Inês joined our lab as an international graduate student from NOVA school of science & technology, Lisbon, Portugal to pursue her M.S. thesis. I had the good fortune of being her thesis advisor. I am excited and happy to report that Inês successfully defended her dissertation and is now a proud graduate of NOVA University.
Effects of spatial resolution on arrhythmia driver detection and localization
Arrhythmia is a cardiac rhythm disorder that can be fatal. Its treatment includes ab- lation of the cardiac tissue and/or defibrillation. Advances are being made for both treatment options to localize the culprit region and apply therapy directly where it is needed. However, success rates have been inconsistent, with frequent arrhythmia recurrence. A likely reason is the limited current resolution of mapping devices, that averages 4 mm. Higher resolution may improve localization of arrhythmia drivers, termed rotors, and consequently improve efficacy of treatment.
This study evaluates the effects of spa- tial resolution on arrhythmia dynamics, rotor tracking, and rotor localization. Optical data from ex vivo human hearts was used, being clinically relevant and with ultra-high spatial resolution. To simulate different resolutions, original data was downsampled by multiple factors and upsampled back to full resolution. Rotors were tracked for each sub-resolution and compared to the rotors in the original data. Further comparisons were made according to arrhythmia type, sex, anatomical region, and mapped surface. Accuracy profiles were created for both rotor detection and localization, describing how accuracy changed with spatial resolution and spatial accuracy.
Rotor detection accuracy for currently used mapping devices was found to be 57±4%. Localization accuracy is 61±7%. Detection accuracy was above 80% only for a resolution of 1.4 mm. Moreover, the detection and localization accuracies were affected by arrhythmia type, and rotor incidence was found to be higher in the endocardium. Therefore, current clinical rotor detection and localization accuracies can be expected to fall within a confidence interl,gttval of 47-67% and 46-75%, respectively. This means that a higher spatial resolution is needed in cardiac mapping devices than what is currently available.
For high accuracy, a resolution of at least 1.4 mm is required. The accuracy profiles provided in this thesis may serve as a guideline for future mapping device development.
To provide context, Dr. Igor Efimov is part of a group of scientists that was awarded a high profile research grant by the Leducq foundation as part of their transatlantic network of excellence. The project description and information on the research group can be found on the Leducq Foundation web-site.
I had the opportunity last year (Oct 1-2, 2018) to present my research at the annual Rhythm conference held at the Amsterdam Medical Center (AMC) in Amsterdam, Netherlands. It was privilege and pleasure to do so.
I had the opportunity to interact with some of the giants in my field of research (cardiac electrophysiology). I also got valuable feedback on my research, which for me, was one of the primary objectives for the trip. Mission accomplished!
One of the privileges of doing cutting edge biomedical research is the opportunity to invent new technology or application that can quickly be translated in to a clinically available product for the benefit of all who may need it. I feel fortunate to have that opportunity working with Dr. Igor Efimov in his lab at George Washington University (GWU). As such, with the guidance from GWU technology commercialization office, we have filed for a US patent. On one side, patents guarantee the return of an inventor’s investment and profit and, on the other side, ensure availability — by patent disclosure — of the invention for the society when the patent terminates. As a scientist, I am more driven by the need to contribute to society, and less so to make a profit. Hopefully, this is the first step in that direction. More details about this technology can be found here
My co-authored research article titled – Critical Volume of Human Myocardium Necessary to Maintain Ventricular Fibrillation was published in the peer review journal – Circulation. Arrhythmia and Electrophysiology. The article is available in print, in the December 2018 issue of the journal.
Briefly, the manuscript documents evidence using donor human hearts that ventricular arrhythmias (e.g., ventricular fibrillation) is only sustained if the cardiac tissue volume exceeds the cardiac wavelength volume . The article can be accessed here
My co-authored research article titled – PFEIFER: Preprocessing Framework for Electrograms Intermittently Fiducialized from Experimental Recordings was published in the peer review journal – Open Source Software. The article is available in print, in the December 2018 issue of the journal.
Briefly, the manuscript documents a Preprocessing Framework for Electrograms Intermittently Fiducialized from Experimental Recordings (PFEIFER) in the form of a MATLAB Graphical User Interface designed to process bioelectric signals acquired from experiments The article can be accessed here