Progressive proximal aortic (aortic root and ascending aorta) dilatation is frequently found in adults with unrepaired (primary aortopathy) or repaired (secondary aortopathy) CHD. In our study, in the primary aortopathy group 25.71% and 17.14% of the patients had dilated ascending aorta and aortic root respectively. Similar results are reported also by other authors. Steward et al (6) found dilated aortic root in 16% .There was a trend to a more abnormally widened aorta in patients who had surgery for repair of CoA later in life. Five of the patients in their series with a history of hypertension that died from aortic aneurysm rupture, had the original surgery at the mean age of 19 years old. It is unclear if early repair of CoA will always be able to prevent late aortic dilatation. Even neonatal intervention does not prevent the occurrence of late hypertension, which by itself may trigger aortic dilatation (7). Biopsies studies of the aortic wall found increased amount of collagen and a decreased smooth muscle content in the pre-stenotic region (8). In our study, no patient after CoA repair needed intervention on the aorta during the follow-up period due to dilatation of the ascending aorta or the aortic root.
Concomitant aortic dilatation is seen in 80% of patients with BAV (9). Studies showed that the dilatation results from a combination of intrinsic aortic wall modifications (genetic theory) and hemodynamic changes induced by the bicuspid valve. The marked heterogenicity of BAV disease leads to different phenotypes, resulting in a large clinical variation of BAV patients (10,11). The strong association of BAV with CoA may indicate that BAV disease involves the ascending aorta and aortic arch extending to the ligamentun arteriosum. Dilatation of the ascending aorta occurs as a consequence of aortic medial degeneration (12). During the follow-up period only one patient with BAV from our study group underwent replacement of the ascending aorta due to aortic aneurysm.
Dilatation of the proximal aorta is a common feature in patients with unrepaired TOF. Corrective surgery has dramatically improved long-term prognosis, and nearly 90% of the patients surviving well into adulthood (13). However, persistent aortic root dilatation in increasingly reported in adult patients, years after the corrective surgery. In 1997 the first series of progressive aortic root dilatation was published, where a substantial cohort developed subsequent aortic valve incompetence, necessitating reoperation on the aortic root (14).
The underlying mechanism of the aortic dilatation in TOF are both hemodynamic and intrinsic wall abnormalities like cystic medionecrosis as in Marfan syndrome. Presence of right to left shunt shunt, other congenital anomalies, complete repair at older age and even a genetic factor have been implicated in aortic dilatation in TOF (15-17). In a homogenous cohort of TOF repaired early in infancy, was found that the ascending aortic size decreases with growth of the patient during the first years after surgery, irrespective of the total histology score at surgery (18). These findings support the presumption that mitigation of the transaortic flow by early surgical repair of TOF triggers a remodeling process that may interrupt the progression of the limited histological alterations of the aortic root, thus preventing late aortic dilatation.
In a recent review by Mongeon et al (19), in adult patients 35 years after repair of TOF at a mean of 7 years of age, an aortic dimension of ≥ 40 mm was found in 29% and moderate to severe aortic regurgitation in 3.5% of the patients. Only 3 cases of aortic dissection later after TOF repair have been described, all in severely dilated aortas of ≥ 70 mm (1)
Moreover, in our study, in the secondary aortopathy group, 50% and 33.30% of the patients had dilated ascending aorta and aortic root respectively.
After the Ross procedure, the neoaortic root dilates mainly at the sinus portion and the sinotubular junction, and less at the neo-aortic annulus itself. Dilatation occurs rapidly within the first days after surgery, with a further increase during the first year of follow-up, without causing significant aortic regurgitation in the medium phase term (20). The postoperative distention of the pulmonary autograft leads to remodeling of the wall with intimal thickening, medial elastin fragmentation, hypertrophic smooth muscle cells and increased medial and adventitial fibrosis (21). Freedom from autograft reoperation has been reported between 74% and 93% at 10 years and between 65% to 82% at 15 years (1). In our study only one patient after the Ross procedure needed reoperation due to pulmonary autograft dilatation during the follow-up period.
