New Prospective Evaluation of Intraarterial Lidocaine During UAE

Pain control during the post-procedural period remains one of the persistent challenges of uterine artery embolization (UAE). Noel-Lamy et al present the results of a prospective randomized clinical trial comparing the efficacy of intra-arterial (IA) lidocaine infusion for pain control after UAE. Sixty patients were randomized to three arms, each with 20 patients: group A - 1% lidocaine infused with the first polyvinyl alcohol (PVA) vial during embolization followed by additional PVA vials to the embolization endpoint, group B – 1% lidocaine infused after PVA embolization to the embolization endpoint, and group C – control group for which saline was infused. The primary outcome was pain score using a validated scale at 4 hours post-UAE, which was significantly lower for the IA infusion groups (group A: infusion during PVA embolization, 28.6, SD: 24.5; group B: infusion post PVA embolization 35.8, SD: 22.6) versus control (59.4, SD: 30.3), p=0.001. This significant difference in pain levels dissipated by the 7 hour and 24 hour post-UAE time points, which were secondary outcomes. The in-hospital narcotic dose was significantly less for the lidocaine infusion groups (group A: 8.5 mg, SD: 7.4; group B: 11.1 mg, SD: 7.6) compared to control (17.4 mg, SD: 10.5), p=0.006. The 24-hour narcotic dose was also significantly less for the lidocaine infusion groups (group A: 11.1, SD: 9.6; group B: 16.3, SD: 11.5) compared to control (21, SD: 10.5), p=0.021. No significant difference in time to discharge was observed between groups. On 3-month post-UAE MRI, there was a significantly lower rate of complete infarction in group A (38.9%) versus group B (77.8%) or control (75%), p=0.045. There were no serious adverse events in any of the treatment arms.

Commentary

This study by Noel-Lamey et al provides a well-designed, prospective evaluation to confirm the efficacy of IA lidocaine infusion for pain control following UAE. The authors used a validated pain scale to provide a more reliable and replicable endpoint measure than previous studies using non-validated pain scores. Their results suggest that IA lidocaine infusion does provide significant analgesic benefit during the immediate post-procedural period, to a degree that is sufficient to reduce the oral narcotic requirement in the first 24 hours. It is important to note that the standard deviations for both the pain scale measures and the narcotic doses were relatively wide, perhaps reflecting inherent differences in pain perception between patients. Interestingly, the degree of analgesia was not significantly different between lidocaine infusion with initial embolization or following embolization, even as the authors acknowledged that most of the infusion likely refluxed from the uterine arteries in the latter approach. Previous studies have shown severe vasospasm with lidocaine infusion during embolization, which was not observed in this study, likely due to usage of a lower lidocaine dose. However, there was a 50% lower percentage of complete fibroid infarction at 3 months post-UAE in the group that received lidocaine with initial embolization versus post embolization, suggesting that distal vasospasm occurred and partially interrupted embolic delivery. Based on these findings, the authors concluded that lidocaine infusion after embolization is preferable to during embolization. Limitations to this study included the lack of investigator blinding to the method of lidocaine injection, narcotic administration by a nurse rather than patient controlled analgesia, and relatively small sample size. Nonetheless, while additional investigation should be done, the study effectively confirms the efficacy and safety of IA lidocaine infusion for UAE pain control and clarifies the optimal infusion timing relative to embolization.

Click here for abstract

Noel-Lamy M, Tan KT, Simons ME, Sniderman KW, Mironov O, Rajan DK. Intraarterial Lidocaine for Pain Control in Uterine Artery Embolization: A Prospective, Randomized Study. J Vasc Interv Radiol 2016. Article in press.

Post Authors:
Jeffrey Forris Beecham Chick, MD, MPH, DABR
Assistant Professor of Vascular and Interventional Radiology
Vice Quality Assurance and Safety Officer
University of Michigan Health Systems

James X. Chen, MD
Resident in Radiology
Hospital of the University of Pennsylvania

From the SIR Residents and Fellows Section (RFS)

Teaching Topic: Treatment of In-Stent Restenosis in Patients with Renal Artery Stenosis

Takahashi E A, McKusick M A, Bjarnason H, Piryani A, Harmsen W S, Misra, S. Treatment of In-Stent Restenosis in Patients with Renal Artery Stenosis. J Vasc Interv Radiol. 2016. 27 (11): 1657 - 1662.

