Aortic valve reconstruction

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As Aortenklappenrekonstruktion refers to the restoration of the shape and thus a function of the natural and malfunctioning aortic valve . Aortic valve reconstruction is usually carried out in the case of aortic valve insufficiency ; it can also be necessary in the case of aortic aneurysm , less often in the case of congenital aortic stenosis .

history

Even before heart valve prostheses were developed, first attempts were made to reconstruct dysfunctional aortic valves. The rupture of a narrowed aortic valve was carried out in 1912 by the French surgeon Théodore Tuffier (1857-1929). In 1958, Dwight Harken reported a small group of patients with aortic regurgitation in whom he had made the valve annulus smaller and reduced the insufficiency. At the time, surgeons and cardiologists had minimal information about the type and severity of the aortic valve dysfunction. This slowly changed after the introduction of echocardiography by Inge Edler and Carl Hellmuth Hertz . Nevertheless, the development of heart valve prostheses meant that heart valve replacement became the standard treatment, especially for the aortic valve. The first ball prosthesis was implanted in 1961 by the Americans Albert Starr and Lowell Edwards , followed by a development with many mechanical and biological prostheses. The positive results of mitral valve reconstruction stimulated surgeons in the 1980s and 1990s to develop aortic valve reconstruction techniques for the various causes of aortic valve insufficiency. These have gradually been improved, and many leaky aortic valves can now be treated by reconstruction.

indication

Diseases

In the case of aortic valve insufficiency, backflow occurs through the valve that does not close properly

Aortic valve reconstruction will realistically be possible if there is no pronounced calcification of the aortic valve. A congenital aortic valve stenosis can therefore now also be treated with a reconstruction; for the acquired aortic valve stenosis, heart valve replacement remains the only realistic option. Usually, aortic valve reconstruction is the treatment of aortic valve insufficiency. It is also used when surgery for aneurysm of the ascending aorta is required to avoid rupture or dissection of the aorta . The need for surgery on the aortic valve is determined by objective criteria and the presence of symptoms.

Indication for aortic valve reconstruction:

• Aortic valve not or only minimally calcified

such as:

• Congenital and severe aortic stenosis with symptoms
• Congenital and severe aortic stenosis with impaired contraction of the left ventricle (EF <50%)
• Severe aortic regurgitation and symptoms
• Severe aortic regurgitation and enlargement of the left ventricle (> 65–70 mm)
• Severe aortic regurgitation and impaired contraction of the left ventricle (EF <50%)
• Aortic aneurysm> 55 mm in diameter
• Aortic aneurysm with a diameter> 50 mm and risk factors (e.g. high blood pressure)
• Aortic aneurysm> 50 mm in diameter and connective tissue disease
• Aortic aneurysm> 45 mm in diameter and connective tissue disease and risk factors

Replacement versus reconstruction

The primary aim of the operation is to improve life expectancy by treating acute or chronic heart failure as a result of the valve defect or by preventing the complications of an aortic aneurysm. Symptom improvement is only to be achieved secondarily. Reconstruction is a newer alternative treatment to heart valve replacement; replacement is still the most sensible solution if the valve is severely damaged or calcified. All operations have in common that the result should be checked intraoperatively by echocardiography.

After aortic valve replacement, the incidence of long-term complications varies depending on the patient's age. These include clot formation on the valve prosthesis, bleeding under the inhibition of blood clotting, the wear and tear of biological prostheses and the sensitivity to inflammation (prosthetic endocarditis). After the aortic valve reconstruction, the risk of clot formation is minimal, inhibition of blood coagulation is usually not necessary and there are no bleeding complications. The likelihood of bacterial aortic valve inflammation ( endocarditis ) is significantly lower than after replacement.

