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Proposed new classification of postendarterectomy carotid duplex scans
LETTERS TO THE EDITORS EDITORS' NOTE; In the selection of an article for publication, the orthodoxy of the author's opinions is generally accepted to be the least consequential and scientific validity or plausibility to be the foremost criterion of assessment. Since opinions may differ and judgment of validity may be fallible, the Editors invite readers to submit letters commenting on opinions or conclusions to which they take exception and pointing out errors they detect. The length of such letters should not exceed 500 words. If the letter is a critique or correction, the author criticized or corrected will, of course, have the privilege of response, Needless to say, the Editors retain the right to judge the suitability of a letter for publication.
Proposed new classification o f postendarterectomy carotid duplex scans To the Editors: Duplex scanning has detected the highest incidence of recurrent stenosis (15% to 50%) ~-4 after carotid endarterectomy. Turbulent blood flow may arise from residual stenosis, recurrent stenosis, or compliance mismatch between the soft endarterectomized segment and the relatively stiff artery. This flow later may become laminar 2's and Ackerstaff et al.5 reported that most mild spectral broadening detected 3 months after operation disappeared or remained stable during follow-up. We showed that 36% of the arteries with spectral broadening had returned to normal at the 6-month review. ~ Russell et al. 6 studied 60 endarterectomized arteries with spectral analysis of Doppler signal and intravenous digital subtraction angiography (DSA). Spectral broadening was identified in half of the arteries, whereas DSA detected irregularities in only 25%. Diaz et al.7 showed that 20% of the early angiographic abnormalities had disappeared 6 weeks after initial evaiuation. Therefore it is more comprehensive to classify this category as flow disturbance rather than less than 50% stcnosis like the preoperative situation. The endarterectomized segment is a site of active cellular proliferation and remodeling. Recurrent stenosis caused by myointimal hyperplasia is characterized by smooth tapered narrowing, which may produce highvelocity laminar flow. A critical point may be reached where smooth laminar flow can no longer be maintained. There-
fore two types of high-velocity signals (greater than 4 kHz) have been observed and both used to indicate greater than 50% stenosis2: "soft" signals that have minimal or no spectral broadening and "harsh" signals with marked spectral broadening. The former signals can also arise because of flow augmentation in the presence of an occluded contralateral artery. 2 Few reports exist that compare postoperative duplex scanning and angiography. Nevertheless, there is a suggestion that the current criteria may overestimate the diagnosis of greater than 50% recurrent stenosis. Roederer et ai.,8 using both modalities, showed that 19% of the arteries were overestimated by duplex scanning into the category of greater than 50% recurrent stenosis. Recently, PeLz et ai.9 implicated intravenous DSA as the cause of underestimation of the degree of recurrent stenosis in 10 of 74 vessels. Regression of myointimal hyperplasia is a more plausible explanation. Zierler et al. 4 reported a reduction in the incidence of greater than 50% stenosis from 36% to 19% within 16 months after operation. Others have shown 10% and 5% reduction in the incidence of greater than 50% stenosis during a mean follow-up of 18 months. We reported that 75% of the endarterectomized arteries with "sofC high-velocity signals reverted to normal by the end of our study. In view of the differing prognostic implications of "soft" and "harsh" high-velocity signals in postendarterectomy scans, it would seem wise to characterize these signals as shown in Table I and Fig. 1. Confirmation with
Fig. 1. Classification of postcarotid endarterectomy Doppler spectra obtained by duplex scanning. For details see text. 200
Volume 8 Number 2 August 1988
Letters to the Editors
201
T a b l e I. P r o p o s e d classification o f postoperative duplex scanning results and c o m p a r i s o n with the current preoperative classification Cuyrent preoperative classification
Proposed postoperative classification
Normal
Normal
-A-
1%-49%
Flow disturbance
-B-
Flow augmentation 50%-99%
"Soft" highvelocity signal "Harsh" highvelocity signal Occluded
-C-
Occluded
postoperative angiography would be desirable, although we believe it is difficult to justify its routine use in asymptomatic patients. Munther I. Aldoori, PhD* Roger N. Baird, ChM Dept. of Surgery/Vascular Studies Unit Bristol Royal Infirmary Bristol BS2 8HW England *Current address: Dept. of Surgery/Vascular Section, Albany Medical College, 47 New Scotland Ave., Albany, NY 12208. REFERENCES
