Comparison of Ultrasound-Accelerated versus Pigtail Catheter-Directed Thrombolysis for the Treatment of Acute Massive and Submassive Pulmonary Embolism 

Summary

This retrospective study expounds on the use of catheter directed lytic therapy in the setting of submassive and massive pulmonary embolism. Its specific aim is to directly compare the effectiveness of ultrasound-accelerated therapy (USAT) to that of nonselective flush catheter (PCDT) thrombolytic infusions. The authors reviewed 101 treatments over a 7 year period, and after exclusion criteria, included 60 treatments in 59 patients, 24 of whom received USAT and 36 of whom received PCDT. Demographics of the two cohorts were similar. Therapy selection was at the discretion of the performing physician, as was thrombolytic dosing and duration. The results demonstrated similar effectiveness of the two techniques, as demonstrated by improved pulmonary artery pressures and Miller index scores (angiographic thrombus scoring system). Placement of the pigtail catheters compared to the USAT catheters took significantly less procedure and fluoroscopy time. There was a nonsignificant trend towards PCDT taking longer, requiring more procedural revisits, and consequently, resulting in an increase in total lytic therapy. However, when normalizing to the first revisit, these trends were no longer observed. There were a total of three 30-day mortalities, only one of which could be directly attributed to lytic therapy. The authors conclude that the clinical efficacy and safety of these two CDT techniques is similar, with the PCDT taking less time to initiate.



Table 3. Reduction in Parameters between Procedures within Groups

Commentary

There has been significant interest in the use of catheter directed therapy (CDT) in the setting of both massive and submassive pulmonary embolism. An increasing body of literature advocates for the use of CDT in both massive and submassive PE. Both patient populations have seen avoidance of hemodynamic collapse, improved PA pressures, decreased thrombus burden, and improved RV function after use of lytic therapy. However, there is little clinical evidence to guide the best technique for administration of this lytic therapy. This paper attempts to shed insight on this matter by comparing USAT to PCDT in a retrospective fashion at a single center. Prior in vivo research has suggested that flow dynamics in the setting of obstruction require infusions to be imbedded in the obstruction for appropriate medication instillation. However, the clinical applicability of this research is not well known. Certainly, USAT has demonstrated effectiveness to lyse thrombus, and some have shown it also to allow a smaller amount of lytic to be administered over a shorter period of time. However, the current study would argue against this literature when applied to routine clinical practice, especially given the similar outcome endpoints, decreases in procedural complexity, and decreased procedure times.

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Graif A, Grilli CJ, Kimbiris, G et al. Comparison of Ultrasound-Accelerated versus Pigtail Catheter-Directed Thrombolysis for the Treatment of Acute Massive and Submassive Pulmonary Embolism. J Vasc Interv Radiol. 2017; 28(10): 1339-1347.

Post Author:
Daniel P. Sheeran, MD
Assistant Professor
Department of Radiology and Medical Imaging
Division of Vascular and Interventional Radiology
University of Virginia

Analysis of Preoperative Portal Vein Embolization Outcomes in Patients with Hepatocellular Carcinoma: A Single Center Experience

Summary

Researchers from Mt. Sinai recently presented their findings on a retrospective analysis of patients with well compensated hepatocellular cancer(HCC) who underwent preoperative portal vein embolization (PVE) that would allow surgical treatment (≤ 40% of functional liver remnant (FLR)) with curative intention was performed. 82 patients underwent PVE, 72(87.8%) were deemed surgical candidates and 69(84.1%) underwent surgical resection.

Embolization was performed using N-butyl cyanoacrylate glue mixed with lipoidol or sodium tetradecyl sulfate foam. Tumor progression, total liver volume (TLV), FLR, hypertrophy rate and the kinetic growth rate were evaluated 4-8 weeks after PVE. Resection was performed in 84% of patients. Post resection follow up protocol included serial imaging performed every 3 months for the first 2 years and every 6 months thereafter.

Rate of major adverse events were 11% which did not depend on the embolic material used. Median increase in the FLR, hypertrophy rate and kinetic growth rate were 14.6 and 10.5%, 9.7% respectively. Radiological progression of HCC occurred in 34.1% after PVE. Post-operative morbidity was 22.2% and mortality was 4.2%. Recurrence after surgical resection was 30.4% with a mean time to recurrence of 41.9 months. The mean survival after surgical resection was 42.8 months. No significant difference in the recurrence rate, time to recurrence and survival rates was observed between patients without and with tumor progression after PVE.



