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 length of stay, and healthcare costs. Furthermore, research has shown that in patients with non-valvular atrial fibrillation, the left atrial appendage serves as the nidus of atrial thrombi in 90% of patients. Long-term anticoagulation is the standard of care for reducing atrial fibrillation-related ischemic stroke, however 30-50% of patients who would benefit from oral anticoagulation have either absolute or relative contraindications due to 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.
The left atrial appendage is an extension of the left atrium and is easily accessible during coronary artery bypass graft surgery. This is the left atrial appendage that is exposed and displayed here. In order 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 and lies in the left atrioventricular groove atop the proximal portion of the circumflex artery. This figure illustrates the relationship of the left atrial appendage to these neighboring structures. Division of the ligament of Marshall is required in order 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 as can be seen here. This is especially true in regards to understanding the location of the circumflex artery in relation to the left atrial appendage as you can see the surgeon is taking great care to dissect the left atrial appendage and avoid the circumflex artery which is identified here with the forceps. Once the left atrial appendage is completely exposed, it is sized with the AtriClip size measurer at its base. In this case, we have decided to select a size 50mm AtriClip device.
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. Here, the AtriClip is being 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. This tips of the forceps here are outlining 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 the clip in a good position.
References
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