LETTERS TO T H E E D I T O R S The Editors invite readers to submit letters commenting on the contents of articles that appear in the Journal. Also welcome are brief communications in letter form reporting investigative or clinical observations without extensive documentation and with brief bibliography (five titles or less), not requiring peer review but open to critique by readers. Letters to the Editors should be no more than 500 words in length and they may have to be edited for publication.

The influence o f elastic compression stockings on

deep venous hemodynamics To the Editors: M a y b e r ~ et al? correctly question "The influence of elastic compression stockings on deep venous haemodynamics." Such questions were being asked by W o o d 2 and me 3 in the early 1970s, and this was the scientific basis on which (but never referred to in their publication) Jones et •,i.,4 whose work/s cited, is based. Our conclusion then was that total tissue pressure and its relation to edema formation was the key issue here, and Mayberry et al. hint at this in their discussion. It would appear from these publications and from a review o f subsequent literature that maintenance of total tissue pressure at the same level as intravascular pressure (in all postures), minimizes the production of edema. It is this effect that almost certainly produces the well-established benefits of support hose on venous disease, s Finally, it may be of interest to your readers (indeed Mayberry et al. may have done this, but it is not clear from their description) that it is possible to scan through stockings. 6 By doing so, it is possible to show when ill-fitted support hose are actually producing a deleterious effect on venous hemodynamics, for instance, a tourniquet effect. A. D. B. Chant, 2HD Consultant Vascular Surgeon Royal South Hants Hospital Brintons Terrace St. Mary's Rd. Southampton 509 4PE _Jnited Kingdom REFERENCES

1. Mayberry JC, Moneta GL, DeFrang RD, et al. The influence of elastic compression stockings on deep venous hemodynamics. J VASC SURG 1991;13:91-9. 2. Wood JE. The venous system. Sci Am 1968;218:86-94. 3. Chant ADB. The effects of posture and bandage pressure on the clearance of 24 Na. Br J Surg 1972;59:552-5. 4. lones NAG, Webb PJ, Rees RI, et al. A physiological study of elastic compression stockings. Br J Surg 1980;67:569-72. 5. Chant ADB. Tissue pressure, posture and venous ulceration. Lancet 1990;336:1050-1. 6. Chant ADB, Humphries KiN. Eur l Vasc Surg 1989;2:47-8. Reply To the Editors: We are pleased to respond to Dr. Chant's letter addressing the mechanisms o f benefit o f elastic compres-

sion stockings, and we acknowledge his contributions to this field. We and others, however, also believe that ascribing the benefits of elastic compression stockings solely to the prevention of edema formation is an oversimplification. It is obvious to anyone who cares for patients with venous disease that properly fitted stockings of sufficient strength reduce lower extremity edema. It does not, however, strictly follow that reduction of lower extremity salt and water content directly results in the healing or prevention of venous ulceration or paramalleolar lipodermatosclerosis. Rather, it is becoming increasingly appreciated that venous ulceration reflects a complex, severe anatomic and functional cutaneous microvascular disorder. We suspect, therefore, that at the microscopic level venous ulcerations stem from cellular malnutrition and ischemia and in essence really differ very little from arterial or vasculogenic ulcers. The factors that contribute to inadequate skin cell nutrition, however, certainly differ in their relative importance in the various forms of cutaneous ulceration. Dr. Chant is therefore correct to emphasize that tissue edema may be a significant factor leading to a total cutaneous microenvironment conducive to the development of a venous ulcer. GregoryL. Moneta, MD John R. Mayberry, M_D Robert DeFrang, MD John M. Porter, MD Department of Veterans Affairs Medical Center 3710 Southwest U.S. Veterans Hospital Rd. Portland, OR 97207

C a r o t i d endarterectomy: Despite the N A S C E T report, the controversy is n o t over To the Editors: The announcement by the National Institute of Neurological Disorders and Stroke (NIH), that the North American Symptomatic Carotid Endarterectomy Trial (NASCET) was being terminated at an interim stage for those symptomatic patients with a high-grade carotid stenosis (70% to 99%) because high statistical significance was found indicating that "carotid endarterectomy was beneficial in the prevention of any stroke of any severity in any territory" is welcome news indeed. 1 There is a sense of elation and relief among those who believe carotid endarterectomy (CEA) is an effective o p e r a t i o n - mostly vascular surgeons and their patients. Likewise, there is undoubtedly disappointment among the therapeutic nihilists, including some neurologists. Both emotions should be muted,

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