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The Pathogenesis of Aortic Valvular Disease Chapter | 4 65
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2014.11.026.
Chapter 5
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Aortic Root Pathologies
Kaan Kırali, Gökhan Kahveci
Koşuyolu Heart and Research Hospital, Istanbul, Turkey
Chapter Outline
Introduction 67
Functional Anatomy 67
Histopathologic Changes 69
Aortic Root Pathologies 69
Aging 70
Aneurysm 70
Poststenotic Dilatation 71
Sinus of Valsalva Aneurysm With/Without Rupture 72
INTRODUCTION
The aortic root is a complex structure, which helps the excellent coaptation work of the aortic valve. Because there is not
a single true ringlike annular attachment of the aortic leaflets, the aortic root with three rounds supplies the semilunar
three-dimensional (3D) shape attachments of the leaflets. This design of the aortic root and pressure gradients between the
left ventricle (LV) and the aorta produces full opening of the aortic leaflets without any gradient and closing without any
regurgitation [1]. The second ergonomic function of the aortic root is to increase the coronary blood flow during the diastole. Different pathologies affecting primarily the aortic root can cause serious clinical conditions with/without aortic valve
dysfunction or silent fatal complications. The structural abnormality or acquired pathologic processes of the aortic root is
the main reason for these pathologies. Aortic root pathologies secondary to diseases of the ascending aorta are seen more
than the isolated aortic root pathologies, which are not discussed here.
Pseudoaneurysm 73
Dilatation Associated With Congenital Heart Diseases 73
Aortic Root Abscess 74
Aorto-Left Ventricular Tunnel 74
Porcelain Aorta 75
Supravalvular Stenosis 75
Aortic Dissection 75
References 76
FUNCTIONAL ANATOMY
The aortic root with the semilunar attachments of the leaflets, interleaflet triangles, and sinuses is a bridge between the LV
and the ascending aorta (Fig. 5.1) [2]. The aortic root takes shape from three parts. There is no any true single circular annular attachment of three aortic leaflets, but there is a zone between the LV and aorta that is termed as the anatomic (histologic)
ventriculo-arterial junction (VAJ). The upper edge of the aortic root is created by the distal circumferential plane joining the
tops of three commissures and named as the sinotubular junction (STJ). The aortic sinus with three sinuses of Valsalva is
located between these two junctions (from VAJ to STJ). Because the coronary arteries arise from two of the three sinuses,
the sinuses are named as the left coronary sinus (LCS), the right coronary sinus (RCS), and the noncoronary sinus (NCS).
The anatomic VAJ occurs as a circular band between lower and upper rings: The basal ring or the anatomic VAJ (recommendation as aortic annulus [3]) is the circular ring at the nadirs of three sinuses of Valsalva, which is supported by the left
ventricular muscle beneath the RCS and ½ anterior LCS, and by the fibrous aortic–mitral curtain beneath the NCS and ½
posterior LCS. The ventriculoarterial ring or the hemodynamic VAJ is the circular ring at the top of the muscular structure
of the sinuses of Valsalva, which is supported only by the aortic wall.
The aortic root is a hollow cylinder with three bulges, which have the main functional effect on the aortic valve opening–
closing cycle and coronary circulation. In fact, the aortic root has two-sided asymmetrical structure [4]. The first asymmetry
is in the longitudinal axis, and the mean heights of each sinus of Valsalva from the base to the STJ (NCS > RCS > LCS)
and each interleaflet triangle (between noncoronary and left coronary cusps ≥ noncoronary and right coronary cusps > right
and left coronary cusps) are not the same and the free margin lengths of the leaflets correspond to this asymmetry [5].
This asymmetry shapes the aortic root as a conic cuff, whereas the NCS is slightly larger. The second asymmetry is in the
New Approaches to Aortic Diseases from Valve to Abdominal Bifurcation. http://dx.doi.org/10.1016/B978-0-12-809979-7.00005-5
Copyright © 2018 Elsevier Inc. All rights reserved.
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RCA
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Ascending aorta
Sinotubular
junction
Crown-like
ring
Ventriculoarterial
junction
FIGURE 5.1 Aortic root. Basal ring is the anatomic ventriculoarterial junction; virtual ring is the hemodynamic ventriculoarterial junction.