Fig 1. Comparison of predicted FLR before (upper image) and after (lower image) PVE.

Commentary

Surgical resection is the procedure of choice for patient with Child A Cirrhosis who are not candidates for transplantation. The authors showed that in well selected patients PVE is a safe technique to improve the outcomes after surgical resection. Tumor progression while awaiting surgical resection can be as high as 34% and use of adjunct loco regional treatments while awaiting resection is a great option. Interestingly in this study, tumor progression after PVE did not have any influence in the recurrence rates, time to recurrence or survival after resection. Post-operative morbidity and mortality remains a concern for these patients. PVE should be considered for patients with HCC with good liver functions after carefully weighing the risks and benefits.

Click here for abstract

Marti J, Giacca M, Alshebeeb K, et al. Analysis of Preoperative Portal Vein Embolization Outcomes in Patients with Hepatocellular Carcinoma: A Single-Center Experience. J Vasc Interv Radiol 2018; 29:920-6.

Post Author:
Anil K Pillai, MD
Associate Professor and Section Chief
University of Texas Health Science Center
@AnkupiMD

Outcomes over Time in Patients with Hostile Neck Anatomy Undergoing Endovascular Repair of Abdominal Aortic Aneurysm

Summary 

This article evaluated outcomes of early (2004-2008) and late (2019-2013) period patients with hostile neck anatomy who underwent endovascular aneurysm repair (EVAR). Hostile neck parameters were at least one of the following: 1) Neck length ≤ 10 mm 2) Focal bulge in the neck (> 3 mm) 3) > 2-mm reverse taper within 1 cm below the renal arteries 4) Neck thrombus or calcification > 50% of the circumference 5) Angulation ≥ 60% below within 3 cm the renal arteries. The study compared 61 of 216 (28%) patients in the early period and 64 of 144 (44%) patients in the late period. No significant differences were observed in hostile neck anatomic factors between the early and late periods in this study. However, abdominal aortic aneurysm sac regression in the late period was better as compared to the early period (late period, 73.5% vs early period, 55.7%; P = 0.038). Another notable observation was; type 1a endoleaks in patients in the late group with suprarenal fixation was higher as compared to patients with infrarenal fixation (suprarenal, 27.0% vs infrarenal, 7.9%; P = 0.025). Otherwise, there were no significant differences observed in periprocedural factors and outcome measures over time in patients with hostile neck who underwent EVAR.

Commentary

This article evaluates differences in outcomes in an early and late period EVAR experience in patients with hostile neck anatomy. Early post-EVAR era, hostile aortic neck used to be an open surgical indication. A large number of patients (up to 40%) would not be suitable for standard EVAR treatment due to anatomic challenges, mainly hostile neck of the aorta. However, as we gained more experience in time, we felt more comfortable to use devices out of their label to use. Noticeably there is very limited data on this topic. This paper (Bryce et al) studied this important topic and correlated early and late experience with suprarenal and infrarenal fixation. It turns out infrarenal is better than suprarenal fixation in terms of type 1a endoleak. Aneurysm sac regression was better in later group. Strikingly, the paper found no significant difference between earlier and later experience even though later group has more anatomically challenging patient group. This is probably linked to gaining more procedural experience and more and better EVAR products commercially available. There are several other methods available such as fenestrated EVAR (FEVAR) especially for elective cases, or “chimney/snorkel” (brachial access) or a periscope (femoral access) techniques especially for emergent/urgent cases. Thanks to the authors for providing suprarenal vs infrarenal fixation outcomes with historical differences for hostile aortic neck EVAR. This is an exciting and challenging topic, more outcome studies needed with other techniques as well.

Click here for abstract

Bryce Y, Kim W, Katzen B, Benenati J, Samuels S. Outcomes over Time in Patients with Hostile Neck Anatomy Undergoing Endovascular Repair of Abdominal Aortic Aneurysm. J Vasc Interv Radiol. 2018 Jul;29(7):1011-1016.

