NASA Teams with MetroHealth To Detect Cardiac Arrhythmias In Astronauts
With NASA looking toward extending missions to further explore space, the NASA Glenn Research Center has partnered with MetroHealth Medical Center in Cleveland to develop a method of measuring whether astronauts are more susceptible to serious cardiac episodes the longer they are in space.
Ultimately, NASA expects the venture will enhance its ability to monitor astronauts' in-flight arrhythmic activity from the ground in real time - via the Internet - using NASA's Embedded Web Technology.
Through the John Glenn Biomedical Engineering Consortium, NASA teamed with MetroHealth to determine a method for assessing the heart's condition during zero and partial gravity conditions like those found on the Moon and Mars.
"NASA is responsible for the health and safety of astronauts in space," said David York, chief engineer for Glenn's Flight Software Branch.
"We are extremely pleased to be working with Dr. David Rosenbaum, director of MetroHealth's Heart & Vascular Center and Division of Cardiologoy. His internationally renowned expertise in the recognition and prevention of cardiovascular disease is an excellent match for this research."
MetroHealth is basing its research on an advanced electrocardiogram (EKG) test that uses technology pioneered at the center to screen for T-wave Alternans (TWAs) or slight disturbances or changes in the heart's rhythm during a specialized exercise stress test.
These subtle, yet virtually invisible changes in the heart's electrical conduction pattern appear on an EKG of someone at risk for cardiac arrhythmias that can lead to sudden cardiac death (SCD), the most common cause of death in the United States, annually claiming the lives of more than 300,000 Americans.
The key to detecting these microscopic disturbances lies in computer software designed to amplify TWA patterns and make it easier for MetroHealth to detect who is at risk.
"Heart disease is so prevalent that if enough individuals go into space for long periods of time, then sooner or later heart problems are likely to become apparent," said David Rosenbaum, M.D.
"T-wave Alternans are a high marker for susceptibility to the risk of cardiac arrhythmias, found in 70 to 80 percent of patients at risk."
"And, since there is clearly evidence indicating that astronauts and cosmonauts have experienced arrhythmias as a part of space flight, the idea with NASA was to use this technology for detecting these micro signals as a means of determining how space flight affects the heart, particularly with regard to how microgravity and weightlessness enhance the heart's electrical instability," he added.
The noninvasive exam was the focus of four weeks of testing performed between May and October involving ground and in-flight measures taken on 15 test subjects using the same computer technology and exercise test.
Testing on the ground, in a controlled environment, was done to identify any problems before testing in flight. MetroHealth relied on NASA's KC-135 aircraft to simulate the effects of weightlessness and zero gravity on test subjects in space. The KC-135 is used by NASA to train astronauts and prepare them for weightlessness experienced in orbit.
MetroHealth was able to gauge the effects of weightlessness in test subjects while the plane conducted a series of severe climbs and descents, called parabolas, which were strung together in a wave-like configuration.
At the peak of each parabola, of which 45 were conducted during each flight in a restricted air space over Lake Michigan or Lake Ontario, subjects experienced approximately 20 seconds of weightlessness and zero gravity.
During the tests, subjects pedaled a stationary bicycle for up to 15 minutes while being hooked up to a 14-lead EKG to gauge their heart rate at rest, during moderate and rigorous exercise, and during recovery. Leads from the EKG were attached to a computer and electrodes placed on the chest and back.
Seven of the electrodes on the EKG were specially designed to allow scientists to distinguish cardiac electrical activity from other electrical signals coming from the body. Data from the testing was acquired through a compact unit inside a holster worn by each test subject on the ground and in flight.
NASA and MetroHealth plan to use the data to analyze whether long-term flight does in fact impact the heart.
NASA's ultimate goal is to couple TWA technology on the International Space Station with its mbedded web system to track astronaut heart activity remotely - in real time - by using an Internet browser. By simply typing in the astronaut's name, much like you would an address for an Internet search engine, an astronaut's live heartbeat pattern could be monitored and tracked.
"This would allow one astronaut on the Space Station to view another astronaut's EKG during exercise. And at the same time, using the Embedded Web Technology, the data would be transmitted to the ground, where the flight surgeons could observe the same EKG in real time," York said.
"This would enhance our ability to recognize a problem as early as possible to provide proper treatment."
The research is part of a multi-phase initiative implemented by NASA and the National Space Biomedical Research Institute (NSBRI) to design and test countermeasures and medical support technologies that maximize human performance in space, reduce biomedical hazards and support medical care.
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