Associated congenital anomalies
Congenital aortic arch malformations present a large spectrum of variations and the prevalence of these abnormalities varies between 1 and 2% among the general population. Kommerell diverticulum is one of such aortic arch anomalies and is defined as an aortic diverticulum arising at the origin of a subclavian artery from the proximal descending aorta. Although the anatomical variants of this anomaly are quite well described in the literature, we found only isolated reports concerning associated congenital anomalies [3, 4]. To the best of our knowledge there is no information regarding the combination of KD with dextrorotation, bovine arch, and bicuspid aortic valve and subsequent single stage surgical treatment.
Dextrorotation is a morphologic entity characterized by heart rotation to the.
right in both frontal and transverse planes of the body, while the location and function of the cardiac chambers are safe and normal. In contrast to dextrocardia, this anomaly is not associated with situs inversus, but is frequently complicated by additional cardiac malformations . Due to the dextrorotation of the heart, the aorta was much deeper and more posterior in the mediastinum, whereas the pulmonary artery was anterior and rotated to the right. This presented us with additional technical challenges, requiring “special tailoring” in the acute settings of our repair.
Bovine arch represents the most common variation of the aortic arch. In the past, it was considered as a physiological abnormality with no clinical impact but now much more attention is being given. The presence of bovine arch could pose significant challenges to the cardiac surgeon with influence on outcome. Moreover, currently the existence of bovine arch is considered a risk factor for inflammatory aortic disease .
Bicuspid aortic valve (BAV) is the most common congenital cardiac defect. BAV is often associated with other congenital lesions. Despite its importance, our understanding of BAV disease is incomplete. Patients with this anomaly may develop aortic post-stenotic dilatation and BAV can exaggerate genetic abnormalities of the aortic wall. Based on our previous observations we believe that with a bicuspid aortic valve paired with another form of aortopathy, such as coarctation, Kommerell diverticulum, and bovine arch, the ascending aorta is at higher risk of pathological aortic wall degeneration .
During the last decade, there has been increasing appreciation for the role of an underlying aortic disease associated with the diverticulum rupture . In histological specimens, we observed a significant degeneration of the aortic media. The presence of large amounts of acidic mucinous polysaccharides in the aortic media accompanied by loss and fragmentation of elastic fibers, can lead to weakness of the aortic wall, which is susceptible to rupture.
The presence of KD may predispose towards development of aortic aneurysm, aortic dissection, and rupture. Up to 6% of KD’s patients have been reported to present with rupture and 53% with either rupture or dissection . There is a strong correlation between the KD rupture and mortality rate. A few decades ago, regardless of treatment, mortality after KD spontaneous rupture was 100% . In recent years, with the advent of new methods of surgical management, this statistic has improved. Nevertheless, KD rupture with mediastinal hemorrhage or hematoma is a life-threatening emergency and requires immediate surgical intervention.
A strategy for surgical treatment of Kommerell diverticulum has not yet been finally established. This is most likely because the choice of surgical treatment, which is usually based on the individual anatomy of the patient, is very diverse. A number of surgical techniques with or without use of partial or total cardiopulmonary bypass, hypothermia, and circulatory arrest have been proposed for treatment of these aneurysms [2, 8,9,10]. The conventional treatment for the malformation includes complete removal of the KD, with reconstruction of the subclavian artery (SA), graft replacement of the aorta with SA ligation or reconstruction, endoaneurysmorrhaphy with SA reconstruction, total arch replacement with reconstruction of SA, and endovascular repair in selected patients. Perfusion strategies are also varied and include left heart or total cardiopulmonary bypass, moderate hypothermia, and deep hypothermic circulatory arrest with arterial cannulation in the femoral artery or descending aorta and venous cannulation in the pulmonary vein or common femoral vein.
In our patient, the KD originated in close proximity to the bovine arch, making proximal control and cross-clamping challenging. Therefore we used circulatory arrest and constructed open distal anastomosis without the impediment of a clamp. Due to dextrorotation we had to use a second piece of Terumo graft to connect the sinotubular junction to our neo-arch graft because of the severely angulated aorta. Our patient had no procedure-related complications or recurrence of symptoms. We believe that the use of this technique has facilitated the conduction of the procedure and improved its efficacy and safety. As we continue to master our strategy in treating complex aortic pathology like Kommerell diverticulum, the additional knowledge and understanding of this cardiovascular pathology will be quite valuable in determining the timing, surgical technique and extent of aortic reconstruction.
We also want to underscore that with the advancement of our surgical technique armamentarium and the improvements of medical technology, conditions that were previously considered “rare” but associated with adverse outcomes should be evaluated and addressed accordingly. In fact, many centers of excellence have started seeing these rare pathologies more frequently. Thus, it’s important that we have a better understanding of these pathologies and strategies for managing these patients, possibly providing excellent and long lasting results. We believe that there is an opportunity to collaborate with medical technology to come up with these new strategies.
In our case, we had a bicuspid aortic valve with ascending aortic dilatation, combined with Bovine aortic arch and Kommerell diverticulum. The cardiac dextrorotation made the “tailoring” of the grafts a little more challenging. With better medical technological designs, we should be able to address these sometimes rather complex aortic cases, even when done in an elective manner.