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Ann Thorac Surg 1998;66:984-985
© 1998 The Society of Thoracic Surgeons

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Correspondence

Why aren’t valve sizers and prostheses labeled accurately?

^a Mid-Atlantic Heart Institute at Lancaster General Hospital, 555 N Duke St, PO Box 3555, Lancaster, PA 17604-3555, USA

To the Editor

Eleven years after my colleagues and I drew attention to the inaccurate labeling of valve sizers [1], there are still measurable discrepancies between the nominal and the actual sizes of most prostheses and their sizers. Although a recent study [2] provides no explanation for these discrepancies, it does confirm that discrepancies still exist, even for prostheses that have been introduced since our 1987 report. Why should this be so? It is definitely not due to the manufacturers’ ignorance, because they tell us that our original report is one of their most frequently requested reprints regarding valve surgery. These inaccuracies must be intentional, because the technological capability to produce accurate valve sizers obviously exists. There are two possible explanations:

1. As we indicated in our 1987 article, manufacturers wish to prevent attempts to insert a prosthesis that is too large to fit. Many manufacturers intentionally oversize their valve sizers but not their prostheses, which assures that if the sizer fits within the annulus, the slightly smaller prosthesis will fit. However, this strategy is not relevant if the tissue annulus diameter of the prosthesis is larger than the sizer (which was frequently noted in the current study), and another explanation is necessary:
   
2. If the prosthesis, rather than the sizer, is larger than its labeled size, its hydraulic function (as reflected in orifice area, transprosthetic gradient, and other variables) will be better than that of an accurately labeled competitive prosthesis, which is actually a smaller valve. This conveys a substantial competitive advantage if the inaccurate labeling is not widely recognized.
   

Reports such as the one by Bartels and coworkers [2] provide important information by drawing attention to prostheses and sizers that are inaccurately labeled. However, the compelling motives for manufacturers to mislabel prostheses are unlikely to change, and some manufacturers will probably continue to oversize their products. Because it is difficult to remember all the variations in prosthesis and sizer labeling, it remains important for surgeons to use a few prostheses they are very familiar with, and to know their dimensions.

References

1. Bonchek L.I., Burlingame M.W., Vazales B.E. Accuracy of sizers for aortic valve prostheses. 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 small aortic root. Ann Thorac Surg 1998;65:1631-1633.[Abstract/Free Full Text]

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				P. Pibarot and J. G. Dumesnil Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its prevention J. Am. Coll. Cardiol., October 1, 2000; 36(4): 1131 - 1141. [Abstract] [Full Text] [PDF]

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): Lawrence I. Bonchek Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bonchek, L. I. Search for Related Content PubMed PubMed Citation Articles by Bonchek, L. I.