- Currently, doctors use invasive electrical procedures to diagnose and localize the source of abnormal heart beats such as atrial fibrillation
- Using signals produced externally at the body surface by the electrical activity of heart (measured as electrocardiogram), scientists have developed a method to reconstruct what is happening deep within the heart
- In future, it may be possible to diagnose and assess response to treatment of cardiac conditions using this non-invasive cardiac imaging algorithm
Reconstructing Heart Electrical Activity Using Inverse Operator ModelThe main aim of noninvasive electrical imaging of the heart is to accurately reconstruct information about the electrical activity of the heart from numerous ECG impulses on the surface of the chest. Quantitative interpretation of these superficial signals in the context of the underlying cardiac electrical activity is an inverse mathematical problem and the current study is one of the many algorithms that have been developed to solve it
As stated above, the basic concept employed by the UC Santa Barbara group's work is that the inverse operator, (a mathematical function that maps body-surface ECG signals to electrical potentials in the innermost layer of the heart), can also be expressed in a non-linear fashion and optimized by adding patient-specific parameters
By carefully including more parameters, presumed models of body tissue can be optimized by actual patient data to provide more precise reconstructions of endocardial potentials.
“This enables development of models for predicting cardiac potentials that are accurate and realistic from electrocardiograms, and may be used as a new cardiac imaging tool," said Rajagopal.
Applications of the Inverse Operator Model
- Someday, instead of a doctor listening to the heart using a stethoscope, they may be able to see a live video of the heart activity via ultrasound with corresponding measurements of local electrical potentials around the heart. This technology will enable doctors to diagnose and treat patients with various heart conditions without the need to perform invasive surgeries just to determine the cause of the problem
- In some cases of atrial fibrillation, it may be possible to localize the origin of the abnormal rhythm and determine whether surgery is recommended for the patient.
ConclusionThe current research is significant because it shows that that much higher resolution of the tissues is possible if nonlinear reconstruction algorithms are employed using a few extended data, compared with what is described theoretically using linear methods and partial data.
Rajagopal said, "We were surprised that we didn't need to explode the number of parameters allowed in the reconstruction. By adding just a few extra parameters -- while still respecting the structure of the original reconstruction algorithm -- we found that high-accuracy reconstruction is possible."
- Noninvasive reconstruction of cardiac electrical activity: update on current methods, applications and challenges - (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4446282/)
- Nonlinear electrocardiographic imaging using polynomial approximation networks - (https://aip.scitation.org/doi/10.1063/1.5038046)