**3. Surgery of the aortic root**

There are several indications to repair the aortic root and the ascending aorta. The most frequent one is the aneurysmal dilation of the aortic root ± ascending aorta that is associated with aortic valve dysfunction (in general regurgitation). In this case, the aortic valve leaflets may be fundamentally normal. This may lead to insufficient coaptation of the leaflets and therefore cause valve-regurgitation. In other patients, the aortic valve leaflets may be abnormal because of bicuspid morphology and the disease is associated with an enlarged ascending aorta. When the primary indication to operate on the patient is the aortic valve disease or myocardial revascularization, the ascending aorta is usually replaced very liberally (this means if the diameter is larger than 4.5 cm). Another situation that calls for the repair of the aortic root and ascending aorta is the patient that presents with severe aortic valve stenosis (either bicuspid or tricuspid aortic valve) and with post-stenotic dilation of the ascending aorta. In this category of patients, if the sinotubular junction is maintained and the aortic root diameter at the level of sinuses of Valsalva does not exceed 4 cm, it is generally accepted that a separate aortic valve replacement and supracoronary replacement of the ascending aorta with a prosthetic graft can be performed.

During the last decade, the authors have been increasingly aggressive in the replacement of the complete ascending aorta and base of the aortic arch using a short period of antegrade cerebral perfusion, performing the distal anastomosis without aortic cross clamp.

Contemporary surgical options for the aortic root include either a full aortic root replacement (biological or mechanical), or valve sparing aortic root replacement. Different graft options and/or valve options exist and are further discussed below.

#### **3.1. Graft and valve options for aortic root surgery**

The aortic root can be replaced with either a synthetic material (usually Dacron) or a biologic prosthesis. Biologic options come in the form of xenografts or homografts. Synthetic graft options includes expanded poly (ethylene terephthalate) (Dacron) or poly(tetrafluoroethylene) (ePTFE), and represent the most widely employed vascular substitutes in cardiovascular surgery. Dacron grafts can come in a straight tubular shape or in a specifically designed form that, on implantation and pressurization, generates pseudosinuses of Valsalva.

#### *3.1.1. Xenografts*

**2. Historical perspective**

122 Structural Insufficiency Anomalies in Cardiac Valves

coronary arteries.

The first successful replacement of a fusiform ascending aortic aneurysm was reported by Cooley and De Bakey in 1956 [1]. That first report was made possible thanks to the introduction of cardiopulmonary bypass to aortic aneurysm surgery. Following, several surgeons

Handling of the aortic root, below the sinotubular junction was first reported in 1964, when Wheat reported his team's efforts to replace the entire ascending aorta [2]. Although the procedure performed may not have involved the entire aorta as the title claimed, its legacy was secured as a description of how to handle pathology extending proximal to the coronary ostia. Their approach to the displaced coronary ostia was to resect the aorta 1.5–2 cm proximal to this level, while leaving a tongue of tissue surrounding the two coronary takeoffs. In this way, they maintained the integrity of the ostia and ensured the sutures were far enough from the

While others continued to work tirelessly, the group at Oregon, including Drs. Herr and Starr, were diligently at work devising mechanical valves that would eventually be used for Bentall's historic procedure [3, 4]. In 1968, they published their ongoing clinical experience and engineering progress. Their ingenuity to use a composite valve-graft prosthesis was a major step in the progression of aortic root surgery, and the composite valve-graft, whether using a mechanical (as originally done) or tissue valve, is still considered the gold standard today [5]. Following, new concepts evolved for sparing the aortic valve and replacing the aortic root only. The first was developed by Sir Yacoub, and had been used in his practice since 1979 [6, 7]. The procedure, which he designed, later became referred to as the "remodeling technique." The functional focus was to preserve the native valve, while recreating the aortic sinuses. This goal was achieved by fashioning a scalloped Dacron® graft such that three tongues extended to replace the intrinsic sinuses. Interposed between these three extensions, native tissue was left intact at the attachment of the cusps. Once the graft was attached, the coronary arteries

