Transcatheter aortic root replacement with chimney grafts for coronary perfusion: a preliminary test in a three-dimensional-printed root model

OBJECTIVES: Transcatheter aortic root repair is still not available because of the technical challenge of coronary perfusion. The use of chimney grafts for coronary ostia can be an option and we tested the flow-through coronary chimney grafts deployed in a 3-dimensionalprinted root model as part of a transcatheter aortic root repair system. METHODS: A 3 dimensional - printed root was used to test the coronary flow after the deployment of 1 root endograft (28 mm diameter) and two 6-mm diameter 10-cm long coronary chimney grafts. Continuous coronary flows were measured in a bench test at different pressure levels (60, 80 and 100 mmHg) and compared to target coronary flows (250 ml/min at rest for the left and 150 ml/min at rest for the right coronary artery). RESULTS: The computed tomography scan-based root was modified with two 5-mm diameter coronary conduits to overcome the limits of the original 3-dimensional-printed coronary ostia. The root was placed in the hydrodynamic system: adjusted coronary free flow at 60, 80 and 100 mmHg of pressure was 1913, 2200 and 2480 ml/min for left coronary and 1633, 2026 and 2366 ml/min for right coronary, respectively. After endografts deployment, mean chimney graft flow at 60, 80 and 100 mmHg of pressure was 1053 ml/min (-45%), 1306 ml/ min (-41%) and 1502 ml/min (-40%) for the left coronary and 1100 ml/min (-33%), 1460 ml/min (-28%) and 1626 ml/min (-31%) for the right coronary, respectively. CONCLUSIONS: In this preliminary study, chimney grafts for transcatheter aortic root repair provided 830% of target flow in the right coronary (-31% of free flow) and 414% of target flow in the left coronary (-42% of free flow) which is more than sufficient for both coronaries in real-life conditions. The potential of this approach should be further explored with specifically designed endografts.