MMCTS
(May 7, 2007). doi:10.1510/mmcts.2006.001917
Copyright © 2007 European Association for Cardio-thoracic Surgery
Procedure
Valve-sparing aortic root replacement: the inclusion (David) technique
Klaus Kallenbach*,
Matthias Karck and
Axel Haverich
Department of Thoracic and Cardiovascular Surgery, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
* Corresponding author: * Department of Cardiac Surgery, University Hospital Heidelberg, INF 110, 69120 Heidelberg, Germany Tel.: +49-6221-5637982; fax: +49-6221-565585. Klaus.kallenbach{at}med.uni-heidelberg.de
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Summary
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Presentation of the aortic valve reimplantation technique (David I): Removal of the diseased ascending aorta, excision of the coronary ostia and resection of aortic sinuses up to a rim of 2–3 mm of aortic wall as well as extensive external dissection and mobilization of the aortic root; placement of horizontal sutures placed circumferentially through the annulus underneath the valve; anchoring a Dacron-graft in the aortic root with the sutures; fixation of commissures high into the tube graft; reimplantation of the sinuses into the graft with a blood-tight running suture line; reimplantation of coronary buttons; establishment of distal aortic anastomosis.
Key Words: Aorta • Aortic aneurysm • Surgery • Valves • Valve reconstruction
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Introduction
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The aortic valve-sparing reimplantation technique, first described by David et al. in 1992, was originally developed as an aortic valve-sparing operation for patients with aortic valve incompetence and aneurysm of the ascending aorta (Schematic 1) [1]. Indication for this technique has been an aneurysm of the aortic root or the ascending aorta causing aortic insufficiency by outward displacement of the commissures, a tricuspid aortic valve without gross structural defects and absence of severe cusp prolapse or asymmetry. With ongoing experience we have expanded its use from patients with aneurysms of the aortic root to patients with aortic dissection, too [2, 3]. Although still a matter of reasonable debate due to its time-consuming and demanding nature, this operation is probably the best treatment of the dissected aortic root, because most of the diseased vessel wall may be resected and replaced by a vascular graft while at the same time retaining the valve [4, 5]. Also, with growing experience, we started on reimplanting bicuspid valves in suitable situations.
Likewise, many surgeons regard aortic valve reimplantation as the first choice for aortic root aneurysm in patients with Marfan's syndrome, who do not present with pronounced leaflet prolapse or extensive fenestrations in the valvular commissures [6, 7]. If this opinion will withstand the test of time is currently challenged by a prospective multicenter clinical trial, initiated by members of the National Marfan Foundation.
In still using the original so-called T. David type I procedure, we have remained resistant to the evolution, which this procedure has undergone in the meantime. However, our follow-up data well justify this attitude, because the incidence of reoperation for late valve failure has remained acceptable [8].
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Surgical technique
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The technique is highlighted by intraoperative photographs of an elective routine aortic valve reimplantation. More detailed, the technique is explained by an intraoperative video of a 43-year-old male who was admitted with a suspected acute myocardial infarction due to angina pectoris symptoms at a distant hospital. CT scan revealed an acute aortic dissection type A, echocardiography showed moderate pericardial perfusion and mild aortic valve insufficiency. The hemodynamically stable patient was transferred immediately to the OR (Video 1).
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Video 1 CT-scan: Computer tomography-scan of a 43-year-old patient presenting in hemodynamically stable conditions. Aneurysmatic dilatation of the ascending aorta and acute aortic dissection type A was diagnosed.
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The operation started with a routine sternal incision, followed by direct cannulation of the aortic arch into the true lumen, controlled by online transesophageal echocardiography, and the right atrium by a two-stage cannula. Cooling to 26 °C with the help of extracorporeal circulation was initiated. After establishing full flow, fibrillation was induced, and a vent catheter was placed into the right upper pulmonary vein. The distal aorta was clamped and the aorta opened above the commissures with a transverse incision 3–5 mm distal to the estimated level of the former sinotubular junction to prevent from injury to both the right coronary ostium and aortic valve commissure between the right and the noncoronary sinus. Antegrade cardioplegia was applied by direct cannulation of both coronary ostia (Video 2).