In the late 1980s, David and his colleagues at the University of Toronto developed an alternative class of valve-sparing procedures [8]. Their procedure went through numerous iterations and variations, but classically the technique became referred to as the "reimplantation technique." [9, 10] This approach had the benefit of stabilizing the aortic annulus by sewing the

There are several indications to repair the aortic root and the ascending aorta. The most frequent one is the aneurysmal dilation of the aortic root ± ascending aorta that is associated with aortic valve dysfunction (in general regurgitation). In this case, the aortic valve leaflets may be fundamentally normal. This may lead to insufficient coaptation of the leaflets and

forged ahead and described similar experiences with similar pathologic entities.

would be mobilized and anastomosed to the neoaorta.

**3. Surgery of the aortic root**

native valve directly into a Dacron® graft of a fixed circumference.

Xenografts can come in the form of stented or stentless valve. Some of the stentless valves present as a full root products and can either be implanted as a full root replacement and/or as a valve replacement alone. The stented valves may be used for valve replacement alone, or may be composed to any graft type in order to be served for full root replacement.

Some options for stentless valves include the following:

#### *3.1.1.1. Freestyle™ porcine aortic root bioprosthesis (medtronic)*

This third-generation device presents as the complete porcine aortic root with thin polyester covering of the septal myocardium. The tissue is glutaraldehyde fixed using the physiologic root pressure technique: there is zero net pressure applied to the valve cusps to preserve collagen crimp while the aorta is distended to normal configuration. The graft may be implanted as a valve replacement in the subcoronary position, as an inclusion root cylinder, or as a full aortic root replacement.

#### *3.1.1.2. Toronto SPV glutaraldehyde-preserved porcine xenograft (St. Jude Medical)*

The aortic tissue is removed from all three sinuses, and the graft is covered with a thin coat of polyester. It can only be implanted as a subcoronary valve replacement. It has no antimineralization treatment. Hemodynamic performance has been excellent and equivalent to the Medtronic Freestyle device.

trunk is then replaced with a cryopreserved pulmonary allograft as described earlier. This operation (Ross procedure) is hemodynamically superior to other procedures for replacing the aortic valve, because the patient's own pulmonary valve is properly sized to accept cardiac

Contemporary Surgical Options for the Aortic Root http://dx.doi.org/10.5772/intechopen.75816 125

Straight tubular Dacron grafts of different manufacturers can be used for a full aortic root replacement when combined with either a stented or a stentless biological valve, and/or a mechanical valve. The advantages/disadvantages of straight tubular grafts versus grafts

The native aortic root is not a stiff tube but rather a highly dynamic structure that accommodates to changes in the pressure-volume relationship in a very subtle way. During the early 1990s, Robicsek described the dynamic function of the aortic root and especially the sinuses of Valsalva [11]. The sinuses of Valsalva reduce the shear stress on the cusps of the aortic valve and promote optimal coronary blood flow during diastole [11, 12]. Another important aspect is of the facilitation of vortex formation that seems to help in smooth valve closure with less bending deformation in the longitudinal direction, and reduce the stress on the coronary anastomosis [12–15]. All the above factors can affect the durability and performance and lon-

Many attempts had been made by both surgeons and commercial companies to create a graft that resembles in shape and function of the native aortic root. The Valsalva graft is a Dacron graft with a specific design that, on implantation and pressurization, it generates three independent pseudosinuses. It is commonly used either in aortic-valve sparing procedures or in aortic root replacements when it is combined with a stented or stentless biological valve.

Combination of either a tubular or a pseudosinuses-graft, with a biological (stented or non-

Various such combinations are clinically common. The clinical differences stem mainly from the type of valve used, and in cases a pseudosinuses-graft is used, its potential benefits can be

The question of whether to replace the aortic root with a composite graft or to perform a valve-sparing operation is dependent on multiple patient characteristics as well as the surgeon preference. Over the last decade surgeons have debated which technique provides the best peri-operative and long-term results. The etiology of the aortic root disease, as well as individual patient preferences, must be taken into account so the correct procedure is per-

incorporating pseudosinuses of Valsalva are discussed in the following paragraph.

output with little or no pressure gradient.

