How-To: Left Atrial Appendage Exclusion During Cardiac Surgery

Postoperative atrial fibrillation is the most common arrhythmia following cardiac surgery. While often self-limiting, studies have demonstrated that it is associated with increased morbidity and mortality, including thromboembolic stroke and recurrent atrial fibrillation, hospital stay length, and healthcare costs. Furthermore, research has shown that in patients with nonvalvular atrial fibrillation, the left atrial appendage serves as the nidus of atrial thrombi in 90 percent of patients.  

Long-term anticoagulation is the standard of care for reducing atrial fibrillation–related ischemic stroke; however, 30 to 50 percent of patients who would benefit from oral anticoagulation have either absolute or relative contraindications because of increased risk of bleeding. The limitations of oral anticoagulation have led to a growing interest in the concept of left atrial appendage exclusion. We routinely exclude the left atrial appendage using the AtriClip device during coronary artery bypass graft surgery for left atrial appendage management.  

This video demonstrates left atrial appendage clip deployment and placement. 

Procedure 

The left atrial appendage is an extension of the left atrium and is easily accessible during coronary artery bypass graft surgery. For the device to effectively exclude the left atrial appendage and avoid leaving a stump, dissection must be performed down to expose its true base. Thus, a thorough understanding of the location of the left atrial appendage and its relationship to important neighboring structures is critical, as serious complications from inappropriate deployment of left atrial appendage exclusion devices have been reported. 

The left atrial appendage is located anterolaterally near the pulmonary trunk, the ligament of Marshall (which is the remnant of the left superior vena cava), and the left pulmonary veins. It also lies in the left atrioventricular groove atop the proximal portion of the circumflex artery. The video above shows a figure that illustrates the relationship of the left atrial appendage to these neighboring structures. Division of the ligament of Marshall is required to reach the true base of the left atrial appendage. 

The left atrial appendage is carefully freed from its attachments to the remainder of the left atrium. This is especially true in regard to understanding the location of the circumflex artery in relation to the left atrial appendage. The surgeon must take great care to dissect the left atrial appendage and avoid the circumflex artery, which is identified with the forceps. Once the left atrial appendage is completely exposed, it is sized with the AtriClip size measurer at its base. In the case illustrated above video, a size 50mm AtriClip device was selected. 

The device is composed of two parallel polyester-covered titanium tubes with elastic nitinol springs. When the device is closed, uniform pressure is applied over the length of the two titanium tubes to ensure consistent and secure left atrial appendage exclusion. In the video above, the AtriClip was positioned at the base of the left atrial appendage. The key is to ensure that you get the whole distance across the base with visualization of the ends of the device tips. Again, care must be taken to ensure not to include the circumflex artery into the clip. At this stage in the accompanying video, the tips of the forceps outline once again how close the circumflex artery is to the left atrial appendage and clip.  

Once the surgeon is satisfied with the position of the clip, it is then deployed. During this maneuver, successful clip deployment is confirmed by the absence of flow in the left atrial appendage after clip application on transesophageal echocardiography. This illustrates that the clip is in a good position.

References

1. 1Villareal RP, Hariharan R, Liu BC, et al. Postoperative atrial fibrillation and mortality after coronary artery bypass surgery. J Am Coll Cardiol. 2004;43(5):742-748.
2. Kaireviciute D, Aidietis A, Lip GY. Atrial fibrillation following cardiac surgery: clinical features and preventative strategies. Eur Heart J. 2009;30(4):410-425.
3. Bramer S, van Straten AH, Soliman Hamad MA, Berreklouw E, Martens EJ, Maessen JG. The impact of new-onset postoperative atrial fibrillation on mortality after coronary artery bypass grafting. Ann Thorac Surg. 2010;90(2):443-449.
4. Kalavrouziotis D, Buth KJ, Ali IS. The impact of new-onset atrial fibrillation on in-hospital mortality following cardiac surgery. Chest. 2007;131(3):833-839.
5. January CT, Wann LS, Calkins H, et al. 2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2019;74(1):104-132.
6. Bedeir K, Holmes DR, Cox JL, Ramlawi B. Left atrial appendage exclusion: An alternative to anticoagulation in nonvalvular atrial fibrillation. J Thorac Cardiovasc Surg. 2017;153(5):1097-1105.
7. Page S, Hallam J, Pradhan N, et al. Left Atrial Appendage Exclusion Using the AtriClip Device: A Case Series. Heart Lung Circ. 2019;28(3):430-435.

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