**3. Aortic root pathology**

This chapter will focus primarily on aortic valve regurgitation, the most common cause of which is aortic root dilatation. Even in patients with an intact aortic root, dilatation of the ascending aorta may result in aortic regurgitation secondary to sinotubular junction dilatation. Age-related aortic dilatation is the most common cause of aortic dilatation. With age, degenerative changes in collagen and elastin leads to weakness and dilatation of the aortic wall. A genetic component also exists, whereby up to 15% of first-degree relatives to those with aortic aneurysms being affected.

Dilatation of the aorta is common in patients with Marfan's syndrome. Here, a defect in the glycoprotein fibrillin-1 results in cystic medical degeneration in the aortic wall, predisposing individuals to aortic dilatation. These patients are usually younger, and the aortic sinuses are the first to dilate, followed by the sinotubular junction and eventually the aortic annulus, result in leaflet prolapse and regurgitation. Loeys-Dietz syndrome is connective tissue disorder, it results from mutations in the genetic coding of transforming growth factor beta 1, which leads to aortic dilatation. Type IV Ehler Danlos syndrome is a deficiency in type III collagen, again increasing the risk of developing aneurysms of the aorta.

Additional causes for aortic aneurysms include arteritis (Giant Cell, Takayasu's, Kawasaki), infection (syphilitic, mycotic), systemic lupus erythematosus, ankylosing spondylitis and rarely due to granulomatous disease.

It has been shown that increased stiffness of the aortic sinuses in advanced age and atherosclerosis contributes towards valve degeneration [6]. With reduced sinus compliance, leaflets may be more inclined to abruptly contact the aortic wall upon opening causing valve damage, while the delay in eddie current formation, with subsequent delay in valve closure

*Reprinted from Heart, Lung and Circulation, 2004;13 Suppl 3, Matalanis G, Valve sparing aortic root repairs--an* 

This chapter will focus primarily on aortic valve regurgitation, the most common cause of which is aortic root dilatation. Even in patients with an intact aortic root, dilatation of the ascending aorta may result in aortic regurgitation secondary to sinotubular junction dilatation. Age-related aortic dilatation is the most common cause of aortic dilatation. With age, degenerative changes in collagen and elastin leads to weakness and dilatation of the aortic wall. A genetic component also exists, whereby up to 15% of first-degree relatives to those

Dilatation of the aorta is common in patients with Marfan's syndrome. Here, a defect in the glycoprotein fibrillin-1 results in cystic medical degeneration in the aortic wall, predisposing individuals to aortic dilatation. These patients are usually younger, and the aortic sinuses are the first to dilate, followed by the sinotubular junction and eventually the aortic annulus, result in leaflet prolapse and regurgitation. Loeys-Dietz syndrome is connective tissue disorder, it results from mutations in the genetic coding of transforming growth factor beta 1, which leads to aortic dilatation. Type IV Ehler Danlos syndrome is a deficiency in type III

Additional causes for aortic aneurysms include arteritis (Giant Cell, Takayasu's, Kawasaki), infection (syphilitic, mycotic), systemic lupus erythematosus, ankylosing spondylitis and

collagen, again increasing the risk of developing aneurysms of the aorta.

Fig. 4. The aortic sinuses form an integral part of the normal aortic valve function both in

*anatomical approach. S13-18., Copyright (2004), with permission from Elsevier* 

may increase the regurgitant volume [3].

diastole and systole

**3. Aortic root pathology** 

with aortic aneurysms being affected.

rarely due to granulomatous disease.

Nevertheless, in many patients, the aetiology of aortic aneurysms is multifactorial, with additional clinical characteristics such as age, hypertension and male gender among others serving as risk factors.

Acute or chronic type A dissections of the aorta is also a cause for valve regurgitation, resulting from commissural detachment due to the proximally propagating dissection. Patients with dissection may also have aortic regurgitation secondary to pre-existing aneurysmal disease.

As one of the most common congenital cardiac anomalies, bicuspid aortic valves (BAV) are found in between 1-2% of the population. BAVs may be anatomically or purely 'bicuspid' (Type 0), that is, consisting of two completely developed cusps, sinuses and commissures. However, most BAVs are functionally bicuspid (Type 1), in that three sinuses exist, with two cusps of different sizes whereby the larger cusp contains a median raphe, representing an obliterated or malformed commissure. This raphe extends from the mid-point of the cusp's free margin to the aortic annulus, inserting at a lower level than the other commissures.

Patients with BAV are at increased risk of developing aortopathy such as aortic dilatation and acute dissection. This may be due to a combination of 1) genetic predisposition, whereby the aortic tissue weakness and fragility responsible for dilatation is a manifestation of a development defect afflicting both the aortic valve and wall and 2) the haemodynamic abnormality caused by a bicuspid valve such as eccentric turbulence is responsible for aortic dilatation. Although there is widespread support for the genetic theory, some debate still exists as to which process exerts the most dominant effect [7].

