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,

565

566

Journal of VASCULAR SURGERY

Letters to the Editors

however, because other major problems remain unaddressed as analyses of both the NASCET and the Rand studies reveal. 2 In 1984, the Rand Corporation convened a ninemember panel composed of three vascular surgeons, a neurosurgeon, a neuroradiologist, two neurologists, one internist, and one family practitioner. This panel rated possible indications for carotid endarterectomy as inappropriate, equivocal, or appropriate. The Rand investigators then retrospectively reviewed the medical records of 1302 Medicare patients in three geographic areas who had CEA in 1981. There was a 30-day perioperative mortality rate of 3.4%, a 6.4% perioperative stroke rate with residual deficit on discharge, and a 1.8% incidence of perioperative nonfatal myocardial infarction. Of even more concern, 32% of the carotid endarterectomies were done for inappropriate indications. Because of do, tbts regarding these figures, the American College of Surgeons convened a different panel composed entirely of vascular surgeons. This group then proposed different, and more liberal, acceptable criteria for endarterectomy. Rand then reanalyzed their patient data based on these new criteria. Twenty percent of the CEAs were still categorized as inappropriate. In 1989, spurred by the Rand review, the Health Care Financing Administration (HCFA) mandated that all nonemergent CEAs (as well as all cataract extractions) be subject to peer review by the regional peer review organizations (PROs) on a preadmission basis. As a consequence, it is highly probable that the number of inappropriate, as would be defined by most vascular surgeons, CEAs has been substantially reduced. What is not yet clear, however, is whether the national perioperative results now being achieved are substantively better than the 9.8% combined perioperative mortality and residual stroke deficit reported in the Rand study. One of the reasons the NASCET study so quickly showed efficacy is that the perioperative major stroke and mortality rate was just over 2% and the perioperative mortality rate alone was under 1%. Two explanations are possible for the disparity between the retrospective Rand study and the prospective NASCET study. Either the surgeons in the Rand study (chosen because they happened to do one or more CEAs in one of the three locations chosen by Rand) operated on sicker patients or the NASCET surgeons, chosen because they "met strict performance standards and had previously demonstrated expertise in the procedure," managed the total care of the patients better. Few would doubt that the latter reason accounts for the remarkable difference between these studies. Thus the lesson from the Rand study was that too many surgeons were performing too many CEAs for too many inappropriate indications with too many complications and deaths. The lesson from the NASCET study is that CEA is a highly successful operation when done for the appropriate individual with the appropriate indication by the appropriate surgeon. Two primary challenges remain regarding issues concerning carotid endarterectomy. The first is the need to

continue to define which groups of patients will be helped by this operation. When resources are made available and the opportunity arises, well trained vascular surgeons should enthusiastically support prospective investigation of appropriate study groups. Perhaps the greater challenge is the need to monitor the results of all surgeons doing CEA. It is necessary to improve the results of those who are not meeting standards that they should achieve as well as to prevent surgeons from continuing to perform endarterectomy when they cannot achieve acceptable outcomes. The Rand study shows what occurs when this does not happen, NASCET demonstrates what can be achieved when it does.

Hugh H. Trout, HI, B/ZD 8218 Wisconsin Ave., Suite 204 Bethesda, MD 20814

REFERENCES 1. Clinical Alert, National Institute of Neurological Disorders and Stroke, Benefit of carotid endarterectomy for patients with high-grade stenosis of the internal carotid artery. 2. Winslow CM, Solomon DH, Chassin MR, Kosecoff J, Merrick NJ, Brook RH. The appropriateness of carotid endarterectomy. N Engl J Med 1988;318:721-7.

Management of postoperative lymphatic leaks by use of isosulphan blue To the Editors: The development of lymphorrhea or a lymphocele complicates 1.8% of arterial reconstructive procedures) The most common site of a postoperative lymphatic leak is the femoral triangle after an aortofemoral, femoropopliteal, or femorotibial artery bypass procedure. Lymphatic leaks may also follow intraabdominal and intrathoracic aortic procedures, extracranial revascularizations performed in the supraclavicular fossa, renal transplants, and various general surgical operations. Operative treatment of persistent lymphatic drainage requires identification of the leaking duct(s) and precise ligation. When formal duct ligation is required accurate localization of the leaking lymphatic channel may be difficult. Failure to ligate the offending duct will result in a recurrent fistula or lymphocele. This communication describes a simple technique we have adopted for lymphatic duct localization by use of the vital dye, isosulphan blue (Lymphazurin; Hirsch Industries Inc., Richmond, Va.) The patient with a persistent leak at the femoral triangle is placed supine on the operating room table and in slight Trendelenburg position. With a 25-gauge needle, 1 ml of a 1% solution of isosulphan blue is injected subdermally into the first and second dorsal webspaces of the affected extremity. Once in the tissue the dye is rapidly absorbed by the dermal lymphatics and ascends cephalad, arriving in the upper thigh and femoral triangle within 15 minutes. After dye injection, the extremity and lower abdomen are stetiMy prepared and draped; the incision overlying the