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Author: search.filters.author.Choy, Young BinSubject: search.filters.subject.Ablation

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    Using electrical impedance to predict catheter-endocardial contact during RF cardiac ablation
    (2002-02-26)
    Cao, Hong
    ;
    Tungjitkusolmun, Supan
    ;
    Choy, Young Bin
    ;
    Tsai, Jang Zern
    ;
    Vorperian, Vicken R.
    During radio-frequency (RF) cardiac catheter ablation, there is little information to estimate the contact between the catheter tip electrode and endocardium because only the metal electrode shows up under fluoroscopy. We present a method that utilizes the electrical impedance between the catheter electrode and the dispersive electrode to predict the catheter tip electrode insertion depth into the endocardium. Since the resistivity of blood differs from the resistivity of the endocardium, the impedance increases as the catheter tip lodges deeper in the endocardium. In vitro measurements yielded the impedance-depth relations at 1, 10, 100, and 500 kHz. We predict the depth by spline curve interpolation using the obtained calibration curve. This impedance method gives reasonably accurate predicted depth. We also evaluated alternative methods, such as impedance difference and impedance ratio.
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    Flow effect on lesion formation in RF cardiac catheter ablation
    (2001-04-23)
    Cao, Hong
    ;
    Vorperian, Vicken R.
    ;
    Tungjitkusolmun, Supan
    ;
    Tsai, Jang Zern
    ;
    Haemmerich, Dieter
    This study investigated the flow effect on the lesion formation during radio-frequency cardiac catheter ablation in temperature-controlled mode. The blood flow in heart chambers carries heat away from the endocardium by convection. This cooling effect requires more power from the ablation generator and causes a larger lesion. We set up a flow system to simulate the flow inside the heart chamber. We performed in vitro ablation on bovine myocardium with three different flow rates (0 L/min, 1 L/rain and 3 L/min) and two target temperatures (60 °C and 80 °C). During ablation, we also recorded the temperatures inside the myocardium with a three-thermocouple temperature probe. The results show that lesion dimensions (maximum depth, maximum width and lesion volume) are larger in high flow rates (p < 0.01). Also, the temperature recordings show that the tissue temperature rises faster and reaches a higher temperature under higher flow rate.