In Situ Laser Fenestration for Revascularization of the Left Subclavian Artery in Diseases of the Aortic Arch

Summary

This article presents a detailed protocol for in situ laser fenestration for revascularization of the left subclavian artery during thoracic endovascular aortic repair, along with an analysis of midterm clinical outcomes. The experience is intended to provide fellow practitioners with insights into its clinical application.

Abstract

Thoracic endovascular aortic repair (TEVAR) has become a widely established treatment for aortic arch pathologies in recent years. However, lesions near or involving the origin of the left subclavian artery (LSA) often present challenges in securing an adequate proximal landing zone. Various technical approaches, including parallel graft techniques, fenestration, chimney grafts, branched devices, and others, have been developed to optimize the proximal landing zone while preserving LSA perfusion. Among these approaches, in situ laser fenestration (ISLF) of the LSA has emerged as a highly versatile and safe technique, demonstrating high success rates. This article provides a comprehensive overview of perioperative management and critical procedural steps for performing ISLF of the LSA, and presents clinical outcomes from a consecutive case series with a technical success rate of 94.5%. The objective is to offer vascular surgeons and interventional radiologists detailed insights to support the safe and effective application of this advanced technique.

Introduction

The treatment of thoracic aortic diseases has rapidly evolved in recent years. Thoracic endovascular aortic repair (TEVAR) is now widely used to manage thoracic aortic aneurysm (TAA), thoracic aortic dissection (TAD), penetrating aortic ulcer (PAU), intramural hematoma (IMH), and thoracic aortic injury (TAI)¹. TEVAR has even become the preferred approach for the elective treatment of descending TAAs and other thoracic aortic pathologies². To secure an adequate proximal landing zone during TEVAR, it is often necessary to cover the left subclavian artery (LSA), a step that may lead to complications³. Coverage of the LSA is associated with an increased risk of arm ischemia and neurological events, prompting the development of various revascularization strategies. These include parallel-graft techniques, fenestration, chimney grafts, branched devices, and others^4,5,6,7,8,9.

In situ laser fenestration (ISLF) is an advanced endovascular technique designed for branch artery revascularization during TEVAR. The objectives of ISLF include extension of the landing zone, preservation of branch artery perfusion, anatomical restoration, and reduction of post-operative ischemic complications. The development of medical diode laser systems has significantly advanced the feasibility and precision of ISLF. These systems function based on electronic transitions within semiconductor materials¹⁰. When an external current excites the semiconductor, electrons shift from higher to lower energy states, releasing photons. These photons are amplified via the gain medium or reflective mechanisms to produce a focused laser beam.

Medical semiconductor laser systems -- using materials such as aluminum, gallium, and arsenide as the gain medium -- generate laser beams through current excitation. The laser is delivered directly and precisely to the target site via an optical fiber, producing high-energy heat capable of cutting vascular grafts with exceptional precision while sparing surrounding tissues. After laser fenestration, a small balloon is used for initial dilation, followed by sequential balloon inflations to reach the desired diameter. A branched stent is then deployed to complete LSA revascularization.

Compared with the debranching technique, in situ laser fenestration (ISLF) avoids the high risk and invasiveness associated with thoracotomy and is associated with a shorter operative time¹¹. ISLF also eliminates the risk of gutter leaks, which can occur due to the grooves formed between parallel stents in chimney graft techniques^12,13. Additionally, branched devices require precise pre-operative measurements and custom fabrication¹⁴, whereas ISLF is more time- and cost-efficient, making it especially suitable for emergency cases¹⁵. Compared to in vitro pre-fenestration, ISLF offers advantages in speed, safety, and precise anatomical alignment¹⁶. These benefits make ISLF a valuable approach for left subclavian artery (LSA) revascularization across a wide range of clinical scenarios.

The authors' team has gained extensive experience in the clinical application of ISLF over several years. This article presents the ISLF protocol, highlights key procedural considerations, and summarizes the outcomes from the current research cohort.