Post Author:
Ulku Cenk Turba, M.D. FSIR
Professor of Radiology
Director, Interventional Radiology Residency, and Fellowship
Rush University Medical Center
@cturba

Covered Stents in the Treatment of Pulmonary Arteriovenous Malformations

Summary

Pulmonary arteriovenous malformations (pAVM) are a unique problem that is seen most often in the rare population of patients afflicted with hereditary hemorrhagic telangiectasia. These patients often require multiple treatments throughout their lives and it is important to prioritize the preservation of normal lung tissue whenever possible. In some cases, this can be achieved with the use of covered stens. This study retrospectively reviews the cases of seven patients (8 total pAVM treatments) who were treated with covered stents at their institution (approximately 1.1% of all pAVM’s treated at the host institution from 2001-2017). The decision to use stent grafts was made based on the presence of a short neck, the inability to cross or enter an existing coil nest in a way that additional coils or plugs could be safely deployed, and the desire to preserve the normal downstream pulmonary vascular bed. No antiplatelet or anticoagulant medications were used due to issues with epistaxis in this patient population. Complete technical success was defined as exclusion of the pAVM with a covered stent while maintaining patency of the parent vessel which was achieved in 7 of 8 cases. In one patient the decision was made to sacrifice the parent vessel due to the presence of multiple feeders to the pAVM which were only seen after initial stent placement. Six of these patients had follow up imaging at a median of 8 months, all of which maintained stent patency without stent migration or deformation. In conclusion, the authors state that covered stents are a useful adjunct for treating select pAVM’s not well suited to coil and/or plug embolotherapy. Intermediate-term patency of this treatment was also favorable despite the small diameters of treated vessels (mean 6mm) and inability to use antiplatelet therapy and/or anticoagulants in this patient population.



Figure 1. (a) Selective right upper lobe pulmonary arteriogram shows PAVM before initial treatment. Note very short communication (arrowhead) between the pulmonary artery (containing catheter) and draining vein (arrow). Note also the large normal pulmonary vascular bed distal to PAVM. (b) Selective right upper lobe pulmonary arteriogram after coil embolization shows occlusion of PAVM. (c) Selective right upper lobe pulmonary arteriogram obtained at follow-up shows recanalized PAVM with prompt arteriovenous shunting (arrowhead shows draining vein). Note very short remaining vessel between catheter tip and coil nest (arrow). (d) Oblique view with catheter tip in the vessel that previously received embolization again shows pronounced shunting with prompt filling of draining vein (arrow). Digitally subtracted (e) and native (f) images after placement of a covered stent (arrows) show good position and exclusion of the feeding artery with no further flow into PAVM. The parent vessel is well preserved. (g) Coronally reformatted image from computed tomography arteriogram obtained 55 months after the procedure shows a patent covered stent with resolution of PAVM.

Commentary

This article demonstrates a novel approach to treating an uncommon entity (pAVM) of a rare disease (HHT) with an emphasis on the preservation of normal pulmonary vasculature in patients who often require multiple treatments throughout their lives. Interestingly, despite the small size of these vessels, the stents remained patient without the use of anticoagulant or antiplatelet medications. In one instance, a separate study reported patency at 120 months without recanalization or persistence of the treated AVM. Pulmonary AVMs are seen nearly entirely in patients with hereditary hemorrhagic telangiectasia and stent-graft exclusion of these lesions is an infrequent treatment approach, which explains the small sample size limitation of this study. However, the particular predilection of pAVMs for patients with HHT raises the question of whether or not their unique genetic makeup and biochemistry helps prevent stent occlusion. While confident use of stent grafts for this purpose requires additional research with long-term follow up, consideration may be given to using these more liberally as they are impermeable to flow and should theoretically eliminate the possibility of recanalization of the treated feeder vessels. They also carry the added benefit of easier follow-up with chest CTA as they do not produce any significant imaging artifact. Finally, a cost based analysis may be warranted to ascertain whether universal use of stent-grafts is financially feasible or should be reserved for complex interventions like those in this study.