Click here for abstract

In the November 2016 issue of JVIR, a retrospective study examined the clinical outcomes of patients treated for renal artery in-stent restenosis (ISR) with atherosclerotic renal artery stenosis was evaluated. 1,090 renal artery stents were placed in 1,052 patients, with an average patient age of 73.6 years +/- 8.3. in 79 patients, 101 bare metal stents developed ISR, and the patients underwent repeat stent placement vs. angioplasty. Diagnosis of ISR was mainly done via duplex ultrasound. Percutaneous Transluminal Angioplasty and or stent placement was performed. If the patient did not have >30% residual stenosis on follow-angiogram or a mean pressure gradient of < 10 mm Hg, the patient received no further treatment. Otherwise, a bare metal balloon expandable stent was used, with exception of using DES in a small group of patients.

Of the 1,090 renal artery stents, 101 developed ISR. Bilateral ISR was identified and treated in 27.8% of patients. Renal arteries with ISR treated with repeat stent placement were 6.89 times more likely to develop restenosis requiring a repeat procedure compared with arteries treated with PTA (P < 0.01). None of the arteries that received DES during repeat stent placement developed significant restenosis. The study did demonstrate a statistically significant decrease in both SBP and DBP after re-intervention. Of the 101 renal arteries treated for ISR, 13 developed secondary ISR. After ISR treatment, serum creatinine levels improved by a statistically insignificant amount.

In conclusion, treatment of renal artery ISR with PTA among patients with atherosclerotic renal artery stenosis has a lower rate of subsequent ISR compared with repeat stent placement.

Clinical Pearls

1. What is a serious potential setback with renal artery stent placement in patients with atherosclerotic RAS?

When a stent is inserted in an artery, the internal elastic lamina becomes disrupted. This results in smooth muscle cell migration and intimal hyperplasia. These intimal lesions incorporate atherosclerotic elements leading to ISR. In turn, intractable hypertension and renal insufficiency may arise secondary to ISR.

2. Did stent diameter contribute to the rate of restenosis?

The stent or PTA diameter did not have a statistically significant association with renal artery patency. However, there tended to be fewer cases of restenosis with stents or PTA diameters > 5.0 mm. Other studies also found that stent diameter was not a significant predictor of recurrent ISR events, although a similar trend can be seen with increasing vessel diameter related to decreased ISR.

Questions to Consider

1. What are the two main causes of renal artery stenosis and eventual renovascular hypertension (RVH)?

Atherosclerotic disease and FMD (Fibromuscular Dysplasia).

Other causes include trauma, renal cystic disease, renal cell carcinoma, pheochromocytoma, renal artery aneurysm, reninoma, vasculitis, extrinsic compression and renal infarction.





Source: www.cvphysiology.com

2. What are the imaging modality methods of diagnosing RAS?

Ultrasound with color doppler is the principal tool for detecting RAS / RVH because it is quick, relatively inexpensive and safe. Criteria for significant renal artery stenosis include intrastenotic peak systolic velocity (PSV) of greater than 180 cm/sec and PSV renal/aortic ratio of greater than 3.0 to 3.5.

CT and MRI have been used as a screening exam in some centers, especially if renal function is close to normal. MR Angiography can detect up to 90% to 100% sensitivity and 75-100% specificity. Weaknesses of the method include identification of disease in accessory and segmental renal arteries and artifacts related to metallic clips, intravascular stents or patient motion. Multidetector row CT angiography achieves comparable sensitivity and specificity to MR angiography in depicting renal artery stenosis.

Renal vein sampling measures renin activity in the renal vein vs. the IVC. In a patient with RVH and two functioning kidneys, the affected kidney overproduces renin, and the renin production of the contralateral kidney is reduced. Renal vein renin ratio between the involved and uninvolved kidney of greater than 1.5 and a ratio of (renal renin – IVC renin) / IVC renin of > 0.48 is indicative of RVH.

