MMCTS
(November 29, 2005). doi:10.1510/mmcts.2004.000646
Copyright © 2005 European Association for Cardio-thoracic Surgery
Procedure
Supra-annular aortic valve replacement with a mechanical prosthesis
Marko Turina*
University Hospital, Rämistrasse 100, 8091 Zurich, Switzerland
* Corresponding author: * Tel.: +41-44-255 3298; fax +41-44-255 4446. E-mail: marko.turina{at}usz.ch
 |
Summary
|
|---|
Supra-annular placement of the aortic valve prosthesis is primarily used in small aortic annulus to prevent a patient-prosthesis mismatch. The most important surgical steps are: careful removal of the diseased valve including annular decalcification; assessment of the prosthesis seating to guarantee free movement of leaflets and to prevent obstruction of coronary orifices; implantation with interrupted stitches placed infra-annularly, with the prosthesis being seated in a supra-annular position. If necessary, a sub-annular resection of asymmetric septal hypertrophy should be carried out prior to placement of the prosthesis.
Key Words: Aortic prosthesis • Mechanical valve • Patient-prosthesis mismatch • Supra-annular placement
|
Introduction
|
|---|
Aortic valve replacement is performed to replace a diseased valve with a new, competent one with minimal pressure gradient. Many prosthetic valves, mechanical and biological, are not free of some obstruction to the blood flow, and a residual gradient is common, especially in small aortic orifices. In 1978 Rahimtoola coined the term ‘patient-prosthesis mismatch’ [1] to describe the condition where an impediment to the blood outflow in patients with small aortic prosthesis results in incomplete regression of the left ventricular hypertrophy, with residual symptoms and possibly a decreased life expectancy. As a lower level of acceptable valve opening area a value of 0.85cm2/m2 is generally acknowledged [2], although the concept of patient-prosthesis mismatch has been questioned recently, possibly due to the improved performance of newer mechanical and biological valves [3,4,5].
The original idea of supra-annular placement of the valve prosthesis was described and patented by Carpentier in 1981.1 By placing the valve prosthesis above the annulus, the narrowing of the left ventricular outflow by the sewing ring of the prosthesis is minimized, resulting in improved hemodynamic performance. Some newer mechanical prosthetic valves are designed for supra-annular placement, to be used in a narrow aortic orifice with a diameter below 21–23 mm (MMCTSLink 78). This procedure depicts the replacement of the stenotic aortic valve with Regent SJM prosthesis (MMCTSLink 79).
|
Surgical technique
|
|---|
The patient is a 55-year-old female with severe aortic stenosis and only minimal aortic incompetence (Video 1). The operation is performed via a short median sternotomy (Video 2), which gives adequate exposure to the ascending aorta and aortic valve, and allows standard cannulation without specially designed equipment and cannulas. After cannulation of the ascending aorta, with a long cannula whose tip is placed into the descending aorta to minimize embolization (MMCTSLink 80), and of the right atrium by a two-stage venous cannula (MMCTSLink 81), cardiopulmonary bypass is instituted and the patient cooled to 30 °C. The left ventricle is vented (MMCTSLink 82), antegrade and retrograde cardioplegia cannulas are placed (MMCTSLink 83 and MMCTSLink 84), aorta is cross-clamped and antegrade cold cardioplegia started (Video 3).
Click on image to view video |
Video 1 Trans-esophageal echocardiography demonstrating substantial calcifications in a degenerative aortic valve disease with predominant stenosis. The aortic annulus is small, measured at 21 mm – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
Click on image to view video |
Video 2 Surgery is performed through a small upper mid-sternal incision reaching to the fourth intercostal space. Good exposure of the aortic valve is achieved, and all necessary cannulations (aorta, right atrium, coronary sinus and left ventricular vent) are possible – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
Click on image to view video |
Video 3 Standard cannulation for cardio-pulmonary bypass is performed, with a long arterial cannula introduced through the ascending aorta, reaching beyond the subclavian artery into the descending aorta, and a conventional two-stage cannula is placed into the right atrium. In cardiopulmonary bypass, left ventricular vent is introduced through the upper right pulmonary vein, and antegrade and retrograde cardioplegia cannulas are placed. With a competent aortic valve, cardioplegia is started in antegrade fashion through the ascending aorta; after achieving a good standstill, retrograde cardioplegia is continued, followed by continuous retrograde administration of cold (16 °C) oxygenated blood – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
After achieving a good electro-mechanical standstill, retrograde cardioplegia is started and the aorta is opened with a conventional hockey-stick incision reaching into the non-coronary sinus. Stenotic, degenerated aortic valve is removed (Video 4), and careful decalcification of the annulus is performed. A surgical sponge is placed into the left ventricle during this procedure to capture calcific debris which is unavoidable at this stage. Special care is taken when working in the left and non-coronary sinuses, to prevent detachment of aorta from the fibrous skeleton of the heart. Calcifications often extend into the outflow tract and onto the anterior mitral leaflet; judicious removal is indicated, taking care to increase the motility and preserve the integrity of the mitral valve; and to stay away from the membranous septum of the heart, to prevent injury to the penetrating His-bundle. The subannular region is checked for possible asymmetric septal hypertrophy, which should be resected at this stage, because it can cause postoperative gradient after valve replacement [6,7].