Click here for abstract

Harrison X. Bai, MD, Reed E. Pyeritz, MD, and Scott O. Trerotola, MD. Covered Stents in the Treatment of Pulmonary Arteriovenous Malformations. J Vasc Interv Radiol 2018; 29:981–985

Post Author:
Caleb L. Mills, MD PGY-4
Department of Radiology
Wake Forest Baptist Medical Center
@WakeForest_IR

Fluorescence Imaging of MMP-2 Activity as a Biomarker of Vascular Remodeling in HD Access

Summary

In a recent article in press, researchers from the Penn Image-Guided Intervention Laboratory at the University of Pennsylvania have presented their findings exploring the capability of near-infrared fluorescence (NIRF) imaging for the detection of matrix metalloproteinase 2 (MMP-2) activity as a biomarker of vascular remodeling (VR) in AVFs in vivo. The manuscript reports that 10 AVFs were created in 10 Wistar rats with sham procedures in the contralateral groins. 4 weeks post creation, a fistulogram was performed in a subset of animals from the left common carotid to confirm stenosis. A MMP-2-activated NIRF probe was given and NIRF imaging performed in vivo and ex vivo on both AVF and sham-treated vessels to measure radiant efficiency (RE) of MMP-2-activated NIRF signal over background. Histologic analysis was also done to assess degree of VR by intimal thickening. When compared with sham-treated vessels, AVFs had a significantly higher percentage of RE over background. There was a significant correlation between MMP-2 activity as measured by relative increase in RE for AVFs and thickness of MMP-2 stained neointima. The authors conclude that NIRF imaging can detect MMP activity in remodeled AVFs compared with sham treatment and MMP-2 may be used as a biomarker of vascular remodeling underlying stenosis.

Figure. Ex vivo near-infrared imaging of MMP-2 activation. (a) Representative near-infrared fluorescence and photographic images of MMPSense activity in explanted fistulae and sham-treated vessels. (b) Bar graph illustrating a higher percent increase in radiant efficiency over background for patent AVFs compared with sham-treated vessels after intravenous injection of MMPSense 750. (c) Bar graph illustrating the higher percentage increase in radiant efficiency over background for AVFs compared with sham-treated vessels after intra-arterial injection of MMPSense 750. (d) Bar graph illustrating the significantly higher percentage increase in radiant efficiency over background for AVFs compared with sham-treated vessels after intra-arterial or intravenous injection of MMPSense 750 (**P = .0078). (e) Bar graph illustrating the fold increase in radiant efficiency over sham-treated vessels for rats injected with MMPSense 750 through intravenous or intra-arterial routes. (f) Bar graph illustrating the significantly higher percent increase in radiant efficiency over background for AVFs after intravenous compared with intra-arterial injection of MMPSense 750 (**P = .00357).

Commentary

Treatment of patients with dysfunctional AVFs and AVGs can be challenging. Primary patency is <70% at one-year and patients return frequently with new stenotic lesions. While AVFs and AVGs have been studied extensively, our ability to accurately predict in which patients a stenosis will occur, why they occur, and how best to prevent/treat them is far less than optimal. Previous research has evaluated the morphologic characteristics of lesions within the AV access circuit and we know in what regions lesions are most likely to occur. While useful, this does not allow us to anticipate a dysfunctional AVF/AVG and prevent the need for endovascular treatment. There are several limitations in the provided manuscript including using animals without CKD, lack of pre-AVF NIRF imaging, and using a single time point for evaluation. However, the study is noteworthy as it advances our understanding of the pathophysiology of dysfunctional AV access and identifies a number of factors that can influence cellular proliferation in neointimal hyperplasia. Identifying access circuits that may be at increased risk of developing access site dynsfunction will be impactful on this patient population.

Click here for abstract

Nadolski GJ, Hunt SJ, Weber CN, et al. Near-infrared fluorescence imaging of matrix metalloproteinase 2 activity as a biomarker of vascular remodeling in hemodialysis access. Article in press. DOI: https://doi.org/10.1016/j.jvir.2018.04.032

Post Author:
Luke R. Wilkins, MD
Assistant Professor
Department of Radiology and Medical Imaging
Section of Vascular and Interventional Radiology
University of Virginia
@LukeWilkins_UVA

Use of the Gore Tigris Vascular Stent in Advanced Femoropopliteal Peripheral Arterial Disease

