Tracking rotors with minimal electrodes: modulation index-based strategy.
BACKGROUND
High-frequency periodic sources during cardiac fibrillation can be detected by phase mapping techniques. To enable practical therapeutic options for modulating periodic sources (existing techniques require high density multielectrode arrays and real time simultaneous mapping capability), a method to identify electrogram morphologies colocalizing to rotors that can be implemented on few electrograms needs to be devised.


RESULTS
Multichannel ventricular fibrillation electrogram data from 7 isolated human hearts using Langendorff setup and intraoperative clinical data from 2 human hearts were included in the analysis. The spatial locations of rotors were identified using phase maps constructed from 112 electrograms. Electrograms were analyzed for repeating patterns and discriminating signal morphologies around the locations of rotors and nonrotors were identified and quantified. Features were extracted from the unipolar electrogram patterns, which corroborated well with the spatial location of rotors. The results suggest that using the proposed modulation index feature, and as low as 1 sample point in the vicinity of the rotors, an accuracy as high as 86% (P<0.001) was obtained in separating rotor locations versus nonrotor locations. The analysis of bipolar electrogram signatures in the vicinity of the rotor locations suggest that 62.5% of the rotors occur at locations where the bipolar electrogram demonstrates continuous activities during ventricular fibrillation.


CONCLUSIONS
Unipolar electrogram extracted modulation index-based detection of rotors is feasible with few electrodes and has greater detection rate than bipolar approach. This strategy may be suitable for nonarray-based single mapping catheter enabled detection of rotors.
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.).
Krishnanand
K
Balasundaram
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.).
Karthikeyan
K
Umapathy
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.).
Joyce
J
Jeyaratnam
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.).
Ahmed
A
Niri
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.).
Stephane
S
Massé
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.).
Talha
T
Farid
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.).
Krishnakumar
K
Nair
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.).
John
J
Asta
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.).
Robert J
RJ
Cusimano
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.).
Edward
E
Vigmond
From the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada (K.B., K.U., J.J., A.N.); Department of Cardiology, THFCFM Laboratory, Toronto, Ontario, Canada (S.M., T.F., K.N., J.A., K.N.); Department of Cardiology, Toronto General Hospital, Toronto, Ontario, Canada (R.J.C.); and LIRYC Electrophysiology and Heart Modelling Institute, Pessac, France (E.V.); and Laboratory IMB, University of Bordeaux, Talence, France (E.V.). k.nanthakumar@uhn.on.ca.
Kumaraswamy
K
Nanthakumar
D000200:Action Potentials; D003198:Computer Simulation; D004566:Electrodes; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation*; D019277:Entropy; D005240:Feasibility Studies; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008955:Models, Cardiovascular; D010363:Pattern Recognition, Automated; D011237:Predictive Value of Tests; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000503:physiopathology
catheter ablation; entropy; modulation index; rotors; ventricular fibrillation