In patients with TGA, after the arterial switch operation (ASO), the native pulmonary valve and root assume the role of systemic arterial valve and root. Progressive dilatation of the neo-aortic root exceeds somatic growth during a long follow-up period. A dilated neoaortic root is seen in at least 50% of all patients after ASO (22). Risk factors that are associated with neo-aortic root dilatation after ASO include the presence of a ventricular septal defect, previous pulmonary artery banding, older age and surgical technical factors (1,22,23).
Also, adults patients with TGA after the atrial switch operation have a greater incidence of dilatation of both the pulmonary artery and aorta (24).
Freedom from aortic root reoperation was reported to be between 83% and 97% after ASO (1), Moreover, only a single case report of surgical repair of aneurysm of the ascending aorta after atrial switch operation has been described (25). In our study group, no patient after ASO or atrial switch operation needed reoperation on the ascending aorta.
Evidence of aortic dilatation has been reported in patients after the Fontan procedure. In a study with a median follow-up of 9 years neo-aortic root dilatation was observed in 98% of the patients (26). Histological analysis demonstrated findings seen in other forms of CHD- associated aortopathies, such as fragmentation of elastic fibers and deposition of myxoid material (27). Aortic dissection in patients after the Fontan procedure was reported in two patients with dilated aortic root (1). In our study group, no patient after the Fontan procedure needed reoperation on the ascending aorta or the aortic root.
One of the main finding of our study is that patients with secondary aortopathy had larger ascending aorta and aortic root dimensions than the patients with primary aortopathy. In the existing literature, so far there are no studies with direct comparison of aortic dimensions between the primary and secondary aortopathy. In our opinion, secondary aortopathy in contrary to the primary aortopathy, the neo-aorta consists mainly of pulmonary artery tissue introduced in the high pressure left- sided system, often leading to more severe dilatation in a time-dependent fashion than in the primary aortopathy.
Regarding aortopathy-associated CHD other than BAV, dissection risk is low (28). Since, there are no specific guidelines recommendations (3), and no reports suggesting high risk of aortic complications at neo-aortic root/ascending aortic diameters ˂ 55 mm, there is a pragmatic attitude to these patients with a restrictive policy following general aortic disease guidelines (55 mm) (3, 29). On the other hand, because the time factor is the principal determinant of late neo-aorta dilatation and some cases of quickly progressive diameter increase or fatal complications have been described, a close observation is warranted (3, 30). In these patients, aortic surgery was performed at lower aortic diameters, particularly if surgery was indicated for aortic valve dysfunction (28).
Regarding BAV the life risk of aortic dissection has been reported to be 9 times higher than that of the general population (1). Moreover, Kuijpers JM et al (28), reported 10-year dissection incidence of 0.3%. This low aortic-dissection risk in BAV is also reported in population-based and post- AVR BAV cohorts (28). Current guideline recommended aortic diameters thresholds for prophylactic surgery in BAV is 55 mm or 50 mm with risk factors, and 45 mm at the time of AVR for dysfunctional BAV (28). Surgical treatment for ascending aortic dilatation in CoA may be considered when the diameter is ˃ 55 mm (˃ 27 mm/m2) or if rapid progression (31). Moreover, the close association between BAV and CoA imply strategies established for BAV may be appropriate (3).
In conclusion, progressive aortic root and/or ascending aorta dilatation is frequently found in adults with repaired or unrepaired CHD. Primary aortopathy is associated with BAV, CoA and conotruncal abnormalities, where secondary aortopathy is after congenital heart surgery, by which the original aotic root/ ascending aorta is replaced by a pulmonary autograft , as in Ross procedure or modified as in ASO of Fontan procedure. It was observed that, more patients with secondary aortopathy had dilated ascending aorta and aortic root, as well as larger aortic diameters compare to the patients with primary aortopathy. Routine follow-up of these patients with attention to aortic diameter is necessary.