Standardized Technique of Aortic Valve Re-implantation for Valve-sparing Aortic Root Replacement

Summary

Valve-sparing aortic root replacement has the advantage of preserving the patient's own aortic valve. The complexity of the reported techniques to date restricts their use to a limited number of cardiac surgeons. This protocol describes step-by-step a standardized technique reproducible by a greater number of cardiac surgeons.

Abstract

Despite the obvious advantages of the preservation of a normal aortic valve during aortic root replacement, the complexity of valve sparing procedures prevents a number of cardiac surgeons from incorporating them into their practice. The aim of this protocol is to describe a simplified and user-friendly technique of an aortic valve-sparing root replacement (VSRR) procedure by re-implantation of the aortic valve. Proper selection of patients and limitations of the technique are discussed.

In 54 consecutive patients, normal appearing aortic valves were re-implanted in a commercially available polyester prosthesis with pre-shaped sinuses by a simplified and standardized technique. Placement of the first row of the proximal suture line, choice of the prosthesis size, and adjustment of the height of the commissures of the patient to the fixed height of the sinus portion of the prosthesis were slightly modified from the reference techniques with the aim of increasing its feasibility for use by other cardiac surgeons. Early mortality and morbidity as well as 5-year survival, freedom from aortic valve reoperation, and freedom from recurrent moderate regurgitation were collected in all patients.

Thirty-day mortality, re-sternotomy for bleeding, re-sternotomy for mediastinitis, and the incidence of stroke were very low, 1.8% for each (1 of 54). No patient required permanent pace-maker implantation. At 5 years, survival, freedom from aortic valve reoperation, and freedom from recurrent moderate regurgitation were 97.5%, 95.2%, and 91.6%, respectively.

Mid-term results of our standardized technique of re-implantation of the aortic valve for valve-sparing aortic root replacement are very good and compare with more complex techniques reported by experienced surgeons. By following the present protocol of the standardized re-implantation technique, a greater number of cardiac surgeons can perform this procedure with comparable good results.

Introduction

During the past twenty years, the surgical treatment of aortic root aneurysm with normal or near-normal aortic cusps has evolved thanks to a series of surgical procedures aiming at preservation of the native aortic valve^1,2,3,4,5. Valve-sparing aortic root replacement is basically accomplished either by re-implantation of the aortic valve inside a synthetic graft^1,3,4,6 or by a remodeling technique which restores the physiological anatomy of the aortic root². Despite the obvious advantages of the preservation of a normal aortic valve during aortic root replacement, many cardiac surgeons replace the aortic valve with either mechanical or biological valve substitutes. According to the Society of Thoracic Surgeons database, only 14% of patients who underwent aortic root replacement in the United States between 2004 and 2010 received a valve-sparing procedure⁷.

In the original re-implantation technique, the aortic valve is sutured inside a tubular horizontally crimped synthetic graft⁸. Although this technique stabilizes the aortic annulus, it eliminates the sinuses of Valsalva. In order to recreate the sinuses of Valsalva, this technique has undergone several modifications by its inventor as well as other authors⁹. A variation of this technique has been proposed by Rama et al., in which the remnants of the aortic wall supporting the commissures are sutured into longitudinal openings made in the tubular polyethylene terephthalate graft⁴.

The remodeling technique achieves a more anatomical reconstruction of the aortic root but leaves the aortic annulus unsupported and exposed to future dilatation. Various surgical techniques have been designed to tailor the aortic annular base in aortic root remodeling, including sub-commissural aortic annuloplasty¹⁰, circumferential suture annuloplasty¹¹, and internal or external annuloplasty by synthetic partial or complete ring¹².

Despite the excellent results reported by experienced authors, the complexity and periodical modifications of these procedures hamper their reproducibility by other cardiac surgeons and thus prevent a number of suitable patients to benefit from retaining their own aortic valve. In order to enhance the reproducibility of the re-implantation technique, we have used a commercially available synthetic graft with an uncrimped, pre-shaped sinus portion and simplified the implantation technique. The aim of this protocol is to describe in detail this standardized and reproducible technique with particular emphasis on the management of the first row of the proximal suture line and of the placement of the commissures inside the graft and the choice of the graft size. Early outcomes and mid-term results are presented. Proper selection of patients for and limitations of this procedure are discussed.