Summary

In a recent study from University of Siena, Italy, researchers published their experience on the new Tigris vascular stent (Gore) for complex femoropopliteal arterial disease. This is a self-expanding stent made of helically wound nitinol wire interconnected by an expanded poly- tetrafluorethylene (ePTFE) structure coated with bonded heparin. In this prospective study 31 patients with Rutherford stage 3 or greater and TASC type B or greater were included. The lesions were located in the common femoral, superficial femoral, popliteal arteries and a femoropopliteal bypass. There were 18 occlusions (58.1%) and 13 stenoses (41.9%). The mean diseased segment length was 15.5 ± 9.9 cm. Patients were treated with Tigris stent alone or in combination with the Viabahn stent (Gore). Technical success was 100% without complications. Primary patency rates at 6, 9, 12, and 15 months were, respectively, 100%, 90.5%, 88.9%, and 80%. Median postprocedural Rutherford stage was 1. Three occlusions occurred, leading to TLR of 9.7% and secondary patency of 100% at 15 months. Intrastent restenosis occurred in four cases (12.9%) without worsening symptoms. Lesion length was associated with re-occlusion (P < 0.003). No stent fractures were observed. The authors concluded that the Tigris stent alone or in combination with a Viabahn stent has an acceptable 12-month primary patency and low reintervention rate for femoropopliteal TASC B–D lesions.



Figure 3. An 83-year-old man with claudication (<100 mt) with TASC D popliteal (P1–P3) chronic occlusion. (a) Angiography demonstratcomplete occlusion of the P1–P3 segments, with hypertrophy of the geniculate vessel arising from the proximal edge of the occluded segment (asterisk). (b) Angiography performed with the knee (d) extended and (e) flexed demonstrate patency of the 5 _ 100 mm Tigris vascular stent. (c–f) 15-Month ultrasound follow-up. (c) Color Doppler examination confirms patency of the collateral geniculate vessel arising from the proximal edge of the stented segments (asterisk in a,c). (d–f) Color Doppler in-stent evaluation from proximal to distal demonstrates progressive increase of the peak systolic values until a ratio >2.0 is reached, indicating in-stent restenosis.

Commentary

Despite the fact that endovascular recanalization has become the first option in many cases of peripheral arterial disease, the femoropopliteal segment remains a challenging territory given its biomechanical properties. Therefore, technological advancements are welcome to help overcome the limitations of the current devices and improve clinical results. Over the years, new options have become available, including drug-eluting and interwoven stents. The Viabahn stent despite its great flexibility may lead to occlusion of collateral circulation, since it is a covered stent. The present study showed that this new Tigris stent (self-expanding non-covered) might be another valuable tool, especially for the distal SFA and popliteal artery, where accentuated “bending” forces are applied and many important collateral vessels are present.

Click here for abstract

Post Author:
Ricardo Yamada, MD
Assistant Professor
Department of Radiology
Division of Vascular and Interventional Radiology
Medical University of South Carolina

Radioembolization for Hepatocellular Carcinoma: A Nationwide 10-year experience 

Summary

This retrospective study evaluated the use and outcomes of Transarterial radioembolization (TARE) for HCC over the span of 10 years in the United States. The authors utilized the National Cancer Data base (NCDB) and identified patients between 2003-2012 with HCC that were treated with TARE. Patients that underwent resection or transplantation were removed; ultimately 1222 were included in this study. The authors evaluated demographics, insurance, socioeconomic status, tumor stage, tumor size, and hospital setting. Univariable and multivariable analyses were performed, and overall survival was estimated using log-rank test. The authors found that over the study period the number of HCC diagnoses and TARE treatments increased five times. Overall survival was 13.3 months, and did not change during the study period. Survival was not influenced by age or whether the procedure was done in an academic or community hospital, however female patients demonstrated improved survival, African American patients showed the lowest median survival, and patients with a higher socioeconomical and private insurance status trended towards improved survival. Survival was improved with tumors smaller than 5 cm, and decreased with increasing AJCC stage. Multivarite analyses showed that sex, tumor size, distance from hospital, insurance status and AJCC stage correlated with overall survival. In this cohort the median survival for patients with extrahepatic disease was 7.8 months, similar to the placebo group in the SHARP trial, therefore the authors suggest that the use of TARE in extrahepatic disease patients should be extensively discussed in a multidisciplinary manner before proceeding. Sex correlated with an improved prognosis however age was not a factor; therefore as long as elderly patients show a good functional status, outcomes will remain similar to their younger counter parts. After multivariate analyses African American patients showed a trend towards worse prognosis when compared to white patients. The authors found that this study is limited by the retrospective design, the use of the NCDB database, and the lack of cost analyses associated with TARE. Ultimately this study concluded that male sex, tumor size and extrahepatic HCC disease was associated with decreased overall survival after TARE treatment. However age alone, is not associated with a worse outcome.




