Catheter Contact Force and Electrograms

Relationship Between Catheter Contact Force and Electrogram Characteristics in Fibrillating Human Atrial Myocardium

Until recently, there was no way of telling how firmly the tip of the catheter was in contact with the heart and how this contact was orientated. The electrical signals measured through the catheters, known as electrograms, are used to guide the sites and duration of ablation, but the effect of catheter contact and orientation on these signals in human heart muscle that is fibrillating is not known. New catheters have now been developed which can measure the force of contact at their tip: using these, the investigators will examine how contact force affects the electrical behaviour of heart muscle tissue in atrial fibrillation. The effect the force of contact has on the electrogram recorded will also be investigated. In so doing we hope to gain a better understanding of the relationship between tissue contact and the electrograms we measure and in so doing improve the safety and effectiveness of ablation procedures. Hypothesis: Catheter contact force and orientation have a significant impact on the characteristics of bipolar electrograms in the fibrillating human atrium.

Effect of changes in contact force and orientation on: slew rate, local mean cycle length, electrogram complexity and fractionation index, dominant frequency, organisation index, CFAE grade, interval confidence level, shortest complex interval and average complex interval

Slew rate, local mean cycle length, electrogram complexity and fractionation index, dominant frequency, organisation index, CFAE grade, interval confidence level, shortest complex interval and average complex interval, amplitude change, AF cycle length, catheter impedance.

The interaction between catheter contact force and orientation and the power attained during power limited ablation

Use of contact catheters - Constellation and/or PentaRay Catheter to record fibrillatory electrograms and identify areas of interest

Inclusion Criteria: Persistent or paroxysmal atrial fibrillation Listed for ablation of atrial fibrillation on clinical grounds Exclusion Criteria: Contraindication to catheter ablation Contraindication to anticoagulation Contraindication to TOE

Ullah W, Hunter RJ, Baker V, Ling LH, Dhinoja MB, Sporton S, Earley MJ, Schilling RJ. Impact of Catheter Contact Force on Human Left Atrial Electrogram Characteristics in Sinus Rhythm and Atrial Fibrillation. Circ Arrhythm Electrophysiol. 2015 Oct;8(5):1030-9. doi: 10.1161/CIRCEP.114.002483. Epub 2015 Jul 7.

Ullah W, Hunter RJ, Baker V, Dhinoja MB, Sporton S, Earley MJ, Schilling RJ. Target indices for clinical ablation in atrial fibrillation: insights from contact force, electrogram, and biophysical parameter analysis. Circ Arrhythm Electrophysiol. 2014 Feb;7(1):63-8. doi: 10.1161/CIRCEP.113.001137. Epub 2014 Jan 18.