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Video 2 Opening and cannulation: At Hannover Medical School, we prefer to start the operation with a standard sternotomy rather than cannulation of the femoral or subclavian/axillary artery before. Direct cannulation of the aortic arch into the true lumen under control of permanent transesophageal echo. Antegrade cardioplegia was installed by direct intubation of the coronary ostia, which were not dissected.
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Before the sinuses carrying the coronary ostia are mobilized, both ostia are cut out of the aortic root as buttons, similar to any other type of aortic root replacement. Aortic sinuses are resected up to a rim of 4–5 mm of aortic wall remaining to the attachment of cusps to the aortic root. Extensive external dissection and mobilization of the aortic root with the ostia carefully held away with stay sutures followed, the aortic root is further mobilized beyond the level of the coronary ostia and near the left/right commissure. Gentle pulls on the commissural stay sutures are helpful for this step of preparation. While the dissection plane underneath the left ostium is easy to identify, preparation beyond the right ostium is to be done with utmost care so as not to accidentally open the right ventricle. Mobilization of the aortic root near the pulmonary artery requires a shallow incision of the membranous septum between the two vessels to get down to the appropriate plane which is required for later anchoring of the vascular graft (Video 3).
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Video 3 Preparation of the aortic root: The aorta was resected circumferentially and stay sutures were placed above the commissures. Inspection of the aortic root revealed a bicuspid valve. Coronary ostia were carefully mobilized and put away by stay sutures. Inspection of the valve revealed a small fenestration close to the commissure between the right and noncoronary sinus, the left and right coronary cusps are fused. Since cusps were morphologically unchanged and free of prolapse, valve-preserving reimplantation with reconstruction of the tricuspid valvular geometry was planned.
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At this point, it is necessary to decide on the diameter of the vascular graft to be implanted. Sizing of the aortic root is given a lot of attention. We believe that it is essential to size at this stage in order to allow for near anatomic reconstruction of the aortic root, thereby avoiding both stenosis, on the one hand, and insufficiency on the other. The sutures through the commissures are again lifted up to create a virtual cylinder resulting in a complete line of coaptation between the leaflets. Attachments of 30–50% of the leaflets are considered ideal (Photo 1).
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Photo 1 For the correct sizing of the appropriate Dacron graft, commissures must be pulled up to create a virtual cylinder with cusp coaptation of 30–50%. (Reprinted from Karck M, Haverich A. Aortic valve reimplantation according to the David type I technique. Operative Techniques in Thoracic and Cardiovascular Surgery 2005;10(4):246–258 with permission from Elsevier.)
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A conventional prosthetic heart valve sizer is placed into the virtual cylinder. If a valve sizer for a 27-mm mechanical aortic valve results in a perfect coaptation, a 30-mm vascular graft is very likely to reshape the near original dimensions of the aortic root following reimplantation. The slight, 2–3 mm, oversizing of the vascular graft compared to the appropriate size of the valve sizer pays credit to the fact that the aortic valve is reimplanted into the graft. Therefore, the graft needs to be slightly wider than suggested by the use of the sizer. This maneuver gives a good estimate of the appropriate vascular graft diameter to be implanted. It is our experience in non-Marfan patients that the majority of female patients needed a graft of 26 mm diameter, while male patients very often received a 28-mm graft. In the majority of patients with Marfan syndrome, who often present with a dilated aortic annulus, the implanted vascular grafts are usually 2 mm wider compared to non-Marfan patients.
Now, after reaching a temperature of 26° C, circulation arrest was initiated. The aortic clamp was opened, the arch inspected and reconstructed during antegrade cerebral perfusion with 15° C cold blood via the left common carotid artery and innominate artery. A Dacron prosthesis was sewn to the clued aortic arch, and a hemiarch replacement conducted with a 26-mm prosthesis. Thereafter, the arterial cannula was placed into the prosthesis, the aorta deaired and clamped, and extracorporeal circulation reinstalled. During re-warming, reconstruction of the aortic valve continued.
When the aortic root is completely mobilized and following the decision for a specific diameter of the vascular graft, 9–13 double armed polyester sutures without pledges were placed transmurally from inside the left ventricular outflow tract out (Video 4 and Photo 2).