Surgical technique

General

The surgical technique depends on the underlying deformation of the valve and must take into account congenital malformations of the aortic valve and the presence of an aneurysm. The most important goal of the operation is to restore the aortic valve to an almost normal shape and function in order to achieve the best possible stability of the valve. For this reason, operations with reconstruction of the aortic valve are usually performed through a sternotomy (opening of the sternum ). Minimally invasive techniques make it difficult to assess the shape of the valve and thus lead to greater uncertainty regarding the long-term durability of the aortic valve reconstruction. The heart-lung machine is then connected to the aorta and right atrium in a tried and tested manner. A careful echocardiographic examination using swallowing echo ( transesophageal echocardiography ) is necessary in order to precisely determine the shape deviations of the aortic valve and thus the causes of the aortic valve insufficiency.

The heart is stopped by cardioplegia and the aortic valve is systematically analyzed. Today there are already known target values ​​for individual shape aspects of the aortic valve, so that the cause of the aortic regurgitation can almost always be precisely determined after echocardiography and intraoperative analysis. The results of the analysis, the type of possible congenital malformation and the presence of an aneurysm of the ascending aorta determine the plan of the aortic valve reconstruction, which must be determined individually for each patient.

Aortic stenosis

A) basic problem

Congenital aortic valve stenosis ( narrowing ) can be treated with aortic valve reconstruction if there is no pronounced calcification. In this situation there is almost always a unicuspid aortic valve; this must be changed in its configuration so that the flap opens better. Due to the unicuspid system, the reconstruction concept is similar to that of aortic valve insufficiency in unicuspid aortic valves.

B) Reconstruction concept

The traditional treatment for congenital aortic stenosis is ballovalvuloplasty or commissurotomy . Neither method can always completely eliminate the constriction; In addition, they lead to a noticeable aortic regurgitation, which in turn puts a strain on the heart and patient. In both procedures only valve tissue is separated; however, the peculiarity of the unicuspid aortic valve system is not taken into account. The reconstruction opens or separates the congenital adhesions of the pockets and creates one or two additional suspension points (commissures). The unicuspid aortic valve is thus made into a bicuspid. This leads to an almost normal function of the aortic valve.

C) Surgical Technique

After carefully analyzing the valve, the individual plan is determined. The currently best-tried concept is to create an aortic valve with two pockets and two commissures so that the valve resembles a bicuspid aortic valve. Tissue of the aortic valve pockets is loosened or removed where it is placed in the wrong place. With the help of patch material, the pockets are supplemented so that their material then extends to a second (newly created) commissure.

Aortic regurgitation

Tricuspid aortic valve

A) basic problem

In the tricuspid aortic valve there is normal application of the valve; when the aorta is dilated, the concept of treating the aortic aneurysm is used. Without expansion of the aorta, the cause of the leak is often the overstretching of the tissue of one or more of the valve elements (pockets). Such overstretching can be combined with congenital tissue gaps in the pockets, so-called fenestrations. An expansion of the valve ring of the aortic valve can also contribute to the insufficiency. In Central Europe, the shrinkage of the pockets is a less common cause of the insufficiency; this cannot currently be treated well with a reconstruction.

B) Reconstruction concept

Shrinkage must be excluded. The extent of the overstretching is precisely determined and then the excess length of the fabric is reduced by gathering seams. A ring expansion makes the additional reduction and stabilization of the aortic valve ring necessary.

C) Surgical Technique

The flap is again carefully analyzed and the pockets are measured to ensure that there is no shrinkage. If the ring is enlarged, it is better normalized in size; the greatest experience for this is with a strong suture that is placed around the aortic valve ring and then fastened to a certain size. The overstretching is corrected by reducing the excess amount of valve tissue to a normal size using individual darts. At the end of the operation, the pocket edges should be symmetrical to each other.

Bicuspid aortic valve

Bicuspid aortic valve that had to be treated by surgery because of severe insufficiency. Two of the three pockets, top left and right, are fused together (fused); the closing defects can be seen in the center of the valve, caused by an overstretching of the fused pocket.

A) basic problem

If the aortic valve is bicuspid, two pockets of the aortic valve have merged since birth. This fused pocket is exposed to increased stress and develops overstretching as the most common cause of aortic regurgitation. An expansion of the valve ring, which increases the insufficiency, is just as common. Even the normally laid pocket can develop overstretching due to prolonged incorrect loading. In half of the cases there is also an aneurysm of the ascending aorta; in this case the concept for the treatment of an aortic aneurysm is used.