Protocol

The protocol follows the institutional guidelines of the human research ethics committee.

1. Pre-selection of the Patient

1. Identify patients with dilation of the sinuses of Valsalva not exceeding 60 mm using the pre-operative computer tomography (CT) scan.
2. Next, select among these patients a subgroup with normal or near-normal appearing aortic valve cusps on their pre-operative echocardiography.
3. Inform the staff of the possibility of a valve sparing aortic root replacement procedure.
4. Make the final decision intra-operatively after inspection of the aortic valve. Verify the absence of calcifications of the cusps and/or thickening and retraction of their free margin.

2. Preparation for Surgery

NOTE: Preparation for surgery follows the institutional guidelines and recommendations for adult cardiac surgery patients.

1. Prepare the surgical suite and patient for surgery as previously described¹³.

3. Surgery

1. Access to the heart through a median sternotomy, as previously described¹³ (Figure 1A).
2. Prepare the aortic root for replacement.
   1. Grab the ascending aorta at the sino-tubular junction with Carpentier dissection forceps. Make a horizontal opening with a #11-blade knife.
   2. Complete the aortotomy circumferentially and horizontally with Metzenbaum scissors.
   3. After having transected the aorta, verify the absence of calcifications of the cusps and/or thickening and retraction of their free margin. Check the coronary ostia.
   4. Dissect free from the surrounding tissue the outer aspect of the non-coronary sinus down to the roof of the left atrium.
   5. Detach the right coronary ostium from the aortic wall with a generous circular patch, leaving 5 mm of the aortic wall remnant attached to the insertion of the cusp (Figure 1B).
   6. Free the commissure between the non-coronary and right coronary sinus from the surrounding tissue.
   7. Dissect free the outer aspect of the aortic wall remnant of the right coronary sinus from the outflow tract of the right ventricle.
   8. Free the outer aspect of the commissure between the non-coronary and left coronary sinus down to the roof of the left atrium.
   9. Excise the aortic wall of the non-coronary sinus leaving 5 mm of the aortic wall remnant attached to the insertion of the cusp.
   10. Separate the outer aspect of the commissure between the right and left coronary sinus from the surrounding tissue. Take care not to injure the pulmonary artery.
   11. Detach the left coronary ostium from the aortic wall with a generous circular patch, leaving 5 mm of the aortic wall remnant attached to the insertion of the cusp (Figure 1B). Mobilize the left main coronary artery over its first 10 mm.
   12. Dissect free the outer aspect of the aortic wall remnant of the left coronary sinus from the roof of the left atrium.
   13. Put a mattress 4/0 polypropylene stay suture on top of each commissure.
3. Start the proximal implantation of the prosthesis.
   1. Perform the first row of the proximal anastomosis by 12 mattress non-pledgeted 2/0 braided polyester sutures. Put these sutures circumferentially in a horizontal plane 1 - 2 mm below the insertion of the cusps and at the base of the commissural triangles except for the commissure between the non-coronary and right coronary sinus (Figure 2A).
   2. Put the first mattress suture at the base of the commissural triangle between the non-coronary and left coronary sinus. Put the second and third sutures 1 - 2 mm below the insertion of the non-coronary cusp, in the direction of the commissure between the non-coronary and right coronary sinus.
   3. Place the forth suture next to the third one in the direction of the commissure between the non-coronary and right coronary sinus by avoiding the base of the commissural triangle between the non-coronary and right coronary sinus and thus not compromising the membranous septum.
   4. Start the first suture of the right coronary sinus 2 mm away from the base of the commissural triangle of the commissure between the non-coronary and right coronary sinus, thus skipping the membranous septum (Figure 2B).
   5. Put the following sutures of the right coronary sinus in the direction of the commissure between the left and right coronary sinus.
   6. Place the forth suture of the right coronary sinus at the base of the commissural triangle of the commissure between the left and right coronary sinus.
   7. Next, pass 4 equidistant mattress sutures 1 - 2 mm below the insertion of the left coronary cusp for fixation of the left coronary sinus.
   8. To choose the size of the prosthesis, add 4 to 6 mm to the size of a commercially available biological valve sizer which passes comfortably through the left ventricular-aortic valve junction.
   9. Determine the commissural height between the commissural stay suture and the mattress suture at the basis of the commissural triangle. To adjust the commissural heights of the patient to the pre-shaped sinuses of the prosthesis, pass the 4/0 polypropylene commissural stay sutures inside-outside of the prosthesis in the vicinity of its sino-tubular junction.
