Importance of catheter contact force during irrigated radiofrequency ablation: evaluation in a porcine ex vivo model using a force-sensing catheter.
BACKGROUND
Ablation electrode-tissue contact has been shown to be an important determinant of lesion size and safety during nonirrigated ablation but little data are available during irrigated ablation. We aimed to determine the importance of contact force during irrigated-tip ablation.


RESULTS
Freshly excised hearts from 11 male pigs were perfused and superfused using fresh, heparinized, oxygenated swine blood in an ex vivo model. One-minute ablations were placed using one of 3 different power control strategies (impedance control-15 Omega target impedance drop, and 20 W or 30 W fixed power) and 3 different contact forces (2 g, 20 g, and 60 g) to give a grid of 9 ablation groups. The force sensing catheter (Tacticath, Endosense SA) was irrigated at 17 mL/min for all of the ablations. Of a total 101 ablations, no thrombus formation was noted but popping was seen in 17 lesions. The lesion depth and incidence of pops was 5.0 +/- 1.3 mm /0%, 5.0 +/- 1.6 mm /10% and 6.7 +/- 2.5 mm /45% for the 15 Omega, 20 W, and 30 W groups (P < 0.01), respectively, and 4.4 +/- 1.8 mm /3%, 5.8 +/- 1.6 mm /17% and 6.6 +/- 2.0 mm /37% for the 2 g, 20 g, and 60 g groups, respectively (P < 0.01). The impedance drop in the first 5 seconds was significantly correlated to catheter contact force: 9.7 +/- 9.9 Omega, 22.3 +/- 11.0 Omega, and 41.7 +/- 22.1 Omega, respectively, for the 2 g, 20 g, and 60 g groups (Pearson's r = 0.65, P < 0.01).


CONCLUSIONS
Catheter contact force has an important impact on both ablation lesion size and the incidence of pops.
Cardiac Electrophysiology Department, Massachusetts General Hospital, Boston, Massachusetts, USA.
Aravinda
A
Thiagalingam
Andre
A
D'Avila
Lori
L
Foley
J Luis
JL
Guerrero
Hendrik
H
Lambert
Giovanni
G
Leo
Jeremy N
JN
Ruskin
Vivek Y
VY
Reddy
D000818:Animals; D017115:Catheter Ablation / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D017097:Electric Impedance; D004867:Equipment Design; D006352:Heart Ventricles / Q000473:pathology / Q000601:surgery*; D066298:In Vitro Techniques; D008297:Male; D008422:Materials Testing; D023421:Models, Animal; D010477:Perfusion; D013552:Swine; D007507:Therapeutic Irrigation / Q000009:adverse effects / Q000295:instrumentation*