Ann Thorac Surg 1999;68:1096-1099
© 1999 The Society of Thoracic Surgeons
How To Do It
Orientation of tilting disc and bileaflet aortic valve substitutes for optimal hemodynamics
Joachim Laas, MDa,
Peter Kleine, MDa,
Michael J. Hasenkam, MDa,
Hans Nygaarda
a Department of Cardiothoracic Surgery, Cardiovascular Center Bad Bevensen, Bad Bevensen, Germany
Address reprint requests to Dr Laas, Department of Cardiothoracic Surgery, Cardiovascular Center, Römstedter Str 25, 29549 Bad Bevensen, Germany
 |
Abstract
|
|---|
Procedures for implantation of mechanical aortic valves have to consider eccentric flow in the aortic root. We describe how to optimize orientation of tilting disc (Medtronic Hall) and bileaflet (St. Jude Medical) valves. In tilting disc valves, an asymmetric design faces an asymmetric flow. Hemodynamic performance of this valve type, regarding turbulence and pressure gradients, is close to normal physiology and superior to the bileaflet valve design. This difference is more pronounced the smaller the valve size.
|
Introduction
|
|---|
The longitudinal axes of the left ventricle and the aortic root form an angle of 140° to 150°, as investigated in 40 patients with different diagnoses (normal ventricle, ventricular hypertrophy, aortic stenosis, and insufficiency), causing a deviation of the bloodstream line of approximately 30° to 40° toward the convexity of the ascending aorta (Fig 1). Thus, flow pattern at the level of the aortic valve is asymmetric, showing highest flow velocities along the noncoronary leaflet with a counterclockwise rotation of 90° between commissures during systole [1]. Figure 2 shows the lateral aspect of flow velocities at the peak of systole whereas Figure 3 gives a surgeon’s view from the ascending aorta.
View larger version (18K):
[in this window]
[in a new window]
|
Fig 1. Angle between the longitudinal axis of the left ventricle and the aorta as defined in 40 patients with different diagnoses (10 patients with aortic stenosis, 10 patients with aortic insufficiency, 10 patients with normotensive coronary artery disease, and 10 patients with hypertensive coronary artery disease.
|
|
View larger version (27K):
[in this window]
[in a new window]
|
Fig 2. Distribution of flow velocities in the aortic root in a patient with a normal aortic valve (1). At the peak of systole, the area of highest flow velocities is located close to the posterior wall (P); with ongoing systole, this area of major flow rotates 90° counterclockwise along the noncoronary leaflet. (L = left; R = right; A = anterior.)
|
|
View larger version (63K):
[in this window]
[in a new window]
|
Fig 3. Schematic drawing (A) and surgeon’s view (B) of the aortic valve from the ascending aorta. The area (region) of major flow is located along the noncoronary cusp; the arrow indicates the counterclockwise rotation during each heart cycle. (RCA = right coronary artery; LCA = left coronary artery; NCC = noncoronary cusp.)
|
|
Orientation of mechanical aortic valves has to be in accordance with this eccentric blood flow pattern. In a previous animal study [2], optimum, almost physiologic, results were found for the tilting disc (Medtronic Hall [MH], Medtronic, Minneapolis, MN) substitute with its large orifice facing the area of major flow along the noncoronary (posterior) leaflet. The bileaflet valve (St. Jude Medical [SJM], St. Jude Medical, St. Paul, MN) had its best results with one leaflet oriented toward the right cusp. However, the SJM could not match the hemodynamic performance of the tilting disc valve in its optimal orientation.
In accord with these experimental findings, we implanted MH and SJM valves in their optimal orientation in clinical practice. Hemodynamic outcome was investigated by intraoperative measurement of turbulence and pressure gradients as well as by measurement of pressure gradients and regression of left ventricular mass at 6 months’ follow-up.
|
Technique
|
|---|
After complete excision of the diseased aortic valve and decalcification of the valve ring, sizing was performed in the usual way. Again as usual, valve sutures either for epiannular, intraannular, or single-stitch implantation techniques were prepared.
Tilting disc (Medtronic Hall)
Optimal orientation for the tilting disc (MH) valve was obtained with the center of the large orifice directed toward the convexity of the left ventricular outflow corresponding with the noncoronary (posterior) cusp (Fig 4 ) [2]. Thus, the suture in the center of the noncoronary (posterior) cusp was identified and placed into the polytetrafluoroethylene sewing ring in the center of the large orifice. Then the remaining stitches were completed. Having lowered the valve substitute into the annulus, free mobility of the disc was controlled. Within a margin of 45° to each side of this position, hemodynamic performance was better than that of a bileaflet valve in any position [2].
