Freezing Hearts Back to Health
Doctors are freezing hearts back to health.
Aug 24, 2009
By DBIS
Inside Science News Service
Science Insider
WHAT IS ARRHYTHMIA? An arrhythmia occurs when the heart beats too fast, too slow, or irregularly. This keeps the heart from pumping blood properly. Normally, the heartbeat starts in the right atrium, when a special group of cells (the "pacemaker" of the heart) sends an electrical signal causing the muscles to contract. These signals travel through connecting fibers to all parts of the ventricles, and must follow the exact route in order for the heart to pump properly. There are many types of arrhythmia, identified by where they occur in the heart (in the atria or ventricles), and by what happens to the heart's rhythm when they occur. One example is atrial fibrillation, an irregular heartbeat that interferes with the heart's ability to pump blood. Abnormal electrical signals cause the atria, or upper chambers of the heart, to contract erratically. Blood then pools in the atria and forms clots. These can travel to the brain and cause a stroke. The most serious arrhythmia is ventricular fibrillation, where the lower chambers quiver and the heart can't pump any blood. This results in collapse and sudden death -- if there isn't immediate medical attention.
FREEZING THE HEART: One way to prevent arrhythmias is to locate the areas of the heart responsible for the problem and freeze them to kill the tissue. Doctors use a catheter loaded with a super-cold solution, and touch it to spots where the electrical signals are thought to be faulty. Doctors can test to see that it has worked, and thaw the tissue if they froze the incorrect spot. If it is working, they cool the probe even more, and kill the tissue.
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Sudden cardiac arrest occurs when your heart abruptly stops. It's the leading cause of death in the U.S., claiming 325,000 lives last year alone. Now, doctors are freezing hearts back to health.
Mary McMichael-Liston doesn't feel like she's 46. "About the 20 mile mark I was wondering what I was doing, by the end I was strong again," McMicheal-Liston told Ivanhoe.
McMichael-Liston finished a marathon -- 26.2 miles -- in less than five hours.
"I was thinking oh man I did it," McMichael-Liston said.
So what a surprise it was to her, when a heart problem snuck up on her.
"My family doctor said the best explanation I have for you Mary, is that you are that young kid out on the football field that you read about that basically falls over dead," McMichael-Liston explained.
McMichael-Liston's heart was beating so fast, that no oxygen could get to her brain. Within minutes critical care physicians at Riverside Methodist Hospital in Columbus Ohio, were able to use hypothermia, to help save McMichael-Liston's heart.
"By cooling them after they have a cardiac arrest, it helps to decrease the body's metabolism and decrease the amount of brain damage that occurs," Simi Bhullar, M.D., a pulmonary and critical care specialist at Riverside Methodist Hospital in Columbus, Ohio, told Ivanhoe.
Doctors inject cold saline solution into the patient and keep them cool with these pads, taking the body temps down from 98 to 90 degrees, giving the brain a break, reducing swelling and protecting brain cells from any further damage. Patients are kept cool for 24 hours.
"It's amazing to see them awake the next day in the ICU," Dr. Bhullar said.
McMicheal-Liston learned she suffers from abnormal heart rhythms.
"You can have something your whole life and never know it," McMichael-Liston said.
A defibrillator, implanted in McMicheal-Liston's chest, now keeps her heart beating regularly.
"To me this is a gift and they way everything happened, it all lined up in such perfect harmony for me to walk away from this."
For hypothermia to work, it must be administered within 15 to 30 minutes of a cardiac arrest. Hypothermia is also used in spinal cord injuries, and it being used to reduce brain swelling in stroke patients.