B) Reconstruction concept

Since the bicuspid system of the aortic valve has a satisfactory valve function, the aortic valve is left as bicuspid; only the changes that led to the insufficiency are corrected. The extent of the overstretching is precisely determined and then the excess length of the fabric is reduced by gathering seams. A ring expansion makes the additional reduction and stabilization of the aortic valve ring necessary.

C) Surgical Technique

Reconstructed bicuspid aortic valve. The overstretching of the merged pocket has been corrected by seams, you can see that the pockets now close well.

As with the tricuspid aortic valve, the valve is measured in order to rule out any shrinkage of the valve tissue. The ring is usually enlarged, it must be made smaller and stabilized by a so-called annuloplasty . In addition, the overstretching of the bag fabric is corrected by gathering seams. At the end of the operation, the pocket edges should be symmetrical to each other.

Unicuspid aortic valve

A) basic problem

The unicuspid application of the aortic valve can not only cause aortic stenosis, it can also primarily lead to aortic valve insufficiency. A significant proportion of those affected have an aortic aneurysm of the ascending aorta that needs treatment. Regardless of the reason for the operation, the aim of the operation is to achieve the most normal valve function possible.

B) Reconstruction concept

The reconstruction opens or separates the congenital adhesions of the pockets and creates one or two additional suspension points (commissures). The unicuspid aortic valve is thus made into a bicuspid. This leads to an almost normal function of the aortic valve.

C) Surgical Technique

After carefully analyzing the valve, the individual plan is determined. The currently best-tried concept is to create an aortic valve with two pockets and two commissures so that the valve resembles a bicuspid aortic valve. Tissue of the aortic valve pockets is loosened or removed where it is placed in the wrong place. With the help of patch material, the pockets are supplemented so that their material then extends to a second (newly created) commissure. The ring is usually enlarged, it must be made smaller and stabilized by a so-called annuloplasty .

Quadricuspid aortic valve

A) Basic problem The aortic valve insufficiency in a quadricuspid aortic valve is mostly due to the additional commissure that hinders the correct closure of the pockets.

B) Reconstruction concept The most reliable concept for reconstructing a quadricuspid aortic valve consists in converting it into a tricuspid or even bicuspid (luciani) aortic valve. For this purpose, the valve tissue is detached from a (possibly 2) commissure and the valve, with its modified configuration, is then brought into a suitable shape.

C) Surgical technique After careful analysis, the individual plan is determined. It is usually obvious to detach one of the 4 commissures and to unite the tissue of the two pockets involved with sutures so that an aortic valve with a normal shape results.

Aneurysm of the ascending aorta

Basic problem

The expansion of the aorta (aneurysm) in its initial part can lead to aortic valve insufficiency that requires treatment, as the pockets of the valve lose their ability to close. Insufficiency can also be caused by a congenital malformation of the aortic valve. The aortic aneurysm can also assume a threatening diameter, so that bursting ( rupture ) or fraying of the aortic wall ( dissection ) can be fatal. Since the aortic valve is suspended in the aortic root, any change in the shape and dimensions of the aortic root can lead to distortion of the valve, which then leads to insufficiency. Finally, asymmetrical dilation of the aorta can mask a pre-existing overstretching of a valve pouch.

In the overwhelming majority of cases, aortic valve reconstruction is required during the operation of an aneurysm of the ascending aorta if the aortic valve is to function as normally as possible. This principle applies to the tricuspid as well as the bicuspid and unicuspid aortic valve.

