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Updated: Aug 6, 2026
The WATCHMAN Left Atrial Appendage Closure Device for Atrial Fibrillation
Published on: February 28, 2012
Evaluation of a novel device for left atrial appendage exclusion: the second-generation atrial exclusion device
Keiji Kamohara1, Kiyotaka Fukamachi, Yoshio Ootaki
1Department of Biomedical Engineering, Lerner Research Institute, the Cleveland Clinic, Cleveland, Ohio 44195, USA.
Insights
A novel atrial exclusion device effectively and safely closed the left atrial appendage in a canine model. This offers a promising new approach to reduce stroke risk in patients with atrial fibrillation.
Area of Science:
- Cardiovascular Surgery
- Biomaterials Science
- Medical Device Engineering
Background:
- The left atrial appendage is a common source of thromboemboli in patients with atrial fibrillation.
- Excluding the left atrial appendage may reduce stroke risk in this patient population.
Purpose of the Study:
- To evaluate a second-generation atrial exclusion device for left atrial appendage exclusion.
- Assess device efficacy and safety in a midterm canine model.
Main Methods:
- Implantation of the modified atrial exclusion device in ten mongrel dogs via left thoracotomy on a beating heart.
- Midterm evaluation at 30 and 90 days using echocardiography, angiography, gross pathology, and histology.
Main Results:
- Successful implantation without complications, device migration, or hemodynamic instability.
- Complete left atrial appendage exclusion confirmed with no damage to adjacent arteries.
- Favorable biocompatibility demonstrated through macroscopic and microscopic assessments.
Conclusions:
- The atrial exclusion device provides rapid, reliable, and safe left atrial appendage exclusion.
- Clinical use could offer a new therapeutic strategy for stroke prevention in atrial fibrillation patients.
Background:
The left atrial appendage is a frequent source of thromboemboli in patients with atrial fibrillation. Exclusion of the left atrial appendage may reduce the risk of stroke in patients with atrial fibrillation. The atrial exclusion device, previously developed to perform left atrial appendage exclusion on a beating heart, was modified to accommodate different anatomic patterns of the human left atrial appendage and to ensure uniform pressure and occlusion. The purpose of this study was to evaluate this second-generation atrial exclusion device during a midterm period in a canine model.
Methods:
Ten mongrel dogs (mean weight 28.9 +/- 4.6 kg) were used in this study. The atrial exclusion device, constructed from two parallel and rigid titanium tubes and two nitinol springs with a knit-braided polyester fabric, was implanted at the base of the left atrial appendage through a left thoracotomy on a beating heart using a specially designed delivery tool. Dogs were evaluated at 30 days (n = 4) and 90 days (n = 6) by epicardial echocardiography, left atrial and coronary angiography, gross pathology, and histologic inspection.
Results:
Device implantation was performed without complications in all dogs. Complete left atrial appendage exclusion without device migration or hemodynamic instability was confirmed, and there was no damage to the left circumflex artery or pulmonary artery. Macroscopic and microscopic assessments revealed favorable biocompatibility during midterm follow-up.
Conclusion:
The atrial exclusion device enabled rapid, reliable, and safe exclusion of the left atrial appendage. Clinical application may provide a new therapeutic option for reducing the risk of stroke in patients with atrial fibrillation.