1. Thomas M, Otis SM, Rush M, ZygroffJ, Dilley RB, Bemstein EF. Recurrent carotid artery stenosis following endarterectomy. Ann Surg 1984;200:74-9. 2. Aldoori MI, Baird RN. Prospective assessment of carotid endarterectomy by clinical and ultrasonic methods. Br J Surg 1987;74:926-9. 3. Nicholls SC, Phillips DJ, Bergelin RO, Beach KW, Primozich JF, Strandness DE. Carotid endarterectomy. Relationship of outcome to early restenosis. J VAsc SURG 1985;2: 375-81. 4. Zierler RE, Bandyk DF, Thiele BL, Strandness DE. Carotid artery stenosis following endarterectomy. Arch Surg 1982; 117:1408-15. 5. Ackerstaff RGA, Sanders EACM, Hoeneveld H, Eikelboom BC, Verrneulen FEE, Lugwig JW: Residual lesions and early restenosis after internal carotid endarterectomy. (Abstract). Presented at the Second International Vascular Symposium, London, September 1986. 6. Russell D, Balle SJ, Wiberg J, Nakstad P, Nyberg-Hansen R, Patency and flow velocity profiles in the internal carotid artery assessed by digital subtraction angiography and Doppler studies three months following endarterectomy. J Neurol Neurosurg Psychiatr 1986;49:183-6. 7. Diaz FG, Patel S, Boulos R, Ausman JI. Early angiographic
-D-E-
Systolic frequency up to 4 kHz No spectral broadening Systolic frequency up to 4kHz Marked spectral broadening Systolic frequency > 4 kHz No spectral broadening Systolic frequency > 4 kHz Marked spectral broadening No diastolic flow in common, carotid enhanced flow in external carotid and no flow in internal carotid arteries
changes following carotid endarterectomy. (Abstract). Stroke 1980;11:35. Roederer GO, Langlois Y, Chan ATW, et al. Postendarterectomy carotid ultrasonic duplex scanning: concordance with contrast angiography. Ultrasound Med Biol 1983; 9:73-8. Pelz D, Rankin RN, Fergusou GG. Intravenous digital subtraction angiography and duplex ultrasonography in postoperative assessment of carotid endarterectomy. J Neurosurg 1987;66:88-92.
Hydrophilic guide wire for laser-assisted angioplasty To the Editors: Vascular surgeons adding arterial balloon and laserassisted angioplasty to their armamentarium may have limited previous experience with guide wires and dilating catheters. Appropriate entry into the designated artery and successful negotiation of catheters across the targeted lesions are vital to the positive outcome of the procedure, and often guide wire positioning is even more crucial than the actual dilating processes. Improper usage and unfamiliarity with the variety of wires available can lead to complications, including dissection and vessel wall perforation. We offer our experience with a new hydrophilic guide wire, which greatly enhances the safety and efficacy of laser and/or balloon angioplasty techniques. The Terumo guide wire (Glidewire, Medi-tech, Inc., Watertown, Mass.) is constructed of a unique hydrophilic material that, when dry, is rough to the touch and easy to handle. However, when moistened with saline solution or blood, the wire becomes uncommonly slippery with far less sliding friction than any other currently available guide wire. So profound is its lubricity that we have nicknamed it the "eel." Currently, the single-use wire is available in a 150 cm
Proposed new classification o f postendarterectomy carotid duplex scans To the Editors: Duplex scanning has detected the highest incidence of recurrent stenosis (15% to 50%) ~-4 after carotid endarterectomy. Turbulent blood flow may arise from residual stenosis, recurrent stenosis, or compliance mismatch between the soft endarterectomized segment and the relatively stiff artery. This flow later may become laminar 2's and Ackerstaff et al.5 reported that most mild spectral broadening detected 3 months after operation disappeared or remained stable during follow-up. We showed that 36% of the arteries with spectral broadening had returned to normal at the 6-month review. ~ Russell et al. 6 studied 60 endarterectomized arteries with spectral analysis of Doppler signal and intravenous digital subtraction angiography (DSA). Spectral broadening was identified in half of the arteries, whereas DSA detected irregularities in only 25%. Diaz et al.7 showed that 20% of the early angiographic abnormalities had disappeared 6 weeks after initial evaiuation. Therefore it is more comprehensive to classify this category as flow disturbance rather than less than 50% stcnosis like the preoperative situation. The endarterectomized segment is a site of active cellular proliferation and remodeling. Recurrent stenosis caused by myointimal hyperplasia is characterized by smooth tapered narrowing, which may produce highvelocity laminar flow. A critical point may be reached where smooth laminar flow can no longer be maintained. There-