   10. Be aware that the height of the commissure between the left and right coronary sinus is often slightly less than that of the other two. Trim circumferentially the lower neck of the prosthesis 2 mm below the measured commissural height to adapt the height of the sinuses of the prosthesis to that of the commissures and to be able to pass the first row of the mattress sutures through the prosthesis.
   11. Now pass the mattress sutures inside-out into the prosthesis. Slide down the prosthesis thus placing the valve inside it (Figure 3A). Tie the mattress sutures gently and cut them.
   12. Start the second row of the proximal anastomosis by three 5/0 polypropylene running sutures, one for each sinus.
   13. Begin the first 5/0 polypropylene running suture at the nadir of the left coronary sinus to fix the remnant of the aortic wall inside the prosthesis by following in parallel the insertion of the cusp up to the commissure between the left and right coronary and then up to the commissure between the left and non-coronary sinus. Put the 2 ends under slight tension.
   14. Continue with the second 5/0 polypropylene running suture at the nadir of the right coronary sinus to fix the remnant of the aortic wall inside the prosthesis by following in parallel the insertion of the cusp up to the commissure between the right and left coronary and then up to the commissure between the right and non-coronary sinus. Put the 2 ends under slight tension.
   15. Place the third 5/0 polypropylene running suture at the nadir of the non-coronary sinus to fix the remnant of the aortic wall inside the prosthesis by following in parallel the insertion of the cusp up to the commissure between the non-coronary and left coronary sinus.
   16. Finish the second row of the proximal anastomosis by fixing the remnant of the aortic wall in parallel to the insertion of the cusp up to the commissure between the non-coronary and right coronary sinus. Tie at each commissure the two suture-ends together (Figure 3B).
   17. Check the absence of aortic regurgitation by filling the prosthesis with saline and applying suction to the vent placed through the right pulmonary vein and the mitral valve into the left ventricle.
4. Reconnect the coronary ostia to the prosthesis (Figure 4).
   1. Create a button hole in the left sinus of the prosthesis adjusted to the size of the left coronary ostium patch.
   2. Begin the anastomosis at the nadir of the button hole in the prosthesis from inside out and to the left coronary ostium from outside in by a 6/0 polypropylene running suture.
   3. Place the second stitch 2 mm to the right of the first one from inside out of the prosthesis and outside in of the left coronary ostium up to the mid-height of the right ridge of the anastomosis. Put the suture end under light tension.
   4. Continue the running suture on the left ridge of the anastomosis from outside in the prosthesis and from inside out of the left coronary ostium to meet the other end. Tie the two ends together.
   5. Create a button hole in the right sinus of the prosthesis adjusted to the size of the right coronary ostium patch.
   6. Connect the right coronary ostium to the prosthesis by a 6/0 polypropylene running suture, starting at the nadir of the right coronary ostium from inside out and into the prosthesis from outside in.
   7. Continue the suture to the mid-height of the right ridge of the anastomosis and put the end under light tension.
   8. Complete the anastomosis by running the left ridge of the anastomosis to meet the other end. Tie the two ends together.
5. Perform the distal anastomosis (Figure 4).
   1. Start the anastomosis at the nadir of the distal end of the prosthesis from inside out and into the distal ascending aorta from outside in by a 5/0 polypropylene running suture. Run up the suture first to the mid-height of the right ridge of the anastomosis.
   2. Complete the distal anastomosis by running the suture on the left ridge to meet the other end. Tie the ends together.
   3. Tilt the operating table in the Trendelenburg position. Let the pump flow reduce to 50% of the full flow and slowly remove the aortic cross-clamp under gentle aspiration of the left ventricular vent.
   4. Resume the full flow of the cardio-pulmonary bypass. Check the operative field for undue surgical bleeding.
   5. Rewarm the patient to 37 °C and separate the patient from the cardio-pulmonary bypass. Stabilize blood pressure, neutralize heparin by protamine infused IV in a 1:1 ratio (3 mg/kg corresponding to 300 U/kg of heparin).
   6. Check for hemostasis and put the chest drainage as needed. Close the chest in standard fashion by reapproximating the sternum with sternal wires and the soft tissue with absorbable sutures in two layers¹³.

