FIRM-Guided Therapy Approach
FIRM-guided therapy is a personalized treatment procedure that involves two phases; first a diagnostic phase, in which individual sustaining sources of the arrhythmia are identified using the FIRMap® catheter and a second treatment phase, in which those diagnosed areas are targeted by ablation catheters to eliminate their presence. This FIRM procedure differs from the current common procedure which involves only a single treatment phase, common to all patients, called the pulmonary vein isolation (PVI).
The general diagnostic stage with diagnostic catheters always precedes the treatment stage using ablation catheters. A diagnostic catheter in the form of a basket (FIRMap) is introduced by vascular access, usually via the groin, to the heart chambers. The diagnostic basket catheter has a round shape that contains 8 splines. Each spline is equipped with 8 miniature electrodes (64 in total). Proper placement of the basket catheter is essential in assuring good contact with the heart chamber walls. Various sizes of the FIRMap catheter exist in order to accommodate larger or smaller heart chambers.
Following the placement of the FIRMap catheter, a computerized system records heart electrical activity derived from all 64 electrodes simultaneously and for period of time. Those recorded electrograms serve as the main component in identifying those individual targets, called rotors. Rotors are defined as electrical rotational activity (like a vortex) creating surrounding disorganized electrical activity/fibrillation. Those rotors are believed to be the sustainers of atrial fibrillation. From the current published clinical experience an individual patient may have 3-5 rotors identified in both atrial chambers.
Following identification and precise localization of those rotors inside the heart chambers, treatment is applied. The inserted ablation catheter is equipped with small electrodes that while in contact with the atrial wall; deliver either radiofrequency or freezing energy causing the ablation (destroying a small number of cardiac cells). Several ablations, covering a small part of the atrial tissue, may be applied in order to assure the elimination of the rotors. Clinical studies have shown that elimination of those inappropriate sources of electrical activity (rotors) is beneficial for the treatment of atrial fibrillation.