Renal denervation has emerged as a safe and effective therapy to lower blood pressure in hypertensive patients. In addition to the main renal arteries, branch vessels are also denervated in more contemporary studies. Accurate and reliable imaging in renal denervation patients is critical for long-term safety surveillance due to the small risk of renal artery stenosis that may occur after the procedure. This review summarizes three common non-invasive imaging modalities: Doppler ultrasound (DUS), computed tomography angiography (CTA), and magnetic resonance angiography (MRA). DUS is the most widely used owing to cost considerations, ease of use, and the fact that it is less invasive, avoids ionizing radiation exposure, and requires no contrast media use. Renal angiography is used to determine if renal artery stenosis is present when non-invasive imaging suggests renal artery stenosis. We compiled data from prior renal denervation studies as well as the more recent SPYRAL-HTN OFF MED Study and show that DUS demonstrates both high sensitivity and specificity for detecting renal stenosis de novo and in longitudinal assessment of renal artery patency after interventions. In the context of clinical trials DUS has been shown, together with the use of the baseline angiogram, to be effective in identifying stenosis in branch and accessory arteries and merits consideration as the main screening imaging modality to detect clinically significant renal artery stenosis after renal denervation and this is consistent with guidelines from the recent European Consensus Statement on Renal Denervation.

Few studies have documented relationships between endovascular therapy, duplex ultrasonography (DUS), post-thrombotic syndrome (PTS), and quality of life (QOL). The Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) trial randomized 692 patients with acute proximal deep vein thrombosis (DVT) to receive anticoagulation or anticoagulation plus pharmacomechanical catheter-directed thrombolysis (PCDT). Compression DUS was obtained at baseline, 1 month and 12 months. Reflux DUS was obtained at 12 months in a subset of 126 patients. Clinical outcomes were collected over 24 months. At 1 month, patients who received PCDT had less residual thrombus compared to Control patients, evidenced by non-compressible common femoral vein (CFV) (21% vs 35%, p < 0.0001), femoral vein (51% vs 70%, p < 0.0001), and popliteal vein (61% vs 74%, p < 0.0001). At 12 months, in the ultrasound substudy, valvular reflux prevalence was similar between groups (85% vs 91%, p = 0.35). CFV non-compressibility at 1 month was associated with higher rates of any PTS (61% vs 46%, p < 0.001), a higher incidence of moderate-or-severe PTS (30% vs 19%, p = 0.003), and worse QOL (difference 8.2 VEINES-QOL (VEnous INsufficiency Epidemiological and Economic Study on Quality of Life) points; p = 0.004) at 24 months. Valvular reflux at 12 months was associated with moderate-or-severe PTS at 24 months (30% vs 0%, p = 0.01). In summary, PCDT results in less residual thrombus but does not reduce venous valvular reflux. CFV non-compressibility at 1 month is associated with more PTS, more severe PTS, and worse QOL at 24 months. Valvular reflux may predispose to moderate-or-severe PTS. ClinicalTrials.gov Identifier NCT00790335.

Carotid artery disease remains a major etiology of ischemic stroke. As data emerges demonstrating the safety and efficacy of carotid artery stenting, the importance of determining patency of carotid stents over time increases. Given alterations in the architecture and compliance of the carotid artery after a stent is deployed, subtleties in the performance and interpretation of carotid duplex ultrasonography must be appreciated. This section describes these factors in detail, and provides optimal methods to interpret these examinations.