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Douglas N Stephens,
Uyen T Truong,
Amin Nikoozadeh,
Omer Oralkan,
Chi Hyung Seo,
Jonathan Cannata,
Aaron Dentinger,
Kai Thomenius,
Alan de la Rama, Tho Nguyen,
Feng Lin,
Pierre Khuri-Yakub,
Aman Mahajan,
Kalyanam Shivkumar,
Matt O'Donnell,
David J Sahn
[show abstract]
[hide abstract]
ABSTRACT: The primary objective was to test in vivo for the first time the general operation of a new multifunctional intracardiac echocardiography (ICE) catheter constructed with a microlinear capacitive micromachined ultrasound transducer (ML-CMUT) imaging array. Secondarily, we examined the compatibility of this catheter with electroanatomic mapping (EAM) guidance and also as a radiofrequency ablation (RFA) catheter. Preliminary thermal strain imaging (TSI)-derived temperature data were obtained from within the endocardium simultaneously during RFA to show the feasibility of direct ablation guidance procedures.
The new 9F forward-looking ICE catheter was constructed with 3 complementary technologies: a CMUT imaging array with a custom electronic array buffer, catheter surface electrodes for EAM guidance, and a special ablation tip, that permits simultaneous TSI and RFA. In vivo imaging studies of 5 anesthetized porcine models with 5 CMUT catheters were performed.
The ML-CMUT ICE catheter provided high-resolution real-time wideband 2-dimensional (2D) images at greater than 8 MHz and is capable of both RFA and EAM guidance. Although the 24-element array aperture dimension is only 1.5 mm, the imaging depth of penetration is greater than 30 mm. The specially designed ultrasound-compatible metalized plastic tip allowed simultaneous imaging during ablation and direct acquisition of TSI data for tissue ablation temperatures. Postprocessing analysis showed a first-order correlation between TSI and temperature, permitting early development temperature-time relationships at specific myocardial ablation sites.
Multifunctional forward-looking ML-CMUT ICE catheters, with simultaneous intracardiac guidance, ultrasound imaging, and RFA, may offer a new means to improve interventional ablation procedures.
Journal of ultrasound in medicine: official journal of the American Institute of Ultrasound in Medicine 02/2012; 31(2):247-56. · 1.25 Impact Factor
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Chi Hyung Seo,
D.N. Stephens,
J. Cannata,
A. Dentinger,
Feng Lin,
Suhyun Park,
D. Wildes,
K.E. Thomenius,
P. Chen, Tho Nguyen,
A. de La Rama,
Jong Seob Jeong,
A. Mahajan,
K. Shivkumar,
A. Nikoozadeh,
O. Oralkan,
Uyen Truong,
D.J. Sahn,
P.T. Khuri-Yakub,
M. O'Donnell
[show abstract]
[hide abstract]
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.
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control 08/2011; · 1.69 Impact Factor
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Chi Hyung Seo,
Douglas N Stephens,
Jonathan Cannata,
Aaron Dentinger,
Feng Lin,
Suhyun Park,
Douglas Wildes,
Kai E Thomenius,
Peter Chen, Tho Nguyen,
Alan de La Rama,
Jong Seob Jeong,
Aman Mahajan,
Kalyanam Shivkumar,
Amin Nikoozadeh,
Omer Oralkan,
Uyen Truong,
David J Sahn,
Pierre T Khuri-Yakub,
Matthew O'Donnell
[show abstract]
[hide abstract]
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.
IEEE transactions on ultrasonics, ferroelectrics, and frequency control 07/2011; 58(7):1406-17. · 1.80 Impact Factor
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Chi Hyung Seo,
D. Stephens,
J. Cannata,
A. Dentinger,
Feng Lin,
Suhyun Park,
D. Wildes,
K. Thomenius,
P. Chen, Tho Nguyen,
A. Delarama,
Jong Seob Jeong,
A. Mahajan,
K. Shivkumar,
O. Oralkan,
D. Sahn,
P. Khuri-Yakub,
M. O'Donnell
[show abstract]
[hide abstract]
ABSTRACT: A method to monitor ablative therapy by examining slope changes in the thermal strain curve caused by speed of sound with temperature is introduced. The variation of sound speed with temperature rise for most soft tissue follows a similar pattern to that of water. Unlike most liquids, the sound speed of tissue 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 48-50°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 using the reduced slope in the thermal strain curve as a function of heating time. Using a prototype intracardiac echocardiography (ICE) array for imaging and a catheter for RF ablation, we were able to observe an obvious slope change in the thermal strain curve in an excised tissue sample. The method was further tested in-vivo, using a specially equipped ablation tip and an 11 MHz microlinear (ML) ICE array mounted on the tip of a catheter. As with in-vitro experiments, the thermal strain curve showed a plateau and a change in the sign of the slope.
Ultrasonics Symposium (IUS), 2010 IEEE; 11/2010