fore two types of high-velocity signals (greater than 4 kHz) have been observed and both used to indicate greater than 50% stenosis2: "soft" signals that have minimal or no spectral broadening and "harsh" signals with marked spectral broadening. The former signals can also arise because of flow augmentation in the presence of an occluded contralateral artery. 2 Few reports exist that compare postoperative duplex scanning and angiography. Nevertheless, there is a suggestion that the current criteria may overestimate the diagnosis of greater than 50% recurrent stenosis. Roederer et ai.,8 using both modalities, showed that 19% of the arteries were overestimated by duplex scanning into the category of greater than 50% recurrent stenosis. Recently, PeLz et ai.9 implicated intravenous DSA as the cause of underestimation of the degree of recurrent stenosis in 10 of 74 vessels. Regression of myointimal hyperplasia is a more plausible explanation. Zierler et al. 4 reported a reduction in the incidence of greater than 50% stenosis from 36% to 19% within 16 months after operation. Others have shown 10% and 5% reduction in the incidence of greater than 50% stenosis during a mean follow-up of 18 months. We reported that 75% of the endarterectomized arteries with "sofC high-velocity signals reverted to normal by the end of our study. In view of the differing prognostic implications of "soft" and "harsh" high-velocity signals in postendarterectomy scans, it would seem wise to characterize these signals as shown in Table I and Fig. 1. Confirmation with
Fig. 1. Classification of postcarotid endarterectomy Doppler spectra obtained by duplex scanning. For details see text. 200
Volume 8 Number 2 August 1988
Letters to the Editors
201
T a b l e I. P r o p o s e d classification o f postoperative duplex scanning results and c o m p a r i s o n with the current preoperative classification Cuyrent preoperative classification
Proposed postoperative classification
Normal
Normal
-A-
1%-49%
Flow disturbance
-B-
Flow augmentation 50%-99%
"Soft" highvelocity signal "Harsh" highvelocity signal Occluded
-C-
Occluded
postoperative angiography would be desirable, although we believe it is difficult to justify its routine use in asymptomatic patients. Munther I. Aldoori, PhD* Roger N. Baird, ChM Dept. of Surgery/Vascular Studies Unit Bristol Royal Infirmary Bristol BS2 8HW England *Current address: Dept. of Surgery/Vascular Section, Albany Medical College, 47 New Scotland Ave., Albany, NY 12208. REFERENCES
1. Thomas M, Otis SM, Rush M, ZygroffJ, Dilley RB, Bemstein EF. Recurrent carotid artery stenosis following endarterectomy. Ann Surg 1984;200:74-9. 2. Aldoori MI, Baird RN. Prospective assessment of carotid endarterectomy by clinical and ultrasonic methods. Br J Surg 1987;74:926-9. 3. Nicholls SC, Phillips DJ, Bergelin RO, Beach KW, Primozich JF, Strandness DE. Carotid endarterectomy. Relationship of outcome to early restenosis. J VAsc SURG 1985;2: 375-81. 4. Zierler RE, Bandyk DF, Thiele BL, Strandness DE. Carotid artery stenosis following endarterectomy. Arch Surg 1982; 117:1408-15. 5. Ackerstaff RGA, Sanders EACM, Hoeneveld H, Eikelboom BC, Verrneulen FEE, Lugwig JW: Residual lesions and early restenosis after internal carotid endarterectomy. (Abstract). Presented at the Second International Vascular Symposium, London, September 1986. 6. Russell D, Balle SJ, Wiberg J, Nakstad P, Nyberg-Hansen R, Patency and flow velocity profiles in the internal carotid artery assessed by digital subtraction angiography and Doppler studies three months following endarterectomy. J Neurol Neurosurg Psychiatr 1986;49:183-6. 7. Diaz FG, Patel S, Boulos R, Ausman JI. Early angiographic
-D-E-
Systolic frequency up to 4 kHz No spectral broadening Systolic frequency up to 4kHz Marked spectral broadening Systolic frequency > 4 kHz No spectral broadening Systolic frequency > 4 kHz Marked spectral broadening No diastolic flow in common, carotid enhanced flow in external carotid and no flow in internal carotid arteries
changes following carotid endarterectomy. (Abstract). Stroke 1980;11:35. Roederer GO, Langlois Y, Chan ATW, et al. Postendarterectomy carotid ultrasonic duplex scanning: concordance with contrast angiography. Ultrasound Med Biol 1983; 9:73-8. Pelz D, Rankin RN, Fergusou GG. Intravenous digital subtraction angiography and duplex ultrasonography in postoperative assessment of carotid endarterectomy. J Neurosurg 1987;66:88-92.
Hydrophilic guide wire for laser-assisted angioplasty To the Editors: Vascular surgeons adding arterial balloon and laserassisted angioplasty to their armamentarium may have limited previous experience with guide wires and dilating catheters. Appropriate entry into the designated artery and successful negotiation of catheters across the targeted lesions are vital to the positive outcome of the procedure, and often guide wire positioning is even more crucial than the actual dilating processes. Improper usage and unfamiliarity with the variety of wires available can lead to complications, including dissection and vessel wall perforation. We offer our experience with a new hydrophilic guide wire, which greatly enhances the safety and efficacy of laser and/or balloon angioplasty techniques. The Terumo guide wire (Glidewire, Medi-tech, Inc., Watertown, Mass.) is constructed of a unique hydrophilic material that, when dry, is rough to the touch and easy to handle. However, when moistened with saline solution or blood, the wire becomes uncommonly slippery with far less sliding friction than any other currently available guide wire. So profound is its lubricity that we have nicknamed it the "eel." Currently, the single-use wire is available in a 150 cm