Protocol

This protocol was approved by the Ethics Committee and Institutional Review Board of the First Affiliated Hospital of Zhengzhou University. Written informed consent for in situ laser fenestration (ISLF) is obtained from all patients undergoing thoracic endovascular aortic repair (TEVAR) at this institution, where the procedure is routinely performed. The inclusion criteria were as follows: (1) Patients with aortic arch pathologies undergoing TEVAR; (2) Patients with a proximal landing zone less than 15 mm adjacent to the aortic arch lesion; (3) Patients who underwent left subclavian artery (LSA) revascularization via ISLF and provided written informed consent. The exclusion criteria included: (1) Lesions involving the left common carotid artery (LCCA) or the proximal ascending aorta; (2) A dominant left vertebral artery originating directly from the aortic arch; (3) Patients with severe comorbidities (e.g., malignancies, hepatic or renal failure) deemed unfit for surgery. The details of the reagents and equipment used are provided in the Table of Materials.

1. Pre-operative planning

1. Perform computed tomography angiography (CTA) of the entire aorta prior to the procedure. Use three-dimensional planning software to reconstruct the aorta and obtain accurate measurements, including the proximal and distal landing zones.
2. Conduct pre-operative assessments, including electrocardiography, cardiac ultrasonography, pulmonary function testing, blood tests, and any additional examinations as clinically indicated.
3. Evaluate the indications for revascularization of the left subclavian artery (LSA).
   1. Consider revascularization when thoracic endovascular aortic repair (TEVAR) is proposed for aortic arch disease, including thoracic aortic aneurysm (TAA), thoracic aortic dissection (TAD), penetrating atherosclerotic ulcer (PAU), traumatic aortic injury (TAI), or intramural hematoma (IMH).
   2. Proceed with LSA revascularization if the proximal landing zone is less than 1.5 cm or if the lesion involves the LSA.
   3. Assess anatomic features for potentially compromised perfusion to critical structures, such as: (1) Presence of a patent left internal mammary artery-to-coronary artery bypass graft; (2) Absence, atresia, or occlusion of the right vertebral artery; (3) Aneurysmal disease in a young patient who may require future treatment involving the distal descending thoracic aorta; (4) Presence of a left upper extremity arteriovenous fistula; (5) Termination of the left vertebral artery into the posterior inferior cerebellar artery.
4. Select an appropriate stent graft based on anatomical and procedural requirements.
   NOTE: Use stent grafts with wide interstices and fabrics that can be easily fenestrated without tearing.

2. Endovascular procedure

1. Place the patient in the supine position. Administer general anesthesia routinely for patients (following institutionally approved protocols). Use local anesthesia with intravenous sedation if general anesthesia is contraindicated.
   NOTE: General anesthesia is performed by anesthesiologists. Administer fentanyl, propofol, and rocuronium intravenously to induce anesthesia, then perform endotracheal intubation or place a laryngeal mask airway. Maintain anesthesia with sevoflurane and remifentanil.
2. Disinfect the bilateral inguinal area and left cubital fossa area, then drape the surgical field.
3. Puncture the unilateral femoral artery using the Seldinger technique¹⁷. Insert a 5 F vascular sheath. Pre-position a closure device over the guidewire using the preclose technique¹⁸. Exchange for 8 F vascular sheaths.
4. Make a 2 cm oblique incision in the left cubital fossa. Puncture the left brachial artery under direct visualization. Insert a 5 F vascular sheath.
5. Initiate systemic heparinization using an intravenous heparin sodium bolus (30-40 U/kg). Administer an additional 1,000 U every hour.
6. Perform aortic angiography: Deliver a gold-labeled catheter with the guidewire to the ascending aorta. Confirm the extent of the lesion and the landing zone using high-pressure angiography. Use left anterior oblique projection for optimal imaging.
   NOTE: Determine the patient-specific degree of left anterior oblique with CTA reconstruction preoperatively.
7. Deploy the aortic stent graft: Exchange for a stiff wire. Deliver the aortic stent graft system over the guidewire.
   1. Position the proximal end of the stent graft distal to the left common carotid artery, covering the left subclavian artery (LSA). Confirm graft positioning with high-pressure angiography before releasing the main body.
8. Withdraw the delivery system. Perform angiography to confirm the positioning and expansion of the stent graft.
9. Perform laser fenestration: Insert a 7 F steerable introducer through the left brachial artery and position the distal end at the opening of the LSA of the main body of the stent.
   1. Deliver a small balloon catheter and laser fiber together through the sheath and position the distal end of the laser fiber at the stent membrane located at the LSA opening. Use the laser fiber to generate localized high-temperature burns and complete fenestration.
      NOTE: Laser parameters: output power, 18 W; fiber diameter, 400 µm; operating mode, intermittent (1 s on, 1 s off, repeated 3 times).
10. Advance the balloon catheter and withdraw the laser fiber after fenestration, then exchange it for a stiff guidewire. Perform pre-dilatation using a small balloon, then exchange for a suitable dilation balloon to enlarge the fenestration.
11. Insert another stent graft over the guidewire to achieve LSA revascularization. Post-dilate the LSA stent using an appropriately sized balloon.
12. Perform angiography to ensure proper stent graft positioning and exclude evidence of type I or type III endoleak¹⁹.
13. Close the incisions with simple interrupted sutures using 2-0 silk suture material in layers. Apply pressure dressings to the puncture sites.

