Heart failure (HF) is one of the major health challenges faced by society today, afflicting 6 million Americans, claiming hundreds of thousands of lives each year and costing more than $30 billion dollars annually.
With the support of a five-year, $2.86 million R01 grant from the National Heart, Lung, and Blood Institute, researchers at the Georgia Institute of Technology, the University of California at San Francisco (UCSF), and Northwestern University are working to address this issue by building wearable and weighing-scale-based ballistocardiogram (BCG) technology for monitoring HF patients at home. This technology quantifies mechanical aspects of cardiovascular function by recording the movements of the body caused by the contraction of the heart and ejection of blood into the aorta, the body's main trunk of the arterial system.
"The ultimate goal of this research is to create an unobtrusive wearable system for continuously monitoring HF patients at home, automatically assessing their risk of experiencing a cardiac event, and providing feedback to caregivers and the patients themselves," said Omer Inan, an assistant professor in the Georgia Tech School of Electrical and Computer Engineering.
According to Inan, the central innovation supporting these efforts is the proposed measurement of hemodynamic responses-or forces involved in the circulation of blood-to stressors experienced in normal activities of daily living, such as walking or climbing stairs. These responses will be measured by using wearable BCG. Inan and his colleagues will work on four specific areas with this research:
- clarify the underlying mechanisms involved in creating wearable BCG signals;
- develop novel predictive analytics algorithms for BCG signals measured from HF patients at home;
- design and implement a wearable sensing system for estimating cardiac output, blood pressure, and activity level from ambulatory patients; and
- evaluate the wearable sensing system with both healthy and HF patients during cardiopulmonary stress testing and pilot the new system for a small population of patients at their homes.
Inan will supervise all engineering aspects of the project, including leading the Georgia Tech team in designing and building the weighing scale and wearable BCG sensing systems, and he will work with May Wang and James M. Rehg to analyze the measured data. Wang, a professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, will advise on the predictive algorithm development and data analytics aspects of the project. Rehg, a professor in Tech's School of Interactive Computing, will work on the software implementation for the interactive computing aspects, leveraging the technology developed in the Mobile Sensor Data to Knowledge (MD2K) Center of Excellence, which he co-directs.
Collaborating with the Georgia Tech team are UCSF and Northwestern colleagues. Liviu Klein and Teresa DeMarco, both heart failure cardiologists in the School of Medicine, will handle all clinical aspects of the project, including patient enrollment, and performing and interpreting the cardiac catheterization and cardiopulmonary stress tests. Shuvo Roy, a professor in the Department of Bioengineering and Therapeutic Sciences, and Mozziyar Etemadi, a recent M.D./Ph.D. graduate of Roy's lab and currently with the Department of Anesthesiology at Northwestern's Feinberg School of Medicine, will work with Inan and his lab on the embedded systems development and will work with the clinical team to deploy the sensing systems.
The first aim will build a strong foundation for better understanding the wearable BCG signal - a measurement of body vibrations in response to the heartbeat - and will inform the placement and modality of the sensor for optimizing the sensing, said Inan. The evaluation of this wearable prototype will include usability testing to assess comfort and robustness to practical challenges, such as the device rubbing on clothing and signal quality disruptions due to walking or other body movements. Based on the results, the design will be refined and improved.
While the team anticipates that the wearable BCG device will provide the best solution, the project risk is mitigated through the more mature, existing scale-based system that Inan developed previously in his graduate and post-doctoral work. These scale-based systems would also be usable in the home, but only for stationary measurements as compared to the continuous monitoring capability offered by wearable BCG systems.
"Successful completion of this project could ultimately reduce heart failure-related hospitalizations, which would improve quality of life for elderly Americans and reduce overall healthcare costs," said Liviu Klein of UCSF.
Source and top image: Georgia Tech
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