LCA
virtual
ring
basal ring
TABLE 5.1 Aortic Valve Apparatus
1. Ascending aorta
2. Sinotubular ring (junction)
3. Sinuses of Valsalva
4. Commissures
5. Interleaflet triangles
6. Aortic leaflets
7. Ventriculoaortic ring (junction)
8. Left ventricle
circumferential axis and the diameters of the aortic root are different (sinus of Valsalva > VAJ > STJ ≈ 1.34 > 1.1 > 1). The
diameter of the STJ is 10%–12% smaller than that of the VAJ; however, the upper parts of the commissures attach just
below the STJ and make a virtual ring with the same diameter of the VAJ.
Because the aortic leaflets attach in the shape of a three-pointed crown (a truncated cone shape) spanning the entire vertical extent of the aortic root from the VAJ to the STJ, it is more meaningful to discuss “the aortic valve apparatus” (Table
5.1). This functional apparatus includes coronet-shaped leaflets insertion and defines the separation level of ventricular and
arterial hemodynamics, and it works with an elegant mechanism. The aortic valve passively opens and closes in response to
pressure differences between the LV and aorta. The aortic root changes its overall configuration from a cone to a cylinder,
and from a cylinder to an inverted cone according to left ventricular filling and contraction [6]. Each part of the aortic root
expands and contracts proportionally and simultaneously during the cardiac cycle: the VAJ diameter does not change (or
marginally increases during the presystolic phase and decreases during systole), whereas the diameters of the aortic sinus
and STJ increase during the systole [7]. In normal aortic roots, the VAJ size is closely related to the body surface area [8].
The outflow part of the aortic root expands approximately 12% during systole and the aortic root gets more cylindrical
shape in the longitudinal axis during ejection because of the dilatation of the STJ relative to the annular base. Although
the aortic sinus is larger than STJ and VAJ, the opened aortic leaflets complete the cylindrical form of the aortic root inner
lumen (Fig. 5.2). The inflow and outflow effective orifice areas of the aortic root become similar during systole, and this
configuration of the aortic root allows a zero resistance to flow from the LV to the aorta during every ejection.
Every part of this aortic valve apparatus has its own function during cardiac cycle. The expansion of the VAJ at the
preejectional phase before aortic valve opening helps to decrease the coaptation area among the leaflets and to separate the
leaflets under minimal stresses (20% of total opening), and the aortic valve opening is completed rapidly by the ejection
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FIGURE 5.2 Aortic root with full opened leaflets becomes a cylindrical shape during systole (2D long-axis transesophageal echocardiography (TEE)
view). a, aortic annulus; b, sinus of Valsalva; c, sinotubular junction; d, ascending aorta.
phase. Sinuses of Valsalva have the main effect on the coronary blood circulation, whereas they permit aortic valve opening
during systole without blocking of the coronary artery ostia and simplify aortic valve closing at the end of systole without
any tension. The STJ is the main structure that promotes aortic valve coaptation, whereas it hangs all three commissures
during the diastole.
HISTOPATHOLOGIC CHANGES
The main histologic components of the aortic root are elastic and collagen fibers, but the ratio of elastin to collagen
decreases along the ascending aorta. The sinuses consist of the aortic wall and contain concentric elastic lamella,
whereas interleaflet triangles contain primary collagen fibers. The aortic root with a normal structure has the primary
effect on the pulsatile blood flow lengthways the aorta and branches. The distensibility of the VAJ is between 5%
and 10% in a healthy aortic annulus, which is lost in pathological situations. Destruction or abnormal narrowing of
the VAJ blocking this expansion in systole causes turbulent blood flow through the aortic root, whereas an abnormal
enlargement of the VAJ causes a coaptation defect with/without leaflet prolapses. Sinuses of Valsalva are the weakest
part of the aortic root and any dilatation at this part results in an enlargement at one or both junctions and, therefore,
aortic regurgitation. On the other hand, fistulas into the cardiac chambers without any dilatation of this part cause
severe aortic regurgitation without any coaptation defects of the aortic valve, and thereupon coronary ischemia. Any
enlargement or destruction of the STJ causes leaflet prolapsing or stretching and that handicaps coaptation of the
aortic valve.
Weakness and turbulent flow are the trigger mechanisms of isolated aortic root pathologies and instability of the aortic
wall allows for dilatation, rupture, infection, calcification, or dissection of the aortic root. The most common pathology is
aortic root dilatation, and histopathological changes cause a decrease in the strength of the aortic root wall, its structural
support, and elasticity. The first step is the tissue thinning at the aortic wall just above the aortic leaflet attachments (sinking
sinus). The aortic wall loses its physiologic pink color and gets pink–purple color, which reflects the myocardium behind
it (myocardial inclusion). Frequently, sinus of Valsalva aneurysm or bicuspid aortic disease causes this dystrophic aortic
root wall insufficiency. The second step is an abnormal increase in the inner diameter of the aortic root, which starts the
pathologic “vicious cycle” and provokes dilatation with/without serious complications. Aneurysmal tissue shows less obvious directional differences in the NCS but failure direction-dependent properties in the RCS and LCS [9]. The third step
is the termination of this vicious cycle by a serious complication such as rupture or dissection, which can result in fatal
hemodynamic changes.
