**9. Aortic root replacement using stentless xenograft**

Stent-less valve conduit (Freestyle™ valve conduit, Medtronic Corporation, Minnesota, USA) are commercially easily available when compared to homograft tissue. Thus, in recent years, they are the prosthesis of choice for aortic root replacement in the elderly or those with an infective etiology [49]. Hemodynamics match those of homograft, especially in patients with a small aortic root [50]. The sinus structure of these valves mirrors the native aortic root; an additional benefit when compared to a stented valve conduit [49]. However, unlike stented bio-prostheses, the mechanism of failure of these valves is often leaflet tears [51]. These can occur suddenly leading to acute aortic regurgitation and left heart failure. LeMaire and colleagues demonstrated in 132 patients who had porcine bioroot replacement that there was no structural valve dysfunction in any case during the 5 year follow up period [52] (**Figure 4**).

Here are the relevant steps that we use for our root replacement procedures. These steps remain the same irrespective of the type of prosthesis (mechanical valved-conduit or bioprosthesis):

1.We routinely cannulate the right axillary artery for arterial access in cardiopulmonary bypass in all patients with ascending aortic involvement with aneurysmal disease and certainly in all patients with aortic dissection. Our preferred method is direct cannulation of the axillary artery with a straight cannula (usually 18 or 20Fr); otherwise, an 8 mm vascular graft anastomosed in end-to-side manner to the vessel is used.

	- Prior to cutting the button out of the corresponding sinus, we recommend marking up the "12 o'clock" point—the top of the button is marked with marker pen or a prolene stitch. This would allow for a precise orientation of the button when re-implanted into a sinus of the valve conduit. Tension or kinking or rotation of the re-implanted button may result in coronary ischemia and create a serious problem at the conclusion of the operation;

**43**

*Aortic Root Reconstruction*

*DOI: http://dx.doi.org/10.5772/intechopen.86034*

button re-implantation;

coronary artery ostium;

with incision made from the other direction.

coronary button to facilitate re-implanting process;

sinus tissue on the button itself as well as on the annulus.

• Once the top of the button is marked, we start with cutting the left coronary sinus from the top of the commissure between the left and non-coronary cusps down towards the annulus of the left sinus. Most of the time, the actual opening of the LMCA is kept in the middle of the button on all four aspects of it. In larger root aneurysms, there is occasionally too much tissue in the sinus, so attention should be paid to the size of the button 0.5–1.0 cm off of the edge of the ostium of the LMCA is usually enough for a safe

• The initial cut has to keep ~5–7 mm of the sinus tissue in place, so as we come down along the commissure, the tip of the scissors is turned away from the annulus and the cut is curved around the lower edge of the

• Next, we start the cut from the top of the commissure between the left and right sinuses. It is critical to fully understand the course of the LMCA to avoid injury to it in case of intramural passing in the aortic wall. Large coronary probe can be placed in the lumen to check the direction of the LMCA. The cut is then curved away from the annulus leaving the same 5–7 mm of the sinus tissue in place and completing a "button" by connecting

• Great care has to be taken here as to not apply any excessive pulling on any portion of the button while making the cuts as this can lead to distortion and asymmetric fashioning of the button making safe re-implantation difficult;

• Once the LMCA button is fashioned out, the connective tissue and fat between the lower edge of the button and rim of the sinus remnant and the annulus is divided with cautery to provide just enough mobility for the

• Preparation of the RCA button follows the same general principles as

8.After both buttons are prepared, inflow suture line is created. For a mechanical prosthesis, we use 2–0 pledgeted stitches with the pledgets placed in a suppraannular position. It is important to ensure that the pledgets are lined next to each other without much gap as this will ensure hemostasis. Some use a secondary continuous prolene layer to seal this anastomosis. With Freestyle bioprosthesis, we use simple 2–0 interrupted stitches. A pericardial strip is then gently placed between the loops prior to knotting. The pericardial strip

acts as a gusset and also provides additional hemostasis to this layer.

unused and has to be over sawn with 4–0 or 5–0 pledgeted sutures.

