Aortic dilatation in complex congenital heart disease

Abstract

A bicuspid aortic valve and/or coarctation of the aorta (COA) are often associated with dilatation of the ascending aorta and para-coarctation. Congenital heart diseases (CHD), such as truncus arteriosus, transposition of the great arteries (TGA), tetralogy of Fallot (TOF), hypoplastic left heart syndrome (HLHS), single ventricle with pulmonary stenosis/atresia and the Fontan procedure, are also associated with aortic root dilatation, aneurysm and rarely, dissection, which can be fatal and require aortic valve and root surgery. A significant subset of adults with complex CHD exhibit progressive dilatation of the aortic root even after repair due to aortic medial degeneration. Medial degeneration in the ascending aorta is prevalent among the above CHD. In Marfan syndrome, bicuspid aortic valve and COA, medial degeneration is more extensive and severe than in another complex CHD. Accordingly, the incidence of ascending aortic dilatation, dissection and rupture is higher in the former. This aortic medial degeneration in CHD may either be intrinsic or secondary to the increased volume overload of the aortic root due to right-to-left shunting, or a combination of both. The association of aortic pathophysiological abnormalities, aortic dilatation and aorto-ventricular interaction is clinically referred to as "aortopathy". The major purpose of medical treatment for aortopathy is to reduce the structural changes within the aortic wall and slow down the progression of aortic dilatation to reduce the risk of cardiovascular events. Several medications have been studied, including β-blockers, angiotensin II type I (AT1) receptor blockers (ARBs) and Ca-antagonists. However, the results, except for Marfan syndrome, are limited. In aortopathy, concomitant aortic valve and aortic root repair/replacement is required. The Bentall operation comprises root replacement with an aortic tube graft and mechanical valve, and has been widely applied. On the other hand, valve-sparing operations have been developed in order to preserve the aortic valve.

Keywords: Aortopathy; aortic aneurysm; aortic dilatation; aortic dissection; aortic medial degeneration.

Figure 1

Histological severity of the aortic media according to aortic biopsy specimens in CHD patients with a dilated aorta (n=88) by light and electron microscopy. Medial degeneration on light and electron microscopy was classified as: absent; non-specific (Grade 1), abnormal; moderate (Grade 2) or abnormal; severe (Grade 3). Specimens were stained by hematoxylin-eosin, elastica van Gieson, trichrome & colloidal iron. AAE, annulo-aortic ectasia; BAV AS, bicuspid aortic valve with aortic stenosis; AR, aortic regurgitation; TOF, tetralogy of Fallot; SV PS, single ventricle with pulmonary stenosis; TA, tricuspid atresia; DORV, double outlet right ventricle; DOLV, double outlet left ventricle; VSD, ventricular septal defect; Do Ao A, double aortic arch; PTA, persistent truncus arteriosus; d-TGA, d-transposition of the great arteries; Controls, transplant donor heart.

Figure 2

Light microscopic semiquantitative grading system (polychromatic staining). Normal (negative controls): closely packed long parallel arrays of intact elastic fibers; Grade 1: mild fragmentation of elastic fibers, a mild increase in collagen; Grade 2: widespread disruption and fragmentation of elastic fibers, a conspicuous increase in collagen; widespread loss of smooth muscle cells; Grade 3 (positive controls): large areas of the complete loss of elastic fibers, a conspicuous increase in collagen and ground substance and overall loss of smooth muscle cells.

Figure 3

Dilated ascending aorta (AAo) in a 3-year-old boy with a VSD and pulmonary atresia. (A) Dilated AAo with hypoplastic pulmonary artery (aortic angiography); (B) Grade 2 abnormality in the aortic media (light microscopy, elastica van Gieson staining).

Figure 4

Dilated aorta in patients with cyanotic congenital heart disease (CT angiography). (A) Aortic aneurysm (53 mm in diameter: m1) in a 17-year-old boy with pulmonary atresia and an intact ventricular septum after the Fontan procedure, and mild aortic regurgitation; (B) dilated ascending aorta (50 mm) in a 50-year-old female with tricuspid atresia and right aortic arch after the Glenn procedure, and moderate aortic regurgitation.

Figure 5

Dilated ascending aorta in a 43-year-old male with persistent truncus arteriosus. (A) Dilated truncal artery (Tr A) with the right pulmonary artery (RPA) directly coming out from the Tr A. Calcium deposition was observed in the RPA (CT angiography); (B) Grade 2 abnormality in the aortic media was noted (light microscopy).