In the CBS drama Numb3rs, the character Charlie Epps, a mathematical genius, helps the FBI solve a wide array of crimes in Los Angeles with a numerical approach. Similarly, investigators at the University of Michigan's Center for Arrhythmia Research (Ann Arbor) are combining experimental, clinical, and numerical approaches to study the origins of abnormal heart rhythms like atrial fibrillation.

To aid the researchers in their work, the center is using high-productivity computing (HPC) systems from SiCortex (Maynard, Massachusetts).

"We are studying the conditions of numerous variables that can interrupt the heart's regular rhythm and lead to an arrhythmia," said Omer Berenfeld, PhD, assistant professor of internal medicine and biomedical engineering at the Center for Arrhythmia Research. "Through sophisticated mathematical modeling and parallel computations running on the SiCortex systems, we can reproduce the heart's electrical activity to pinpoint more precisely where and how abnormal rhythms originate within the heart muscle. Understanding the origin is an important step in determining the underlying cause of the problem."

Berenfeld's project, funded in part by grants from the National Institutes of Health, the American Heart Association (Dallas) and the Heart Rhythm Society (Washington), runs mathematical modeling applications on two SiCortex systems: one that serves as the mainframe system and the other as an auxiliary development unit. The numerical simulation studies produced so far provide valuable new insight by presenting data in stunning visual displays.

"This important initiative demonstrates HPC's far-reaching power to solve a wide array of problems, including those directly linked to medical conditions and treatments," said Chris Stone, president/CEO of SiCortex.

According to the company, SiCortex computers also are used by academic institutions and national laboratories to facilitate research in a variety of other areas, including engine design, aerodynamics, weather pattern mapping, ecology, astrophysics and complex signal processing.

Until recently, scientists thought fibrillation was caused by random electrical disturbances in the heart. However, Berenfeld told Medical Device Daily that new research shows the electrical activity during fibrillation is not completely random. In fact, the seemingly chaotic disturbances are found to originate in many cases from organizing centers in the form of spiral vortices, also called rotors, he said.

Berenfeld likened these rotors to hurricanes. He said they are impulses that orbit around the organizing centers very fast, much faster than a normal heart beat.

The U-M team will study computer simulations generated by the SiCortex systems to evaluate the many combinations of variables that can cause rotors and determine their dynamics.

"Our goal is to understand the dynamics of that organizing center because it is the driver; if we address that, we remove the engine that maintains the fibrillation," Berenfeld said.

The finding that these disturbances are not completely random was an important advancement in arrhythmia research, Berenfeld said. Now investigators are not "shooting at the dark" anymore, they have more specific mechanisms to study, he said.

Although it's a long way off, Berenfeld said the ultimate goal of the research is to develop new diagnostics or therapies for fibrillation.

The computer simulations are studied together with electrical data collected from various modalities, including fluorescence imaging and electrodes threaded into the heart's chambers. To accurately simulate and analyze the fine characteristics of voltage and motion of ions that penetrate all the way to the molecular level, the researchers needed a system with fast and efficient connectivity. According to SiCortex, its systems were a natural choice, as they consist of processers linked together by a very fast communication fabric, making them ideally suited to run these complex simulations.

"In addition to the performance considerations, the system needed to fit in a small computer room since the research lab lacks space big enough to house a large HPC system," Berenfeld said. "As medical researchers first and HPC users second, we needed a system that we could easily configure into an existing space, plug in and start using. The SiCortex HPC systems also offered the highest performance per dollar compared to competing systems."

Berenfeld told MDD that the researchers at the Center for Arrhythmia Research are motivated by the significant clinical need to be able to predict and prevent fibrillation. More than two million Americans suffer from fibrillation, an irregular electrical activity in the heart that precludes the blood pumping. The disease can cause stroke, heart failure and sudden death.

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