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Video 4 Implantation of the aortic prosthesis: Placement of horizontal mattress sutures for anchoring the Dacron graft. The first stitch was positioned underneath the commissure between the left and the noncoronary sinus at the hinge line of the anterior mitral valve leaflet. Then, sutures were placed clockwise; keeping the horizontal subvalvular plane that was mentioned previously. Care is taken not to pass the needles accidentally through the bottom of the remnants of the sinuses of valsalvae. After shortening of the graft, its perimeter was divided into three segments by marking the expected position of the commissures with a line drawn with a sterile pencil. In this case with a bicuspid valve, the fused commissure between left and right coronary sinus was treated in the same fashion as in a tricuspid valve to create a sufficient geometry of the reconstructed root. The stay sutures at the commissures were transferred into the lumen of the graft without fixing them at this point. The sutures previously placed in the horizontal subvalvular plane are stitched out of the cardiac end of the graft perimeter at corresponding sites. The graft is anchored in the aortic root by tying the suture with the graft held in position by the assistant.
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Photo 2 Horizontal mattress sutures without pledges are placed in one lane underneath the sinuses for later fixation of the graft to the aortic root. (Reprinted from Karck M, Haverich A. Aortic valve reimplantation according to the David type I technique. Operative Techniques in Thoracic and Cardiovascular Surgery 2005;10(4):246–258 with permission from Elsevier.)
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The vascular graft was shortened to the estimated length of the ascending aortic segment to be replaced. In case of an isolated aneurysm of the aortic root, a length of 6–7 cm is usually appropriate. We believe that it is key not to pull too much on these sutures while tying them, because this may result in unfavorable plication of both the graft and the annulus. Therefore, these knots should be tied like ‘wet toilet paper’ and it should be kept in mind that this is not a hemostatic suture line (Photo 3).
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Photo 3 When knots of the horizontal mattress are gently tied, the graft must be pushed down and held in position by the assistant. (Reprinted from Karck M, Haverich A. Aortic valve reimplantation according to the David type I technique. Operative Techniques in Thoracic and Cardiovascular Surgery 2005;10(4):246–258 with permission from Elsevier.)
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Once the graft is anchored in the aortic root, the commissures were trimmed by placing the stay sutures at the appropriate height inside the vascular graft. The drawn marks at the outside of the graft help for orientation; the goal is for perfect geometry of the root and the valve. We believe that it is important to reimplant the commissures as high as their individual anatomy suggests thus preventing early postoperative valve failure. There is no need to tie these sutures at this point (Photo 4).
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Photo 4 A pivotal step of the reimplantation procedure is the positioning of the commissures high enough into the Dacron tube by pulling on the stay sutures, reshaping a correct geometry of the valve. (Reprinted from Karck M, Haverich A. Aortic valve reimplantation according to the David type I technique. Operative Techniques in Thoracic and Cardiovascular Surgery 2005;10(4):246–258 with permission from Elsevier.)
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The tissue remnants of the partially resected sinuses of valsalvae were reimplanted into the vascular graft using 4-0 monofilament running sutures starting off in the depth of the left coronary sinus. The suture line was then continued to the commissure between the left and the noncoronary cusp. A slight mismatch between redundant tissue of the neosinus and the vascular graft can be easily compensated. In case that the mismatch appears too big at this point, the remnant may be shortened by another 1 or 2 mm. If this is not the reason for a mismatch, the graft is probably too narrow and should be replaced by a wider one. Following reimplantation of the neosinuses, the respective sutures were tied at the tip of the commissures. The initial stay sutures through the commissures were tied too (Video 5).
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Video 5 Valve implantation: The correct position of the commissures inside the graft is identified by slightly pulling on both the commissure and the vascular graft before stitching the sutures through the graft. At this moment, the graft should extend roughly by half of its maximum length at this segment. Insertion of saline allows a first judgment of leakproofness of the valve. The reimplantation of partially resected sinuses of valsalvae starts at the Nadir of the three coronary sinuses, each with double armed monofilament sutures going up to both commissures, where sutures were tied to each other. This suture line must be hemostatic! Stay sutures are tied and cut too.