Figure- Use of radioembolization in patients with HCC during the period 2003–2012.

Commentary

The findings of this study identify some prognostic factors that might influence the overall survival in HCC patients being treated with TARE. In the current environment where HCC can be treated with surgery, transplantation, catheter directed therapies (TAE, TACE, TARE), ablations, and systemic therapy, it is important to identify which patients will benefit the most from TARE therapy. The use of the NCDB database provides strength to this study since a large number of patients are included. Patients had various demographic characteristics, presented either to academic or community hospitals, possessed different types of insurance, belonged to different socioeconomic groups, and presented with different tumor sizes and tumor stages. Therefore this analysis evaluates many variables that are encountered in every day practice. The results in this study highlight that age of presentation is not as important as sex, AJCC stage, tumor size and insurance type. More studies are necessary to identify which HCC patients benefit the most from TARE treatment.

Click here for abstract

Tohme S, Bou Samra P, Kaltenmeier C, Chidi AP, Varley PR, Tsung A. Radioembolization for Hepatocellular Carcinoma: A Nationwide 10-Year Experience. J Vasc Interv Radiol. 2018; 29(7):912-919.

Post Author: 
Carlos J. Guevara, MD
Assistant Professor
Department of Radiology, Interventional Radiology Division
University of Texas Health Sciences, Houston
@UTHouston_IR

Biologic Drug Effect and Particulate Embolization of Drug-Eluting Stents versus Drug-Coated Balloons in Healthy Swine Femoropopliteal Arteries

Summary 

It has become clear that addition of antineoplastic drugs to intervention in peripheral vascular disease lesions has improved patency on all intervention platforms vs no drug. However, Drug coated Balloon (DCB) vs Drug eluting stent (DES) in femoro-popliteal artery remains an area of controversy with limited to non-existent robust direct head to head comparison studies.

Researchers recently published an animal study that contributes significant insight into this ongoing controversy. In their preclinical study in normal pig vessels they compared the biologic effects of POBA + DES vs DES + DCB vs DCB + BMS vs DCB alone in a direct head to head fashion. After 1 month, they measured local vessel histomorphometric parameters and objectively evaluated histologic changes in the downstream vessels for potential harmful effects of distal embolic paclitaxel. Angiographic diameter measurements were also performed.

The DES group demonstrated the best biological effect regardless of preceding POBA or DCB vs DCB + BMS or DCB alone. Of further significant note is that, downstream histological changes of damage from distal paclitaxel embolization were only seen in the limbs were a DCB had been utilized. No significant difference in luminal loss in all groups at 1 month.



Figure 1. Representative histologic images of the biologic responses to DCB + DES, PTA + DES, DCB + BMS, and DCB alone in swine iliofemoral arteries. Fibrin deposition in each treatment group is demonstrated in the middle panels, whereas depth of SMC loss is demonstrated with yellow arrows in the lower panels. Mild medial SMC loss with focal proteoglycan accumulation is observed in the DCB-alone group (a–c). Moderate medial SMC loss is observed in the DCB + BMS group, with minimal fibrin around stent struts (d–f). The greatest biologic drug effect is observed in the DCB + DES (g–i) and PTA + DES (j–l) groups in the form of extensive medial SMC loss and extensive fibrin around stent struts

Commentary

This animal study provides useful scientific concepts to assist in improving our understanding in addressing the current clinical conundrum of DCB vs stenting in lesions that otherwise have no mechanical issues causing flow limitations post intervention. The study findings suggest DES has superior biologic effects regardless of preceding PTA with POBA or DCB. Subgroup analysis of the study also suggests there is non-uniform biologic effects with DCB vs with DES.

We also learn from this study that DCBs appear to be the only ones associated with histologically significant downstream vessel damage/changes from paclitaxel distal embolization. Overall, the findings in principle appear to favor DES in terms of biological efficacy and potential histological side effects. It is also interesting to note in the same study that at 1 month there were no statistically significant differences in luminal change at angiography between all the groups studied. Although this is clearly a very short term follow up it raises the question about how significant these histological advantages may translate to meaningful clinical benefits or disadvantages in real world clinical patient scenarios.

With all these points in mind, the pragmatic appeal of treating a patient without having to leave a metal foreign body will require a lot more robust data and trials to move the dial in favor of DES in uncomplicated vascular lesions.

