Heart Attack Microbubbles

April 2, 2006 A heart attack occurs when a part of the heart muscle is deprived of oxygenated blood. Without treatment, the affected area of the heart muscle will eventually die. The American Heart Association estimates 1.2 million Americans will have a heart attack this year. Nearly half of them will die - many before even 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 disease, smoking, high blood pressure, high cholesterol levels, obesity, diabetes, lack of physical activity, low consumption of fruits and vegetables and excessive consumption of alcohol. After a heart attack, patients continue to be at risk for complications. Within one year of a heart attack, 25 percent of men and 38 percent of women will die. Within six years, 18 percent of men and 35 percent of women will have another heart attack, 22 percent of men and 46 percent of women will develop disabling heart failure, 8 percent of men and 11 percent of women will have a stroke, and 7 percent of men and 6 percent will experience sudden death. Assessing Heart Function There are several tests that can be done to assess heart function. An electrocardiogram (EKG) measures the electrical activity in the heart to determine if there are any irregularities that could signal a problem with heart function. Blood tests look for markers in the blood that increase in response to heart muscle damage. In cardiac catheterization, a thin tube is passed through the circulatory system to the heart. Doctors can measure pressure and blood flow within the hearts chambers. Coronary angiography, often performed at the time of catheterization, is the injection of a special dye into the circulatory system. The dye is detected on X-rays and can be used to monitor the flow of blood through the coronary arteries. Echocardiography uses sound waves to create images of the heart, allowing doctors to assess heart function and performance. More sophisticated tests include a nuclear scan (PET) to measure blood flow through the heart and heart function while at rest and during periods of stress, and cardiac MRI, which looks at the size, function and health of the heart muscle as well as blood flow through the heart. Assessing Chest Pain - Microbubbles A heart attack is a medical emergency. Prompt treatment can help prevent or reduce heart muscle damage. But not all cases of chest pain are caused by a heart attack. Traditional tests, like EKGs can be inconclusive and cardiac catheterization and echocardiography may not be immediately available. Doctors at Oregon Health & Science University are using another technique to look at heart function, called myocardial contrast echocardiography, or MCE. The procedure uses microbubbles, tiny gas-filled bubbles that are injected into the bloodstream. The vibrating bubbles are lighter in color than red blood cells and are easily imaged with ultrasound. As the tiny bubbles flow through the heart, doctors can clearly see how well blood is flowing through the hearts chambers and in the heart muscle itself. The procedure can enable physicians to determine if the heart muscle wall is weak and not pumping properly. The technique can also show areas of the heart that arent getting enough (or any) blood flow. Doctors say MCE can quickly provide clearer information about heart function. It is especially useful for patients who may not be able to undergo traditional testing, like those who are in intensive care or on a ventilator. It may also provide more information when standard images aren`t clear, like in obese patients or those with lung disease. In the future, researchers hope they can develop microbubbles that target a specific area of the body (like a tumor). If possible, doctors may be able to attach drugs to the microbubbles and deliver strong doses of medication directly to the target site. AUDIENCE INQUIRY For general information on heart disease or heart attack: American Heart Association, http://www.americanheart.org National Heart, Lung and Blood Institute, http://www.nhlbi.nih.gov BIBLIOGRAPHY Adam, D., et al., "On the Relationship Between Encapsulated Ultrasound Contrast Agent and Pressure," Ultrasound Medicine and Biology, May 2005, Vol. 31, No. 5, pp. 673-686. "Coronary Artery Disease," Bethesda: National Heart, Lung and Blood Institute, downloaded from website (http://www.nhlbi.nih.gov), March 6, 2006. Corsi, Cristiana, Ph.D., et al., "Volumetric Quantification of Global and Regional Left Ventricular Function From Real-Time Three-Dimensional Echocardiographic Images," Circulation, August 23, 2005, Vol. 112, No. 8, pp. 1161-1170. Dokainish, Hisham, M.D., et al., "Usefulness of Tissue Doppler Imaging in the Diagnosis and Prognosis of Acute Right Ventricular Infarction with Inferior Wall Acute Left Ventricular Infarction," The American Journal of Cardiology, May 1, 2005, Vol. 95, No. 9, pp. 1039-1042. "Heart Attack," Bethesda: National Heart, Lung and Blood Institute, downloaded from website (http://www.nhlbi.nih.gov), March 6, 2006. "Heart Disease and Stroke Statistics- 2006 Update," Dallas: American Heart Association, 2006. Lessick, Jonathan, M.D., D.Sc., et al., "Comparison of Multidetector Computer Tomography Versus Echocardiography for Assessing Regional Left Ventricular Function," The American Journal of Cardiology, October 1, 2005, Vol. 96, No. 7, pp. 1011-1015. Nixdorff, U., et al., "Three-dimensional Echocardiography," Cardiology, 2005, Vol. 104, No. 2, pp. 76-82. Paetsch, I., M.D., et al., "Comparison of Dobutamine Stress Magnetic Resonance, Adenosine Stress Magnetic Resonance, and Adenosine Stress Magnetic Resonance Perfusion," Circulation, August 17, 2004, Vol. 110, No. 7, pp. 835-842. Senior, Roxy, M.D., D.M., et al., "Myocardial Contrast Echocardiography in Acute Coronary Syndromes," Cardiology Clinics, May 2004, Vol. 22, No. 2, pp. 253-267. Tong, Khim Leng, M.D., et al., "Myocardial Contrast Echocardiography Versus Thrombolysis in Myocardial Infarction Score in Patients Presenting to the Emergency Department with Chest Pain and a Nondiagnostic Electrocardiogram," Journal of the American College of Cardiology, September 6, 2005, Vol. 46, No. 5, pp. 920-927. Villenueva, Flordeliza, M.D., et al., "Targeted Ultrasound Imaging Using Microbubbles," Cardiology Clinics, May 2004, Vol. 22, No. 2, pp. 283-298. Research compiled and edited by Barbara J. Fister