Click on image to view video |
Video 4 Calcified aortic valve is removed by sharp dissection using a knife, heavy scissors and rongeur, followed by careful decalcification of the annulus. A sponge is placed into the left ventricular cavity to catch any calcific debris, and a thorough irrigation of the area is performed, again to catch any calcified material becoming loose during valve removal – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
Sizing of the annulus is performed next (Video 5), first determining the diameter, and later checking the seating of the prosthesis, especially in relation to the orifices of coronary arteries and to the aortotomy itself. Misleading dimensions of the sizers must be kept in mind [8,9], to select a prosthesis which will actually fit into the annulus.
Click on image to view video |
Video 5 Sizing of the annulus, using first a plain numbered sizer, and later a ring sizer which delineates the position of the prosthesis after implantation. Coronary arteries should be well visible at this stage – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
The prosthesis is implanted using sub-annular, non-everting pledgetted mattress stitches (Schematic 1), which assure a supra-annular seating of the prosthesis (Schematic 2), and might reduce the incidence of paraprosthetic leaks [10]. All stitches are placed first, and the prosthesis is kept at a distance of 8–0 cm by the assistant; the use of two-colored sutures (MMCTSLink 7) greatly facilitates the procedure (Schematic 3). Videos 6 and 7 show the stitches being placed in the right (Video 6) and left sinuses (Video 7). It is essential to keep the sutures which have been already placed under constant tension, to elevate the aortic annulus and stabilize the area for the next stitch. Continuous retrograde cardioplegia can be interrupted for several minutes if blood obscures the field.
View larger version (31K):
[in this window]
[in a new window]
|
Schematic 1 Difference between intra- and supra-annular placement of the aortic valve prosthesis, by courtesy of Carbomedics2.
|
|
View larger version (55K):
[in this window]
[in a new window]
|
Schematic 2 Infra-annularly placed, pledgetted non-everting mattress sutures, by courtesy of Carbomedics.
|
|
View larger version (61K):
[in this window]
[in a new window]
|
Schematic 3 Schematic implantation technique with interrupted non-everting mattress, by Courtesy of Sorin 3.
|
|
Click on image to view video |
Video 6 Three heavy sutures are passed through the commissures and traction is applied: this brings the annulus higher into the aortotomy and stabilizes the tissue when stitching. Interrupted, double armed, pledgetted sutures are placed infra-annularly, exiting slightly above the annulus. Suturing is started in the right coronary sinus; strong perpendicular traction is applied to each stitch, preparing the tissue for the placement of the next suture – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
Click on image to view video |
Video 7 Left coronary commissure sutures are placed next; continuous retrograde blood administration can be interrupted at this stage for several minutes, to assure adequate visualization. Again, strong perpendicular traction is applied to sutures already placed – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
Last sutures are placed in the non-coronary sinus; the prosthesis is left in the holder and it is lowered into the supra-annular position (Schematic 4, and Video 8).
Click on image to view video |
Video 8 Non-coronary commissure is the last where the sutures are placed; after completion of the sewing the prosthesis is lowered into position, but the valve holder is kept in place. The assistant exerts strong downward pressure on the holder to seat the prosthesis, to prevent any undue tension being placed on the sutures when tying – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
All sutures are tied, with the assistant pressing the valve holder into the annulus, so then no additional tension has to be placed on the sutures during tying (Video 9). This holder can be usually kept in place until sutures in the non-coronary and left coronary sinuses are tied; afterwards the holder has to be removed, and a gentle downward pressure on the sewing ring can be exerted by a small hemostat. After all sutures have been securely tied, they are cut very short, practically in the knot, to prevent any possible impediment of the leaflet motion by too long knot rests (Video 10).
