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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
DIAGNOSTIC
Masking
SINGLE
Enrollment
55
Variable contact force as measured at the catheter tip within the left atrium
St Bartholomew's Hospital
London, United Kingdom
Electrogram characteristics
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
Time frame: Baseline and 30 seconds
Electrogram amplitude
Time frame: Baseline and 30 seconds
Electrogram responses to ablation
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.
Time frame: Baseline and 30 seconds
Ablation Power (Watts)
The interaction between catheter contact force and orientation and the power attained during power limited ablation
Time frame: Baseline and 30 seconds
Electrogram Contact Mapping
Use of contact catheters - Constellation and/or PentaRay Catheter to record fibrillatory electrograms and identify areas of interest
Time frame: During Study
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