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The aortic valve as a whole was now reimplanted into the vascular graft prosthesis and should present with a ‘Mercedes star’ like configuration of the leaflets within the vascular graft. The prospective valvular competence may now be estimated by assessing the lines of leaflet coaptation and/or instilling some saline into the aortic root. Sometimes, small tissue segments may still prolapse into the lumen near the commissures. They may be either carefully resected or plicated to the graft by additional sutures (Photos 5 and 6).
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Photo 5 After completion of the reimplantation, the valve must appear in means of the geometry like a ‘Mercedes star’, but individual differences in length of cusps are possible. Inserted saline should remain in the closed valve to rule out significant insufficiency. (Reprinted from Karck M, Haverich A. Aortic valve reimplantation according to the David type I technique. Operative Techniques in Thoracic and Cardiovascular Surgery 2005;10(4):246–258 with permission from Elsevier.)
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Photo 6 Outside aspect of the graft after completion of reimplantation. (Reprinted from Karck M, Haverich A. Aortic valve reimplantation according to the David type I technique. Operative Techniques in Thoracic and Cardiovascular Surgery 2005;10(4):246–258 with permission from Elsevier.)
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After careful creation of holes into the neosinuses of the graft avoiding injury of the cusps, the coronary ostia were reimplanted anatomically in the left- and the right neo sinus using a 4-0 or 5-0 monofilament running suture as in any other type of aortic root replacement. The stitches should pass through the rim of the ostium rather than through the aortic wall surrounding to prevent later aneurysmatic dilatation of the ostial implantation site (Photo 7).
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Photo 7 Inside aspect of reimplanted aortic valve and coronary ostia. (Reprinted from Karck M, Haverich A. Aortic valve reimplantation according to the David type I technique. Operative Techniques in Thoracic and Cardiovascular Surgery 2005;10(4):246–258 with permission from Elsevier.)
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Before the distal aortic anastomosis completes the repair, both the prosthetic (or native) distal ascending aorta and the proximal vascular graft segment carrying the reimplanted valve need to be tailored in a way that allows for a tension- and torsion-free anastomosis. This may imply that the commissure between the left and noncoronary cusps is located very close to the anastomotic suture line.
The operation was finished in the same way as ascending aortic replacement is usually conducted. Apical deairing was undertaken, removal of cannulas were followed by careful establishment of hemostasis. Graft inclusion was only applied for the distal part of the graft aimed at avoiding malperfusion of the left coronary artery (Video 6).
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Video 6 Completion of the procedure: Coronary ostia are reimplanted into the Dacron prosthesis by use of 5-0 monofilament running suture. The prosthesio-prosthesio anastomosis was sewn in a routine fashion with 3-0 running monofilament suture. Weaning from extracorporeal circulation and deairing is performed, followed by control for bleeding. A graft inclusion should only include the distal portion of the graft.
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We routinely check for competence of the reimplanted valve by intraoperative transesophageal echocardiography. In this specific case of a bicuspid valve, the aortic valve was competent without insufficiency (Photo 8).
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Photo 8 Postoperative echo shortly before discharge of the patient showed a competent reconstructed aortic valve.
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Conclusions
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The reimplantation technique for valve-sparing aortic root reconstruction, originally developed for patients presenting with aortic valve incompetence due to an aneurysm of the ascending aorta, is applicable to a wide range of patients with various indications [8, 9]. Aortic valve reimplantation is a safe and straightforward procedure with a well predictable outcome once a few key issues are addressed. The decision to retain the valve or not should be founded on careful examination of the valvular leaflets for structural changes, such as dense calcifications, large fenestrations or severe valve prolapse. Once the decision to retain the valve has been made, the aortic root has to be mobilized around its entire circumference except for a small segment of the perimeter near the membranous septum. Excision of the sinuses should be done with utmost care so as not to damage the valvular leaflets. Sizing of the graft is a key issue, too. The commissures need to be trimmed high enough into the vascular graft to prevent later prolapse; cusp coaptation below the edge of the graft is associated with increased risk for early valve failure (Graph 1) [10]. The suture lines for reimplantation of the neocoronary sinuses and the coronary ostia must be blood-tight in the first place because secondary hemostatic sutures may be difficult to position.
