Speed and accuracy are critical in diagnosing heart attacks. An injection of bubbly-gas might just be the key to saving lives.
A few months ago, 52-year-old Cesar Castilla was working at his computer when he felt pains on his left side, "and I was worried about, there was something wrong with my body or my heart," he says.
In the emergency room, doctors gave Cesar an IV full of microbubbles, tiny packets of a safe, inert gas. Once the bubbles reach the heart, they vibrate, setting off bell-like signals highlighting any damage. The imaging technology is called MCE or myocardial contrast echocardiography and it is being used in select chest pain centers around the nation.
Dr. Jonathan Lindner says, "They allow us to see where blood is, either in the cavity of the heart for example or in the tissue itself which is how we measure blood flow with these tracers."
The darkened areas of an ultrasound reveal locations of damage, "and so that allows us to pick up areas that may have had a heart attack in the past or areas that are not functioning well because of blockages," Dr. Lindner says.
The sooner they see the problem, the sooner doctors can treat it. The bubbles ruled out heart problems for Cesar Castilla.
Millions of Americans go to the hospital every year complaining of chest pains. The vast majority are not having a heart attack but must still go through long and expensive tests and hospital stays to rule that out. Microbubbles might one day offer a quick and easy alternative.
Fast Facts:This year, about 1.2 million Americans will have a heart attack.
When a patient comes into an emergency room with chest pain, doctors must determine if the symptoms are caused by the heart or other problems.
Traditional diagnostic tests for a potential heart attack are sometimes inconclusive and may take time.
Some doctors are using a new 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, and can be imaged through ultrasound, giving doctors a better understanding of the function and blood flow in the heart.
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 heart’s 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 EKG’s 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 heart’s 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 aren’t 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.
Web ResourcesAmerican Heart Association Web site
For general information on heart disease or heart attack:
National Heart, Lung and Blood Institute Web site