Catheter tip force required for mechanical perforation of porcine cardiac chambers.

AIMS: Catheter manipulation during ablation procedures can produce injury and tamponade. We evaluated the mechanical forces required to perforate a porcine heart with an ablation catheter. METHODS AND
RESULTS: A 7 Fr, 3.5 mm irrigated radiofrequency (RF) ablation catheter with a force sensor (FS) within its tip was used to create right atrial (RA) free wall lesions in pigs. The intact heart was removed and the FS-equipped catheter was used to mechanically perforate (without RF delivery) the free walls of both atria and ventricles: directly and through an introducer sheath to prevent catheter shaft buckling. Perforation was also performed through epicardially visible RA lesions and adjacent unablated tissue. Twenty-four RA free wall lesions were created in four pigs. One hundred and forty-four mechanical perforations were performed: 44 RA, 30 left atrial (LA), 37 right ventricular (RV), and 33 left ventricular (LV). The RA and RV perforation force (PF) was lower than through the LA and LV (P<0.0001). The LV perforation time was shorter when the catheter was gripped through an introducer sheath (0.8±0.5 vs. 3.2±3 s, P<0.0001). Perforation force through transmural RA lesions was lower than through unablated RA tissue (172.4±79.1 vs. 300.6±116.8 g, P<0.0002).
CONCLUSION: The force threshold for mechanical perforation in the porcine heart is lower for right- compared with left-sided chambers, and also lower through recently created RA RF lesions compared with unablated RA tissue. Left ventricular perforation is achieved more rapidly with the ablation catheter in a sheath despite the same PF because the sheath prevents catheter buckling.