Extravascular Ultrasound (EVUS) to Assess the Results of Peripheral Endovascular Procedures

Abstract

Contrast arteriography (CA) is considered the gold standard to evaluate any phase in peripheral arterial disease (PAD) interventions, from diagnostics to final results. Nevertheless, duplex ultrasonography (DUS) mostly used for the pre/postoperative phase and follow-up control, could be a potential intraoperative adjunctive imaging tool to assess the effects of endovascular revascularization in patients with iliac and femoropopliteal lesions. The PAD "duplex-assisted" protocol includes a preoperative DUS control followed by an intraoperative and a postoperative control. The most important parameters are pulsed doppler spectral analysis and waveform changes, which are impossible to detect with intravascular ultrasound (IVUS). By using a similar acronym, the intraoperative DUS has been previously described as extravascular ultrasound (EVUS). B-mode imaging, color flow, and peak systolic velocity (PSV) are considered. EVUS could be very useful to evaluate the effects of endovascular treatment, mainly in cases of unclear CAs, severe calcifications and/or dissections. In the context of the "leaving nothing behind" strategy, EVUS can drive the physician to evaluate the absence of flow-limiting dissections and decide which target lesion should be treated with antirestenotic therapy, further vessel preparation, or stenting. The EVUS protocol could be a safe and feasible option to improve the completion assessment of endovascular PAD treatment. A better ultrasound waveform is a sign of improved luminal gain and compliance, which is extremely important to finalize the results of new peripheral device technology, such as intravascular lithotripsy.

Keywords: EVUS; PAD; angiography; duplex ultrasound; lithotripsy.

Figure 1

EVUS (extravascular ultrasound): Sterile setting in the operatory room before a peripheral endovascular procedure (occlusion of the right superficial femoral artery) with three different spots upon the projections of femoral, popliteal, and tibial arteries. The leg is prepared with a double sterile drape to approach any leg spots during the procedure.

Figure 2

Diagnostic algorithm for peripheral arterial endovascular treatments and EVUS protocol. * In the absence of stenting, a waiting time of 15 min should be considered mandatory in case of heavily calcified plaque at high risk of recoil [10]. DUS, duplex ultrasound; ABI, ankle-brachial index; EVUS, extravascular ultrasound; POBA, plain old balloon angioplasty; IVL, intravascular lithotripsy; DCB, drug-coated balloon.

Figure 3

Case 1, right iliac external subocclusion, treated by intravascular lithotripsy without stenting from brachial access. (A) Preoperatory CT scan; (B) initial angiogram; (C) completion angiogram; (D) EVUS with preoperative (E) and postoperative (F) waveforms, changing from monophasic to biphasic flow.

Figure 4

Case 2, right common iliac artery calcified stenosis treated by IVL stand-alone therapy from right femoral access. (A) Preoperatory CT scan.; (B) initial angiogram; (C) completion angiogram; (D) EVUS with preoperative (E) and postoperative (F) waveforms, changing from monophasic to biphasic flow.

Figure 5

Case 3, right superficial femoral artery subocclusion treated by IVL/DCB. (A) Preoperative CA; (B) Preoperative DUS superficial femoral artery; (C) Preoperative DUS popliteal artery; (D) POBA predilatation; (E) IVL at first cycle; (F) DCB after IVL (10 cycles) treatments; (G) Postoperative CA; (H) Postprocedural DUS superficial femoral artery; (I) Postoprocedural DUS popliteal artery waveforms, changing from monophasic to triphasic flow.

Figure 6

Case 4, right superficial femoral artery occlusion, treated by POBA/DCB. (A) CTA showing short SFA CTO with diseased inflow vessel (multiple stenoses with monophasic waveform) and patent outflow vessels/popliteal and tibial; (B,C) Preoperative DUS showing very low monophasic waveform at popliteal and tibial vessels. (D,E) EVUS shows a better outflow with improved monophasic waveforms. (F,G) Postoperative DUS showing a further better outflow with triphasic waveforms.