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Graph 1 Relationship between height of resuspension of the reimplanted valve and occurrence of postoperative aortic insufficiency.
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At Hannover Medical School, the David-I procedure is the operation of choice for any suitable patient presenting with an aneurysm of the ascending aorta or aortic root and aortic valve insufficiency. Furthermore, we expended our indication from the classical setting described by T. David towards patients with bicuspid valves, aortic valves with significant cusp prolapse, patients with Marfan's syndrome with a root diameter above 4 cm with a family history of acute aortic dissection, patients with complex aortic pathologies, patients scheduled for reoperation, patients presenting in emergency situation with acute aortic dissection type A, as well as younger or older patients. Likewise, any patient presenting with an acute aortic dissection type A is a potential candidate for this procedure. An early mortality rate of 1.3% for elective and 11.3% for emergency (aortic type A dissection) patients justify our strategy. Furthermore, a relatively low incidence of reoperation for failure of the reconstructed aortic valve (Graph 2), as well as an actuarial survival comparable to life curves of the average population (Graph 3), reveal the value of this operation. Freedom of anticoagulation represents the most important benefit of this operation, demonstrated by absence of relevant thromboembolic or bleeding events during follow-up [8]. This is particularly appealing for young female patients expecting pregnancy or those with Marfan syndrome anticipating further major operation on the downstream aorta or skeleton.
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Graph 3 Actuarial survival for patients after aortic valve-sparing reimplantation surgery during follow-up. Early (30-day) mortality is excluded.
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Even though evolution of this procedure towards a more physiological operative result is attractive for theoretical reasons, we still trust the original David type I operation and we believe that our confidence is well supported by the favorable follow-up data we have obtained so far.
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References
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- David TE, Feindel CM. An aortic valve-sparing operation for patients with aortic incompetence and aneurysm of the ascending aorta. J Thorac Cardiovasc Surg 1992;103:617–622.[Abstract]
- Kallenbach K, Pethig K, Leyh RG, Baric D, Haverich A, Harringer W. Acute dissection of the ascending aorta: first results of emergency valve sparing aortic root reconstruction. Eur J Cardiothroac Surg 2002;22:218–222.[CrossRef]
- Erasmi AW, Stierle U, Bechtel JF, Schmidtke C, Sievers HH, Kraatz EG. Up to 7 years' experience with valve-sparing aortic root remodelling/reimplantation for acute type A dissection. Ann Thorac Surg 2003;76:99–104.[Abstract/Free Full Text]
- Kallenbach K, Oelze T, Salcher R, Hagl C, Karck M, Leyh RG, Haverich A. Evolving strategies for treatment of acute aortic dissection type A. Circulation 2004;110 (11 Suppl 1):II243–II249.
- Miller DC. Valve-sparing aortic root replacement in patients with the Marfan syndrome. J Thorac Cardiovasc Surg 2003;125:773–778.[Free Full Text]
- Karck M, Kallenbach K, Hagl C, Rhein C, Leyh R, Haverich A. Aortic root surgery in Marfan syndrome: comparison of aortic valve sparing reimplantation versus composite grafting. J Thorac Cardiovasc Surg 2004;127:391–398.[Abstract/Free Full Text]
- de Oliveira NC, David TE, Ivanov J, Armstrong S, Eriksson MJ, Rakowski H, Webb G. Results of surgery for aortic root aneurysm in patients with Marfan syndrome. J Thorac Cardiovasc Surg 2003;125:789–796.[Abstract/Free Full Text]
- Kallenbach K, Karck M, Pak D, Salcher R, Khaladj N, Leyh R, Hagl C, Haverich A. Decade of aortic valve sparing reimplantation: are we pushing the limits too far? Circulation 2005;112 (9 Suppl):I253–I259.
- David TE, Armstrong S, Ivanov J, Feindel CM, Omran A, Webb, G. Results of valve-sparing operations. J Thorac Cardiovasc Surg 2001;122:39–46.[Abstract/Free Full Text]
- Pethig K, Milz A, Hagl C, Harringer W, Haverich A. Aortic valve reimplantation in ascending aortic aneurysm: risk factors for early valve failure. Ann Thorac Surg 2002;73:29–33.[Abstract/Free Full Text]
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Summary
Introduction
