The publication of clinical case “In-situ fenestration and endograft for complicated type B aortic dissection”1 by the team at Hospital Central Ramón Carrillo in San Luis, Argentina, represents an excellent example of how technical innovation, precise planning, and institutional experience combine to resolve complex thoracic aortic situations through minimally invasive approaches.

This work demonstrates the successful use of in-situ fenestration (ISF) guided by fusion imaging to preserve flow in the left subclavian artery in a case of thoracic endovascular aortic repair (TEVAR) for complicated type B dissection. The use of navigation tools and specific fenestration systems evidences the technical growth of interventional teams in our country.

Why is in-situ fenestration a key strategy?

The need to cover the left subclavian ostium during a TEVAR or even an EVAR procedure (when the mesenteric or renal artery is involved) offers the challenge of maintaining perfusion to critical areas. In such cases, in-situ fenestration emerges as an effective technique to avoid hybrid procedures, reimplantations, or extra-anatomical bypasses, provided it is performed after strict anatomical planning and in experienced centers.

The concept of in-situ fenestration of endovascular stent grafts (that is, the creation of fenestrations in the prosthesis graft after deployment within the aorta) is well established, particularly for cases of complex aortic arch and thoracoabdominal repairs, including those involving aortic dissection.

For type B aortic dissection, especially when the dissection involves branch vessels or with an unfavorable proximal landing zone, several endovascular strategies have been cited:

In-situ fenestration techniques have been used to maintain or restore perfusion to branch vessels during endovascular repair, particularly in the aortic arch. A recent systematic review and meta-analysis found that in-situ and ex-situ fenestration techniques for endovascular arch repair, including in patients with aortic dissection, are associated with favorable short-term outcomes, with low 30-day mortality and stroke rates. However, the durability of these techniques remains uncertain due to limited long-term data. These techniques are more frequently used in emergent or rescue situations, but their indications may expand as experience grows2.

For acute type B aortic dissection with malperfusion, other current options are endovascular fenestration (creation of a reentry tear in the dissection flap) and stent placement in the branch vessels. Both are well established approaches. These techniques are used to treat dynamic and static malperfusion and have shown excellent short- and long-term results in large series, with low mortality and paraplegia rates. In such cases, fenestration generally refers to the creation of communication between true and false lumens, not to endoprosthesis fenestration in itself3-4.

In cases of type B aortic dissection involving the subclavian artery, in-situ fenestration techniques—mostly performed for the left subclavian artery (LSA)—are increasingly used to preserve branch perfusion when a proximal landing zone for TEVAR would require intentional coverage of the LSA. Key considerations include technical feasibility, procedural complexity, device selection, and comparative outcomes versus alternative revascularization strategies.

Technical success rates for LSA ISF are consistently high, generally exceeding 90% in both retrospective series and systematic reviews, and some studies report rates as high as 97%2, 10. The most common approaches use laser or needle fenestration, and energy-based techniques (laser or radiofrequency) are generally preferred because they fray the fabric less, thus creating a more controlled fenestration2, 5, 7. Covered stents are routinely deployed to maintain patency and minimize the risk of endoleak6, 9.

Perioperative outcomes are favorable. ISF is associated with low rates of stroke, spinal cord ischemia, and mortality. These are comparable to those observed with carotid-subclavian bypass or other revascularization techniques8. Neurological complications are uncommon, and most series do not report significant differences in major adverse events between ISF and surgical bypass8-9. ISF also avoids the morbidity of open surgical exposure, which is particularly advantageous in patients with hostile neck anatomy or high surgical risk6-7.

Medium- and long-term outcomes demonstrate excellent LSA patency (generally >95% at 3–5 years), low reintervention rates, and durable aortic remodeling3, 6, 9-10. Endoleak rates are generally low, and most cases of type I endoleak resolve spontaneously or are amenable to secondary intervention4, 6, 9. Comparative studies indicate that ISF is associated with lower rates of endoleak and branch occlusion than the chimney technique, although ISF is technically more demanding and requires more time3-4. Compared with carotid-subclavian bypass, ISF offers similar survival and patency, with a trend toward fewer early complications8, 10.

Device selection and procedural technique are highly important. Multilayer polyethylene terephthalate grafts are preferred for their durability, and non-compliant balloon dilation is recommended to optimize fenestration size and minimize fabric damage2, 5. Operator experience is critical, as ISF is technically complex and best performed in high-volume centers8, 10.

In summary, in-situ fenestration for LSA revascularization during type B aortic dissection TEVAR is a safe and effective alternative to surgical bypass or parallel graft techniques, with high technical success, excellent patency, and low complication rates in appropriately selected patients2, 10. Long-term durability is promising, but continuing evaluation is warranted.

