Impact of contact force in local impedance characterisation of cardiac tissue
Regions with pathologically altered substrate have been identified as potentially responsible for atrial fibrillation (AFib) and atrial flutter (AFlut) maintenance. However, these areas are not well characterized using magnetic resonance imaging or low voltage maps as they entail drawbacks when concluding on the underlying substrate. Local impedance (LI) measurements have recently gained attention in radiofrequency ablation because changes in conductivity may indicate alterations in myocardial electrophysiology. In these procedures, a decrease of 10-20% of the initial LI value is used as a marker of successful ablation. Moreover, the low electrode-tissue contact force is associated with ineffective lesion formation. The IntellaNav Stable PointTM catheter (Boston Scientific, Marlborough, MA, USA) offers both parameters, LI and contact force, as a novel combined technique to characterize the substrate and potentially also the success of lesion formation. LI values are expected to distinguish between healthy and scar tissue independently from the atrial rhythm, which can improve the understanding of underlying substrate, even more, when corrected for an eventual lack of contact by combining it with contact force.
Being able to analyse the effects of this tissue-catheter contact in impedance simulations will help us to better understand the relation with the phenomena we see in clinical settings.