J Thorac Cardiovasc Surg 2006;132:727-728
© 2006 The American Association for Thoracic Surgery
Reply to the Editor
Farhad Bakhtiary, MD,
Omer Dzemali, MD,
Thomas Wittlinger, MD,
Anton Moritz, MD,
Peter Kleine, MD
Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
We appreciate the comments of Nemes and associates regarding our recent article and would like to point out the following issues in response to their comments.
The current published clinical trial followed our previous animal studies,1,2
in which we investigated the effects of valve design and orientation on acute changes of coronary flow in different mechanical valve substitutes and the native aortic valve. In the group in which we did not replace the aortic valve but only performed 90 minutes of extracorporeal circulation and 60 minutes of myocardial ischemia, coronary flow rates increased significantly. No mechanical aortic valve could achieve this reactive hyperemia, with superior results for the Medtronic Hall and Advantage valves compared with the St Jude standard bileaflet valve. Coronary flow rates depended not only on valve design, but also on valve orientation; the previously defined optimal orientations with respect to hemodynamics also provided the highest coronary artery flow. We explained these findings by lower intraventricular diastolic pressures and reduced levels of aortic root turbulence in the optimal orientations.
In the recent study, our patients had no history of coronary artery disease, but angina pectoris was present in more than 50%. The improvement of coronary flow reserve (CFR) in the stentless group was independent of the left ventricular mass regression. However, we observed a trend toward accelerated regression of left ventricular mass regression in the stentless group, without any statistical significance (P = .06).
We share the opinion that aortic valve design has a significant influence on improvement of CFR after prosthetic aortic valve replacement. The increased long-term mortality described in recent studies in patients with severe aortic valve disease after aortic valve replacement3,4 compared with the normal population could be partially caused by these findings. Therefore, CFR should be included if in vivo hemodynamic performance of prosthetic aortic valves is investigated.
Regarding the optimal clinical method for measurement of CFR, we agree with Nemes and colleagues that magnetic resonance imaging can provide more objective results compared with echocardiography; conversely, the echocardiography method is less complex and easier to perform. We have just completed a retrospective study on 20 aortic valve patients (Advantage, n = 10; St Jude Medical, n = 10; interval from the operation, >6 months). Echocardiographic measurement of CFR (adenosine 140 µg · kg–1 · min–1 over 7 minutes) was possible in 17 patients (85%). Normal CFR was demonstrated in only three Advantage patients (Table 1). Because this was not a randomized study, we have not yet published these data, but we have initiated a randomized clinical multicenter study with echocardiographic measurement of CFR between the two bileaflet mechanical valve substitutes with large patient numbers to investigate chronic changes of CFR after mechanical aortic valve replacement.
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TABLE 1. Measurement of coronary flow reserve (CFR) in 20 patients after aortic valve replacement with either a Medtronic Advantage or a St Jude Medical (SJM) standard valve
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References
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- Kleine P, Abdel-Rahman U, Klesius AA, Scherer M, Moritz A. Comparison of hemodynamic performance of Medtronic Hall 21 mm versus St Jude Medical 23 mm prostheses in pigs. J Heart Valve Dis. 2002;11:857-863.[Medline]
- Kleine P, Scherer M, Abdel-Rahman U, Klesius AA, Moritz A. Effect of mechanical aortic valve orientation on coronary artery flow. comparison of tilting disc versus bileaflet prostheses in pigs. J Thorac Cardiovasc Surg. 2002;124:925-932.[Abstract/Free Full Text]
- Arata K, Iguro Y, Masuda H, et al. Long-term follow up in patients receiving a small aortic valve prosthesis. J Heart Valve Dis. 2002;11:780-784.[Medline]
- Emery RW, Erickson CA, Arom KV, et al. Replacement of the aortic valve in patients under 50 years of age. long-term follow-up of the St. Jude Medical prosthesis. Ann Thorac Surg. 2003;75:1815-1819.[Abstract/Free Full Text]
Related Article
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The effect of aortic valve replacement on coronary flow reserve
- Attila Nemes, Tamás Forster, Marcel L. Geleijnse, Folkert J. ten Cate, and Miklós Csanády
J. Thorac. Cardiovasc. Surg. 2006 132: 726-727.
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