Catheters able to measure the
force and vector of contact between the catheter tip and myocardium are now
available. Pre-clinical work has
established that the degree of contact between the radiofrequency ablation
catheter and myocardium correlates with the size of the delivered lesion. Excess contact is associated with steam pops
and perforation. Catheter contact varies
within the left atrium secondary to factors including respiration, location,
atrial rhythm and the trans-septal catheter delivery technology used. Compared with procedures performed without contact
force (CF)-sensing, the use of this technology has, in some studies, been found
to improve complication rates, procedure and fluoroscopy times, and success
rates. However, for each of these
parameters there are also studies suggesting a lack of difference from the availability
of CF data. Nevertheless, CF-sensing
technology has been adopted as a standard of care in many institutions. It is likely that use of CF-sensing
technology will allow for the optimization of each individual radiofrequency
application to maximize efficacy and procedural safety. Recent work has attempted to define what
these optimal targets should be, and approaches to do this include assessing
for sites of pulmonary vein reconnection after ablation, or comparing the
impedance response to ablation. Based on
such work, it is apparent that factors including mean CF, force time integral
(the area under the force-time curve) and contact stability are important
determinants of ablation efficacy. Multicenter
prospective randomized data are lacking in this field and required to define
the CF parameters required to produce optimal ablation.
Credits: Waqas Ullah; Richard Schilling; Tom Wong