Click on image to view video |
Video 9 Sutures are tied sequentially; two-colored sutures greatly simplify the task and expedite the procedure. The valve holder is kept in place and downward pressure is exerted until non-coronary and left coronary stitches are tied. At this stage, the holder is removed and residual stitches in the right commissure are tied – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
Click on image to view video |
Video 10 Sutures are cut individually, one by one; they are cut short, practically in the knot, to guarantee free movement of the prosthetic leaflets. Leaflet movement is assessed by a special soft-tipped instrument, sub-annular region is inspected for any possible residual material or hypertrophic muscle which might lead to reduced leaflet mobility, and coronary orifices are checked with a right-angle clamp. Warm retrograde cardioplegia is started during closure of the aortotomy – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
Movement of both leaflets is checked by a soft-tipped instrument provided by the manufacturers; with both leaflets held open the subvalvar region is inspected for possible tissue residues which might cause pannus ingrowth later. Warm retrograde cardioplegia (‘hot-shot’) is started, and aortotomy is closed by running monofilament suture (MMCTSLink 50). With the heart de-aired and ejecting, the function of the prosthesis is checked by echocardiography (Video 11). This last step is highly recommended, because it can detect potential technical problems which cannot be recognized by standard hemodynamic monitoring [10,11].
Click on image to view video |
Video 11 After the heart resumes its activity and begins ejecting, trans-esophageal echo is repeated, to check leaflet motion and rule out paravalvular leaks. The probe is left in place to check for adequate de-airing before decannulation – © St. Jude Medical Inc. Courtesy of St. Jude Medical. All rights reserved.
|
|
|
Results and discussion
|
|---|
Early mortality of aortic valve replacement lies in large databanks4,5,6 between 3 and 4%. It is obviously higher in emergency procedures, endocarditis, reoperations, and in aged patients, to quote only a few factors (Tables 1 and 2). Reliable risk calculators are available for assessing the hazard of aortic valve replacement in a particular patient [12,13]. Careful attention to technical details is still essential, especially in elderly patients and in those with small aortic annulus, to prevent problems which might arise from coronary orifice obstruction [14] or impeded leaflet motion [15,16]. Supra-annular placement of the prosthesis results in very satisfactory hemodynamics, even in small aorta [17,18], and various interventions to enlarge the annulus are hardly needed.
View this table:
[in this window]
[in a new window]
|
Table 1 Odds ratio for hospital mortality – reprinted from Astor BC, Kaczmarek RG, Hefflin B, Daley WR. Mortality after aortic valve replacement: results from a nationally representative database. Ann Thorac Surg 2000;70:1939–1945 (Ref. [12]), with permission from the Society of Thoracic Surgeons
|
|
View this table:
[in this window]
[in a new window]
|
Table 2 Odds ratio for hospital mortality, with major risk factors identifieda – reprinted from Jin R, Grunkemeier GL, Starr A. Validation and refinement of mortality risk models for heart valve surgery. Ann Thorac Surg 2005;80: 471–479 [13], with permission from the Society of Thoracic Surgeons
|
|
|
Footnotes
|
|---|
1 Carpentier A, Lane E. Original patent for supra-annular valve replacement. http://www.freepatentsonline.com/4451936.html 
2 http://www.carbomedics.com/pdfs/thwhtppr.pdf
3 http://www.sorin-cid.com/bicar_slim_tec.htm.
