Niwa et al. [1] reported that in 88 congenital heart disease patients with dilated aorta with age of 3 weeks to 81 years (32 ± 6 years) (48 males, 40 females), surgical biopsy aortic specimens were obtained, and cystic medial necrosis in the aortic media was observed in all of these patients.

Independent variables that alter the structure of ascending aortic media include Marfan syndrome, annuloaortic ectasia or Turner syndrome, systemic hypertension [31], aging [32], pregnancy [33], and others (Table 13.2). Marfan syndrome is characterized by a defect in the chromosome 15 gene that codes for fibrillin-1 [34], in the absence of which elastin is more readily degraded by metalloproteinase [35]. Deletion of TGF-β receptor has a relation with aortic dilatation [36]. The genetic fault in Marfan syndrome apparently impairs aortic medial elastic fibers more extensively than impairment in congenital heart disease, and the incidence of ascending aortic dilatation, dissection, or rapture is higher, and the degree of aortic root medial lesions is greater in former than the latter.

Higher histologic grading scores in tetralogy of Fallot patients are found even in infants, which suggests the intrinsic abnormality has crucial role for this dilatation [20]. Evidence for the role of aortic overflow over time in tetralogy of Fallot includes the associations of higher age at operation, pulmonary atresia versus pulmonary stenosis, and longer presence of surgical aortopulmonary shunting with aortic dilation [37, 38]. There is a 12% increase in mean aortic diameter after surgical aortopulmonary shunting [38].

Comparing patients with A-P phenotype (R-L cusp fusion) bicuspid aortic valve with R-L phenotype (R-N cusp fusion), the former is more common in male and is larger and stiffer at the sinus of Valsalva and smaller at ascending aorta and aortic arch than the latter [39, 40]. This aortic shape difference is possibly due to inborn errors of aortic wall than due to hemodynamic effect [41]. Therefore, bicuspid aortic valve phenotype can predict elastic properties of ascending aorta and have potential impact on clinical outcomes.

50.9% prevalence of fibrillin-1 gene polymorphisms or mutations is found in tetralogy of Fallot patients with dilated aorta, and there is >8 times risk of aortic dilation in patients with these variants [42]. In patients with chromosome 22q11.2 partial deletion without conotruncal abnormality, aortic dilation is found in 10/93 (10.8%) [43], and chromosome 22q11.2 partial deletion is one of the risk factors of aortic dilatation [37].

Aortic dilation might eventually cause aortic annular enlargement that will in turn predispose to severe aortic regurgitation (AR). Marfan syndrome is the most frequently associated not only with aortic dilation but aortic dissection because of hereditary disease. In such patients, concomitant aortic valve surgery together with an aortic root replacement will be required. The Bentall operation [50] was originally developed to repair the complex lesions of an annuloaortic ectasia (AAE) associated with severe AR with a composite graft that contained a mechanical valve. For the patients of whom aortic valve might be preserved, Yacoub et al. developed the remodeling procedure [51], and David et al. made progress the reimplantation method [52]. Both procedures are well known as valve-sparing operations.

In the Ross operation [53], the intact pulmonary autograft is harvested in order to replace the aortic valve (inclusion technic) or to replace the aortic root. Enucleated RV outflow tract and the pulmonary artery are usually reconstructed with a homograft, hard to obtain in Japan, or other prosthetic valve conduits. However superiority of freedom from anticoagulation longevity of pulmonary autograft has been substantiated in many reports; application of the Ross operation for the adult patients is controversial because of complexity of the procedure.

In 1968, Bentall and de Bono described the first successful aortic root replacement with a composite Teflon tube graft and a ball valve prosthesis (Starr valve) in a male associated with ascending aortic dilation, aortic annular enlargement, and severe AR.

The Bentall operation consists of replacement of the ascending aorta and the aortic valve including the aortic root with a composite tube graft. Coronary ostia are reimplanted to the tube graft. In order to replace the ascending aorta as far distally as possible, cardiopulmonary bypass is usually established by retrograde arterial perfusion through the femoral artery. After cross-clamp of the ascending aorta, the aneurysmal ascending aorta is resected (Fig. 13.1a). The aortic valve is also excised (Fig. 13.1b), and then a composite tube graft prosthesis of appropriate size, including a prosthetic valve, is sutured to the aortic annulus. Usually a mechanical valve is used in this graft because of its longevity (Fig. 13.1c).

Circular holes are made in the tube graft at the positions of the coronary ostia. Originally, coronary ostia were approximated to the graft and directly sutured to the holes of the graft. This method might cause significant tension to the suture lines and bleeding, so that many modifications have been developed. Recently, coronary ostia are detached as large buttons of the aortic wall and dissected free along their courses to allow their mobility. The coronary buttons are directly sutured to the holes of the aortic graft (Carrel patch method) or interposing a small caliber graft (Piehler method) (Fig. 13.1d).

The Bentall operation was most indicated for AAE. The proximal arch and neck vessels are usually not involved in AAE, and then only replacement of the ascending aorta would be required. Marfan syndrome is frequently associated with aortic dilation and aortic dissection because of hereditary degenerative disease. However, in most cases of Marfan syndrome, the ascending aorta is first affected by aneurysmal lesion [54]. When the aortic valve is not damaged, a valve-sparing operation can be applicable [55].

A large ascending aorta is frequently observed in TOF patients, especially in the case with pulmonary atresia. Fifteen percent of adult patients with repaired TOF have a dilated aortic root [21] (Fig. 13.2a–c). Since only a small number of these patients are reported to advance to an aortic dissection, the indication for aortic replacement in TOF would be decided at a later stage compared to patients who developed an aortic aneurysm in other anomalies. However, careful follow-up will be required when the diameter of the aortic root excesses 55 mm [53, 56]. If significant aortic regurgitation appears due to annular dilation, AVR with ascending aortic replacement or Bentall operation would be considered (Table 13.3).

Aortic dilation is prone to aortic annular dilation. Severe AR frequently occurs only due to the annular dilation. When the aortic valve is not affected with apparent structural lesions, it can be preserved by reducing the diameter of the aortic annulus and suspension of cusps. Based on this concept, two types of valve-sparing root replacement had been described by Yacoub in 1979 (remodeling method [51]) and by David in 1992 (reimplantation method [52]). In the remodeling method, sinuses of Valsalva are replaced by the trimmed tube graft, whereas the entire aortic root after resection of sinuses is reconstructed in the tube graft in the reimplantation method. Valve-sparing procedures have been developed as alternative methods to the Bentall operation in the patients whose aortic valve is suitable for preservation. Good results have been reported in patients with Marfan syndrome or Loyes-Dietz syndrome, who have undergone elective valve-sparing procedures [55–57]. Boodhwani et al. [58] reported their excellent systematic approach to repair regurgitant BAV using valve-sparing procedures. However, not a few authors advocated superiority of the Bentall operation to valve-sparing operation because of uncertainty of long-term durability [59, 60]. The criteria for the aortic root replacement have been recommended in many reports and guidelines (Table 13.3): the aortic root diameter of more than 55 mm in non-Marfan adult patient, 50 mm in BAV, and 45 mm and 40 mm in Marfan syndrome and Loyes-Dietz syndrome, respectively [54, 55, 61, 62].