An aberrant subclavian artery was historically considered a rare diagnosis. The combination of an aberrant left subclavian artery and a right aortic arch forms a vascular ring capable of causing tracheoesophageal compression. Similarly, a left aortic arch with an aberrant right subclavian artery may also produce a similar pinch mechanism. Many aberrant subclavian arteries are associated with dilatations at their aortic origin, referred to as Kommerell diverticula (KD). These diverticula carry a risk of aneurysmal degeneration, dissection, and aortic rupture. 

In recent years, advancements in imaging techniques and systematic study of the aortic arch in neonates have led to an increase in incidental diagnoses of these conditions. However, due to the lack of consensus on measurement methods and the limited data available, criteria for repair and resection of diverticula remain inconsistent and poorly defined. 

This single-center retrospective study included adult patients who underwent surgical repair of an aberrant subclavian artery or KD over a twenty-year period (01/01/02 – 12/31/21). A total of 37 patients were included, with follow-up data available for >97% of cases beyond one month. KD was defined when the diameter of the aberrant artery at its aortic origin was ≥ 50% larger than that of the ipsilateral carotid artery. Additionally, the authors introduced the “ASCA/Thoracic Inlet Index,” calculated as the ratio between the diameter of the aberrant artery at its thoracic outlet and the anteroposterior diameter of the thoracic inlet, with a reference normal value of 0.18. They evaluated symptom improvement and anatomical imaging characteristics across various groups. 

The mean age of the patients was 46 ± 17 years. Of the total, 62% were classified as left aortic arch with aberrant right subclavian artery (LAA + ARSA), while 38% had a right aortic arch with aberrant left subclavian artery (RAA + ALSA). At the time of diagnosis, 84% of the patients were symptomatic, and 51% had a KD meeting surgical indication criteria. Symptomatic patients exhibited larger KD diameters: 20.60 mm (interquartile range: 16.42-30.68 mm) in patients with ≥ 3 symptoms; 22.05 mm (interquartile range: 17.52-24.21 mm) in those with 2 symptoms; and 13.72 mm (interquartile range: 12.70-15.95 mm) in patients with only 1 symptom. Regarding surgical outcomes, while no mortality related to the intervention was reported, 30% of patients experienced complications (vocal cord dysfunction 11%, chylothorax 8%, Horner syndrome 5%, spinal deficit 5%, stroke 3%, transient dialysis requirement 3%), and 59% required aortic replacement. Indications for surgery included persistent symptoms, size/growth of KD, size/growth of the aberrant artery, thoracic aneurysm, type B dissection, and/or contained rupture. After a mean follow-up of 2.3 years, most patients reported resolution of dysphagia (92%) and dyspnea (89%), although symptoms of gastroesophageal reflux persisted in nearly half (47%). 

The authors concluded that KD aortic diameter correlates with the number of symptoms and that surgical repair of KDs, along with their aberrant arteries, resolves symptoms in most cases. However, they emphasize the importance of proper indication due to the complexity of these procedures and their associated complication rates. 

COMMENTARY: 

The fact that prevention is one of medicine’s most powerful tools is no secret. However, historically, surgeons have often perceived it as outside their scope. It is easy to think that our role is to address the patient’s current problem, despite many of our surgical indications being based on anticipating future issues to avoid reaching a point where surgery carries unacceptable risk or becomes excessively complex. 

Fortunately, we are increasingly aware that managing cardiovascular surgical pathology should not be limited to the surgical act itself. We recognize that many of our interventions and the materials we use are not definitive. We strive to design the best therapeutic sequence for our patient’s life expectancy, even if debates such as those surrounding TAVI in our country make us feel like we take one step forward and two steps back. 

This approach becomes particularly complex when discussing scenarios far apart in time. Childhood and adulthood are often perceived as completely separate. In a country where the large number of centers performing pediatric cardiac surgery is hardly justifiable (at least if we seek excellence in outcomes), there are still many populations linked to centers exclusively handling adult patients where the diagnosis, follow-up, and management of congenital cardiovascular pathologies remain somewhat neglected. 

This study is an excellent example of the importance of understanding the natural history of a pathology and addressing it in a multidisciplinary manner, applying the available evidence. Over the past years, we have observed how, across Europe, centers specializing in congenital heart diseases that have implemented systematic pre- and postnatal aortic arch study protocols have gone from rarely performing these types of surgeries to occasionally doing them weekly. Studies like this make us realize the impact of applying such protocols. Generally, these childhood interventions carry very low risk, are often performed using minimally invasive approaches, do not require aortic replacement or cardiopulmonary bypass, and result in hospital stays of just 3-4 days. In contrast, as shown by the authors, surgical complexity increases significantly in adulthood, along with morbidity. KD tissue in adults is more fragile and frequently associated with aneurysmal dilation. Nearly 60% of cases required aortic replacement, with 11% necessitating total arch replacement. It should not go unnoticed that 8% of patients arrived at the hospital with type B dissection or contained rupture, raising the question: what percentage never made it to the hospital? Additionally, it must be acknowledged that while surgery provides high symptom resolution, it is not absolute. A lifetime of airway and esophageal compression can lead to tracheomalacia and/or esophageal dysfunction that may not fully resolve upon relieving the compression. 

But one question remains: what should we do with patients referred to our clinic with asymptomatic KD or dilation? What should we do with incidental findings? In this article, the authors recommend intervening in children if the KD is >1.5 times the size of the aberrant artery and in adults when the KD measures 4 cm or exhibits growth >0.5 cm/year. However, it is worth noting that patients presenting with dissection/rupture had KDs smaller than 4 cm. Other authors (e.g., Idrees et al.) advocate for more aggressive indications, proposing surgery if the KD exceeds 3 cm. Meanwhile, other studies suggest that in asymptomatic cases, conservative management may be appropriate (Hale et al.). We have seen that surgical approaches are complex in many cases and not without complications. The reality is that we do not fully understand the actual risk of dissection or rupture, which are not minor complications. 

REFERENCE:

Griffeth EM, Stephens EH, Dearani JA, Francois C, Todd A, Miranda WR, et al. Outcomes of Surgical Repair of Aberrant Subclavian Arteries in Adults. Ann Thorac Surg. 2024 Feb;117(2):396-402. doi: 10.1016/j.athoracsur.2023.03.031.