Coronary Study Seeks to Reduce Blood Transfusions During Surgeries

The Texas Heart Institute at St. Luke's Episcopal Hospital announced Sept. 5 its participation in a multinational clinical trial that could lead to new options for patients undergoing coronary artery bypass grafting surgery, an operation performed on patients with narrowed or blocked arteries in the heart. During a routine procedure, surgeons remove a healthy vein or artery from another part of the body and attach it to the heart to create a bypass that serves as a "detour" around the blockage.

The clinical trial will evaluate "Hemolink," an investigational agent from an emerging class of drugs called oxygen therapeutics. Hemolink is a hemoglobin replacement product derived from human red blood cells.

It may be tempting to refer to oxygen therapeutics as "substitute blood," but actually the agents do not have the same properties as whole blood, such as fighting infections or coagulating blood during wound healing.

Oxygen therapeutics are designed to deliver oxygen to tissues in the body. Normally, the hemoglobin inside the red blood cells carries oxygen throughout the circulatory system to all areas of the body. Delivery of oxygen to tissues is necessary to sustain life.

During coronary artery bypass grafting surgery, there is some blood loss and, as a result, a loss of hemoglobin. This loss of hemoglobin can result in a critical reduction in the body's oxygen levels, resulting in a potentially serious condition known as acute anemia. In cases such as this, patients often require transfusions of donor blood. Oxygen therapeutics are currently being evaluated to determine if they may be used safely and effectively to avoid or reduce the need for transfusions while preventing the clinical consequences of acute anemia.

"This is an opportunity for the medical community to learn more about what could be a very promising treatment for acute anemia," says Nancy Nussmeier, M.D., director of cardiovascular anesthesia research at Texas Heart Institute and a primary investigator in the study. Nussmeier is also an attending anesthesiologist in the cardiovascular anesthesia division at St. Luke's Hospital.

"Researchers have been evaluating medications like this to improve the way doctors manage the effects of blood loss and treat acute anemia. This may alleviate concerns of a blood supply shortage or not having the correct type of blood available when needed," explains Nussmeier.

The current trial will lead to the third and final phase of clinical trials of Hemolink before it will be submitted to the Food and Drug Administration for market approval. While the current study evaluates whether this oxygen therapeutic results in fewer transfusions during bypass surgery, Nussmeier says the implications for other uses are far-reaching and encouraging.

"It appears that an oxygen therapeutic can serve as a temporizing measure - it buys us time when blood is not available. So, for example, it could be used in the field when an injury requires blood but none is immediately available. A great advantage is that it requires no cross matching. Oxygen therapeutics may become very important in times of critical blood shortages. Such products could also prove to be lifesaving for patients who are Jehovah's Witnesses, whose religion does not allow them to accept donated blood transfusions," says Nussmeier.

To date, more than 300 participants in seven studies have received Hemolink. Some of the more common side effects with this Hemolink are temporary increases in certain liver and pancreatic enzymes, increases in blood pressure, yellowing of the skin, and pink urine. These transient changes have not been associated with any long-term complications.

Texas Heart Institute at St. Luke's is one of the sites in the United States, Canada, and the United Kingdom participating in the study.

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©2006 Texas Medical Center

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