*3.1.4. Grafts incorporating pseudosinuses of Valsalva*

gevity of the aortic bio-prosthetic valves.

stented) or mechanical valve, will create a composite graft.

**3.2. Composite versus valve sparing root replacement**

added to that of the valve it is combined with.

*3.1.5. Composite grafts*

formed for each patient.

*3.1.3. Straight tubular grafts*

### *3.1.1.3. Edwards Prima (Edwards Lifesciences)*

The Prima device is a low-pressure glutaraldehyde-fixed porcine aortic root similar to the Freestyle device. It has a thin cloth reinforcement over the muscle bar. The porcine coronaries were excised in the earlier version but preserved in the later version without ligation. The **Prima Plus** is a low-pressure fixed valve with proprietary XenoLogiX treatment for calcium mitigation.

### *3.1.1.4. CryoLife-O'Brien (CryoLife International)*

Stentless porcine aortic valve is a manufactured composite of the noncoronary sinus and cusp from three porcine aortic roots. It is designed to be implanted below the coronary arteries in a supra-annular position in the sinuses of Valsalva by a single suture line.

The tissue is fixed in glutaraldehyde but there is no specific antimineralization treatment of this valve. Experience is limited to a few centers, and the technical aspects of implantation may be more difficult than with other stentless bioprostheses.

#### *3.1.1.5. Pericarbon Freedom (Sorin Group).*

The Pericarbon Freedom stentless valve is composed of two sheets of bovine pericardium sewn together to produce a cylindrical shape and fixed with glutaraldehyde.

#### *3.1.1.6. Biocor stentless (Biocor Industria e Pesquisas LTDA)*

Biocor stentless (Biocor Industria e Pesquisas LTDA) is a porcine aortic valve treated with the No-React (Shelhigh Inc., Union, NJ) process.

#### *3.1.2. Allografts*

#### *3.1.2.1. Cryopreserved aortic allograft*

Human donor aortic valve allografts are presented as the complete aortic root, ascending aorta, and some or all of the aortic arch. The anterior leaflet of the mitral valve typically remains attached.

#### *3.1.2.2. Pulmonary autograft*

Pulmonary autograft, the patient's own pulmonary trunk, including the pulmonary valve, may be used to replace the aortic valve, usually as a full aortic root replacement. The pulmonary trunk is then replaced with a cryopreserved pulmonary allograft as described earlier. This operation (Ross procedure) is hemodynamically superior to other procedures for replacing the aortic valve, because the patient's own pulmonary valve is properly sized to accept cardiac output with little or no pressure gradient.

#### *3.1.3. Straight tubular grafts*

*3.1.1.2. Toronto SPV glutaraldehyde-preserved porcine xenograft (St. Jude Medical)*

Medtronic Freestyle device.

124 Structural Insufficiency Anomalies in Cardiac Valves

mitigation.

*3.1.2. Allografts*

remains attached.

*3.1.2.2. Pulmonary autograft*

*3.1.1.3. Edwards Prima (Edwards Lifesciences)*

*3.1.1.4. CryoLife-O'Brien (CryoLife International)*

*3.1.1.5. Pericarbon Freedom (Sorin Group).*

No-React (Shelhigh Inc., Union, NJ) process.

*3.1.2.1. Cryopreserved aortic allograft*

The aortic tissue is removed from all three sinuses, and the graft is covered with a thin coat of polyester. It can only be implanted as a subcoronary valve replacement. It has no antimineralization treatment. Hemodynamic performance has been excellent and equivalent to the

The Prima device is a low-pressure glutaraldehyde-fixed porcine aortic root similar to the Freestyle device. It has a thin cloth reinforcement over the muscle bar. The porcine coronaries were excised in the earlier version but preserved in the later version without ligation. The **Prima Plus** is a low-pressure fixed valve with proprietary XenoLogiX treatment for calcium

Stentless porcine aortic valve is a manufactured composite of the noncoronary sinus and cusp from three porcine aortic roots. It is designed to be implanted below the coronary arteries in a

