ElectroCardiographic Imaging (ECGI)

Just to share an interesting development in Medical Imaging that I read earlier at ImagingEconomics.com

A new technique in development may provide more accurate details than conventional methods about how the heart beats, and what goes wrong when it’s off beat.


In a healthy adult at rest, the heart beats 60 to 100 times a minute. In an unhealthy heart, this beat can vary, and the rate or rhythm can be thrown off. This condition is known as an arrhythmia and can refer to a beat that is too fast (tachycardia), too slow (bradycardia) or off rhythm.

There are four main types of arrhythmias, and a number of specific disorders. The most common is atrial fibrillation, which impacts an estimated 2.2 million people in the US and accounts for roughly one-third of hospitalizations for cardiac rhythm disturbances. A joint task force of the American College of Cardiology and the American Heart Association analyzed associated costs and found that the disease incurs $3,600 per year per patient, making it a costly public driver (approximately $15.7 billion).

Unfortunately, it has been difficult to fully understand the beating heart without opening up the chest. The primary method to diagnose heart rhythm disorders has been the electrocardiogram, also known as the ECG or EKG. The method uses electrodes placed on the skin to indirectly measure the electrical activity in the heart.

“The ECG is an extremely useful tool, which has been with us for more than a hundred years. It’s practical. It’s cheap, relatively speaking. It’s easy to apply. But it has severe limitations because you are measuring a reflection of the electrical activity of the heart—far away from the heart,” says Yoram Rudy, PhD, the Fred Saigh distinguished professor of engineering; professor of biomedical engineering medicine, Cell Biology and Physiology, Cardiology, and Pediatrics; and director of the Cardiac Bioelectricity and Arrhythmia Center, at Washington University in St Louis (Mo).

Rudy is part of a team that has been working on a new technique, called electrocardiographic imaging or ECGI, for non-invasive mapping of a patient’s heartbeat for nearly 30 years. Supported by grants through the National Institute of Health, it has recently published papers on the use of this experimental methodology in atrial fibrillation and ventricular tachycardia (fast, regular beating that may last for a few seconds or longer).

Proven Research Value, Potential Clinical Use

The new technique combines a more extensive EKG (250 electrodes rather than the typical 12) with a thoracic CT scan, which captures images, including the electrode positions, of the chest and upper abdomen. “We then use mathematical and computer algorithms in a mathematical and physical approach that we have developed over many years,” Rudy says.

In the latest study looking at ventricular tachycardia, the researchers were able to use ECGI to map the activation sequence in the heart and identify the location and depth of the disorder’s origin in individual patients. They concluded that the method improved significantly upon the data available through a more conventional EKG.

In general, the information collected using ECGI has proven to be extremely useful for both research and clinical purposes, though the system is still in experimental stages. The University of Wisconsin is implementing the technique through research trials looking at a number of different issues (another paper addressing the association between heart attack, arrhythmia, and risk is expected out in October).

Ultimately, ECGI is intended for use as a clinical tool, one that will provide an advanced, non-invasive imaging technique for assessing cardio-electrical activity and rhythm disorders in the heart. “It can be used as a tool for diagnosis—precise diagnosis of an arrhythmia mechanism—and once a diagnosis is made, for therapy guidance and follow up,” Rudysays.

Rudy notes that a commercial effort is underway through CardioInsight Technologies, Inc, in Cleveland, Ohio. The corporate leaders were former PhD students under Rudy, and he sits on the company’s scientific advisory board. “It’s not available as a clinical tool yet, but once it is FDA approved and available, I believe it will have widespread use,” Rudy says.

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