Plass, Andre

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Letters to the Editor / European Journal of Cardio-thoracic Surgery 39 (2011) 281—285 283Reply to the Letter to the EditorAndre Plass *Reply to BediClinic for Cardiovascular Surgery,University Hospital Zurich, Raemistr. 100, 8091 Zurich, SwitzerlandReceived 19 May 2010; accepted 20 May 2010; Available online21 July 2010Keywords: CT angiography; Coronary arteries; ImagingIt is a pleasure to answer and explain the three requestsmentioned in your letter to the editor [1]:1. OLetter to the Editorur study [2] should describe a practical tool not onlyfor diagnosis, but also for preoperative planning anddecision making of coronary bypass grafting. We adoptedand modified the classical segment model of the AmericanHeart Association. This coronary tree model is mainlydesigned for diagnosis of any coronary disease from acardiologist’s perspective. We still used segments, but wedifferentiated these sections more from a cardiac-surgicalperspective. Definitely, this is discussable; however, webelieve that we assess invasive coronary angiographies(ICA) on different aspects compared with cardiologists. Ofcourse, thismodification is an individual classification fromour clinic and can also be used in a classical way. However,it should demonstrate that it is timely and necessary toassess imaging in the cardiac-surgical perspective, whichcan differ from others because the goals are different.2. Of course, we used existing protocols, neither had we re-programmed the software and/or developed new hard-ware, nor have we changed the contents of the protocolsthemselves. The modifications and new features were theapplication and composition of soft- and hardware,respectively, the different parts of the imaging toolsand techniques. In addition, the definition of arrange-ments of responsibilities and manpower is important.Radiologists are responsible for optimal image qualityfor diagnostic, but cannot decide how many coronarybypass grafts are necessary and where they should beplaced on the heart. This decision can only be done bycardiac surgeons. Because of that, they have to be able touse at least the basic steps at an original workstation todefine the strategy themselves. This cannot be donebased on images of radiologists because the purpose ofthese images is different. Especially, cardiac surgeonsneed three-dimensional (3D) images for overview of thetopography and orientation to plan a potential surgicalprocedure, which is not possible in 2D images.3. We believe it is important to ‘keep it simple’, so thattransfer to clinical routine is easier to accomplish. Thequantification of degree of stenosis was performed in theICA in different views such as those commonly used inclinical routine. The diameter measurements in comput-ed tomography (CT) were performed with an electroniccalliper tool.It is now the responsibility of cardiac surgeons to use CTas adiagnostic and planning tool instead of ICA. Our article shouldbe an alert and encouragement to proceed. However, we alsorealised the problem of a certain inhibition threshold. Cardiacsurgeons receive the prepared images by radiologists, whichare definitely not optimal to prepare surgery. On the otherhand, they do not have the time and practice to professionallyuse the workstation of a CT scanner. Our article illustratesone possibility to differentiate the work between radiologistsand cardiac surgeons. Cardiac surgeons should be at leastable to perform by themselves the steps which are describedin this article. Otherwise, it will not be possible to transferCT into clinical routine in the way it is desired and to replaceICA, not only for exclusion diagnostic.References[1] Singh Bedi H. Accuracy of dual source computed tomography coronaryangiography: evaluation with a standardized protocol for cardiac surgeons.Eur J Cardiothorac Surg 2011;39:282.[2] Plass A, Azemaj N, Scheffel H, Desbiolles L, Alkadhi H, Genoni M, Falk V,Grunenfelder J. Accuracy of dual source computed tomography coronaryangiography: evaluation with a standardized protocol for cardiac surgeons.Eur J Cardiothorac Surg 2009;36:1011—7.* Corresponding author. Tel.: +41 44 2555 11 11; fax: +41 44 255 44 46.E-mail address: Andre.Plass@usz.ch.doi:10.1016/j.ejcts.2010.05.028Re: Early failure of xenogenous de-cellularised pulmonaryvalve conduits: a word of caution!Wilhelm Erdbru¨gger *, Marita Stein-KonertzAutoTissue Ltd., Goerzallee 305 D, D-14167 Berlin, GermanyReceived 31 March 2010; accepted 7 May 2010; Available online17 June 2010Keywords: RVOT; Right ventricle outflow tract; Pulmonary valvereplacement; Xenograft; De-cellularised valve; Porcine; Tissue engineeringAutoTissue GmbH as the manufacturer of the Matrix PPlusW has some comments to the article of Ru¨ffer et al. [1].1. For production of the Matrix P Plus, only one patch is usedand not three as stated in the ‘Materials and Methods’section.2. In the ‘Surgical Technique’ section, the authors describedtheir positioning of the valve as close to the bifurcation.This is not in accordance with AutoTissue’s recommenda-tions. It is suggested to place the valve like a homograft,which means in a more or less orthotopic position.3. Selection of valve sizes is very problematic in this article.Of the six explanted valves, one has been too small, threewere too large and only two valves in this cohort had theappropriate size.4. Five out of six patients had stenoses at the distalanastomosis. This has nothing to do with the tissue-engineered valve but with the residual glutaraldehyde inthe equine patch, which envelopes the valve.5. The authors described ‘a’ dissection like ‘separation ofthe layers between the internal and