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Thursday, March 23, 2017

Outcome Results on Ablation versus Surgery for HCC: A Report from the SEER Registry


Summary

The comparative efficacy of percutaneous ablation versus surgical resection for hepatocellular carcinoma (HCC) remains a controversial topic, with conflicting literature reporting equivalent outcomes between modalities or superior outcomes with surgery. This study by Mironov et al used the Surveillance, Epidemiology, and End Results (SEER) database to compare survival outcomes for small solitary HCCs treated with thermal ablation versus surgical resection. Only cases with available Ishak fibrosis score were included in the analysis to account for the effect of cirrhosis. To reduce confounding, patients with metastatic disease, treatment other than ablation or surgery, both surgery and ablation, and liver transplantation were excluded. There were baseline differences in the ablation and surgery patients including a higher prevalence of fibrosis in the ablation group (higher Ishak scores) and smaller tumors in the ablation group (mean 2.6 cm versus 3.0 cm, p<0.001). For tumors ≤2 cm (ablation = 264; resection = 79) and tumors between 2.1 and 4 cm (ablation = 335; resection = 209), there was no significant difference in observed or disease-specific survival between ablation and surgical resection. For tumors between 4.1 and 5 cm (ablation = 46; resection = 66), there was a significantly longer observed and disease-specific survival for surgical resection when stratified by presence of fibrosis (observed survival p=0.009, disease specific survival p=0.046). The 5-year observed survival was 72% (surgery) versus 29% (ablation) and disease-specific survival was 80% (surgery) versus 40% (ablation). Notably, the difference in disease-specific survival was not clinically significant by Cox regression with fibrosis covariate (p=0.145). When all tumors ≤4 cm were pooled, there was again no difference in survival outcomes between ablation and surgical resection. Significant predictive factors for observed and disease-specific survival by Cox model included tumor size and degree of fibrosis.





Commentary

Percutaneous ablation is maturing as an important part of the treatment armamentarium for HCC. The relative efficacy of ablation techniques compared to surgery remains controversial and current guidelines from the Barcelona Clinic Liver Cancer (BCLC) recommend ablation only for patients who are not surgical candidates. These recommendations are derived from a very limited evidence base, with only one prospective study demonstrating superior outcomes after surgery. The SEER registry offers a powerful resource to answer these questions, affording a large patient sample from diverse medical institutions and detailed survival outcome data. The authors of this paper effectively identified potential confounders including patients who had received both treatments or went on to receive a liver transplant. The results of their study demonstrate equivalent survival outcomes in tumors <4 cm, which suggests that it would be reasonable to consider ablation as an alternative to surgery in this patient population. The results in the 4-5 cm tumor group demonstrated superiority of surgery, reflecting limitations of ablation in larger tumor sizes. The SEER population included both patients who had been treated with radiofrequency and microwave ablation (and does not differentiate the two modalities), so it could not be determined in this study whether outcomes in these larger tumors may be superior with microwave. It is important to recognize limitations to the SEER data including lack of BCLC or Child-Pugh scores, performance status, or comorbidities, which may all be important contributors to survival. Nonetheless, this study serves as additional evidence that percutaneous ablation affords equivalent survival outcomes to surgery in HCC ≤4 cm and may help to further define the evolving role of ablation in the treatment of HCC patients.

Click here for abstract

Mironov O, Jaberi A, Kachura JR. Thermal Ablation versus Surgical Resection for the Treatment of Stage T1 Hepatocellular Carcinoma in the Surveillance, Epidemiology, and End Results Database Population. J Vasc Interv Radiol 2017; 28:325-33.

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

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

Wednesday, March 22, 2017


From the SIR residents and fellows section


Topic: Gastric Artery Embolization Trial for the Lessening of Appetite Nonsurgically (GET LEAN): Six Month Preliminary Data 


Syed, M I, Morar K, Shaikh A, Craig P, Khan O, Patel S, Khabiri, H. Gastric Artery Embolization Trial for the Lessening of Appetite Nonsurgically (GET LEAN): Six Month Preliminary Data. J Vasc Interv Radiol. 2016. 27 (10): 1502-8.

Click here for abstract

In the October 2016 edition of JVIR, a report on the 6 month safety and efficacy results of a pilot study of left gastric artery (LGA) embolization for the treatment of morbid obesity was discussed. Four patients, three women, one man, with an average age of 41 y (range 30-54), with a mean weight of 259.3lbs, and mean BMI of 42.4 kg/m2 had their LGA embolized with 300-500-um Bead Block particles for the treatment of morbid obesity.



Weight loss was calculated as a percentage versus baseline, as well as b percentage excess body weight loss as follows, where IBW represents “Ideal Body Weight”, using the Devine formula.



Treatment with a PPI was started one week prior to embolization, and continued one month after the procedure. The procedure was performed via a femoral artery access or a left radial artery access.



No immediate complication other than nausea and mild vomiting was reported. Average body weight loss among the four patients at 6 months was 20.3 lbs. Average body weight loss as a percentage was 8.5%. Average excess body weight loss at 6 months was 17.2%. Patient 4, a diabetic patient taking only oral medications, showed improvement in hemoglobin A1c levels (7.4% to 6.3%) at 3 months, which remained at 6 months. QOL measures showed that the average physical component score improved by 9.5 (on an absolute scale of 0–100), and the average mental component score improved by 9.6 (on an absolute scale of 0–100), at 6 months.