AORTIC ROOT PATHOLOGIES
The etiologic factors causing isolated aortic root pathologies are various (Table 5.2). Structural abnormalities or acquired
pathologies cause mostly aortic root dilatation or rarely aortic narrowing. Etiological factors also influence surgical treatment approaches, which are discussed in Chapter 25.
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TABLE 5.2 Isolated Aortic Root Pathologies
1. Aging
2. Aneurysm
3. Poststenotic dilatation
4. Sinus of Valsalva aneurysm with/without rupture
5. Pseudoaneurysm
6. Dilatation associated with congenital heart diseases (pre- or postoperatively)
7. Aortic root abscess
8. Aorto-left ventricular tunnel
9. Porcelain aorta
10. Supravalvular stenosis
11. Dissection
Aging
Increasing dimension of the aortic root in healthy adults has a close relationship with aging, higher body surface area, and
male gender [10]. Any other systemic disease (hypertension, diabetes mellitus, hypercholesterolemia, etc.) does not have
any relation to increase in the aortic root diameter in healthy humans with a healthy proximal aorta. The aortic root diameter increases 0.8–0.9 mm per decade in normal individuals [11]. The dimensions of the proximal aorta increase progressively with aging at all levels with the exception of the VAJ, and the mean STJ/VAJ ratio increases from 1.02 at age 20 to
1.16 at age 50–60 years [12]. The aorta undergoes changes with aging, especially in the molecular composition. The whole
aorta with aortic leaflets becomes stiffer in advancing age, and the normal physiologic mechanisms of the aortic leaflets
and aortic root are disrupted because of fragmentation and degradation of the elastin. Replacement of the flexible elastin
with stiffer collagen, medionecrosis, and calcification increases stress on the aortic root and leaflets. These pathological
changes associated with the other systemic diseases decrease the resistance of the aortic root and valve, leading to aortic
valve and/or root degeneration. Aortic valve degeneration causing regurgitation or stenosis creates turbulent blood flow in
the aortic root and that in turn changes the hemodynamics in the aortic root and can cause several pathological changes.
Treatment of one or more of these systemic diseases can prevent late aortic valve (±aortic root) degeneration with/without
calcification [13].
Aneurysm
Aortic root dilatation with/without aortic regurgitation is the most observed pathological change of the aortic root, which is
regularly diagnosed in the second to fourth decades of life, and is different from native growth of the aortic root in a healthy
population. In a healthy population, native aortic root growth relating particularly to aging and body surface area also
causes a natural increase in aortic root diameters at all levels (and also to the whole aorta). Aortic root aneurysms appear in
less than 1% of open-heart surgery patients, but they can cause aortic regurgitation, dissection, and rupture with high morbidity and mortality. Progressive dilatation of the aortic root is caused by medial degeneration and destruction of the elastic
and collagen fibers and can be also associated with high blood pressure, high stroke volume, and inflammatory diseases
[14–17]. Medial degeneration is a fated trend caused by the primary syndrome such as Marfan syndrome, Ehlers–Danlos
syndrome, or Loeys–Dietz syndrome. In the majority of patients with these syndromes, the primary dilatation develops at
the aortic root, especially at the aortic sinus. A new biomechanical viewpoint could assess specific mechanical properties on
stresses in the aortic root, which are better predictors for aneurysmal enlargement than Laplace’s law [9]. The mechanical
and histologic adaptation of each sinus to the intraluminal stress results in the asymmetric enlargement of the aortic root.
Annuloaortic ectasia causes a significant enlargement of the aortic root lengthways. Because annuloaortic ectasia usually
involves the fibrous component of the left ventricular outflow tract, the most affected or dilated part of the aortic root is
the VAJ, especially aortic–mitral curtain. The pathology can progress aggressively and cause aneurysm or dissection in
the early decades (Fig. 5.3). Aortic dilatation secondary to the ascending aorta aneurysm affects first the STJ and then the
whole aortic root (Fig. 5.4).
