AMDS to Frozen Elephant Trunk Conversion: A Safe and Reproducible Redo Aortic Surgery Approach

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The patient had a previous type A dissection repair using an Ascyrus Medical Dissection Stent (AMDS) four years prior to the current operation. Follow-up computed tomography (CT) imaging showed arch aneurysm formation with persistent flow in the false lumen. The surgical plan was to extend the repair by adding a frozen elephant trunk (FET) to the AMDS, avoiding the need to remove the embedded stent. 

After performing a careful redo sternotomy, adhesions were released, and the previous Dacron graft was identified. The innominate vein and head-and-neck vessels were dissected out first, as there was adequate space for this. 

Arterial cannulation was established via direct cannulation of the innominate artery, which allowed antegrade cerebral perfusion during circulatory arrest. Venous drainage was achieved through the right atrium using a two-stage venous cannula, with a vent in the right superior pulmonary vein to drain the left ventricle during cardiopulmonary bypass (CPB). The aorta was cross-clamped and antegrade cardioplegia was given. Cooling was initiated to 20 degrees Celsius once on bypass. 

Once cooled, the aorta was opened under circulatory arrest with selective cerebral perfusion and snaring of the head vessels. The Dacron graft was dissected out. The head vessels were detached, and the stump on the arch was oversewn. The left carotid artery was cut open and clamped to stop backflow from the head during cerebral perfusion, and then the left subclavian artery was opened.  

After oversewing, the FET was deployed within the arch containing the AMDS. A 28 mm FET graft was introduced and deployed into the descending aorta. The sewing collar was aligned and anastomosed to the distal ascending aorta using continuous 4-0 Prolene sutures. The side branch of the graft was cannulated to re-establish full-body perfusion. 

The three main branches of the FET were used to reconstruct the innominate, left carotid, and left subclavian arteries. The left subclavian artery was found to be very friable, so the decision was made to tie off the vessel and oversew the stump. The left carotid and innominate arteries were reconstructed using a strip of Teflon and continuous 5-0 Prolene sutures. After careful deairing, flow was restored sequentially to the head and neck vessels, and the patient was rewarmed fully. 

Attention was then turned to the proximal anastomosis, connecting the FET to the proximal ascending aorta as a graft-to-graft anastomosis, just above the sinotubular junction, using continuous 4-0 Prolene. Once secured, the cross-clamp was released, and the heart resumed beating. Full perfusion was reestablished, and hemostasis was confirmed. The operation concluded with decannulation and chest closure. 

This case highlighted the safe conversion of an AMDS system to a FET using a graft. While it is possible to remove the AMDS in cases of infection, this technique showed a safe and reproducible approach of deploying the FET inside the stent.  

References

1. Maximilian Luehr, Christopher Gaisendrees, Abdul Kadir Yilmaz, Leila Winderl, Georg Schlachtenberger, Arnaud Van Linden, Thorsten Wahlers, Thomas Walther, Tomas Holubec, Treatment of acute type A aortic dissection with the Ascyrus Medical Dissection Stent in a consecutive series of 57 cases, European Journal of Cardio-Thoracic Surgery, Volume 63, Issue 3, March 2023, ezac581, https://doi.org/10.1093/ejcts/ezac581

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