4 http://www.sts.org/documents/pdf/Spring2005STS-ExecutiveSummary.pdf
5 http://www.ctsnet.org/file/SCTS2000pages66-71General.pdf
6 http://www.health.state.ny.us/nysdoh/heart/pdf/2000-2002_cabg.pdf
|
References
|
|---|
- Rahimtoola SH. The problem of valve prosthesis-patient mismatch. Circulation 1978;58:20–24.[Abstract/Free Full Text]
- Pibarot P, Dumesmil JG, Lemieux M, Cartier P, Métras J, Durand LG. Impact of prosthesis-patient mismatch on hemodynamic and symptomatic status, morbidity and mortality after aortic valve replacement with a bioprosthetic heart valve. J Heart Valve Dis 1998;7:211–218.[Medline]
- Banbury MK, Cosgrove III, DM, White JA, Blackstone EH, Frater RWM, Okies JE. Age and valve size effect on the long-term durability of the Carpentier-Edwards aortic pericardial bioprosthesis. Ann Thorac Surg 2001;72:753–757.[Abstract/Free Full Text]
- Medalion B, Blackstone EH, Lytle BW, White J, Arnold JH, Cosgrove DM. Aortic valve replacement: is valve size important? J Thorac Cardiovasc Surg 2000;119:963–974.[Abstract/Free Full Text]
- Aupart M, Simonnot I, Sirinelli A, Meurisse Y, Babuty D, Marchannd M. Pericardial valves in small aortic annuli: ten years' results. Eur J Cardiothorac Surg 1996;10:879–883.[Abstract]
- Turina M. Asymmetric septal hypertrophy should be resected during aortic valve replacement. Z Kardiol 1986;75(Suppl 2):198–200.
- Hess OM, Schneider J, Turina M, Carroll JD, Rothlin M, Krayenbuehl HP. Asymmetric septal hypertrophy in patients with aortic stenosis: an adaptive mechanism or a coexistence of hypertrophic cardiomyopathy? J Am Coll Cardiol 1983;1:783–789.[Medline]
- Bartels C, Leyh RG, Matthias Bechtel JF, Joubert-Hubner E, Sievers HH. Discrepancies between sizer and valve dimensions: implications for small aortic root. Ann Thorac Surg 1998;65:1631–1633.[Abstract/Free Full Text]
- Bonchek LI, Burlingame MW, Vazales BE. Accuracy of sizers for aortic valve prostheses. J Thorac Cardiovasc Surg 1987;94:632–634.[Abstract]
- Ionescu A, Fraser AG, Butchart EG. Prevalence and clinical significance of incidental paraprosthetic valvar regurgitation: a prospective study using transoesophageal echocardiography. Heart 2003;89:1316–1321.[Abstract/Free Full Text]
- Shapira Y, Vaturi M, Weisenberg DE, Raanani E, Sahar G, Snir E, Battler A, Vidne BA, Sagie A. Impact of intraoperative transesophageal echocardiography in patients undergoing valve replacement. Ann Thorac Surg 2004;78:579–583.[Abstract/Free Full Text]
- Astor BC, Kaczmarek RG, Hefflin B, Daley WR. Mortality after aortic valve replacement: results from a nationally representative database. Ann Thorac Surg 2000;70:1939–1945.[Abstract/Free Full Text]
- Jin R, Grunkemeier GL, Starr A. Validation and refinement of mortality risk models for heart valve surgery. Ann Thorac Surg 2005;80:471–479.[Abstract/Free Full Text]
- Santini F, Pentiricci S, Messina A, Mazzucco A. Coronary ostial enlargement to prevent stenosis after prosthetic aortic valve replacement. Ann Thorac Surg 2004;77:1854–1856.[Abstract/Free Full Text]
- Ovrum E, Tangen G. Acute leaflet arrest in St. Jude Medical regent aortic valve. J Thorac Cardiovasc Surg 2005;129:1446.[Free Full Text]
- Grattan MT, Thulin LI. Leaflet arrest in St. Jude Medical and CarboMedics valves: an experimental study. Eur J Cardiothorac Surg 2004;25:953–957.[Abstract/Free Full Text]
- Walker DK, Brendzel AM, Scotten LN. The new St. Jude Medical Regent mechanical heart valve: laboratory measurements of hydrodynamic performance. J Heart Valve Dis 1999;8:687–696.[Medline]
- Vitale N, Caldarera I, Muneretto C, Sinatra R, Scafuri A, Di Rosa E, Contin A, Tedesco N, Pierangeli A, Abbate M, Gherli T, Casarotto D, Di Summa M, Marino B, Chiariello L, de Luca L. Clinical evaluation of St. Jude Medical Hemodynamic Plus versus standard aortic valve prostheses: the Italian multicenter, prospective, randomized study. J Thorac Cardiovasc Surg 2001;122:691–698.[Abstract/Free Full Text]
|
|
Top
Summary
Introduction