MMCTS
(October 18, 2007). doi:10.1510/mmcts.2007.002618
Copyright © 2007 European Association for Cardio-thoracic Surgery
Procedure
Technique for implant of the stentless aortic valve Freedom Solo
Mattia Glaubera,*,
Marco Solinasa and
Jamshid Karimova,b
a CNR Institute of Clinical Physiology ‘G. Pasquinucci’ Hospital, Via Aurelia Sud, 54100 Massa, Italy
b Sant'Anna School of Advanced Studies, Piazza Martiri della Libertà 33, 56127 Pisa, Italy
* Corresponding author: * Tel.: +39-0585-493604; fax: +39-0585-493614. glauber{at}ifc.cnr.it
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Summary
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In this presentation we provide a summary of aortic valve replacement with a supra-annular stentless aortic valve, the Freedom Solo prosthesis. Stentless valves were designed to provide more physiological flow and lower transvalvular gradient, which is offered by the novel design of the valve and by its implantation technique. The supra-annular stentless aortic valve implantation is demonstrated with a special emphasis on its surgical technique peculiarities.
Key Words: Aortic valve disease • Stentless valve • Supra-annular placement
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Introduction
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Aortic valve replacement is a common cardiac surgical procedure aiming to substitute the native (pathologic) aortic valve with an aortic valve prosthesis. Aortic valve replacement is associated with low peri-operative mortality, minimal morbidity, and good long-term outcomes [1, 2].
With an idea to create a more physiological aortic valve, it was supposed that the optimal flow and valve function can be available with a valve which could be free of stent, synthetic materials, preserve the root dynamics, restore flexibility of the native valve annulus after decalcification and have minimal xenograft aortic wall, short implantation time and excellent hemodynamic performance to facilitate the left ventricular function [3].
Several stentless valves are available at the present time; hence, one can choose the optimal valve which meets the patients' and surgeons' requirements. All being stentless, different valves have various characteristics of hemodynamic performance.
Particular characteristics of each valve depend on its materials and structure, particular geometry, thus predicting a novel technique of implantation and making possible to establish the optimal flow and performance, to maintain a natural aortic valve and root geometry and architecture.
Within this presentation we would like to consider one of the modern stentless valves available on the market, putting an emphasis mainly on the surgical technique of implantation of the aortic valve Freedom Solo (Sorin Biomedica Cardio, Saluggia, Italy – MMCTSLink 153).
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Surgical technique
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The patient is prepared as for conventional aortic valve surgery. The operation is performed through a median sternotomy.
The standard exposure is achieved and the patient is cannulated, cardiopulmonary bypass is established and the operation proceeds in a standard fashion.
An aortic cannula is inserted into the ascending aorta and a two-stage venous cannula is positioned into the right atrium. The vent is positioned through the right superior pulmonary vein into the left ventricle to provide the surgeon with the bloodless field.
The patient is cooled to 34 °C, the aorta is cross-clamped, cardioplegia solution is administered antegradely and retrogradely. The intermittent warm blood cardioplegia is administered directly into the coronary ostia after transverse aortotomy is performed, every 20 min, referring to the protocol applied by the team.
The transverse aortotomy is made just 0.5–1.0 cm above the sinotubular junction, which gives a perfect valve and annulus exposure (Video 1, Schematic 1).
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Video 1 Cardiopulmonary bypass is established and the aorta is cross-clamped. When cardioplegia solution is administered and proper electro-mechanical standstill is achieved, the transverse incision of about two thirds of the aortic circumference is made in the ascending aorta approximately 0.5 cm above the sinotubular junction.
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After transecting the ascending aorta for exposure the diseased valve is excised and this is followed by total debridement of the calcified annulus (Video 2). Now the annulus can be carefully sized (Schematic 2).
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Video 2 The aortic valve is investigated and excised. The aortic annulus is debrided of all calcium deposits.
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Schematic 2 Sizing of an aortic annulus with a dedicated aortic valve Freedom Solo sizer. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Three commissural stay sutures are placed to mobilize the aorta and for better exposure of the root. The stay sutures help to keep the aortic wall in a straight line during measurement (Schematic 3, Video 3).
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Schematic 3 Stay sutures are placed as shown in the picture. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Video 3 Stay sutures are placed into each of the three commissures, which help to expose and measure the aortic annulus diameter.
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The sizing of the annulus is performed using dedicated sizers, which were developed specifically for this type of prosthesis (Video 4).
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Video 4 Measurement of the aortic annulus using a dedicated Freedom Solo aortic valve sizer. See the text for details.
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There are some principal considerations regarding the sizing technique, which are fundamental in the application of these type of valves:
- The sizer should tightly fit the aortic annulus. No oversizing is needed; the stentless aortic valve Freedom Solo is already upsized by the manufacturer. Oversizing results in higher postoperative transvalvular gradients, caused by abundance of valve tissue at the place of coaptation of bioprosthesis leaflets and deformation of valve geometry.
