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J Thorac Cardiovasc Surg 2002;123:1223-1224
© 2002 The American Association for Thoracic Surgery
Letters to the Editor |
University of Verona, Verona, Italy
Reply to the Editor:
We read with interest the letter by Fedak and associates from the University of Toronto. In an attempt to reconcile the findings from their previous study
1 with the ones presented in our recent work,
2 Fedak and coworkers highlight the shortcomings inherent with our study.
We are pleased that they share our own concern on its limitations, namely sample size, retrospective analysis, and nonblinded evaluation of the data. Unfortunately, the very same limitations affect their study,
2 including inadequate power/sample size (21 pulmonary artery roots examined versus 17 in our series), biased and nonrepresentative sample (only 13 aortas and 10 pulmonary roots in the "Ross age group," mean age 27 years, vs 17 aortas and pulmonary roots in actual Ross patients, mean age 24 years), partial blinding of the histologic examination (only one of two pathologists was blinded). In addition, the study by the Toronto group fails to present any clinical data relative to the patients enrolled, including follow-up.
3 On the basis of these premises, it is difficult to establish a correlation between pulmonary autograft root dilatation and pre-existing histologic changes of the pulmonary artery root in patients with bicuspid aortic valve,
2,4 particularly considering the fact their own observations,
4 as well as those of Elkins,
5 Laudito,
6 and their associates, do not demonstrate any correlation between bicuspid aortic valve and autograft root dilatation in large series of Ross patients.
Unlike Fedak and associates, we believe that the problem of root dilatation after the Ross procedure is probably more complex and thus not simply caused by pre-existing histologic abnormalities of the pulmonary artery.
2 Although the experience of others,
7,8 as well as our own, has shown that the autograft root dilates acutely under systemic pressure and loses the gross anatomic configuration of the native aortic root, aneurysmal dilatation after operation has variable rate of progression, and so does neoaortic valve insufficiency. Technical factors (root replacement versus inclusion, stabilization of anulus, and sinotubular junction) certainly play a role in the prevalence and evolution of postoperative root dilatation.
4,8 Histologic changes of the neoaortic root have thus far been demonstrated only in explanted autografts and therefore may conceivably occur after exposure of the pulmonary artery root to systemic pressure, as seen in pulmonary hypertension.
9 Only continued observation and larger clinicopathologic series will provide reliable information to guide us in the selection of patients and technique for the Ross operation.
12/8/124395
References
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