title: Mechanical compliance of the endocardium.
abstract: Radio-frequency (RF) ablation is an accepted treatment for cardiac arrhythmias related to abnormal focal cardiac substrate. The penetration depth of the electrode into the endocardium affects lesion size, a critical determinant of success of RF ablation. We measured the relation between the mechanical compliance and the penetration depth of RF ablation catheter electrode at frequently ablated areas of the endocardium and examined the influence of time after death on mechanical properties of the tissue. We measured force versus time for eight insertion depths of the catheter electrode into full-thickness endocardial samples derived from the mitral valve annulus, the left ventricular free wall and the tricuspid valve annulus. We varied the time after death at 15, 40 min, 3, 8, and 18 h and repeated our measurements. At 15 min after death, the first 0.5mm penetration depth caused the fastest relaxation at 55 s. Force decay decreased dramatically at 15 min after death as the penetration depth increased from 0.5 to 4mm. We used the force data sampled at 60s after insertion to approximate the elasticity. We observed the relations between the force versus the insertion depth. The force increased by a factor of 5 for the mitral valve annulus and 8 for the left free wall from 15 min to 18 h. We derived coefficients of a second-order polynomial equation relating the force data to insertion depth with R(2)>0.99.
authors.affiliation: Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801, USA.
authors.forename: Young
authors.initials: Y
authors.lastname: Bin Choy
authors.forename: Hong
authors.initials: H
authors.lastname: Cao
authors.forename: Supan
authors.initials: S
authors.lastname: Tungjitkusolmun
authors.forename: Jang-Zern
authors.initials: JZ
authors.lastname: Tsai
authors.forename: Dieter
authors.initials: D
authors.lastname: Haemmerich
authors.forename: Vicken R
authors.initials: VR
authors.lastname: Vorperian
authors.forename: John G
authors.initials: JG
authors.lastname: Webster
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D004548:Elasticity; D004699:Endocardium / Q000503:physiopathology* / Q000601:surgery*; D006352:Heart Ventricles / Q000503:physiopathology / Q000601:surgery; D066298:In Vitro Techniques; D008943:Mitral Valve / Q000503:physiopathology / Q000601:surgery; D011180:Postmortem Changes; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013552:Swine; D014261:Tricuspid Valve / Q000503:physiopathology / Q000601:surgery; D014783:Viscosity