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FIGURE 5.3 Dissection of the proximal ascending aorta in Marfan syndrome (2D long-axis transthoracic echocardiography (TTE) view). Ao, aorta;
arrow, dissection flap; LA, left atrium; LV, left ventricle; RV , right ventricle.
FIGURE 5.4 Annuloaortic ectasia often affects proximal aorta and causes aortic dilatation, especially at the sinotubular junction (2D long-axis TEEview). Arrow = 5.7 cm.
Poststenotic Dilatation
This type of aortic root dilatation develops secondary to particular pathologies. Bicuspid aortic valve (BAV) disease is a
typical pathology and is the most common congenital disease with 1%–2% incidence in general population, and it is often
(40%–50%) associated with a dilated proximal aorta (Fig. 5.5). This dilatation (bicuspid aortopathy) can be confined to
the aortic root, the ascending aorta, or extend from the VAJ up to the aortic arch (Table 5.3) [18]. The descending aorta is
usually not affected. The combination of aortic medial degeneration and BAV-related hemodynamic changes causes aortic
wall distention. This ongoing pathologic process with turbulent flow character and disproportional regional wall shear
stress distribution results proximal aortic dilatation. This aortic enlargement occurs earlier in life and is usually affected
by aging and hypertension. The development of the aortic leaflets’ fusion is usually associated with the patterns of aortic
valve pathology and proximal aortic dilation: “right coronary leaflet/noncoronary leaflet” fusion is more likely to result in
ascending aortic dilation with/without aortic stenosis, but the “right coronary leaflet/left coronary leaflet” fusion is more
likely to result in aortic root dilatation [19]. Early phase of stenotic BAV is associated with the normal aortic wall; however,
a regurgitatic BAV has a thicker aortic wall at the beginning [20]. The aortic wall becomes thinner after dilatation (>5 cm).
This slimming of the aortic wall starts at the lowest level of the aortic root, just above aortic leaflets’ attachment. During
surgery, this area should be supported to prevent ongoing enlargement of the VAJ.
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FIGURE 5.5 Anterior sinus of Valsalva aneurysm with the bicuspid aortic valve disease. Left: 2D short-axis TEE view; right: 3D sagittal view; below:
2D long-axis TEE view (lower).
TABLE 5.3 Bicuspid Aortic Valve Disease Configuration (Cluster Classification)
Cluster I Aortic root 13%
Cluster II Tubular ascending aorta 14%
Cluster III Ascending and aortic arch 28%
Cluster IV All together 45%
Sinus of Valsalva Aneurysm With/Without Rupture
Sinus of Valsalva aneurysm is a dilatation of the aortic root between the VAJ and the STJ, and it may be congenital or
acquired in origin. Most frequently, a sinus of Valsalva is congenital in origin due to the absence of the continuity between
the aortic media and the annulus fibrosis and it forms first a blind diverticulum embryologically. Occurrence of acquired
sinus of Valsalva aneurysm can be secondary to a weakness in the aortic wall by trauma, infectious etiologies, cystic medial
necrosis, or atherosclerosis, which can gradually give way under aortic pressure to form an aneurysm. The RCS is affected
most frequently than the others. Most nonruptured sinus of Valsalva aneurysms are asymptomatic, but they can be complicated by aortic regurgitation [21]. If nonruptured sinus of Valsalva aneurysm enlarges it can lead to arrhythmia, heart
block, myocardial ischemia, or LV outflow tract obstruction. Rupture of the sinus of Valsalva aneurysm into any cardiac
chamber is the worst complication, which most often occurs into the right ventricle followed by the right atrium, and forms
an aorto-cardiac fistula (Fig. 5.6) [22].
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FIGURE 5.6 Ruptured noncoronary sinus of Valsalva aneurysm into the right atrium (arrow) (Left: 2D short-axis TEE-view; right: 2D shot-axis colored
TEE-view with regurgitated flow).
Pseudoaneurysm
Aortic pseudoaneurysms can develop months or years after aortic root surgery, dissection, infective endocarditis, or blunt
trauma. The most important detrimental fate is the continuity of the expansion with/without rupture of the aneurysmal
sac. The typical pathologic development of pseudoaneurysms in the aortic root occurs after aortic root surgery. The pseudoaneurysm develops from any anastomotic site, aortic suture line, prosthetic graft or patch, or aortic infection. After
aortic root replacement, the development of a pseudoaneurysm from coronary ostial anastomoses is rare, but it can cause
fatal complications leading to myocardial ischemia due to compression [23]. Retrograde dissection of the ascending aorta
may involve areas below the STJ and results a chronic pseudoaneurysm formation; however, isolated chronic aortic root
pseudoaneurysm is rare. Infective endocarditis involving the aortic valve can result in the formation of pseudoaneurysm
with/without aortic root abscess, which can occur subacutely after the completion of intravenous antibiotic therapy [24].
