Lessons learned from experimental models of cerebrovascular aneurysms to improve endocardial device occlusion of the left atrial appendage

Figures

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  Figure 1. A 71-year-old patient with atrial fibrillation who underwent a simultaneous ablation and a 27 mm Watchman device implantation with a large acute leak. A: Transesophageal echocardiography (TEE) image (left) and corresponding cartoon image depicting the leak (right). B: Left image shows ablation catheter (white arrow) placed within the leak. During radiofrequency ablation, bubbles are seen. C: Left image shows inflammation and edema at the ablation site (white arrow), appearing thicker and more echogenic. D: Left image shows a TEE image obtained 3 months later, showing complete occlusion with adhesions at the appendage ostium. The corresponding cartoon image (right) depicts expected fibrosis and leak closure.

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  Figure 2. Angiographic and macroscopic results after mechanical endothelial denudation (ED) and coiling of canine bifurcation venous pouch aneurysm. Selected views of angiograms performed immediately (a, d) and 3 months (b, e) after coiling, preceded (d, e) or not (a, b) by endothelial denudation. Large recurrence 3 months after coiling is seen (b), whereas aneurysms treated with denudation remain occluded (e). En face macroscopic view of the aneurysm shows that neointima formation at the neck at 3 months is more complete after ED (f) as compared with controls (c). (Image borrowed with permission from Raymond J, Guilbert F, Metcalfe A, Gevry G, Salazkin I, Robledo O. Role of the endothelial lining in recurrences after coil embolization. Prevention of recanalization by endothelial denudation. Stroke 2004;35:1471-1475.)

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  Figure 3. Prevention of canine vertebral artery recanalization after coil occlusion by radiofrequency (RF) ablation: angiographic results. Subclavian angiograms obtained before (a,e,i), immediately after (f), and at the end of the procedure (c,g), and 1 month after (d,h) coil occlusion of vertebral artery show recanalization of the right vertebral artery (arrow in h) but no recanalization (arrow in d) when RF ablation is applied before coil embolization (b). RF ablation alone (before coil occlusion in insert in b and without coil occlusion in j,k,l) does not lead to substantial angiographic changes. In this model, coil occlusion without ablation of the endothelial lining (e–h) routinely leads to occlusion by 1 hour (g) that recanalized at 2 weeks (h). (Image borrowed with permission from Raymond J, Savard P, Salazkin I, Bouzeghrane F. Radiofrequency endothelial ablation prevents recanalization after endovascular coil occlusion: in vitro and in vivo assessment. J Vasc Interv Radiol 2010;21:101–107.)

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  Figure 4. Results of bipolar radiofrequency (RF) ablation performed between an endovascular stent and the coil of coiled bifurcation venous pouch aneurysms 3 months after procedure. A: En face view of control pouch with coiling alone. B: Aneurysm treated with endovascular coiling and bipolar radiofrequency ablation. Neointimal closure of the aneurysm neck was dramatically better with RF ablation compared with controls. There is now no gap between the coil and the aneurysm wall, with complete sealing of the aneurysm neck. In addition, there is a layer of neointimal tissues covering the coil. (Image borrowed with permission from Boileau X, Zeng H, Fahed R, et al. Bipolar radiofrequency ablation of aneurysm remnants after coil embolization can improve endovascular treatment of experimental bifurcation aneurysms. J Neurosurg 2017;126:1537–1544.)