Image-based electrode array tracking for epicardial electrophysiological mapping in minimally invasive arrhythmia surgery.
OBJECTIVE
Electrophysiological mapping is effective in realizing a precise minimally invasive arrhythmia surgery. Recently, an epicardial electrophysiological mapping system for minimally invasive arrhythmia surgery was reported. The system requires a small electrode array, a tracking system and a global mapping algorithm. The optical tracking system employed in the research requires line of sight and complicated configuration. This paper proposes a new tracking method for locating an electrode array.


METHODS
We developed a small electrode array and optical markers. Center points of respective optical markers and the electrode array are tracked via an endoscopic stream and calculated in image space. The orientation of the electrode array is calculated using the dot product between the vector joining two center points of two upper optical markers and the vector joining two end points of the longest edge of the electrode array.


RESULTS
Mean tracking errors of position and orientation of the electrode array were 0.51 mm and 0.64°, respectively. And the processing time was constant at 46 ms per frame. Our method could successfully track the electrode array on the epicardium during in vivo experiment and a global epicardial electrophysiological map was reconstructed from separately measured epicardial electrograms by the small electrode array.


CONCLUSIONS
An image-based tracking method for locating an electrode array was proposed. Tracking accuracy, processing time and applicability to surgical environment of our method proved to be acceptable. Consequently, our method enables the electrode array tracking system to be simplified with no separate tracking system.
Kim
Hongho
H
Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo, Tokyo, Japan. kimhongho@bmpe.t.u-tokyo.ac.jp
de Lange
Paul
P
Ando
Takehiro
T
Joung
Sanghyun
S
Taniguchi
Kazuhiro
K
Liao
Hongen
H
Kyo
Shunei
S
Ono
Minoru
M
Takamoto
Shinichi
S
Kobayashi
Etsuko
E
Sakuma
Ichiro
I
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology* / Q000601:surgery; D006348:Cardiac Surgical Procedures / Q000379:methods*; D004195:Disease Models, Animal; D004566:Electrodes; D056149:Epicardial Mapping / Q000295:instrumentation*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019060:Minimally Invasive Surgical Procedures; D015203:Reproducibility of Results; D013552:Swine