Pseudoaneurysm of the mitral–aortic intervalvular fibrosa is rare and can develop secondary to aortic valve endocarditis
[25]. The typical sequence of blunt aortic injury in patients with stable condition involves the rupture of the intimal and
medial layers, which is followed by the rupture of the adventitial aortic wall, and more than half of them suffer pseudoaneurysm [26].
Dilatation Associated With Congenital Heart Diseases
In patients with congenital heart disease, aortic root dilatation can be a feature at presentation (primary) or during follow-up
after surgical intervention (secondary) [27].
Primary aortic root dilatation extends into the entire ascending aorta, and in the majority of patients it is mainly associated with coarctation of the aorta, BAV, and conotruncal abnormalities (tetralogy, pulmonary atresia with ventricular septal
defect, truncus arteriosus). The best example for primary aortic root dilatation associated with a congenital heart disease is
Tetralogy of Fallot. This pathology results in aortic root dilatation due to increased and altered flow through the overriding
aorta and displaced conotruncal tissue between the aorta and pulmonary artery. The aortopathy is characterized by fragmentation of elastic lamellae, medionecrosis, muscle disarray, and fibrosis during the infancy. The incidence of aortic root
dilatation is ≈ 29%, but the overall prevalence of aortic root dilatation, as defined by an indexed observed-to-expected ratio,
is ≈ 6.5% in unrepaired patients [28]. Although no factor is linked to aortic root dilatation in Fallot children, earlier surgical
repair in infancy may prevent such enlargement.
Secondary dilatation of the aortic root extends lesser to the ascending aorta, and it can be observed after congenital cardiac surgery when the original aortic root is replaced by a pulmonary autograft (Ross, arterial switch, or systemic outflow
tract reconstruction in single ventricle). Pathologies repaired with a pulmonary autograft often lead to secondary dilatation
of this neo-aortic root over time because the neo-aortic root consists of pulmonary tissue and is introduced into the highpressure left-sided system. The dilatation of the aortic root mostly occurs at the sinus portion and the STJ and develops
rapidly in the early follow-up period. This complication affects mostly adult patients, and older age is the common risk
factor for late neo-aortic root dilatation.
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Aortic Root Abscess
Aortic root infections develop mostly from aortic valve infections and can evolve into abscess form. Aortic root abscess
is a destructive pathology and ruins all structure in the aortic root. Uncontrolled aortic root abscess can spread to the surrounding tissue, develop aortoventricular discontinuity, and spread to the other annuli, rupture into a cardiac chamber,
develop a pseudoaneurysm, or cause fatal arrhythmia. The size and penetration of the abscess is an important criterion for
the severity of this pathology. The type of abscess affects prognosis and surgical treatment modalities [29]. A localized
abscess is small and does not exceed one aortic cusp. A circular abscess affects larger than one aortic cusp without aorto-
ventricular dehiscence. An aortoventricular dehiscence is a discontinuity between the aorta and the LV of more than half
of the aortic circumference. One of the main issues for aortic root abscess is whether the etiology is native or prosthetic
valve endocarditis. Native valve endocarditis causing periannular abscess involves the aortic valve more often than the
mitral valve. The extension of infection to surrounding tissues occurs relatively more often in prosthetic valve endocarditis, despite the prevalence of native valve endocarditis being higher than prosthetic. Infection of a stented prosthetic valve
is usually located in its sewing ring and extends into surrounding structures, especially into the left ventricular outflow
tract [30]. A pseudoaneurysm can develop secondary to any rupture or dehiscence of the anastomosis in the area of abscess
cavity (Fig. 5.7). Rarely, a huge abscess and/or pseudoaneurysm can compress coronary arteries and cause myocardial
ischemia [31].
