fails, the circulatory system reacts by relaxing the muscular coating that surrounds blood vessels. This allows blood vessels to open wider, causing blood to flow more rapidly through the vessels. As a result, to maintain blood pressure at safe levels, the heart must beat faster and the amount of blood pumped by the heart (the cardiac output) must increase. This altered condition of the circulatory system, known as a “hyperdynamic circulatory state,” puts a dangerous strain on the heart and may cause death. Certain types of bacteria cause this problem when they invade the bloodstream. Doctors have speculated that the circulatory changes that accompany liver failure occur because the liver, which normally removes bacteria that leak into the bloodstream from the bowel, can no longer perform this function. Until now, no effective treatment has been available for the hyperdynamic circulatory state that accompanies liver failure.