BackgroundBranched and fenestrated endovascular aortic repair (b/fEVAR) for thoracoabdominal aortic disease as well as thoracic disease (b/fTEVAR) has been well described. Its utilization has also grown over time with the need for solutions having outpaced technologies available in the United States. As more practitioners utilize these and other complex aortic repairs there is a growing utilization of adjunctive modalities expanding the capabilities of current devices. In-situ fenestration (ISF) has arisen as one of those modalities for both vessel fenestration and endoleak repair. ISF has been described for its role in bailout of thoracic endovascular aortic repair (TEVAR) particularly in fenestration for the left subclavian artery, but has not been well described in b/fEVAR in respect to the visceral vessels with most data limited to case series. We sought to review our single institution experience with this technique. MethodsSingle institution retrospective review of ISF during initial b/fEVAR, TEVAR from 2020 to 2022. Laser fenestrations post original b/fEVAR or TEVAR for endoleak repair were also included. Perioperative outcomes were obtained as well as angiographic results and short -term results found on follow up CT scans per SVS guidelines. Detailed operative techniques are discussed. ResultsA total of 13 patients were identified with 17 laser fenestrations. 11 ISF were planned preoperatively and 2 were intra-op decisions. The indications for surgery were type B aortic dissection with malperfusion (3), thoracoabdominal aortic aneurysm (TAAA): Non-ruptured (7), Ruptured (1), Type III endoleak post b/EVAR (1) and Type IA endoleak s/p fEVAR (1). Laser fenestration was used in conjunction of 3 TEVAR and 10 (b/fEVAR). The distribution of vessels fenestrated was: 5 left renal artery (LRA), 5 right renal artery (RRA), 4 left subclavian artery (LSCA), 1 superior mesenteric artery (SMA), 1 Celiac. Technical success was achieved in all 17 fenestrations with no 30-day mortalities, no post op dissection or spinal cord ischemia. There were 3 cases of endoleak at the completion of the operation, 1 type II and 1 type IIIc. ConclusionISF of aortic stent grafts in b/fEVAR and TEVAR is useful as a bailout in complex aortic repair with high likelihood of technical success and low morbidity.