Aorto-Left Ventricular Tunnel
The aorto-left ventricular tunnel (ALVT) is a rare congenital pathologic defect of the aortic root and affects the left interleaflet triangle (between the left and right coronary leaflets) and forms an abnormal communication between the proximal
aorta and the LV cavity [32]. The main hemodynamic pathology is severe aortic regurgitation. Possible etiologic reasons
can be an abnormality of the coronary artery, a malformation of the bulbus cordis, weakness of the aortic wall, or intrauterine rupture of a sinus of Valsalva aneurysm. The ALVT usually begins above the coronary ostium, courses in the visceral
pericardium between the aortic sinus and subpulmonary infundibulum, and opens into the LV just below the attachment of
the aortic valve. The aneurysmal bulge part (inflow) consisted of true aortic wall tissue, the tunnel (tract) becomes thinner
and membranous, and the ventricular orifice (outflow) is composed of fibrous tissue [33]. The ALVT can be a simple tract
without valvular distortion, as a large extracardiac conduit with valvular distortion, a septal aneurysm with/without right
ventricular outflow tract obstruction, or a combination [34]. The aortic orifice of the ALVT is often located above the STJ
at the RCS. The main difference between a tunnel and a ruptured true aneurysm is the location of the aortic orifice to the
STJ: above is ALVT, below is ruptured sinus of Valsalva aneurysm.
FIGURE 5.7 Pseudoaneurysm after prosthetic endocarditis (Left 2D short-axis TEE view). Right 2D short axis TEE view with color Doppler.
Aortic Root Pathologies Chapter | 5 75
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Porcelain Aorta
Porcelain aorta is an extensive completely or near-completely circumferential calcification of the aorta. It can be seen
mostly in an elderly population with associated coronary artery disease or aortic valve stenosis, but isolated total calcification of the aortic root is a seldom pathology. Chronic kidney disease [35], mediastinal radiation [36], and systemic inflammatory diseases (Takayasu arteritis, systemic lupus erythematosus, rheumatoid arteritis) can be associated with porcelain
aorta. The etiologic factor can be atherosclerosis involving the intima (atheromatous aortic disease) or medial calcification
without atheroma (nonatheromatous aortic disease) [37]. The main difference between both types is the presence of a heavily calcified atheromatous aorta, which is associated with a significantly increased risk of embolic stroke and peripheral
embolism during cardiac surgery. Nonatheromatous calcification of the aorta is limited to the tunica media; it excludes a
significant source of embolization because the intima is relatively intact. Porcelain aorta interferes with aortic cannulation, aortic clamping, aortotomy, and proximal coronary bypass anastomosis, which can cause aortic dissection, surgically
untouchable ascending aorta, or release of thromboembolic material.
Supravalvular Stenosis
Supravalvular aortic stenosis (SVAS) is a narrowing at the level of the STJ with a partial adhesion or thickening of aortic
leaflets to the sinotubular ridge (Fig. 5.8). Severity of SVAS ranges from discrete ringlike thickening to diffuse involvement. The congenital SVAS is caused by mutations in the elastin gene sporadically or segmental chromosomal deletions
syndromically [38,39]. Elastin is the predominant extracellular protein in elastic arteries and has a key role in regulating the
vascular smooth muscle cells’ function. Elastin arteriopathies are characterized by low levels of elastin, hyperproliferation
in smooth muscle cells, a marked decrease in actin filament bundle formation, and an increase in migration lead to severe
vascular disease [40]. This pathology is characterized by abnormal proliferation of vascular smooth muscle cells and narrowing of the proximal ascending aorta. Other arteries can be involved including branches of the aorta, pulmonary, and
coronary arteries. Acquired SVAS can be developed secondary to malignant familial hypercholesterolemia causing soft or
calcified plaques [41], idiopathic aortitis causing aortic wall thickness [42], or associated other cardiac pathologies [43].
Iatrogenic SVAS can develop after the surgical replacement of the proximal ascending aorta, especially due to using smaller
tubular grafts. Adults with SVAS can be exposed at risk for adverse cardiac complications and reoperations, while progression of SVAS in adulthood is rare [44].
Aortic Dissection
Isolated aortic root dissection is also a rare pathology and can be life threatening if it involves the coronary arteries, ruptures
into the pericardial cavity, or causes severe acute aortic regurgitation (Fig. 5.9). The late complication of asymptomatic
aortic root dissection is pseudoaneurysm formation causing significant aortic regurgitation. The intimal tear is restricted
by surrounding tissue and the chronic healing process can protect the spread of the dissection into the coronary ostia or
distal ascending aorta and late rupture (Fig. 5.10). On the other hand, most aortic root dissections develop secondary to the
Stanford type A aortic dissection, and the natural history of these descending dissections is seldom benign. If the dissection
FIGURE 5.8 Supra-aortic stenosis. Left: 2D long-axis TEE view (arrows); right: 3D short-axis TEE view.
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