The tissue is fixed in glutaraldehyde but there is no specific antimineralization treatment of this valve. Experience is limited to a few centers, and the technical aspects of implantation

The Pericarbon Freedom stentless valve is composed of two sheets of bovine pericardium

Biocor stentless (Biocor Industria e Pesquisas LTDA) is a porcine aortic valve treated with the

Human donor aortic valve allografts are presented as the complete aortic root, ascending aorta, and some or all of the aortic arch. The anterior leaflet of the mitral valve typically

Pulmonary autograft, the patient's own pulmonary trunk, including the pulmonary valve, may be used to replace the aortic valve, usually as a full aortic root replacement. The pulmonary

supra-annular position in the sinuses of Valsalva by a single suture line.

sewn together to produce a cylindrical shape and fixed with glutaraldehyde.

may be more difficult than with other stentless bioprostheses.

*3.1.1.6. Biocor stentless (Biocor Industria e Pesquisas LTDA)*

Straight tubular Dacron grafts of different manufacturers can be used for a full aortic root replacement when combined with either a stented or a stentless biological valve, and/or a mechanical valve. The advantages/disadvantages of straight tubular grafts versus grafts incorporating pseudosinuses of Valsalva are discussed in the following paragraph.

#### *3.1.4. Grafts incorporating pseudosinuses of Valsalva*

The native aortic root is not a stiff tube but rather a highly dynamic structure that accommodates to changes in the pressure-volume relationship in a very subtle way. During the early 1990s, Robicsek described the dynamic function of the aortic root and especially the sinuses of Valsalva [11]. The sinuses of Valsalva reduce the shear stress on the cusps of the aortic valve and promote optimal coronary blood flow during diastole [11, 12]. Another important aspect is of the facilitation of vortex formation that seems to help in smooth valve closure with less bending deformation in the longitudinal direction, and reduce the stress on the coronary anastomosis [12–15]. All the above factors can affect the durability and performance and longevity of the aortic bio-prosthetic valves.

Many attempts had been made by both surgeons and commercial companies to create a graft that resembles in shape and function of the native aortic root. The Valsalva graft is a Dacron graft with a specific design that, on implantation and pressurization, it generates three independent pseudosinuses. It is commonly used either in aortic-valve sparing procedures or in aortic root replacements when it is combined with a stented or stentless biological valve.

#### *3.1.5. Composite grafts*

Combination of either a tubular or a pseudosinuses-graft, with a biological (stented or nonstented) or mechanical valve, will create a composite graft.

Various such combinations are clinically common. The clinical differences stem mainly from the type of valve used, and in cases a pseudosinuses-graft is used, its potential benefits can be added to that of the valve it is combined with.

#### **3.2. Composite versus valve sparing root replacement**

The question of whether to replace the aortic root with a composite graft or to perform a valve-sparing operation is dependent on multiple patient characteristics as well as the surgeon preference. Over the last decade surgeons have debated which technique provides the best peri-operative and long-term results. The etiology of the aortic root disease, as well as individual patient preferences, must be taken into account so the correct procedure is performed for each patient.

Patients with connective tissue disorders, bicuspid valves, or history of valve infection may be best served with Bentall-type replacement rather than valve-sparing reconstruction. Despite the surgical complexity, long-term experience with VSRR among bicuspid and/or patients with connective tissue disorders are associated with excellent outcomes [16].

CPB is established at 34°C using a single two-stage venous cannula and left atrial vent. The aorta is occluded just proximal to the brachiocephalic artery. Cardioplegia is given. The ascending aorta is opened transversely in its midportion. The patient's aortic root is dissected from the surrounding tissues. Traction stitches are placed above each aortic valve commissure to expose the aortic root. The aortic valve is excised. The coronary arteries are mobilized, retaining a generous button of sinus aorta. A limited dissection of the coronary artery is sufficient to ensure that excision of the coronary artery is complete and that the coronary button will move easily up to the composite prosthesis without kinking or creating undue tension on the artery. The remaining sinus aorta is removed. Diameter of the annulus is calibrated, and an appropriately sized composite prosthesis is chosen. Stitches are placed through the annulus of the aortic valve and brought up through the sewing ring of the prosthesis preferably using single interrupted braided sutures. It is the authors' preference to implant the valve in the vascular graft 2–3 mm above the lower end of the graft, and to place the root stitches through the graft itself and not through the valve ring itself. Doing so, provides the future option of explanting the valve itself if need be for replacement without disrupting the entire root. The composite valve is brought down, and sutures are tied down. Next, a direct anasto-