- If one size is too small while the larger one fits the annulus with some resistance, the larger one should be implanted into the patient.
Having an idea about the size of the valve which has to be implanted, we can proceed with its further implantation procedure.
No preparation is required for the valve before implantation. There is no need for washing the valve in saline solution because of the special (detoxifying) posttreatment step applied to the valve, which removes residual glutaraldehyde from the valve tissue. Care must be taken while handling the valve; preferably soft-tipped instruments must be used for possible manipulations with the valve. Special attention should be given to make sure that the valve leaflets are kept moist during the valve implantation.
Three equidistant polypropylene 4-0 sutures are placed in the supra-annular position at the nadir of the commissures, at 2–3 mm from the host annulus of each of the sinuses, exiting the sinus wall supra-annularly (Schematic 3, Video 5).
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Video 5 Three monofilament sutures are placed equidistantly. These sutures will be used to suture the bioprosthesis to the aortic wall at the supra-annular level.
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Each of these sutures has to be placed at the corresponding part of the prosthetic commissures (Schematics 4 and 5).
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Schematic 4 Suturing starts from the middle point between each commissure of the bioprosthesis. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Schematic 5 Placement of stay sutures and subsequent valve lowering. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Care must be taken to avoid any stitch placement under the annulus and suturing it. When the valve is properly positioned within the aorta supra-annularly, the valve holder is removed and each of the three sutures must be tied, taking into consideration that the node has to remain in the middle of both sutures equidistantly. At the end of this procedure we should have six sutures altogether, and proceed with putting a running suture for each of them, as shown in schematics and video and (Schematics 6, 7, 8, Video 6).
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Schematic 6 Aortic valve Freedom Solo holder removal. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Schematic 7 Stay sutures are positioned correctly; the valve is lowered and ready to be sutured to the aortic wall. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Video 6 Three polypropylene sutures are placed through a bioprosthesis; the holder is removed and the valve is lowered into the left ventricular outflow tract and takes its position supra-annularly. Sutures are then knotted in the midpoints of each coronary sinus.
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Then, each of those six sutures has to suture the valve with the aorta supra-annularly, a host annulus, with deep, full-thickness bites, from the midpoint to the top of the post (Schematics 9, 10, 11, Videos 7, 8, 9).
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Schematic 9 Correct (supra-annular) suture placement is shown. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Schematic 10 The suture is knotted in the midpoint. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Schematic 11 The suture is knotted in the midpoint; valve fixation is continued by placing of running sutures to the top of the post. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Video 7 Each of those six remaining polypropylene sutures has to suture the bioprosthesis with the aortic wall using a continuous suture technique.
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Video 8 Placing a continuous suture in the region of a right coronary sinus. Attention is given so as to avoid any damage of the bioprosthesis body with a needle.
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Video 9 Placing another continuous suture in a part of a non-coronary sinus. The suture lines are carried to the top of the commissures. Placing the last stitches and exiting, we will have six polypropylene sutures outside of the aortic wall.
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The main mistakes that could occur during the valve implantation are shown in Schematics 12 and 13:
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Schematic 12 Care must be taken to avoid making too small of a suture bite in the pericardial wall and aortic root. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Schematic 13 Intra-annular placement of the bioprosthesis is shown in this illustration. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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- Inaccurate removal of the diseased valve
- Inaccurate sizing and prosthesis selection
- Too small of a suture bite in the pericardial wall and aortic root
- Intra-annular seating
Care must be taken to avoid any laceration of the valve leaflets with a needle tip, and also preventing any damage of the assembly suture of the valve.
Once at the top of the commissure, each suture is passed through the patients aortic wall, with a finishing knot being placed outside the aorta and preferably reinforced with pledgetes. Adjacent sutures are then tied [4, 5] (Schematics 14, 15, 16, 17, Video 10).
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Schematic 14 Continuous suture placed around the bioprosthesis is demonstrated. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Schematic 15 The final result; running sutures are placed around the bioprosthesis and knotted. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Schematic 16 Correct positioning of the aortic valve Freedom Solo in patient's aortic root. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Schematic 17 Supra-annular position of the bioprosthesis. Courtesy of Sorin Biomedica Cardio, Saluggia, Italy.
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Video 10 All the sutures are then knotted carefully. Teflon felt pledgetes also could be placed if reinforcement of the sutures coming out from the aortic wall is considered necessary.
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When the valve is implanted, the aortotomy is closed in a standard fashion with a 5-0 polypropylene running suture. The aorta is declamped (Video 11). Valve function is checked by intraoperative echocardiography (Videos 12 and 13).
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Video 11 The aorta is declamped.
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Video 12 Valve function is checked intraoperatively by transesophageal echocardiography.
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Video 13 Real-time 3-D Transesophageal echocardiography gives a perfect visualization of valve function intraoperatively.
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Results
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The aortic valve replacement with a Freedom Solo aortic bioprosthesis was initiated in our Department from November 2004 for patients with isolated aortic valve disease.
