Cathether contact geometry affects lesion formation in radio-frequency cardiac catheter ablation

Abstract

One factor which may be important for determining proper lesion creation in an atrial ablation procedure is catheter-endocardial contact. Little information is available that relates geometric contact, depth and angle, to ablation lesion formation. We present an electrothermal computer model of ablation that calculates lesion volume and temperature development over time. The Pennes bioheat equation was coupled to a quasistatic electrical problem. This method simulates importantly, not just catheter penetration depth, but also several different incident catheter angles as may occur in practise. Results show that for deeply penetrating tips, greater catheter angles reduce the rate of temperature buildup, allowing for larger lesions to form before temperatures become dangerous. It was also found that greater penetration may not lead to greater transmurality in lesion formation. We conclude that catheter contact angle plays a significant role in lesion formation, and the time course must be considered. This is clinically relevant because it makes proper identification and prediction of geometric contact variables a necessity in order to improve ablation efficacy and safety.

A computational model of open‐irrigated radiofrequency catheter ablation accounting for mechanical properties of the cardiac tissue

“…Specifically, the physical properties of the blood are obtained from the virtual population database from the IT IS foundation . The electrode and thermistor physical properties were found in the literature . We assume the electrical conductivity of the external factors board σ b to be constant, and we tune it to match the initial impedance of the experimental setup, as detailed in Section .…”

“…In particular, the catheter is unphysically penetrating the tissue without deforming it, as shown in the bottom row of Figure . However, the need for the incorporation of mechanical deformation in RFA modelling was hinted in a previous work . Indeed, the amount of power delivered to the tissue depends on the surface of contact between the electrode and the tissue itself .…”

“…12,13 Three-dimensional cardiac RFA models that use the same mathematical equations as the 2D axisymmetric models are also available. [14][15][16] For open-irrigated catheters, some models include the interaction of the saline inflow with a layer of saline in epicardial modelling 17 or with the surrounding blood in endocardial RFA. 18 Typically, a sharp insertion of the catheter in the tissue is considered, disregarding its elastic deformation.…”

“…However, the need for the incorporation of mechanical deformation in RFA modelling was hinted in a previous work. 16 Indeed, the amount of power delivered to the tissue depends on the surface of contact between the electrode and the tissue itself. 19 Sharp insertion produces larger surfaces of contact and is likely to overestimate the actual effect of the RFA treatment.…”

Mechanistic insights into heterogeneous radiofrequency ablation effects at the left atrial posterior wall during pulmonary vein isolation

“…Importantly, catheter angle was a more important determinant of impedance at greater modelled depth of tissue penetration. 19…”