Abstract
Background: Mechanical stretch is known to affect atrial electrical properties. Within the left atrium (LA) the mapping catheter delivers a stretch stimulus which may also affect the tissue's electrical properties. Methods and Results: Across 22 patients (16 in atrial fibillation (AF), 6 in sinus rhythm (SR)), undergoing first-time AF ablation, 1,774 stable LA mapping points comprising 8 second contact force (CF) and electrogram data were acquired. CF data was collected using a SmartTouch catheter with the Carto3 electroanatomic navigation system (Biosense Webster Inc, USA). Electrogram data was collected using LabSystem Pro (Bard Electrophysiology Division, USA). The electrogram data was analysed using custom-written automated scripts and the Carto3 automated complex fractionated electrogram (CFE) analysis tools. Points were taken in groups of 3 to 4 eight second recordings at the same location with CF or catheter orientation actively changed between acquisitions. There was no correlation between bipolar electrogram size and baseline CF in AF or SR, with a significant variation in electrogram size by atrial location (p 0.2). Changing catheter orientation from perpendicular to parallel did not affect bipolar electrogram size, DF or CFE measurements, but did result in a more negative electrogram (p=0.003). An increasing CF correlated with an increase in atrial ectopic incidence during SR (Point-Biserial Correlation 0.12, p=0.03). On sub-analysis by location, the correlation at the infero-posterior LA was strongest (Point-Biserial correlation 0.38, p=0.01). Conclusions: CF changes weakly correlate with changes in the SR and AF electrogram. CFE and DF measurements are not significantly affected by changes in CF or catheter orientation but higher CF is associated with increased atrial ectopics in sinus rhythm. These results suggest that electrograms observed in mapping studies are only minimally affected by changes in contact force and confirm the sensitivity of the left atrium to mechanical stretch. ![Graphic][1] [1]: /embed/inline-graphic-1.gif
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