Abstract

Biophysical models of the atrium provide a physically constrained framework for describing the current state of an atrium and allow predictions of how that atrium will respond to therapy. We propose a work flow to simulate patient specific electrophysiological heterogeneity from clinical data and validate the resulting biophysical models. In 7 patients, we recorded the atrial anatomy with an electroanatomical mapping system (St Jude Velocity); we then applied an S1-S2 electrical stimulation protocol from the coronary sinus (CS) and the high right atrium (HRA) whilst recording the activation patterns using a PentaRay catheter with 10 bipolar electrodes at 12 ± 2 sites across the atrium. Using only the activation times measured with a PentaRay catheter and caused by a stimulus applied in the CS with a remote catheter we fitted the four parameters for a modified Mitchell-Schaeffer model and the tissue conductivity to the recorded local conduction velocity restitution curve and estimated local effective refractory period. Model parameters were then interpolated across each atrium. The fitted model recapitulated the S1-S2 activation times for CS pacing giving a correlation ranging between 0.81 and 0.98. The model was validated by comparing simulated activations times with the independently recorded HRA pacing S1-S2 activation times, giving a correlation ranging between 0.65 and 0.96. The resulting work flow provides the first validated cohort of models that capture clinically measured patient specific electrophysiological heterogeneity.

Highlights

  • Atrial fibrillation (AF) is a supra-ventricular tachyarrhythmia that is characterised by an uncoordinated activation of the atrial tissue (Skanes et al, 1998; Konings et al, 1994), with a consequent deterioration of mechanical function, Reant et al (2005)

  • On bipolar electrodes, where measurements are available, we evaluated conduction velocity (CV) using a piecewise linear approach, similar to that described in Cantwell et al (2015) and summarised below as follows: 1. On the site identified by the electrodes forming the PentaRay catheter, we interpolate the local activation times (LATs) measured at the 10 bipolar electrodes using piecewise-linear polynomia and a Delaunay triangulation

  • We locally compute the gradient of the interpolated LATs and we evaluate the modulus of the local CV as the inverse of the modulus of the gradient

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Summary

Introduction

Atrial fibrillation (AF) is a supra-ventricular tachyarrhythmia that is characterised by an uncoordinated activation of the atrial tissue (Skanes et al, 1998; Konings et al, 1994), with a consequent deterioration of mechanical function, Reant et al (2005). In many patients the mechanisms underpinning AF are unknown and there are no consensus guidelines for treating all patients (Marchlinski, 2008; Cosío, 2011), with many patients requiring multiple procedures to achieve sinus rhythm (Cappato et al, 2005). Local tissue properties, identified by fractionated electrograms (Nademanee et al, 2004), and a heterogeneous atrial substrate, O’Neill et al (2006) have been proposed to play a significant role in initiating and sustaining AF. Measuring these patient characteristics and linking them to AF sustenance and treatment remain challenging

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