Bicuspid Aortic Valve, Bovine Aortic Arch and early Atherosclerosis: When one plus one equals three

Despite that even normally functioning bicuspid aortic valves can have abnormal transvalvular-fl ow patterns, resulting in regional increases in wall shear stress and aortic dilatation, most often are preserved during ascending aorta replacement. On the other hand, the most common normal variant of aortic arch branching, known as bovine aortic arch, may be considered a risk factor for the development of ascending aorta dilatation, as recent studies have shown. However, data are lacking in the literature regarding the involvement of bicuspid aortic valve and/or bovine aortic arch in early atherosclerosis development.


Discussion
We present a case of a young female patient with BAV and surgically corrected bicuspid aortopathy, BAA, newly diagnosed essential hypertension, generalized early atherosclerosis and carotid atherosclerotic disease. Are those entities interrelated? BAV is the most common congenital heart defect in adults, affecting 1.3% of the population worldwide [1]. Although aortic stenosis and aortic regurgitation are the most common complications of BAV, dilatation of any or all segments of the proximal aorta from the aortic root to the aortic arch, known as bicuspid aortopathy, is also present in approximately 50% of the affected persons. The development of aortopathy and its specifi c types has been attributed to genetic and hemodynamic factors. The concept that abnormal valve dynamics lead to bicuspid aortopathy is supported by the observation that even normally functioning BAV, as in the case of our patient, can result in regional wall shear stress abnormalities, which predispose to aortic aortopathy.
Recent ESC guidelines for aortic diseases recommend that surgery should be considered in patients with a BAV who have aortic root aneurysm with maximal ascending aortic diameter ≥ 55 mm without other risk factors and ≥ 50 mm with the presence of at least one of the following risk factors: coarctation of the aorta, systemic HTN, family history of dissection or an expansion rate of the ascending aortic aneurysm (AAA) of ≥ 3 mm per year. However, guidelines emphasize that the decision for surgery in patients with small body size, must be based on the aortic diameter indexed to BSA, with a threshold ≥ 27.5 m 2 [1]. Accordingly, the referral for cardiovascular surgery of our patient was appropriate, considering her ascending aortic dilation index equal to 30 mm/m 2 .
Considering the 'unexplained' advanced carotid fi ndings of our patient, the preservation of the 'normal' functioning BAV, without valve tricuspidization or replacement in concert with aortic graft placement may possibly aggravate even The patient's relative 10-year cardiovascular risk according to HeartScore was 4 times greater compared with normal subjects of the same sex and age, mainly due to smoking (explaining 65% of her total CVD risk).   and aortic aneurysm in patients over 70 years old [7]. The authors tried to explain this association using Coanda effect [8].
They proposed that the wide origin of the combined innominate and left common carotid arteries leads to a streaming phenomenon, which would marginalize high velocity blood fl ow and potentially increase vessel wall shear stress. Increased shear stress has been linked to ascending aortic wall injury and dilatation. The last 3 years several studies have demonstrated the association of BAA with dilatation of the ascending aorta and suggested that BAA should be considered a risk factor for aortic dilatation [9][10][11][12]. Furthermore, Elefteriades JA et al have proceeded with histological assessment studies of the aortic wall in patients with BAV and BAA and found that both entities seem to affect vascular wall architecture [13].
Up to date, the association of BAA with carotid atherosclerosis was assessed only in one study of Baadh et al in a small number of patients, which showed no signifi cant correlation [14].  [15]. In the case of BAA, the origin of the left common carotid artery from the innominate artery may have a signifi cant effect on the geometry of the carotid bulb, altering regional blood fl ow dynamics and thus contributing to an increased susceptibility for the development of atherosclerotic carotid disease.

Conclusion
Complete cardiovascular system evaluation often reveals "normal" anatomical variants, such as bovine aortic arch and normally functioning bicuspid aortic valve, as signifi cant etiological factors of early atherosclerosis development. To our knowledge this is the fi rst case report connecting those two entities with aortic dilatation and early carotid atherosclerosis.
Consequently, a thorough evaluation of the entire arterial tree in such individuals should be an integral part of the diagnostic and therapeutic investigation.