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Ann Thorac Surg 1998;66:985
© 1998 The Society of Thoracic Surgeons

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Correspondence

Reply

^a Klinik für Herzchirurgie, Medical University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany

To the Editor

We thank Dr Bonchek for his kind and interesting remarks and would like to emphasize that his group was the first demanding correct labeling of sizer and protheses [1].

In concordance with Dr Bonchek we cannot fully explain why manufacturers produce mechanical prostheses with tissue annulus diameters larger than the corresponding sizers. Our results demonstrate that this is the case for Baxter Edwards Tekna, Carbomedics Standard, and some Medtronic Hall prostheses [2]. Advanced design, eg, sewing cuff reduction, resulted in reduced tissue annulus diameters of Carbomedics Standard prostheses. Thus, the tissue annulus diameter of the Carbomedics Reduced shows no difference from the corresponding sizer. As the orifice area is not different between the Standard and Reduced valve, we believe that the Carbomedics Standard prostheses has historical significance only. The same holds true for 21-mm and 23-mm Medtronic Hall devices. These valves have the same orifice areas as the 20-mm and the 22-mm prostheses, respectively, and thus no hemodynamic difference. One can assume that the manufacturer produces these protheses to provide a complete set of devices with different sizes; however, this might lead to some confusion of the consumer.

A possible explanation for oversizing valve sizers compared with the corresponding tissue annulus diameters may be a contribution to different implantation techniques, eg, sutures with or without pledget. Thus the reason for oversizing the corresponding sizer may be the attempt to reduce difficulties by tying the valve down—a homage to the surgeon’s convenience.

We totally agree with Dr Bonchek, who mentioned that a prosthesis with a tissue annulus diameter larger than its labeled size may result in superior hemodynamic performance and possible competitive advantage compared with correctly labeled valves. Therefore, the substantial differences in orifice areas of the studied protheses are summarized in our contribution. Whether different orifice areas of valves labeled as the same size contribute to differences in hydraulic function has to be determined.

Summarizing Dr Bonchek’s and our concern, manufacturers should indicate the correct dimensions of the sizer equipment, the tissue annulus diameter, and the orifice area. These essential data should be clearly depicted on the label of the device.

References

1. Bonchek L.I., Burlingame M.W., Vazales B.E. Accuracy of sizers for aortic valve protheses. J Thorac Cardiovasc Surg 1987;94:632-634.[Abstract]
2. Bartels C., Leyh R.G., Bechtel J.F.M., Joubert-Hübner E., Sievers H.-H. Discrepancies between sizer and valve dimensions: implications for the small aortic root. Ann Thorac Surg 1998;65:1631-1633.[Abstract/Free Full Text]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Claus Bartels Hans-Hinrich Sievers Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bartels, C. Articles by Sievers, H.-H. Search for Related Content PubMed PubMed Citation Articles by Bartels, C. Articles by Sievers, H.-H.