Reconstruction concept

The aim of the operation is to eliminate the aneurysm according to its individual extent and to maintain or normalize the function of the aortic valve. Depending on the longitudinal extent of the aneurysm, the replacement of the aortic root is necessary or can be left in place. If the root has a diameter of less than 40–45 mm, it is usually not necessary to replace it. In this case, the replacement of the aorta above the root is sufficient (so-called tubular ascendens replacement). If the diameter is more than 45 mm, the root replacement will usually be useful and necessary. There are two different surgical procedures for this, which are often named after their inventors and both lead to comparable results. Both methods have in common that after the replacement of the aortic root, a targeted reconstruction of the aortic valve must be carried out if a good and long-term function of the aortic valve is to be achieved.

Surgical technique

A) Tubular aortic replacement

Aortic valve severed. A suitable vascular prosthesis made of Dacron is now sewn to the aortic root. The shape of the aortic valve may have changed as a result of this maneuver, so it must be checked afterwards. Usually an overstretching of one or more pockets comes to light, which then has to be corrected by gathering seams.

B) Replacement of the aortic root

After the heart has stopped, the enlarged aorta is removed up to the edge of the aortic valve. The branches of the coronary arteries must also be detached from the aorta. For the Magdi Yacoub procedure, a Dacron prosthesis is cut to size to create three lips that correspond to the normal shape of the aortic wall. These are only sutured to the edges of the aortic valve. Some surgeons combine this procedure with aortic valve ring stabilization. In the Tirone David procedure, the aortic valve is further freed from the surrounding tissue. A Dacron prosthesis is now placed over the flap and the flap is fixed in the prosthesis with sutures.

Both procedures have in common that after replacement of the aortic root, the shape of the aortic valve must be carefully checked. In the overwhelming majority of cases there is an overstretching of one or more pockets, which, if not corrected, leads to "penetration" (prolapse) with considerable insufficiency. Reconstruction of the aortic valve is therefore very often necessary and follows the principles of the tricuspid aortic valve or bicuspid aortic valve. In all cases, the aortic replacement is expanded to such an extent that the aneurysm is completely eliminated. This can also include the replacement of the aortic arch.

Aftercare

Anticoagulation

In contrast to valve replacement, no inhibition of blood coagulation ( anticoagulation ) is required after the reconstruction . Only the occurrence of an irregular heartbeat ( atrial fibrillation ) may require anticoagulation to prevent clots from forming in the left atrium.

Endocarditis prophylaxis

After aortic valve replacement, endocarditis prophylaxis is recommended for all interventions in the oropharynx (e.g. dental surgery, tonsillectomy). It is unclear whether this is also necessary after a heart valve reconstruction.

See also

• Heart valve reconstruction
• Heart valve with a folding wing
• Bioreactors for cultured heart valves
• Possibilities and limits of minimally invasive heart valve replacement

literature

• Hans-Joachim Schäfers : Current treatment of aortic regurgitation . UNI-MED Science, Bremen / London / Boston 2013, ISBN 978-3-8374-1406-6 .
• Hans-Joachim Schäfers: Clinical basics of cardiac and thoracic surgery. 1st edition. ABW Wissenschaftsverlagsgesellschaft, Berlin 2003.

