title: The feasibility of using thermal strain imaging to regulate energy delivery during intracardiac radio-frequency ablation.
abstract: A method is introduced to monitor cardiac ablative therapy by examining slope changes in the thermal strain curve caused by speed of sound variations with temperature. The sound speed of water-bearing tissue such as cardiac muscle increases with temperature. However, at temperatures above about 50°C, there is no further increase in the sound speed and the temperature coefficient may become slightly negative. For ablation therapy, an irreversible injury to tissue and a complete heart block occurs in the range of 48 to 50°C for a short period in accordance with the well-known Arrhenius equation. Using these two properties, we propose a potential tool to detect the moment when tissue damage occurs by using the reduced slope in the thermal strain curve as a function of heating time. We have illustrated the feasibility of this method initially using porcine myocardium in vitro. The method was further demonstrated in vivo, using a specially equipped ablation tip and an 11-MHz microlinear intracardiac echocardiography (ICE) array mounted on the tip of a catheter. The thermal strain curves showed a plateau, strongly suggesting that the temperature reached at least 50°C.
authors.affiliation: University of California, Davis, Department of Biomedical Engineering, Davis, CA, USA.
authors.forename: Chi Hyung
authors.initials: CH
authors.lastname: Seo
authors.forename: Douglas N
authors.initials: DN
authors.lastname: Stephens
authors.forename: Jonathan
authors.initials: J
authors.lastname: Cannata
authors.forename: Aaron
authors.initials: A
authors.lastname: Dentinger
authors.forename: Feng
authors.initials: F
authors.lastname: Lin
authors.forename: Suhyun
authors.initials: S
authors.lastname: Park
authors.forename: Douglas
authors.initials: D
authors.lastname: Wildes
authors.forename: Kai E
authors.initials: KE
authors.lastname: Thomenius
authors.forename: Peter
authors.initials: P
authors.lastname: Chen
authors.forename: Tho
authors.initials: T
authors.lastname: Nguyen
authors.forename: Alan
authors.initials: A
authors.lastname: de La Rama
authors.forename: Jong Seob
authors.initials: JS
authors.lastname: Jeong
authors.forename: Aman
authors.initials: A
authors.lastname: Mahajan
authors.forename: Kalyanam
authors.initials: K
authors.lastname: Shivkumar
authors.forename: Amin
authors.initials: A
authors.lastname: Nikoozadeh
authors.forename: Omer
authors.initials: O
authors.lastname: Oralkan
authors.forename: Uyen
authors.initials: U
authors.lastname: Truong
authors.forename: David J
authors.initials: DJ
authors.lastname: Sahn
authors.forename: Pierre T
authors.initials: PT
authors.lastname: Khuri-Yakub
authors.forename: Matthew
authors.initials: M
authors.lastname: O'Donnell
mesh_terms: D000818:Animals; D006348:Cardiac Surgical Procedures / Q000379:methods*; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods*; D004452:Echocardiography / Q000379:methods*; D005240:Feasibility Studies; D006358:Hot Temperature; D007431:Intraoperative Complications / Q000517:prevention & control; D009206:Myocardium / Q000166:cytology; D012815:Signal Processing, Computer-Assisted; D013552:Swine