3. Post-operative patient care

1. Closely monitor blood pressure and heart rate. Administer prophylactic antibiotics. Orally administer antiplatelet and/or anticoagulant medications.
2. Perform CTA at 1 month and 12 months post-procedure. Conduct annual CTA thereafter. Increase imaging frequency if an endoleak or other complications are detected.

4. Data collection and statistics

1. Perform follow-up. Assess technical success (complete exclusion of the arch lesion, successful LSA revascularization, and absence of type I and type III endoleak). Record procedural complications and mortality.
2. Report continuous variables as means ± standard deviation. Report categorical variables as numbers with percentages.

Results

This study retrospectively analyzed follow-up data from 127 patients who underwent thoracic endovascular aortic repair (TEVAR) with in situ laser fenestration (ISLF) for left subclavian artery (LSA) revascularization at this institution between July 2019 and April 2022. The median follow-up duration was 43 months (range: 28 to 65 months). The mean patient age was 55.1 ± 12.4 years, with 107 males (84.3%) and 20 females (15.7%) (Table 1).

The primary diagnoses included...

Discussion

ISLF is becoming more prevalent in the revascularization of branch vessels during TEVAR. ISLF for revascularization of branch vessels during TEVAR is safe and does not require much time for pre-operative measurements and stent design²⁰. The intraoperative fenestration process also does not require much time and is suitable for patients with acute or unstable conditions^21,22. Relatively few maneuvers are performed within the aortic lumen, w...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Angiographic Catheter	Merit Medical System	7602-20M	Catheter for angiography
Angiographic Catheter	Cordis Corporation	451-503H5	Catheter for angiography
Aortic Covered Stent System	Lifetech Scientific	XJZDZ232100	Stent graft system
basixCOMPAK	Merit Medical System	IN4130	A digital inflation device for balloons
Flexor Check-Flo Introducer	COOK Incorporated	KCFW-7.0-35-55-RB-HFANL1-HC	Used to introduce interventional devices
Laser Fiber Transmission System	Wuhan Gigaa Optronics Technology Co	GA-400-2	Deliver the laser
Perclose ProGlide	Abbott Vascular	12673	Vascular suture system
PTA Dilatation Catheter	ev3	AB35W03060135	Dilate blood vessels or stents
PTA Dilatation Catheter	Boston Scientific Corporation	H74939171100410	Dilate blood vessels or stents
Short Sheath Introducer	Merit Medical System	PSI-8F-11-035-18G	Sheath Introducer
Short Sheath Introducer	Merit Medical System	PSI-5F-11-035-18G	Sheath Introducer
Steerable Introducer	Lifetech Scientific	SVA7F-700	Establish access for device introduction
vascular stent graft	Angiomed GmbH & Co.MedizintechnikKG	FVL1004010*40	Stent graft
Wire	TERUMO	RF*GA35183M	Soft and ultra-smooth guidewire
Wire	TERUMO	RF*GA35263M	Soft and ultra-smooth guidewire
Wire	William COOK Europe ApS	TSCMG-35-300-LESDC	Guidewire