Certified cath labs: an essential requirement

It is worth highlighting that this intervention was conducted in a cath lab certified by the Argentinian College of Interventional Cardiologists (CACI). At this point, I would like to pause and emphasize the value of cath lab certification for our healthcare system, not only as a symbol of quality, but also as a guarantee of minimum standards of safety, equipment, and continuing professional training.

The increasing complexity of structural and endovascular procedures requires not only technical knowledge, but also controlled environments, multidisciplinary support, and access to advanced technology. CACI’s effort in promoting these certifications must be supported by public and private institutions, prioritizing the development of specialized centers, especially outside major urban hubs.

Implications for the future

The presented case successfully resolves a highly complex pathology while also providing a roadmap for future procedures where 3D planning, device access, and integration between imaging and intervention will be essential.

These techniques can be progressively applied to the treatment of abdominal pathologies such as juxtarenal aneurysms or dissections with reentry, where targeted fenestration could replace more costly or surgical solutions.

Final thoughts

This article is more than a clinical case: it is an invitation to ponder on how modern interventional medicine requires planning, teamwork, institutional certification, and continuous training. As a specialized journal, RACI encourages the publication of experiences such as this one, which not only demonstrate technical resolution but also commitment to patient safety and the federal growth of our specialty.

Dr. PhD Carlos Fernández Pereira FACC, FESC, FSCAI

Editor-in-Chief, Argentinian Journal of Interventional Cardiology (RACI)

cfernandezpereira@centroceci.com.ar

1. Pollini Hugo, Fernandez Cambra Juan Manuel, Daniel Horacio José, Brisa Cora, Bravo Alfredo. Fenestración In-Situ y Endoprótesis en Disección Aórtica Tipo B Complicada: Innovación Endovascular Guiada por Imágenes. Revista Argentina de Cardioangiologí­a Intervencionista 2025;(02): 62-64. Doi: 10.30567/RACI/202502/0062-0064.

2. Prendes CF, Lindström D, Mani K, Tegler G, Wanhainen A. A Systematic Review of Experimental and Clinical Studies Reporting on in Situ Laser Fenestration of Aortic Endografts. Journal of Vascular Surgery. 2022;75(2):740-752.e1.

3. Ye P, Miao H, Zeng Q, Chen Y. Comparison of Total Percutaneous in Situ Microneedle Puncture and Chimney Technique for Left Subclavian Artery Fenestration in Thoracic Endovascular Aortic Repair for Type B Aortic Dissection. European Radiology. 2024;34(11):7136-7144.

4. Weng X, Zhang T, Hu Y, Li X, Zhou W.Castor Single-Branched Stent Graft and in Situ Fenestration in Treating Stanford Type B Aortic Dissection Involving the Left Subclavian Artery: A Retrospective Case-Control Study. Medicine. 2024;103(47): e40623.

5. Crawford SA, Sanford RM, Forbes TL, Amon CH, Doyle MG. Clinical Outcomes and Material Properties of in Situ Fenestration of Endovascular Stent Grafts. Journal of Vascular Surgery. 2016;64(1):244-50.

6. Sonesson B, Dias N, Abdulrasak M, Resch T. Midterm Results of Laser Generated in Situ Fenestration of the Left Subclavian Artery During Thoracic Endovascular Aneurysm Repair. Journal of Vascular Surgery. 2019;69(6):1664-1669.

7. Li X, Li Z, Jiao Z, et al. In Situ Laser Fenestration for Revascularization of the Left Subclavian Artery in Diseases of the Aortic Arch. Journal of Visualized Experiments: JoVE. 2025;(220).

8. Ozcinar E, Dikmen N, Baran C, et al. Comparative Retrospective Cohort Study of Carotid-subclavian Bypass Versus in Situ Fenestration for Left Subclavian Artery Revascularization During Zone 2 Thoracic Endovascular Aortic Repair: A Single-Center Experience. Journal of Clinical Medicine. 2024;13(17):5043.

9. Zhao Z, Qin J, Yin M, et al. In Situ Laser Stent Graft Fenestration of the Left Subclavian Artery During Thoracic Endovascular Repair of Type B Aortic Dissection with Limited Proximal Landing Zones: 5-Year Outcomes. Journal of Vascular and Interventional Radiology: JVIR. 2020;31(8):1321-1327.

10. Fan B, Fang K, Tian C, et al. In Situ Fenestration and Carotid-Subclavian Bypass for Left Subclavian Artery Revascularization During Thoracic Endovascular Aortic Repair. Cardiovascular and Interventional Radiology. 2024;47(6):717-727.

Para descargar el PDF del artículo
In situ fenestration: a precision technique in endovascular therapy and the role of accredited procedure suites

Haga click aquí