Lastly, catheter angiography is the gold standard for the diagnosis of RAS. This method allows direct and live visualization of the renal arterial narrowing under fluoroscopic guidance. Hemodynamic significance is proved by the following criteria:

• Reduction in luminal diameter of > 75%. 
• Systolic pressure gradient cross stenosis in the main renal artery greater than 10-20mm hg or greater than 20% of aortic systolic pressure. 
• A stenosis with a 50-75% reduction in luminal diameter may be hemodynamically significant, but in such cases, pressures should be measured. 

Other sources used: The Practice of Interventional Radiology by Karim Valji

Post author:
Ali Alikhani, MD
Diagnostic Radiology Resident, PGY-4
University of Tennessee Methodist Healthcare

It's All in the PROBIO: 12-month Results of the Nitinol Astron Stent in Iliac Artery Lesions 

Multiple stents are currently on the market for use in treating iliac atherosclerotic occlusions, but the optimal system remains to be determined. Burket et al. present the results of a prospective registry evaluating the safety and efficacy of the Astron stent (Biotronik; Bulach, Switzerland), a new amorphous silicon carbide (PROBIO)-coated nitinol self-expanding stent, in treatment of iliac occlusive disease. The PROBIO coating reduces metal ion release, which decreases stent thrombogenicity and promotes endothelialization. 161 patients underwent stent placement at 30 sites, of whom 145 patients completed 12-month study follow-up. The patient demographics and comorbidities as well as iliac lesion characteristics were comparable with other similar stent studies. The primary endpoint, a composite major adverse event (MAE) rate, including 30-day all-cause mortality, 12-month target lesion revascularization (TLR) rate, and 12-month index limb amputation, demonstrated a MAE rate of 2.1%, which was well within the performance goal of 15% (determined based on results of prior similar stent studies). The secondary outcomes included primary patency rate at 12-months (89.8%), freedom from target vessel revascularization (97.9%), freedom from bypass or amputation at 12-months (100%), and acute and 30-day technical success rates (95% for both metrics). ABI increased by a mean of 0.23 (p<0.001) and 6-minute walk increased by a mean of 158 feet (p<0.001) after stenting. Technical adverse events occurred in four cases, including uneven stent expansion (n=2), stent misplacement (n=1), and failure to deliver the stent at the intended site (n=1).

Commentary

The results of this prospective registry demonstrated promising efficacy and a favorable safety profile for the Astron stent in treating iliac occlusive disease. Although the 12-month composite MAE of 2.1% was similar to the range of results seen in other stent models (2.2-7.5%), direct comparisons were hampered by heterogeneity in MAE score definition between studies, and additional studies (ideally prospective randomized controlled trials with standardized endpoints) are necessary to elucidate the optimal stent device for iliac occlusive disease. Given known durability of iliac stenting and previous studies with freedom of 92% at 48 month2, long term outcomes beyond 12-months will also be important to determine durability of this stent, and may provide additional clarification on the potential real-world benefits of silicon carbide-coating versus non-silicon carbide coating for iliac arterial stenting. In the discussion, the authors referred to the CLEVER trial, which demonstrated similar efficacy between supervised exercise and stenting, a finding which raises fundamental questions regarding the risk and benefit ratio of endovascular intervention in these patients. These results are an important consideration for future iliac occlusive disease study designs, which may need to not only compare outcomes between multiple stent models, but also against supervised exercise testing, to best define the optimal treatment paradigm.

Click here for abstract

1. Burket MW, Brodmann M, Metzger C, Tan K, Jaff MR. Twelve-Month Results of the Nitinol Astron Stent in Iliac Artery Lesions. J Vasc Interv Radiol 2016; 27: 1650-1656.

2. Sabri SS, et al. Outcomes of covered kissing stent placement compared with bare metal stent placement in the treatment of atherosclerotic occlusive disease at the aortic bifurcation. J Vasc Interv Radiol 2010; 21: 995-1003.

Post Authors:
Jeffrey Forris Beecham Chick, MD, MPH, DABR
Assistant Professor of Vascular and Interventional Radiology
Vice Quality Assurance and Safety Officer
University of Michigan Health Systems

James X. Chen, MD
Resident in Radiology
Hospital of the University of Pennsylvania