The study has several limitations, most of which are well acknowledged by the authors. I would add that the biological benefits of DES with regards to Smooth muscle Cell (SMC) loss may have been confounded and potentially overestimated by the natural SMC loss that occurs with stent centrifugal compression. Despite these limitations, the study moves the ball forward in helping our understanding of this controversial topic and perhaps sets up a good platform for robust true direct head to head clinical RCTs.

Click here for abstract

Torii S, Yahagi K, Mori H, et al. Biologic Drug Effect and Particulate Embolization of Drug-Eluting Stents versus Drug-Coated Balloons in Healthy Swine Femoropopliteal Arteries. J Vasc Interv Radiol. 2018; 29:1041-1049.

Post Author:
Rodrick C Zvavanjanja, MD, MSc, FRCR, DABR(VIR/DR)
Assistant Professor
Department of Diagnostic and Interventional Radiology
University of Texas at Houston McGovern Medical School
@RodZvavanjanja

Long-Term Outcome of Portal Vein Stent Placement in Pediatric Liver Transplant Recipients: A Comparison with Balloon Angioplasty

Summary

Portal vein stenosis remains a significant cause of graft failure and postoperative morbidity in liver transplant recipients. In the case of pediatric liver transplants it is particularly important because these patients have much longer life expectancies and there are frequent size discrepancies between the donors and recipients. In this study the investigators retrospectively analyzed the cases of 50 patients with a median age of 14 months who underwent percutaneous transhepatic balloon angioplasty (n=12), transhepatic stent placement (n=18), or intraoperative transmesenteric (n=20) stent placement. For the evaluation of patency of angioplasty vs. stent placement, primary patency was defined as the lack of portal vein restenosis detected via ultrasound and/or CT. The authors also looked at procedural complications, functional stent stenosis, and stent fractures. Within these groups the 1-, 5-, and 10-year primary patency rates were 75% (angioplasty), 100% (transhepatic stent), and 85-90% (transmesenteric stent). Clinical success was seen in 8 out of 9 cases of angioplasty only, 16 out of 16 cases of transhepatic stent, and 20 out of 20 cases of transmesenteric stent placement. There were 3 recurrences seen with angioplasty only and with transmesenteric stent placement. There was only one major complication seen with transhepatic stent placement which was a portal vein tear during post-stent angioplasty. There were three major complications seen with transmesenteric stent placement which manifested as acute stent thrombosis. No major complications were seen with angioplasty only. The researchers ultimately concluded that there was no statistically significant difference between the three groups in terms of the long term primary patency rates and that angioplasty should be considered as the first line treatment for portal vein stenosis in pediatric liver transplant recipients.



Figure 4. An 11-month-old boy who underwent lateral-segment living donor liver transplantation and transmesenteric stent placement. (a) Venogram via the inferior mesenteric vein after end-to-end portal vein anastomosis shows near total occlusion of the main portal vein (arrow). (b) A self-expandable stent (8-mm diameter) was placed in the main portal vein, followed by balloon angioplasty (6-mm diameter). (c) Post-procedural fluoroscopy shows a remaining waist deformity (arrows) in the stent. (d) Coronal reconstructed computed tomography obtained 2 weeks after stent placement shows fully expanded stent with portal vein flow maintenance. (e) Doppler ultrasonography obtained 114 months after liver transplantation shows brisk portal vein flow.

Commentary

This paper emphasizes the importance of starting conservatively in treating portal vein stenosis following pediatric liver transplant. It also emphasizes the fact that regardless of method, these patients still require very close follow up and often require repeated angioplasty for re-stenosis early in life. While stenting in these patients is often inevitable, it does not come without risks and can even limit the ability to undergo future repeat liver transplant if needed. As with all things IR, every case poses unique challenges and there will likely be instances when using a stent as the first line treatment may be necessary. This article opens the door for future research, as there is currently no consensus on specific indications and timing of stent placement.

Click here for abstract

Shim D, Ko G, Sung K, Gwon D, Ko H. Long-Term Outcome of Portal Vein Stent Placement in Pediatric Liver Transplant Recipients: A Comparison with Balloon Angioplasty. J Vasc Interv Radiol. 2018; 29: 800-808.

Post Author:
Caleb L. Mills, MD PGY-4
Department of Radiology
Wake Forest Baptist Medical Center
@WakeForest_IR