*Reprinted from Heart, Lung and Circulation, 2004;13 Suppl 3, Matalanis G, Valve sparing aortic root repairs--an anatomical approach. S13-18., Copyright (2004), with permission from Elsevier* 

Fig. 5. Leaflet prolapse (a) results in reduction of the area of coaptation between the leaflets and thus the security of the "seal" in diastole. Asymmetrical prolapse (b) will result in aortic regurgitation at a much earlier stage

Valve-Sparing Aortic Root Replacement and Aortic Valve Repair 93

doppler allows quantification of the severity of regurgitation and its direction. Eccentricity

Contrast-enhanced computed tomography of the chest is used to assess aneurysm morphology and coronary angiography should be routinely performed to determine the

Access to the heart is obtained via median sternotomy. Cardiopulmonary bypass with ascending aorta, femoral or axillary artery cannulation may be required depending on the

Valve-sparing aortic root reconstruction involves preservation of the native aortic valve while replacing the ascending aorta. This procedure was initially described by Dr Tirone David [10] and Sir Magdi Yacoub [11]. The two main techniques in widespread practice are

Repair of the aortic valve leaflets may be essential for short and long term success of the

The first technique for correction of aortic root dilatation was described by Sir Magdi Yacoub [11] and subsequently also by Dr Tirone David (David Remodelling procedure). This procedure corrects STJ dilatation and creates neo-aortic sinuses, but does not affect the

In this technique, the ascending aorta is transected and the aortic root is excised to within 2–3mm of the valve attachment. Subsequently, a Dacron graft sized to the ideal STJ diameter is incised to create 3 evenly spaced tongues. This mimics the aortic sinuses, thus creating a neo-aortic root (Fig. 6 and 7). The apices of the valve commissures are then anastomosed to the corresponding points on the trimmed graft with pledgeted mattress sutures. The

In a modification of the David Remodelling procedure, a separate Teflon "annuloplasty" is added in an attempt to prevent future annular dilatation. This annular plication is not done circumferentially, but over the length of the fibrous LVOT, which is the component most

The re-implantation technique is performed by excising the aortic sinuses and placing a row of braided non-absorbable horizontal mattress sutures evenly around the left ventricular outflow tract below the level of the annulus (Fig. 8). These are passed through the proximal end of the graft which is tied in position as an external annuloplasty. The commissures are firstly secured within the graft ensuring that they are taught and vertically upright (Fig. 9 and 10), then the remnant of the aortic sinus tissue is then re-implanted inside the prosthesis

In the David re-implantation procedure, a single Dacron graft is used to achieve both annular and STJ plication. The advantages are greater simplicity and haemostasis. The disadvantages are incorporation of the muscular LVOT in the plication process, which if

proximal sewing line is completed with a running polypropylene suture.

excessive may result in a higher than normal sub-annular gradient.

of the jet can give vital clues of leaflet prolapse or restriction.

need for concomitant bypass grafting.

specifics of concomitant ascending arch pathology.

aortic valve re-implantation and aortic root remodelling.

operation, if there is significant leaflet prolapse or restriction.

**4.3 Valve sparing aortic root replacement** 

**4.2 Intra-operative technique** 

**4.3.1 Aortic root remodelling** 

often affected by dilatation.

**4.3.2 Aortic valve re-implantation** 

with running polypropylene suture.

annular size.

#### **3.1 Classification of aortic regurgitation**

While the Carpentier classification for mitral valve regurgitation has seen widespread application, in recent years, a similar functional classification system for aortic regurgitation has been developed by El Khoury and colleagues [8]. In this system, the aortic valve is viewed as two components, the annulus and valve leaflets, the former consisting of the ventriculo-aortic junction and the sinotubular junction.

The system classifies aortic regurgitation as secondary to I) dilatation of the aortic root structures, II) excessive leaflet motion (ie. prolapse) or III) restriction in leaflet motion such as that in bicuspid, rheumatic and other degenerative processes. One or more of these lesions may be present in to a given case of aortic regurgitation [8].

### **3.2 Clinical consequences of aortic regurgitation**

Untreated symptomatic aortic regurgitation carries a poor prognosis. In patients with New York Heart Association Class III or IV symptoms, 4-year survival is around 30% [9] Symptomatic patients should be offered prompt surgical intervention for aortic regurgitation. Asymptomatic patients should be considered for surgery when left ventricular dimensions increase above the normal range or when ventricular function begins to decline.

In patients with aneurysms of the aortic root, valve-sparing aortic root surgery should be considered when root diameter exceeds 50mm. In those with Marfan's syndrome or a history of aortic dissection, surgery should be considered at 45mm regardless of the prospect of valve preservation.

*Conditions when 45mm is a trigger for replacement* 


Table 2. Conditions where aortic dilatation of 45mm is a trigger for replacement

Surgery for replacement of the ascending aorta should be considered when the diameter reaches 50mm.

Surgery may be offered earlier in the presence of a rapidly enlarging aneurysm or coexisting moderate to severe aortic regurgitation. In the case of the latter, earlier surgery before the aneurysm has reached a substantial size may increase the chances of valve preservation by limiting further stretching of valve cusps beyond repair. Aneurysms of the aortic root are the most common indication for surgery.