View larger version (17K):
[in this window]
[in a new window]
|
Fig 4. Optimal orientation of the tilting disc valve (Medtronic Hall). The large valve orifice is directed toward the area of major flow at the noncoronary leaflet (NCC). (RCA = right coronary artery; LCA = left coronary artery.)
|
|
Bileaflet valve (St. Jude Medical)
Optimal orientation was achieved with one leaflet directed toward the right cusp. In this position, the eccentric area of major flow was distributed to one lateral portion of all three openings (Fig 5). Thus, the stitch in the center of the noncoronary cusp was identified and placed in the center of the SJM, which was marked black on the Dacron cuff. However, there was only minor variation of flow dynamics with respect to other orientations [2].
View larger version (16K):
[in this window]
[in a new window]
|
Fig 5. Optimal orientation of the bileaflet valve (St. Jude Medical). Distribution of the area of major flow is to all three openings with one leaflet facing the right coronary cusp. (RCA = right coronary artery; LCA = left coronary artery; NCC = noncoronary cusp.)
|
|
|
Results
|
|---|
The hemodynamic performance of MH and SJM (standard) valves with both valves implanted in their optimal orientation was investigated in a prospective randomized study (approved by the local ethical committee on February 9, 1998) at the Department of Cardiothoracic Surgery at the Cardiovascular Center Bad Bevensen. A total of 24 patients with aortic stenosis and left ventricular hypertrophy had aortic valve replacement with or without coronary artery bypass grafting. The patient groups receiving SJM (n = 12) and MH (n = 12) valves did not show significant differences with respect to patient characteristics. Operation time, bypass time, or cross-clamping time, as well as valve size (23.8 mm) also did not differ between the groups.
Transvalvular pressure gradients (
p) were measured by intraoperative transesophageal echocardiography (Table 1). The MH valve showed significantly lower pressure gradients. This difference was more pronounced in the smaller sized valves.
Downstream turbulence was investigated by measuring the velocity profile approximately 4 cm downstream from the aortic valve in 17 points throughout the cross-section of the aorta by a perivascular ultrasound Doppler [3]. Reynold’s normal stress values were calculated as key markers for turbulent stresses. The results are listed in Table 2. Again, the MH valve showed superior results, especially in smaller sizes.
At 6 months’ follow-up, pressure gradients were reduced by half for both valve substitutes (MH, 5.3 ± 1.7 mm Hg; SJM, 10.4 ± 2.3 mm Hg; p < 0.05), with the difference between the valves being maintained. Regression of left ventricular mass was accelerated for patients with the MH with respect to the interventricular septum thickness (Fig 6). No significant differences were observed for posterior wall thickness.
View larger version (14K):
[in this window]
[in a new window]
|
Fig 6. Regression of left ventricular hypertrophy is accelerated in patients receiving Medtronic Hall (MH) valves compared with patients receiving St. Jude Medical (SJM) valves with respect to the interventricular septum. *p < 0.05. (IVSsyst = interventricular septum at systole; IVSdiast = interventricular septum at diastole; preop = preoperative period.)
|
|
|
Comment
|
|---|
Orientation of mechanical aortic valve substitutes has to take into account the eccentric blood flow pattern in the aortic root. In a previous animal study [2], the effect of orientation on downstream turbulence as a key marker for transvalvular energy loss was investigated for MH and SJM aortic valves. For the MH valve, hemodynamic results close to normal physiology were obtained in optimal orientation (large orifice directed toward the noncoronary cusp, the area of major flow) and within a margin of 45° from this position to each side. In the worst position (large orifice facing the commissure between the left and right cusps), significant turbulence was observed. In the bilaterally symmetric SJM valve, the best results were found with one leaflet toward the right cusp. The bileaflet valve design showed less variation with respect to other orientations, but could not achieve the almost physiologic values of the MH in its optimal orientation [2]. After this animal study, both valves have been implanted in their optimal orientation in patients with aortic stenosis. Corresponding to our experience in swine, the asymmetric MH tilting disc, being exposed to the eccentric blood flow, showed superior hemodynamic performance compared with the bilaterally symmetric SJM valve. Especially in smaller valve sizes, the superiority of the tilting disc mechanism is expressed by less downstream turbulence and lower transvalvular pressure gradients, leading to acceleration of left ventricular remodeling. Because the anatomic prerequisite, ie, angulation between left ventricle and ascending aorta, also accounts for this disease, these results can be applied to patients with aortic insufficiency. These results correspond with previous findings about optimal orientation of the Björk-Shiley tilting disc valve [4] and might explain the observation by the St. Louis University group that regression of left ventricular mass was accelerated in patients with MH tilting disc valves compared with SJM bileaflet valves in the aortic position [5].