4. Post-operative Patient Care

1. Following the transfer to the intensive care unit, provide the patient with standard post-operative care for cardiac surgical operation on aortic root¹³.

Results

Statistical Analysis:

Continuous variables are presented as mean ± standard deviation and categorical variables as percentages. Kaplan-Meier curves are calculated for survival, freedom from aortic valve reoperation, and freedom from recurrent moderate regurgitation using a commercially available software package.

Patient Population:

Discussion

In patients presenting with aortic root aneurysm with normal or near-normal aortic cusps, valve-sparing aortic root replacement is a more physiological and hence attractive alternative to composite graft replacement of the aorta and the aortic valve with mechanical or tissue valve. In this protocol, we describe a simplified technique of valve-sparing aortic root replacement by re-implantation of the aortic valve. In contrast to the majority of the previously reported techniques^3,

Materials

Name	Company	Catalog Number	Comments
Heart surgery infrastructure:
Heart Lung Machine	Stockert	SIII
EOPA 24Fr. arterial cannula	Medtronic	77624
Atrial caval venous cannula 34/48Fr.	Medtronic	93448
LV vent catheter 17Fr.	Edwards	E061
Antegrade 9Fr. cardioplegia cannula	Edwards	AR012V
Retrograde 14Fr. cardioplegia cannula	Edwards	NPC014
Coronary artery ostial cannula 90°	Medtronic	30155
Coronary artery ostial cannula 45°	Medtronic	30255
Name	Company	Catalog Number	Comments
Pre-shaped sinus graft
Cardioroot 28 mm	Maquet	HEWROOT0028
Cardioroot 30 mm	Maquet	HEWROOT0030
Cardioroot 32 mm	Maquet	HEWROOT0032
Name	Company	Catalog Number	Comments
Electrocautery	Covidien	Force FX
Name	Company	Catalog Number	Comments
Sutures:
Polypropylene 4/0	Ethicon	8871H
Polypropylene 5/0	Ethicon	8870H
Polypropylene 6/0	Ethicon	EH7400H
Braided polyesther 2/0 ligature with polybutylate coating	Ethicon	X305H
Name	Company	Catalog Number	Comments
Micro knife Sharpoint	TYCO Healthcare PTY	78-6900
Name	Company	Catalog Number	Comments
Drugs:
Midazolam	Roche Pharma	N05CD08
Rocuronium	MSD Merck Sharp & Dohme	M03AC09
Propofol	Fresenius Kabi	N01AX10
Fentanil	Actavis	N01AH01
Heparin	Braun	B01AB01
Protamin	MEDA Pharmaceutical	V03AB14
Name	Company	Catalog Number	Comments
Instruments:
Cooley vascular aortic clamp	Delacroix-Chevalier	DC40810-16
Dissection forceps Carpentier	Delacroix-Chevalier	DC13110-28
Scissors Metzenbaum	Delacroix-Chevalier	B351751
Needle holder Ryder	Delacroix-Chevalier	DC51130-20
Dissection forceps DeBakey	Delacroix-Chevalier	DC12000-21
Micro needle holder Jacobson	Delacroix-Chevalier	DC50002-21
Micro scisors Jacobson	Delacroix-Chevalier	DC20057-21
Lung retractor	Delacroix-Chevalier	B803990
Allis clamp	Delacroix-Chevalier	DC45907-25
O’Shaugnessy Dissector	Delacroix-Chevalier	B60650
18 blade knife	Delacroix-Chevalier	B130180
Leriche haemostatic clamp	Delacroix-Chevalier	B86555
Name	Company	Catalog Number	Comments
Data analysis
Kaplan Meier curves	GraphPad	Prism 7