Published Online
on December 3, 2008

A more recent version of this article appeared on February 1, 2009

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Original Article

Canine Model of Esophageal Injury and Atrial-Esophageal Fistula After Applications of Forward Firing High-Intensity Focused Ultrasound and Side-Firing Unfocused Ultrasound in the Left Atrium and Inside the Pulmonary Vein

Katsuaki Yokoyama¹; Hiroshi Nakagawa^1,3; Kenneth A Seres¹; Eugene Jung²; Jaime Merino²; Yong Zou²; Atsushi Ikeda¹; Jan V Pitha¹; Ralph Lazzara¹ and Warren M Jackman¹

¹ University of Oklahoma Health Sciences Center, Oklahoma City, OK;
² ProRhythm, Inc., Ronkonkoma, NY

³ E-mail: hiroshi-nakagawa{at}ouhsc.edu

Background—Left atrial-esophageal(LA-Eso) fistula is a serious and poorly understood complication of catheter ablation of atrial fibrillation. The purpose of this study was: 1) develop a canine model of esophageal injury and LA-Eso fistula after applications of forward-firing high-intensity focused ultrasound(HIFU) and side-firing unfocused ultrasound(SFU); 2) examine the relationship to esophageal temperature(Eso-temp); and 3) evolution of injury/healing.

Methods and Results—Twenty dogs were studied. After transeptal puncture, HIFU catheter(ProRhythm, 13dogs) was positioned close to the esophagus, either outside(n=6) or inside(n=7) the inferior pulmonary vein(PV). In 7 other dogs, SFU-catheter was placed deep inside PV, close to the esophagus. A balloon(20-25mm diameter) with 7 thermocouples(2mm-separation) was positioned in the esophagus(Eso-balloon). Variable air-filling of Eso-balloon controlled the distance from the esophagus to the sonication source, pressing the esophagus against LA/PV. One-9(median5) HIFU(35Watts) and 5-7(median5) SFU(40Watts) sonications were delivered for 40sec. Maximum luminal Eso-temp was closely related to HIFU-Eso-balloon distance. For HIFU outside PV, Eso-temp50°C occurred only for HIFU-Eso-balloon distance2mm. For HIFU/SFU inside PV, Eso-temp50°C with HIFU-Eso-balloon distance up to 6.8mm. Eso-endoscopy identified esophageal ulcer immediately after ablation in 11/13HIFU dogs and 7/7SFU dogs, all with Eso-temp50°C. Endoscopy at 2weeks showed ulcer healing in 5/11 chronic dogs and ulcer size progression with relaxation of the lower esophageal sphincter and esophagitis in 6 dogs. Two dogs developed LA-Eso fistula and died at 2weeks.

Conclusions—This model produces Eso-ulcer when Eso-temp50°C. Eso-temp is higher with HIFU/SFU-applications closer to the esophagus and with HIFU/SFU-applications inside PV. Ulcer progression and LA-Eso fistula were associated with reflux esophagitis.

Key Words: catheter ablation • atrial fibrillation • complications

Related Article

Canine Model of Esophageal Injury and Atrial-Esophageal Fistula After Applications of Forward-Firing High-Intensity Focused Ultrasound and Side-Firing Unfocused Ultrasound in the Left Atrium and Inside the Pulmonary Vein

Katsuaki Yokoyama, Hiroshi Nakagawa, Kenneth A. Seres, Eugene Jung, Jaime Merino, Yong Zou, Atsushi Ikeda, Jan V. Pitha, Ralph Lazzara, and Warren M. Jackman
Circ Arrhythm Electrophysiol 2009 2: 41-49. [Abstract] [Full Text] [PDF]