Take the icy plunge: frozen elephant trunk technique to repair penetrating aortic ulcers of the arch
Year: 2021
Type: editorial
Abstract: Penetrating aortic ulcer (PAU) is a focal disruption in the arterial intima and elastic lamina, extending into the media. Patients with PAUs are characterized by a high atherosclerotic burden [1]. Risk factors include advanced age, male gender, smoking, hypertension, coronary artery disease and chronic obstructive pulmonary disease [2]. The pathophysiology of PAUs is attributed to the erosion of atherosclerotic plaque and inflammatory changes in the aortic wall. PAUs have a variable course; some may develop in an aneurysm, intramural haematoma or aortic dissection [2]. PAUs are classified by acuity, location and presence of high-risk features; this classification guides the treatment strategy. PAU is on the spectrum of acute aortic syndromes, along with aortic dissection and intramural haematoma [3]. An acute PAU affecting the ascending aorta is an indication for urgent repair [4, 5]. Acute PAU of the aortic arch or descending thoracic aorta necessitates repair if high-risk features are present, including persistent or recurrent pain, contained rupture, rapid growth, periaortic haematoma or pleural effusion [5, 6]. Otherwise, uncomplicated PAUs are managed with anti-impulse therapy, cholesterol management and careful surveillance [5]. PAUs compromise 2–7% of all patients with acute aortic syndromes, and most are located in the abdominal or descending thoracic aorta [2]. Only 6.8% of PAUs are located in the aortic arch [7]. Asymptomatic, chronic PAUs with a diameter of >20 mm or a neck of >10 mm have a high risk of progression and benefit from repair [5]. Thoracic endovascular aortic repair (TEVAR) is the preferred technique to treat PAUs in the distal aortic arch and descending thoracic aorta [6]. However, there are instances in which a hybrid frozen elephant trunk (FET) technique is preferred. In this issue of the European Journal of Cardiothoracic Surgery, Kreibich et al. [8] describe a multicentre experience of 34 patients who underwent an FET to repair a PAU of the aortic arch during a 12-year period. This subgroup of PAUs represented less than one-tenth of the 364 FET procedures performed at 3 high-volume aortic institutions in Germany (Freiburg, Heidelberg and Salzburg). The patients had a median age of 69 years and a high incidence of cardiovascular risk factors. About 25% of patients underwent repair in the acute phase of this aortic syndrome, whereas the remaining patients underwent repair in the chronic phase. PAUs in the aortic arch were treated with the FET technique when TEVAR was not suitable for one of the following reasons: a landing zone of normal aortic tissue <20 mm, even after rerouting the arch vessels (left carotid-subclavian bypass/transposition, double transposition); dilation of the ascending aorta or aortic arch (>40 mm); or ‘shaggy’ proximal thoracic aorta. The FET technique used by the authors relied on one of two hybrid devices: the Thoraflex 100 mm (Vascutek, Terumo, Inchinnan, UK) or the Jotec E-vita 130 mm (Jotec GmbH, Hechingen, Germany) with 10% oversizing at the distal landing zone of the hybrid graft. All patients underwent selective antegrade cerebral perfusion, and the right axillary artery was the preferred arterial inflow site. Nearly 40% of the patients underwent a concomitant coronary artery revascularization. Prophylactic spinal cord drainage was not utilized preoperatively, and patients were cooled to a body temperature of 25°C. In most patients (59%), there were multiple PAUs present. Kreibich et al. reported an in-hospital mortality rate of 18%. The late mortality rate after discharge was 6% at a median follow-up time of 7 months. Postoperative stroke was observed in 15% of patients. Aortic reinterventions were observed in 29% of patients, with most of those patients undergoing TEVAR. No postoperative spinal cord ischaemia was observed. The study by Kreibich et al. makes an important contribution to our understanding of the outcomes and pitfalls of using the FET technique to treat PAUs of the aortic arch that are not amenable to endovascular repair. Patients with PAUs are older and have a higher atherosclerotic burden than do patients with other aortic arch pathologies. In a recently published systematic review of a large, all-comers cohort from 35 studies that included 3154 patients treated with the total arch replacement FET procedure in the acute and chronic setting, the operative mortality rate was 8.8% and the incidence of stroke was 7.6% [9]. The operative outcomes in the all-comers cohort were better than those in the study by Kreibich et al., which examined only patients with PAUs. This highlights the fact that patients with PAUs represent a high-risk cohort of patients who are older and have more cardiovascular risk factors. The higher incidence of stroke observed by Kreibich et al. is most likely attributed to the higher atherosclerotic burden of PAUs. It is important to emphasize that Kreibich et al. utilized strategies to reduce the risk of embolization, including a ‘no-touch’ technique when mobilizing the arch vessels, clamping the arch vessels away from their origin at the aortic arch (where most of the atherosclerosis occurs) and using the disease-free arterial site as a cannulation strategy. Perhaps using retrograde cerebral perfusion via the superior vena cava to flush atheromatous debris may be beneficial and warrants further investigation for mitigating the risks of neurological complications in this high-risk group [10]. How do we decide between TEVAR and a hybrid total arch replacement with FET in patients with PAUs of the aortic arch? We believe that these patients should be treated at dedicated aortic centres by an interdisciplinary team. Our preference is to utilize a TEVAR approach with liberal use of arch vessel debranching procedures. However, situations arise that favour a hybrid total arch replacement with FET. Specific considerations include endovascular technical factors and patient factors [6]. Inadequacy of a landing zone of healthy aorta even after arch vessel rerouting procedures, a dilated ascending aorta, ‘shaggy aorta’ and poor access vessels favour the use of the hybrid FET approach. Other factors including age, comorbidities, frailty and concomitant cardiac lesions determine the suitability of open surgery. Kreibich et al. provide evidence that a hybrid FET approach is a good treatment option for patients with PAUs of the aortic arch that are not amenable to TEVAR. However, these patients with PAUs have a large atherosclerotic burden and represent a high-risk cohort with greater operative mortality and stroke rates than patients with other aortic arch pathologies. The authors thank Nicole Stancel, PhD, ELS(D), of the Department of Scientific Publications at the Texas Heart Institute for her editorial contributions.
Institution: Baylor College of Medicine
Language: English
Subfield: Pulmonary and Respiratory Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
Funder: Texas Heart Institute
OpenAlex ID: W3128184602