|
References
|
|---|
-
Paulsen P.K., Nygaard H., Hasenkam M.J., Gormsen J., Stökilde-Jörgensen H., Albrechtsen O. Analysis of velocity in the ascending aorta in humans. A comparative study among normal aortic valves, St. Jude Medical and Starr-Edwards Silastic Ball valves. Int J Artif Organs 1988;11:293-302.[Medline]
-
Kleine P., Perthel M., Nygaard H., et al. Medtronic Hall versus St. Jude Medical mechanical aortic valve. J Heart Valve Dis 1998;7:548-555.[Medline]
-
Hasenkam M.J., Pedersen E.M., Östergard J.H., et al. Velocity fields and turbulent stresses downstream of biological and mechanical aortic valve prostheses implanted in pigs. Cardiovasc Res 1988;22:472-483.[Medline]
-
Olin C.L., Bomfim V., Halvazulis V., Holmgren A.G., Lamke B.J. Optimal insertion technique for the Björk-Shiley valve in the narrow aortic ostium. Ann Thorac Surg 1983;36:567-576.[Abstract]
-
Dolan M.S., Castello R., St. Vrain J.A., et al. Relationship of left ventricular hypertrophy regression and outflow turbulence following aortic valve replacement. Circulation 1996;8(Suppl):721.
Accepted for publication May 26, 1999.
This article has been cited by other articles:
|
|
|
|
 
L. Guerrieri Wolf, B. P. Choudhary, Y. Abu-Omar, and D. P. Taggart
Solid and gaseous cerebral microembolization after biologic and mechanical aortic valve replacement: Investigation with multirange and multifrequency transcranial Doppler ultrasound
J. Thorac. Cardiovasc. Surg.,
March 1, 2008;
135(3):
512 - 520.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
H. Machler, G. Reiter, M. Perthel, U. Reiter, P. Bergmann, M. Zink, R. Rienmuller, and J. Laas
Influence of a tilting prosthetic mitral valve orientation on the left ventricular flow -- an experimental in vivo magnetic resonance imaging study
Eur. J. Cardiothorac. Surg.,
July 1, 2007;
32(1):
102 - 107.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
W. Hassanein, A. Albert, I. Florath, Y. Y. Hegazy, U. Rosendahl, S. Bauer, and J. Ennker
Concomitant aortic valve replacement and coronary bypass: the effect of valve type on the blood flow in bypass grafts
Eur. J. Cardiothorac. Surg.,
March 1, 2007;
31(3):
391 - 396.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
E. M. Kirsch, N C. Radu, E. Allaire, and D. Y Loisance
Pathobiology of Idiopathic Ascending Aortic Aneurysms
Asian Cardiovasc Thorac Ann,
June 1, 2006;
14(3):
254 - 260.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
A. LeGuyader, R. Watanabe, J. Berbe, A. Boumediene, M. Cogne, and M. Laskar
Platelet activation after aortic prosthetic valve surgery
Interactive CardioVascular and Thoracic Surgery,
February 1, 2006;
5(1):
60 - 64.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
S. Mottl-Link, I. Wolf, M. Hastenteufel, S. Witte, H.-P. Meinzer, S. Hagl, and R. De Simone
Non-invasive assessment of differences between bileaflet and tilting-disc aortic valve prostheses by 3D-Doppler profiles
Interactive CardioVascular and Thoracic Surgery,
October 1, 2005;
4(5):
383 - 387.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
H. Machler, M. Perthel, G. Reiter, U. Reiter, M. Zink, P. Bergmann, A. Waltensdorfer, and J. Laas
Influence of bileaflet prosthetic mitral valve orientation on left ventricular flow--an experimental in vivo magnetic resonance imaging study
Eur. J. Cardiothorac. Surg.,
October 1, 2004;
26(4):
747 - 753.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
S. B Kale, D. S Saksena, Y. C Agnihotri, and K. H Ayyer
Thrombectomy With Disc Rotation of Medtronic Valves
Asian Cardiovasc Thorac Ann,
December 1, 2003;
11(4):
309 - 313.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
M. Hartrumpf, J. M. Albes, T. Krempl, V. Rudolph, and T. Wahlers
The hemodynamic performance of standard bileaflet valves is impaired by a tilted implantation position
Eur. J. Cardiothorac. Surg.,
March 1, 2003;
23(3):
283 - 291.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
J. Laas, S. Kseibi, M. Perthel, A. Klingbeil, L'E. El-Ayoubi, and A. Alken
Impact of high intensity transient signals on the choice of mechanical aortic valve substitutes
Eur. J. Cardiothorac. Surg.,
January 1, 2003;
23(1):
93 - 96.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
J. van der Linden, L. Hadjinikolaou, P. Bergman, and D. Lindblom
Postoperative stroke in cardiac surgery is related to the location and extent of atherosclerotic disease in the ascending aorta
J. Am. Coll. Cardiol.,
July 1, 2001;
38(1):
131 - 135.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
E. G. Butchart, H.-H. Li, N. Payne, K. Buchan, and G. L. Grunkemeier
Twenty years' experience with the Medtronic Hall valve
J. Thorac. Cardiovasc. Surg.,
June 1, 2001;
121(6):
1090 - 1100.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. A. DeWall, N. Qasim, and L. Carr
Evolution of mechanical heart valves
Ann. Thorac. Surg.,
May 1, 2000;
69(5):
1612 - 1621.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