10.Once an opening in the new left sinus is made with coronary punch, the coronary button is anastomosed using 5–0 prolene. We use a technique of

9.Additional important point has to be made for cases when Freestyle conduit is used. Orientation of the valve is of critical importance prior to drawing inflow sutures through the valve. We recommend rotating the valve 120°clockwise from its natural orientation, so that a non-coronary sinus of the valve would now become a left coronary sinus into which LMCA is re-implanted. Such rotation will make left coronary sinus of the valve a new right sinus into which RCA button will be re-implanted. The right button of the Freestyle remains

described for the LMCA button—marking the top to maintain orientation, avoiding excessive pulling while fashioning the button, maintaining enough

#### *Aortic Root Reconstruction DOI: http://dx.doi.org/10.5772/intechopen.86034*

*Cardiac Surgery Procedures*

2.Upon median sternotomy, pericardium is opened and suspended. Ascending aorta is prepared depending on distal extend of aortic intervention. If feasible, ascending aorta is freed of attachments from the right PA posteriorly and main PA to on the left and taken with an umbilical tape which facilitates further manipulations of the ascending aorta. During this step, it is important to stay close to the aortic wall to avoid injury to the pulmonary artery. For primary aortic root replacement, it is almost always possible to identify and follow such connective tissue plane between the aorta and the pulmonary artery. For a redo operation, it is more difficult and carries some serious risks. We prefer to use cautery dissection rather than scissors or blunt dissection as we feel this technique reduces postoperative bleeding. Small arterial and venous branches are often present between the aorta and pulmonary artery, particularly as one proceeds with dissection more proximally. These are divided between clips.

This initial dissection is preferably done prior to full heparinization.

an LV vent inserted via the right superior pulmonary vein.

main coronary artery (LMCA).

critical points and pitfalls:

3.Once the ascending aorta is mostly free of attachments and likely looped with an atraumatic tape, we give IV Heparin and cannulate aorta or the right axillary artery and right atrium for cardiopulmonary bypass. We always use retrograde cardioplegia delivered into the coronary sinus and use either a PA or

4.Once aorta is cross-clamped and heart is arrested with a combination of antegrade and retrograde cardioplegia, the aorta is transected in mid portion. Clear identification of the ostium of the right coronary artery (RCA) is required, so that the initial cut through the ascending aorta is placed far enough away from the RCA ostium. It is also important to divide ascending aorta in a way that there is at least a couple of centimeters of the aortic wall above the ostium of the left

5.At this stage we place 4–0 silk stay sutures at the tips of the aortic valve commissures. Aortic valve is then excised, annulus is sized. When a Freestyle valve conduit is used, there is no need to have a cylinder-shaped sizer pass into the LV through the annulus as the prosthetic valve will be fixed in the supra annular position. As such, a larger prosthetic valve can be used. Sizing for a mechanical valve conduit has to be done according to the manufacturer recommendations as most of the mechanical valves are designed for an intra-annular position.

6.At this stage, additional dissection is carried out between the aortic root and pulmonary artery and RVOT. Unlike for a valve sparing aortic root replacement with root re-implantation, this dissection for a Bentall operation is limited to clearing the space for a safe fashioning of the coronary buttons, particularly, for the LMCA. There is no need to dissect deep between the aortic

7.Preparation of the coronary buttons is similar for any aortic root replacement operation. Normally, we start with the left coronary button. Here are the

• Prior to cutting the button out of the corresponding sinus, we recommend

marking up the "12 o'clock" point—the top of the button is marked with marker pen or a prolene stitch. This would allow for a precise orientation of the button when re-implanted into a sinus of the valve conduit. Tension or kinking or rotation of the re-implanted button may result in coronary ischemia and create

root and the RVOT to expose the aortic annulus from the outside.

a serious problem at the conclusion of the operation;

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plicating the wall of the coronary button. A second layer is then used to ensure further hemostasis. Re-implantation of the right button is performed in a similar fashion. Once the aortic root is replaced and buttons re-implanted, we use local hemostatic glue to provide further sealing of needle holes.

