April 16, 2006 A heart attack occurs when the flow of blood to an area of the heart muscle is disrupted or cut off, depriving the affected area of oxygen. In most cases, the patient has coronary artery disease (a build-up of fatty deposits and plaque along the inner walls of the arteries). A blood clot can become trapped in a narrowed portion of an artery and block the flow of blood. Sometimes the plaque builds up enough to impede or completely block blood flow. This year, the American Heart Association estimates 1.2 million Americans will have a heart attack. Nearly half of them will die - many before reaching the hospital. Heart attacks are more common in men over 45 and in women over 55. Some other risk factors include: family history of heart attack, smoking, high blood pressure, high cholesterol, diabetes, obesity and lack of physical activity. Treating a Heart Attack A heart attack is a medical emergency. If the blockage is not treated quickly, cells in the affected area will die. If the patient gets to the hospital fast enough, doctors may try giving clot-busting drugs - medications that dissolve blood clots to improve blood flow through the artery. Clot-busting medications are most effective when started within one hour of the onset of symptoms. Some hospitals offer angioplasty to heart attack patients. A balloon-tipped catheter is fed through the circulatory system to the area of the blockage in the coronary artery. The balloon is inflated, which compresses the plaque against the arterial wall and opens the artery. An expanding metal device, called a stent, may be placed in the artery to keep the area open. In some cases, doctors may be able to perform emergency coronary artery bypass surgery. A vessel from the chest wall or a vein from the leg or arm is used to re-route blood around the area of blockage. Increasing Oxygen to the Heart Doctors say when a patient is treated for a heart attack, treatment may successfully restore blood flow to the main arteries. But some of the smaller vessels are also injured and may not function properly. Thus, even though blood flow has improved, some of the damaged tissue may still not get enough oxygen, causing further damage. Researchers at Main Line Health/Bryn Mawr Hospital are testing another treatment for heart attack patients, called HyperOxemic oxygen therapy, using the TherOx® Aqueous Oxygen (AO) System. The treatment delivers a high concentration of oxygen directly to the area of the heart muscle affected by the blockage. First, the blocked artery is opened with angioplasty. Then, the patients blood is diverted out of the heart through a tube inside the catheter. The blood flows into a machine where its mixed with a saline solution containing concentrated oxygen. The saline-oxygen solution is prepared in a miniature hyperbaric (pressurized) chamber, which allows the solution to carry ten times more oxygen than the amount normally carried in blood. Next, the blood with the super-concentrated oxygen is carried through another tube in the catheter to flow back into the body at the angioplasty site. The therapy is given continuously for 90 minutes. By delivering a higher concentration of oxygen to the heart muscle after a heart attack, doctors hope to reduce some of the damage caused by the blockage. Animal studies suggest the treatment may prevent permanent damage to some of the small vessels, allowing the heart to recover and repair the damage. The current study is called the Acute Myocardial Infarction with HyperOxemic Therapy II (AMIHOT II). It is taking place at more than 20 sites across the country and will enroll more than 300 patients. Researchers are studying the treatment for a specific kind of heart attack, called ST segment elevation, which refers to a rise in specific points of the electrocardiogram. The treatment appears to have the best results when started within six hours of the onset of symptoms. Acute Myocardial Infarction with HyperOxemic Therapy II (AMIHOT II) Study Sites St. Bernards Hospital, Jonesboro, AR St. Agnes Cardiovascular Associates, Fresno, CA Mercy Heart Institute, Sacramento, CA Mercy Research Institute, Miami, FL Munroe Regional Hospital, Ocala, FL St. Josephs Hospital, Atlanta, GA Harper University Hospital, Detroit, MI Henry Ford Health System, Detroit, MI William Beaumont Hospital, Royal Oak, MI Providence Hospital Heart Institute, Southfield, MI Buffalo General Hospital, Buffalo, NY Millard Fillmore Hospital, Buffalo, NY Mercy Hospital, Buffalo, NY Columbia University Medical Center, New York, NY Saint Josephs Hospital, Syracuse, NY East Carolina University, Greenville, NC Tri-State Medical Group Cardiology, Beaver, PA Bryn Mawr Hospital, Bryn Mawr, PA Geisinger Clinic, Danville, PA Lancaster General, Lancaster, PA Allegheny General Hospital, Pittsburgh, PA Lankenau Hospital, Wynnewood, PA Providence Hospital, Columbia, SC Jackson-Madison County General Hospital, Jackson, TN Wellmont Holston Valley Medical Center, Kingsport, TN Scott and White Hospital, Temple, TX East Texas - Tyler Cardiovascular, Tyler, TX Charleston Area Medical Center, Charleston, WV AUDIENCE INQUIRY For information about the trial: http://www.clinicaltrials.gov For general information about heart attacks: American Heart Association, http://www.americanheart.org, or contact your local chapter National Heart, Lung and Blood Institute, http://www.nhlbi.nih.gov BIBLIOGRAPHY Bartorelli, A., "Hyperoxemic Perfusion for Treatment of Reperfusion Microvascular Ischemia in Patients With Myocardial Infarction," American Journal of Cardiovascular Drugs, 2003, Vol. 3, No. 4, pp. 253-263. Corno, Antonio, M.D., et al., "Myocardial and Pulmonary Effects of Aqueous Oxygen With Acute Hypoxia," Annals of Thoracic Surgery, September 2004, Vol. 78, No. 3, pp. 956-960. Deja, Maria, M.D., et al., "Goal-Directed Therapy of Cardiac Preload in Induced Whole-Body Hyperthermia," Chest, August 2005, Vol. 128, No. 2, pp. 580-586. Dixon, Simon, et al., "Initial Experience with Hyperoxemic Reperfusion After Primary Angioplasty for Acute Myocardial Infarction," Journal of the American College of Cardiology, February 6, 2002, Vol. 39, No. 3, pp. 387-392. Glazier, James, M.D., "Attenuation of Reperfusion Microvascular Ischemia by Aqueous Oxygen," American Heart Journal, April 2005, Vol. 149, No. 4, pp. 580-584. "Heart Attack," Bethesda: National Heart, Lung and Blood Institute, downloaded from website (http://www.nhlbi.nih.gov), March 9, 2006. "Heart Disease and Stroke Statistics - 2006 Update," Dallas: American Heart Association, 2006. "Risk Factors and Coronary Heart Disease," Dallas: American Heart Association, downloaded from website (http://www.americanheart.org), March 9, 2006. Spears, J., et al., "Aqueous Oxygen Hyperbaric Reperfusion in a Porcine Model of Myocardial Infarction," Journal of Invasive Cardiology, April 2002, Vol. 14, No. 4, pp. 160-166.