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Commentary

Duplex scanning after stent placement: Are there significantchanges compared with nonstented arteries?

Robert Alan McCready, MD*

Clarian Health Partners, Vascular surgery, 1801 North Senate Boulevard, Suite 755, Indianapolis, Indiana 46202

a r t i c l e i n f o

Article history:

Received 23 March 2012

Received in revised form

23 March 2012

Accepted 28 March 2012

Available online 16 April 2012

DOI of original article: 10.1016/j.jss.2012.0* Corresponding author. Clarian Health Partn

Tel.: þ1 317 923 1787; fax: þ1 317 962 6259.E-mail address: rmccready@iuhealth.org.

0022-4804/$ e see front matter ª 2013 Elsevdoi:10.1016/j.jss.2012.03.069

Theauthorsare tobecongratulatedfor thiselegantstudy,which

attempts to address a clinically important question, which is

whether or not the presence of a stent alters the compliance of

an artery, thereby affecting the velocity of the stented arteries

and theestimateddegreeof stenosis [1]. If the stent significantly

alters the flow velocity by altering the arterial compliance, this

could lead to a false suggestion of a significantly recurrent

stenosis leading to unnecessary angiographic studies. The

authors’ conclusion is that Doppler velocity estimates are not

substantially affected by endoluminal stents.

Given the largenumber of stents being placed in the carotid,

visceral, and lower extremity arteries, an accurate noninvasive

method to follow thesepatients is vital. Furthermore, recurrent

stenosis after stent placement occurswith sufficient frequency

in all arterial beds that follow-up is necessary at regular inter-

vals to maintain patency of the stented vessels. Being able to

monitor patients and detect severe recurrent stenoses while

avoiding unnecessary catheter-based angiograms or CT

angiograms is certainly a desirable goal for duplex scanning.

Some authors have argued that stent placement alters the

compliance of an artery, thereby producing a stiffer conduit,

3.004.ers, Vascular surgery, 180

ier Inc. All rights reserved

and therefore, the criteria for detecting a hemodynamically

significant stenosis need to be altered [2e5]. If this postulate is

accepted a priori, a higher peak systolic velocity (PSV) and end-

diastolic velocity (EDV) should be used in estimating the degree

of stenosis. In their report discussing the ultrasound criteria for

in-stent restenosis (ISR) after carotid artery stenting, Lal et al.

stated that “carotid ultrasound is deemed unreliable for a post-

stent surveillance” [3]. However, when these authors applied

the same velocity criteria for measuring a greater than 70%

stenosis in a nonstented carotid artery and applied these criteria

to stented carotid arteries inwhich therewas a greater than 70%

ISR, confirmed by angiography, they noted a “surprising simi-

larity to the criteria fornon-stentedarteries.”However, only 23of

the 256 patients in their study had catheter-based angiograms,

which is somewhat of a weakness of their study.

Chi et al. [5] studied a large group of patients with renal

artery stents in whom angiograms were performed for sus-

pected severe ISRs. For any level of angiographic stenosis

greater than 50%, the ISR group had relatively higher PSV and

renal aortic ratio compared with the nonstented group. These

authors found that a PSV greater than or equal to 395 cm/s or

1 North Senate Boulevard, Suite 755, Indianapolis, IN 46202, USA.

.

j o u r n a l o f s u r g i c a l r e s e a r c h 1 8 3 ( 2 0 1 3 ) 9 8e9 9 99

a renal aortic ratio greater than equal to 5.1 was most

predictive of the angiographic ISR of greater than 70% and

which produces some increase in the flow velocities. These

velocity criteria are not all that dissimilar to the criteria for

nonstented renal arteries.

My own opinion is that although there may be some

decrease in arterial compliance after stent placement, this

difference is not all that dramatic. Serial examinations may

demonstrate a progressive increase in the PSV or end-diastolic

velocity, which underscores the importance of obtaining an

early poststent placement Duplex scan. Furthermore, the flow

velocity criteria for severe ISR are similar to nonstented

arteries. These patients can be further investigated with

arteriographic studies. Each vascular laboratory should

provide its own quality controls and correlate findings from

Duplex scans and arteriographic studies.

r e f e r e n c e s

[1] Kuppler CS, Christie JW, NewtonWB 3rd, et al. Stent effects onduplex velocity estimates. J Surg Res 2013;183:457.

[2] Armstrong PA, Bandyk DF, Johnson BL, et al. Duplex scansurveillance after carotid angioplasty and stenting: Arational definition of stent stenosis. J Vasc Surg 2007;46:460.

[3] Lal BK, Hobson RW, Goldstein J, et al. Carotid artery stenting:Is there a need to revise ultrasound velocity criteria? J VascSurg 2004;39:58.

[4] AbuRahma AF, Abu-Halim AHS, Besenhaver J, et al. Optimalcarotid duplex velocity criteria for defining the severity ofcarotid in-stent restenosis. J Vasc Surg 2008;48:589.

[5] Chi YW, White CJ, Thornton S, et al. Ultrasound velocitycriteria for renal in-stent restenosis. J Vasc Surg 2009;50:119.