Eur Radiol (2004) 14:539–540 DOI 10.1007/s00330-003-1891-y

Dierk Vorwerk

Published online: 7 May 2003 © Springer-Verlag 2003 This reply refers to the Letter to the Editor at http://dx.doi.org/10.1007/s00330-003-1893-9

D. Vorwerk (✉) Department of Diagnostic and Interventional Radiology, Klinikum Ingolstadt, Krumenauerstrasse 25, 85049 Ingolstadt, Germany e-mail: [email protected] Tel.: +49-841-8802801 Fax: +49-841-8802808

LETTER TO THE EDITOR

Reply

Sir, This is to respond to the letter of L. Turmel-Rodrigues concerning our overview article on the treatment of occluded dialysis shunts and grafts. L. Turmel-Rodrigues claims that recent literature, including his own, is not included in the paper. To a certain extent he is right, but as a prominent author himself in the field of interventional radiology, he might know that the publication process is sometimes lengthy, particularly for overview articles, and there is a significant time gap—sometimes years—between writing an article and its publication, which often prevents inclusion of recent publications. Furthermore, to my understanding, there has been nothing published recently that opposes in any significant way what is said in the article. L. Turmel-Rodrigues is right that an underlying stenosis is the most frequent cause of shunt thrombosis. Nevertheless, stenoses may exist for months without causing thrombosis, whereas additional factors, such as hypovolemia or others, are finally responsible for the thrombotic event. Hot weather, for example, is well known to create a significant cluster workload for shunt thromboses. This is another shared practical knowledge, even if no published and stratified data exist on this finding. That is all that should be said by use of the word “manifold”.

L. Turmel-Rodrigues is right pointing out that intentional pulmonary embolism in dialysis patients has to be avoided if a major thrombus load is present. But in small thrombi, the risk is exceptionally rare, and under reconsideration of an 18-year experience with interventional radiology in dialysis connections we never experienced a major side effect limiting percutaneous transluminal angioplasty to small thrombi. Moreover, clinically masked spontaneous pulmonary embolism is a frequent finding in patients undergoing hemodialysis. L. Turmel-Rodrigues is a well-experienced interventional radiologist, and his major technique in fistulas is based on thromboaspiration, a technique in which he is a leading specialist. I am sure that he might find that technique easier to perform than others relying on his vast experience with this approach. Nevertheless, he published a considerable mean procedure time of close to 2 h even in forearm fistulas—which appears pretty lengthy in the eyes of our personal experience—indicating that, even in his hands, the technique requires some time and presents difficulties. Taking into account that there was a mixture of extended and limited thrombosis, these data obviously show that aspiration may not be so easy and quick in many cases. A fierce supporter of aspiration myself in the field of arterial work,

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I found that for the dialysis work I prefer to rely more on other techniques. In the same article, L. TurmelRodrigues reports on a stent frequency of 18% in forearm fistulas and more than 40% in upper arm fistulas and grafts. In our opinion, stenting is something that needs to be avoided in the arm, if possible. These data are suspicious for indicating a limited technical outcome using the basis techniques [1]. Claiming that the technical outcomes in L. Turmel-Rodrigues personal series are better than ours is like comparing apples with oranges, neglecting the fact that both his series and ours are historical including different types of shunt anatomy and quality as well as different policy of referral and maintenance. All these factors may contribute to the individual technical outcome. Furthermore, the relatively small numbers of patients included make a true statistical comparison difficult and vague. Stenoses are located everywhere in the venous and sometimes arterial vasculature of hemodialysis connec-

tions, and, most importantly,nearly all are prone to percutaneous treatment. I have no problem with L. Turmel-Rodrigues reporting on a prevalence of distant stenoses in upper-arm fistulas in his patients, which represents only a small subset among all shunts; nevertheless, I am not sure that this will have any influence on the approach to the problem. Thrombolysis was not covered greatly since particularly in Europe it is not an option for native fistulas, and we abandoned it from our approach many years ago including grafts. It does play a role in the U.S. for declotting graft connections, which only account for 20% of shunt connections in Europe, and even for this indication. Barth et al. have shown that mechanical thrombectomy by use of hydrodynamic devices can achieve at least equal results [2]. We tried to describe the principles of treatment of thrombosed fistulas and grafts and think that we included the basic principles. Nevertheless, there are numerous devices—sometimes working on very similar principles—that have been described for this purpose: some are still available and some are no longer on the market or have been used only in small

series. The good news is, whatever has been used, these devices have shown their ability to deal mechanically with the problem of clots in dialysis connections, and it is up to the experience of each individual operator to determine what system is preferred. Comparative data are usually not available. The main message, however, should be that interventional radiology of thrombosed dialysis shunts and grafts is well feasible and worth being included into the service of interventional radiology—a conclusion on which I am sure L. TurmelRodrigues will agree.

References 1. Turmel-Rodrigues L et al. (2000) Treatment of failed native arteriovenous fistulae for hemodialysis by interventional radiology. Kidney Int 57:1124–1140 2. Barth K et al. (2000) Hydrodynamic thrombectomy versus pulse-spray thrombolysis for thrombosed hemodialysis grafts: a multicenter prospective randomized comparison. Radiology 217:678–684