external conduitmembrane, which was still blood perfused during theReLetters to the Editor / European Journal of Cardio-thoracic Surgery 39 (2011) 281—285284explantation’. This is very difficult to understand as bloodbetween the valve and the patch will exit through theholes into the pericardial space. Hopefully, duringsurgery, the surgeons from Erlangen had not closed thoseprefabricated holes in the patch.6. The histology shows the same pattern as with Contegra orShellhigh valves, which means fibro-proliferative tissue atthe level of the distal anastomosis. This is probably due toresidual glutaraldehyde in the patch material.7. The authors described that the outer patch remained cell-free, which is actually impossible. The outer patch isglutaraldehyde-fixed equine pericardium, which is notcell-free, only the valve within the patch is cell-free. Thevalve looked very nice at least in five out of the six cases,as authors wrote in the article.8. The authors speculate about antigenicity. In fact,AutoTissue could show that the tissue is non-antigenicas there is no other antigenic material from porcine cellmembranes left in the de-cellularised tissue [2].9. The authors claim this to be the first publication regardingshort- and midterm results of the Matrix P PlusW. TheMatrix P PlusW came into the market in 2005; since thenapproximately 30 publications, original publications andabstracts, have been published in the surgical literature(references on file at AutoTissue).AutoTissue is alert to the problems arising from the use ofglutaraldehyde in its valved conduit and soon will bring out aconduit totally free from glutaraldehyde.References[1] Ru¨ffer A, Purbojo A, Cicha I, Glo¨ckner M, Potapov S, Dittrich S, CesnjevarRA. Early failure of xenogenous de-cellularised pulmonary valve conduits —a word of caution! Eur J Cardiothorac Surg 2010;38:78—85.[2] Erdbru¨gger W, Konertz W, Dohmen PM, Posner S, Ellerbrok H, Brodde OE,Robenek H, Modersohn D, Pruss A, Holinski S, Stein-Konertz M, Pauli G.Decellularized xenogenic heart valves reveal remodeling and growthpotential in vivo. Tissue Eng 2006;12:2059—68.* Corresponding author. Address: AutoTissue GmbH, Goerzallee 305 D,D-14167 Berlin, Germany. Tel.: +49 30 3302 925 80; fax: +49 30 3302 925 89.E-mail address: erdbruegger@autotissue.de (W. Erdbru¨gger).doi:10.1016/j.ejcts.2010.05.004ply to the Letter to the EditorReply to Erdbru¨gger and Stein-KonertzAndre´ Ru¨ffer *, Iwona Cicha, Sven Dittrich,Robert Anton CesnjevarDepartment for Pediatric Cardiac Surgery, University Hospital Erlangen,Erlangen, GermanyReceived 28 April 2010; accepted 7 May 2010; Available online25 June 2010Keywords: RVOT; Right ventricle outflow tract; Pulmonary valveFirst, I would like to thank Dr Erdbru¨gger for his kindinvitation and his hospitality duringmy visit to AutoTissue andthe Charite´ Cardiovascular Surgery Department in Berlin. Iwas able to observe the production of Matrix valves, includingtheir implantation during a Ross procedure.Regarding his letter to the editor [1] as a reply to our wordof caution [2], I have a few comments:(1) The single patch forming the conduit wall of theMatrix P plus has three segments: one envelopingthe valve and two outer ones for proximal anddistal anastomosis.(2) Our operative technique used for pulmonary valvereplacement in Ross procedures complies with theCharite´ technique. Moreover, there is no ortho-topic positioning possible in patients without rightventricular outflow tract (RVOT), as in pulmonaryatresia or congenitally corrected transposition ofthe great arteries with left ventricular insertion ofthe conduit.(3) According to generally applied nomograms ofcardiac structures in relation to body size [3],oversizing up to 0, 19, 9, 9, 9 and 8% (mean: 9  6%)was present in the Matrix P plus failure group(n = 6). There was certainly no undersizing! Sur-prisingly, the group of patients without conduitfailure had oversizing in a higher degree (mean:15  13%); however, this difference was statistical-ly not significant (p = 0.65) [2].(4 and 6) We agree to the comments.(5) The prefabricated holes were not closed bysurgery, but might have been blocked by theclotting system. Blood flow in the wrong compart-ment should not persist — if it does, it may be aproblem of conduit design.(7 and 8) The patch remained host-cell free. In all explantedconduits, the porcine pulmonary artery wall wascovered by fibro-proliferative neo-intima contain-ing inflammatory cells.(9) Until now, upon searching PubMed, no originalpublications regarding clinical results with theMatrix P plus for pulmonary valve replacementhave been found. We would be grateful to besupplied with the published mid- and long-termresults from other institutions.References[1] Erdbru¨gger W, Stein-Konertz M. Letter to the editor. Re: early failure ofxenogenous de-cellularized pulmonary valve conduits: a word of caution!Eur J Cardiothorac Surg 2011;39:283—4.[2] Ru¨ffer A, Purbojo A, Cicha I, Glo¨ckler M, Potapov S, Dittrich S, CesnjevarRA. Early failure of xenogenous de-cellularized pulmonary valve conduits:a word of caution! Eur J Cardiothorac Surg 2010;38:78—85.[3] Daubeney PE, Blackstone EH, Weintraub RG, Slavik Z, Scanlon J, WebberSA. Relationship of the dimension of cardiac structures to body size: anechocardiographic study in normal infants and children. Cardiol Young1999;9(4):402—10.* Corresponding author. Address: Department for Pediatric Cardiac Surgery,University Hospital Erlangen, Loschgestrasse 51, 91054 Erlangen, Germany.Tel.: +49 9131 85 41962; fax: +49 9131 85 34011.E-mail address: andre.rueffer@uk-erlangen.de (A. Ru¨ffer).doi:10.1016/j.ejcts.2010.05.005

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