Peak systolic velocity ratio derived from quantitative vessel analysis for restenosis after femoropopliteal intervention: a multidisciplinary review from Endovascular Asia

Abstract

With technological improvements in the endovascular armamentarium, there have been tremendous advances in catheter-based femoropopliteal artery intervention during the last decade. However, standardization of the methodology for assessing outcomes has been underappreciated, and unvalidated peak systolic velocity ratios (PSVRs) of 2.0, 2.4, and 2.5 on duplex ultrasonography have been arbitrarily but routinely used for assessing restenosis. Quantitative vessel analysis (QVA) is a widely accepted method to identify restenosis in a broad spectrum of cardiovascular interventions, and PSVR needs to be validated by QVA. This multidisciplinary review is intended to disseminate the importance of QVA and a validated PSVR based on QVA for binary restenosis in contemporary femoropopliteal intervention.

Keywords: Angiography; Intervention; Methodology; Restenosis; Ultrasound.

Fig. 1

Quantitative FP artery analysis (citation from Ref. [10]). a Nitinol stents implanted in the left FP artery. b Angiography showing intimal hyperplasia in the stented femoropopliteal artery. Note the proximal and distal edges of the nitinol stent (arrows). c Automatically applied tracings show lumen contour (yellow lines) and assumed vessel (red lines). d Magnified view of the minimum lumen diameter within the stent (arrow). The minimum lumen diameter can be determined based on the lumen contour (yellow lines), and the assumed vessel (red lines) can be used as the reference vessel

Fig. 2

QVA for multiple restenosis. a Angiography showing multiple stenoses due to intimal hyperplasia in a stent in the mid-distal FP artery. b In the QVA, the most critical restenosis can be depicted by automatically applied tracings of lumen contour (yellow lines) and assumed vessel (red lines). The % diameter stenosis is 76.9%, suggesting binary restenosis

Fig. 3

Difference in stent edge immediately after nitinol stenting and in follow-up angiography. There are 2 types of angiographic appearance at the stent edge in follow-up angiography. a Type A. No gap between the stent line and the intraluminal line outside the stent (arrow), b Type B. A gap caused by significant intimal hyperplasia and stent expansion at the stent edge between the stent line and the intraluminal line outside the stent (arrow)

Fig. 4

DUS for restenosis after balloon angioplasty. a The proximal PSV is 35.8 cm/s (upper) and the PSV at the point of stenosis is 224.0 cm/s (lower). The PSVR is 6.26, suggesting binary restenosis. b In accordance with DUS findings, confirmatory angiography shows restenosis in the distal FP artery (arrow)

Fig. 5

DUS for in-stent restenosis after nitinol stenting. a The proximal PSV is 22.9 cm/s (upper) and the PSV at the point of stenosis is 187.5 cm/s (lower). The PSVR is 8.20, suggesting binary in-stent restenosis. b In accordance with DUS findings, confirmatory angiography shows in-stent restenosis in the mid-segment of the stented FP artery (arrow)

Fig. 6

Illustration showing differences between an unstented and stented FP artery in terms of the effect of vessel compliance on flow velocity (citation from Ref. [10]). a Unstented FP artery. b Stented FP artery. The stented FP artery has less compliance than the unstented SFA. The PSV and the PSVR increased more in the stented FP artery than in the unstented FP artery, despite the same degree of stenosis

Fig. 7

Representative sample of difference in %DS between QVA and visual estimation analysis (citation from Ref. [10]). QVA results in a %DS of 48%; however, when stent diameter is used as the reference diameter (white line), %DS based on visual estimation analysis is 65%

Fig. 8

Representative cases of drawbacks of DUS for assessing restenosis. a Subtotal occlusion. In this stented case, there is no acceleration or increase in blood flow because of subtotal occlusion (arrow), although a Doppler color signal is present. b Diffuse lesion. In this stented case with critical restenosis embedded in diffuse intimal hyperplasia (arrow), determination of the proximal reference point for Doppler sample volume might be confusing. c Calcified lesion. In this stented case, angiography demonstrates significant in-stent restenosis (arrow) in the mid-FP artery (left). However, the underlying calcification in the arterial wall prevents visualization of the artery and measurement of velocity on DUS because of the acoustic shadow (right)