Individual evidence

1. ↑ Barbara I. Tshisuaka: Tuffier, Théodore. In: Werner E. Gerabek , Bernhard D. Haage, Gundolf Keil , Wolfgang Wegner (eds.): Enzyklopädie Medizingeschichte. De Gruyter, Berlin / New York 2005, ISBN 3-11-015714-4 , p. 1424.
2. ^ WJ Taylor et al .: The surgical correction of aortic insufficiency by circumcision . In: J Thorac Cardiovasc Surg. , 1958,35, pp. 192-231.
3. ^ HJ Schäfers et al .: Bicuspidization of the unicuspid aortic valve: a new reconstructive approach . In: Ann Thorac Surg. , 2008 Jun, 85 (6), pp. 2012-2018
4. ^ D Aicher, HJ. Schäfers: Aortic valve repair - current status, indications, and outcomes . In: Semin Thorac Cardiovasc Surg. , 2012, 24 (3), pp. 195-201
5. ^ A Vahanian et al .: Guidelines on the management of valvular heart disease (version 2012). In: Eur Heart J. , 2012 Oct, 33 (19), pp. 2451-2496.
6. ↑ ^{a b} Hans-Joachim Schäfers: Current treatment of aortic regurgitation . UNI-MED Science, 2013 (English)
7. ^ K Hammermeister et al .: Outcomes 15 years after valve replacement with a mechanical versus a bioprosthetic valve: final report of the Veterans Affairs randomized trial . In: J Am Coll Cardiol. , 2000, 36, pp. 1152-1158.
8. ^ D Aicher et al .: Aortic valve repair leads to a low incidence of valve-related complications . In: Eur J Cardiothorac Surg. , 2010, 37, pp. 127-132.
9. ^ F Langer et al .: Aortic valve repair using a differentiated surgical strategy . In: Circulation , 2004, 110, pp. II 67-73.
10. ^ HJ Schäfers et al .: Bicuspidization of the unicuspid aortic valve: a new reconstructive approach . In: Ann Thorac Surg. , 2008 Jun, 85 (6), pp. 2012-2018.
11. ↑ RH. Anderson: Understanding the structure of the unicuspid and unicommissural aortic valve . In: J Heart Valve Dis. , 2003 Nov; 12 (6), pp. 670-673.
12. ↑ ^{a b c} D Aicher, U Schneider, W Schmied, T Kunihara, M Tochii, HJ. Schäfers: Early results with annular support in reconstruction of the bicuspid aortic valve . In: J Thorac Cardiovasc Surg. , 2013 Mar, 145 (3 Suppl), pp. S30-534.
13. ↑ KI Schmidt et al. Tricuspidization of the quadricuspid aortic valve. Ann Thorac Surg. 2008 Mar; 85 (3), pp. 1087-1089.
14. ^ HJ Schäfers et al .: Remodeling of the aortic root and reconstruction of the bicuspid aortic valve . In: Ann Thorac Surg. , 2000, 70, pp. 542-546. M Franciulli et al .: Root remodeling and aortic valve repair for unicuspid aortic valve . In: Ann Thorac Surg. , 2014, Sep, 98 (3), pp. 823-829.
15. ↑ ^{a b} MA Sarsam, M. Yacoub: Remodeling of the aortic valve annulus . In: J Thorac Cardiovasc Surg. , 1993, 105, pp. 435-458. TE David, CM. Feindel: An aortic valve-sparing operation for patients with aortic incompetence and aneurysm of the ascending aorta . In: J Thorac Cardiovasc Surg. , 1992 Apr, 103 (4), pp. 617-621
16. ^ HJ Schäfers et al .: Reexamining remodeling . In: J Thorac Cardiovasc Surg. , 2015 Feb, 149 (2 Suppl), pp. S30-536.
17. ↑ ^{a b} TE. David: Current readings: Aortic valve-sparing operations . In: Semin Thorac Cardiovasc Surg. , 2014 Autumn, 26 (3), pp. 231-238.
18. ↑ T Kunihara et al .: Preoperative aortic root geometry and postoperative cusp configuration Primarily deterministic mine long-term outcome after valve-preserving aortic root repair . In: J Thorac Cardiovasc Surg. , 2012 Jun, 143 (6), pp. 1389-1395.
19. ↑ E Lansac et al .: An aortic ring: from physiologic reconstruction of the root to a standardized approach for aortic valve repair . In: J Thorac Cardiovasc Surg. , 2010, 140, pp. S28-35.
20. ^ TE David, CM. Feindel: An aortic valve-sparing operation for patients with aortic incompetence and aneurysm of the ascending aorta . In: J Thorac Cardiovasc Surg. , 1992 Apr, 103 (4), pp. 617-621
21. ↑ HJ Schäfers, B Bierbach, D. Aicher: A new approach to the assessment of aortic cusp geometry . In: J Thorac Cardiovasc Surg. 2006, 132, pp. 436-438.
22. ↑ Endocarditis prophylaxis according to the new guidelines of the European Cardiological Society . (PDF; 869 kB) In: Journal für Kardiologie , 2011, accessed June 19, 2011.

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