Chimney technique for coronary obstruction after aortic valve in valve: pros and cons

Valve-in-valve transcatheter aortic valve implantation (TAVI) is associated with an increased risk of coronary obstruction because the surgical valve leaflets are pushed toward the coronary ostia and they also cover the TAVI stent which loses its free-flow nature. In this iconic case, a SAPIEN XT n20 was implanted inside a degenerated surgical Mitroflow n19 prosthesis that is known to be particularly prone to cause coronary obstruction due to its externally mounted pericardial leaflets. The left coronary was protected with preventive positioning without implantation of a drug-eluting stent 3.5 × 18 mm. After TAVI implantation acute severe left ventricle dysfunction with diffuse hypokinesia, coronary slow flow and obstruction of the left main developed (A and B). Stent deployment according to the ‘Chimney technique’ was therefore necessary to restore adequate flow (C and D). The post-operative computed tomography (E) demonstrates the radiolucent surgical leaflet (asterisk) compressed between the TAVI and coronary stent, highlighting the ‘Chimney’ created by the coronary stent between the degenerated leaflet and aortic wall above the top of the prosthesis to maintain coronary patency. This image also shows the significant stent protrusion and residual underexpansion caused by the extrinsic compression from the transcatheter valve surgical leaflet and the aortic wall, highlighting the high radial strength needed (at the time of the procedure stent post-dilatation was not considered necessary). These factors, along with the large amount of foreign material inside such a small aortic root may represent an environment with increased thrombogenicity, jeopardizing the long-term outcome. Alternative solutions to prevent coronary obstruction after TAVI are eagerly needed.