From November 2004 to April 2007 aortic valve replacements with the aortic Freedom Solo valve was performed in 87 patients: (males – 31, females – 56; age: 73.4±10.16 years logistic EuroSCORE: 9.34±8.78).
All cases were carried out using a standard median sternotomy approach. Preoperative hemodynamics were presented by peak (82.5±32.4 mmHg) and mean (44.8±12.5 mmHg) gradients. At discharge, we revealed perfect hemodynamic outcomes as peak gradient of 15.08±7.88 mmHg and mean of 6.3±2.5 mmHg.
In 41 (47.2%) patients we performed aortic valve replacement associated with other cardiac surgery procedures: CABG – 19 patients (21.9%); mitral valve repair – 13 (14.9%); ventricular septal myectomy operation (Morrow procedure) – 3 (3.5%); mitral valve replacement – 4 (4.6%); CABG with mitral valve repair – 2 (2.3%).
Mean cross-clamping time was 82.07±34.8 min which was comparable with conventional aortic valve replacement procedures, including cases with concomitant procedures. Overall mortality was 4.4%. Sizes of the aortic valve Freedom Solo implanted are shown in Graph 1.
There were no complications associated with this type of valve and particular implantation technique.
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Conclusions
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Being completely stentless, the aortic valve Freedom Solo offers several advantages in the surgical treatment of aortic valve pathology. The stentless valve's design is postulated to impart characteristics, which more closely emulate the normal physiology of the aortic valve and root [6].
The choice of bioprosthesis still remains a debatable question and depends on the surgeon's personal consideration and patient's choice. The advantages of the stentless design are providing a larger effective orifice area (EOA) for transvalvular blood flow, lower rest and exercise gradients in comparison with a stented aortic bioprosthesis, and patients have a lower valve-related mortality than those receiving stented valves.
The better performance of stentless aortic bioprostheses is explained mostly by the following data: one of the proposed benefits of stentless prostheses is that they can continue to remodel within the aortic root [7, 8]. Also, it has been noted that the use of stentless bioprostheses may be advantageous in the setting of preoperative ventricular impairment. Based on the results of a few investigators, this probably could advocate the stentless valves as the valve of choice where improvement in left ventricular function postoperatively is a focus [9].
Importantly, no anticoagulation is required for this type of valve. There is high freedom from thromboembolism and endocarditis. However, there are few studies showing the real benefits of stentless valves compared to stented valves.
Summing up, we would like to highlight the present position of a stentless bioprosthesis in the treatment of aortic valve stenosis or insufficiency. The aortic valve Freedom Solo, in our experience, gives excellent hemodynamic results and postoperative outcomes in terms of patients' survival and morbidity, and could be a bioprosthesis of choice in aortic valve surgery.
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References
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- David TE, Ropchan GC, Butany JW. Aortic valve replacement with stentless porcine bioprosthesis. J Card Surg 1988;3:501–505.[Medline]
- Peterseim DS, Cen YY, Cheruvu S, Landolfo K, Bashore TM, Lowe JE, Wolfe WG, Glower DD. Long-term outcome after biologic versus mechanical aortic valve replacement in 841 patients. J Thorac Cardiovasc Surg 1999;117:890–897.[Abstract/Free Full Text]
- O'Brien MF, Gardner MA, Garlick RB, Davison MB, Thomson HL, Burstow DJ. The Cryolife-O'Brien stentless aortic porcine xenograft valve. J Card Surg 1998;13:376–385.[Medline]
- Repossini A, Kotelnikov I, Bouchikhi R, Torre T, Passaretti B, Parodi O, Arena V. Single-suture line placement of a pericardial stentless valve. J Thorac Cardiovasc Surg 2005;130:1265–1269.[Abstract/Free Full Text]
- Beholz S, Claus B, Dushe S, Konertz W. Operative technique and early hemodynamic results with the Freedom Solo valve. J Heart Valve Dis 2006;15:429–432.[Medline]
- Ali A, Halstead JC, Cafferty F, Sharples L, Rose F, Coulden R, Lee E, Dunning J, Argano V, Tsui S. Are stentless valves superior to modern stented valves? A prospective randomized trial. Circulation 2006;114(1 Suppl):I535–540.[Medline]
- Maselli D, Pizio R, Bruno LP, Di Bella I, De Gasperis C. Left ventricular mass reduction after aortic valve replacement: homografts, stentless and stented valves. Ann Thorac Surg 1999;67:966–971.[Abstract/Free Full Text]
- Del Rizzo DF, Goldman BS, Christakis GT, David TE. Hemodynamic benefits of the Toronto stentless valve. J Thorac Cardiovasc Surg 1996;112:1431–1445; discussion 1445–1446.[Abstract/Free Full Text]
- Jin XY, Zhong MZ, Gibson DG, Yacoub MH, Pepper JR. Effects of valve substitutes on changes in left ventricular function and hypertrophy after aortic valve replacement. Ann Thorac Surg 1996;62:683–690.[Abstract/Free Full Text]
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Summary
Introduction
