Extravascular Images of a Penetrating Aortic Ulcer Discovered During Robotic Segmentectomy

Abbreviations

CT

computed tomography

PAU

penetrating aortic ulcer

Case Description

A 68-year-old woman with a 25.3–pack-year history of smoking, hypertension, and hyperlipidemia was noted to have a left lower lobe nodule during a lung cancer screening computed tomography (CT) study. Positron emission tomography CT showed a hypermetabolic lesion suspicious for bronchogenic carcinoma. She also had a fusiform abdominal aortic aneurysm that did not meet criteria for intervention.

Left lower lobe superior segmentectomy with mediastinal lymph node dissection was performed via a robot-assisted thoracoscopic approach. After the left lung was retracted anteriorly and apically, a penetrating aortic ulcer (PAU) became visible in the descending thoracic aorta just distal to the arch (Fig. 1). Posterior hilar and fissure dissection were performed with successful transection of the left lower superior bronchopulmonary segment. Indocyanine green fluorescent dye was injected after pulmonary artery ligation to delineate the intersegmental boundary line. This dye allowed visualization of the PAU under near-infrared light, showing areas of decreased or absent fluorescence representing disruption of the vasa vasorum from atherosclerotic degeneration of the media (Fig. 2).

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Postoperative contrast-enhanced CT with angiography did not reveal abnormalities of the thoracic aorta (Fig. 3). Retrospective measurements revealed a PAU depth of roughly 6 to 7 mm and a maximum diameter of 1.8 cm. Thoracic endovascular aortic repair was performed with deployment of a 41 by 10-mm GORE TAG graft (W.L. GORE & Associates), and the patient was discharged 2 days later with a follow-up CT scheduled. Patient consent was obtained for publication.

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Comment

Penetrating aortic ulcer is a recognized category of acute aortic syndrome and can lead to morbidity and mortality.¹ This report includes intraoperative images of an isolated PAU from outside the vessel, discovered during an index thoracoscopic case for pulmonary malignancy. Enhanced visualization was provided by minimally invasive thoracoscopy and indocyanine green contrast. Postoperative CT angiographic imaging did not reveal abnormalities of the thoracic aorta, yet subsequent retrospective measurements revealed a PAU with a depth of 6 to 7 mm from the intima and a maximum diameter of 1.8 cm.

Although CT angiography is highly sensitive for acute aortic syndrome, data on accurate radiologic identification of PAU in particular are scarce, and subtle lesions can be overlooked.² In this case, the maximum diameter of 1.8 cm suggested a high-risk lesion. Other imaging characteristics indicative of intervention include a maximum PAU depth of at least 10 mm, a maximum diameter of 1.3 to 2.0 cm, associated intramural hematomas, saccular aneurysms, or increasing pleural effusions.³ Therefore, this case highlights the importance of intraoperative identification to decrease missed diagnoses of clinically significant PAU.

In addition, intraoperative extravascular images of PAUs are infrequently reported in the literature,⁴ and those that are reported do not provide the same exceptional clarity as robotic thoracoscopy.⁵ Near-infrared indocyanine green is ideal for real-time assessment of vascular flow and quickly revealed poorly perfused, necrotic regions that contribute to PAU pathogenesis and eventual rupture.⁶ The images provided in this report should serve as valuable educational tools because intraoperative recognition of PAU is critical to allow prompt vascular intervention and improve patient outcomes.