Contemporary Surgical Options for the Aortic Root http://dx.doi.org/10.5772/intechopen.75816 127

The distal end of the graft is then shortened to approximate the distal end of the aorta. The anastomosis is constructed using continuous stitches of 4–0 or 5–0 polypropylene, depending

It is the author's preference to use a composite graft constructed from a 27 to 29 mm Freestyle MS valve (Medtronic) sutured into a 28–30 mm Gelweave Valsalva prosthesis (Sulzer Vascutek, Renfrewshire, Scotland) as the choice when implanting a biological tissue valve. This composite requires 30–40 min preparation time, but provides the patient with the potential benefits of: (1) avoiding the need for anticoagulation, (2) excellent hemodynamic performance of stentless valves, (3) incorporation of sinuses of Valsalva into the neoaortic root can

This is typically performed in the setting of an aortic root infection. An aortic allograft may be used to replace the patient's aortic root completely. The initial steps of the surgery are similar to those mentioned in Section 4.1.2. Typically, the allograft is used intact and in natural anatomic orientation, with only the excess of septal myocardium and the anterior leaflet of the mitral valve removed. Size match is not nearly as important as it is for freehand subcoronary valve replacement, but if the aortic annulus is more than 3 mm larger in diameter than the largest available aortic allograft, the patient's aortic root should be narrowed to approximate the size of the allograft. This can be done conveniently by placing a pledgeted mattress stitch through the aortic annulus alongside the commissures so that when tied, the intercusp triangle below the commissure is obliterated. The allograft is attached to the LVOT at the aortic annulus and below the commissures by simple interrupted stitches of 3–0 or 4–0

mosis of the coronary ostia to the graft is made.

improve the function and longevity of stentless valves.

on the thickness and strength of the aorta.

*4.1.2. Aortic root replacement with an allograft*

polypropylene.

The current literature still lacks a definite answer to that question. Different authors publish very promising short, intermediate and long-term outcomes with both types of surgery. One recent large series published by Girardi et al. describes the outcomes of 890 patients (289 mechanical composites, 421 biological composites, and 180 VSRR). Operative mortality was 0.2% (0% in the VSRR group); the incidence of major postoperative complications was less than 0.5%. Predictors of adverse in-hospital outcome were age, nonelective operation, renal status, reoperation, New York Heart Association class, ejection fraction, and concomitant procedures. Five-year survival was 89.4%. In the propensity-matched groups, the type of operation performed did not affect in-hospital and late outcome. Aortic reintervention rates at 5 years were 0% for the mechanical composite valved graft group, 2.4% for the biologic composite valved graft group, and 7.3% for the valve-sparing reconstruction series. The authors concluded that in the current era, aortic root replacement can be performed with low perioperative risk in high-volume aortic centers. The type of operation performed does not affect early or late survival. Although the mechanical composite valved graft remains the gold standard for durability, the biologic composite valved graft and valve-sparing reconstruction are excellent options for those who cannot take or want to avoid long-term anticoagulation.

Another recent paper by David et al. was looking into the outcomes of a young (<70 years) patients group (total of 616 patients); and used propensity matching to compare valve-sparing root replacement to mechanical composite root replacement. The mean age at the work was 46 ± 14 years, mean follow up was 9.8 ± 5.3 years. Their outcomes showed reduced cardiac mortality among the valve-sparing group, the authors concluded that valve-sparing surgery should be the operation of choice for young patients with aortic root aneurysm and normal or near-normal aortic cusps [17].