In conclusion, preliminary data supports LGA embolization as a potentially safe procedure that warrants further investigation for weight loss in morbidly obese patients.

Clinical Pearls


What were some patient selection and clinical management steps considered for this procedure?

Patients with morbid obesity, (BMI ≥ 40 kg/m2) whose previous attempts at weight loss through diet, exercise, and behavior modification had failed were recruited for this study. These patients also declined to participate in bariatric surgery, as part of the consent process. A complete history and physical exam was performed prior to the procedure.

All patients had dietary consultations for preoperative evaluation and were followed the procedure by a dietician. Any patient with type II diabetes (n = 1) was evaluated by an endocrinologist before participation in the study. Blood glucose levels were monitored with adjustments of diabetic drugs as needed by the endocrinologist throughout the study. Any female patient of childbearing potential (n = 2) was required to use two forms of contraception during the study (oral and barrier), which was monitored by their primary care provider or gynecologist. An upper endoscopy study was performed at baseline and 3 days after the procedure in all patients.

If any patient had any abnormality on 3-day endoscopy (n = 3), upper endoscopy was repeated at 30 days. Fasting morning, plasma ghrelin, leptin, and CCK measurements, in addition to BMI and other baseline and follow-up tests or procedures, were performed at regular intervals.

What were the confounding factors and limitations of this study?

The presence of superficial symptomatic gastric ulcerations (n = 3) was a confounding variable regarding mechanism of weight loss. One known mechanism of weight loss caused by gastric ulcerations is the postprandial pain that creates a fear of food. This postprandial pain was absent in the patients who had superficial gastric ulcerations after the initial few days. 

One other mechanism of weight loss caused by gastric ulceration is appetite suppression. In the present study, all patients except for patient 2 subjectively reported appetite reduction that persisted beyond 30 days (after documented ulcer healing by endoscopy).

Another potential confounding variable was the medications used (PPI and sucralfate). There is no evidence that the short-term use of a PPI or sucralfate has any effect on weight loss. In fact, according to literature, long-term PPI use may result in weight gain. Notably, no dietary restrictions (to promote healing) were given to patients who had superficial gastric ulcerations.

Another confounding variable is that diet modification and nutritional supervision may have occurred that could have accounted for weight loss.

Limitations of this study included the small sample size and relatively short follow up period. Another limitation of the study was that diet and caloric intake records were not obtained.

Questions to Consider


What physiologic pathway is altered when LGA is embolized?


Left gastric artery (LGA) embolization may fulfill a role as a minimally invasive alternative to the current surgical treatment of gastric bypass or reduction surgery for morbidly obese patients. The LGA supplies the fundus of the stomach, where it is known that the hormone ghrelin (one of the hormones responsible for appetite) is produced. Ghrelin is a 28-amino acid hunger-stimulating peptide and hormone that is produced mainly by P/D1 cells lining the fundus of the stomach and epsilon cells of the pancreas. Ghrelin is the only known circulating orexigenic, or appetite-enhancing, hormone

What are the risks / complications of Bariatric Surgery to manage obesity?


Anastomotic leaks, bowel obstruction, deep vein thrombosis, pulmonary embolism, GI bleed, dumping syndrome, and anesthesia risks. Also reported, the 30 day mortality rate associated with BS is 0.31%, as of 2014, lower than previously reported in 2004. However, it is reported that repeat operation rate is 7%, and the overall complication rate is 17%. It is estimated that only 1% of eligible patients elect to undergo bariatric surgery.

Post author:

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

Wednesday, February 22, 2017

Y-90 with Resin Microspheres without Routine Embolization of the Gastroduodenal Artery


Summary

Ward et al present a retrospective analysis of gastrointestinal complications in patients following radioembolization with resin microspheres without routine embolization of the gastroduodenal artery. In this study, 62 consecutive patients underwent Yttrium-90 (Y90) radioembolization with resin microspheres for cholangiocarcinoma or metastatic liver disease. Prior to treatment, preparatory angiography was performed with embolization of high-risk hepaticoenteric anastomoses and administration of technetium-99m macroaggregated albumin. On the day of treatment, repeat digital subtraction angiography and cone-beam computed tomography (CT) was utilized to identify and embolize additional hepaticoenteric anastomoses prior to resin microsphere administration. In addition, if the treatment vessel was less than ~2 cm distal to a hepaticoenteric anastomotic vessel that could not receive coil embolization, administration of RE was done via an antireflux microcatheter (ARMC) (Surefire Infusion System). Patients were discharged with a 1-month prescription for a proton pump inhibitor and a 10-day steroid taper. Follow-up was scheduled for 1 and 3 months post-treatment with an examination focused to detect symptoms of gastrointestinal complications. During planning angiography, 68% of patients had one or more hepaticoenteric vessels embolized, with the right gastric artery being the most commonly embolized. The gastroduodenal artery was embolized in only three patients, two during planning angiography and one immediately prior to radioembolization. ARMC was used in 14% (10 of 69) treatments. Stasis of flow was identified in three patients and administration of resin microspheres was terminated in these patients prior to complete administration of the prescribed dose. Clinical follow-up was available in 60 out of 62 patients and no patients experienced Grade 3 or 4 gastrointestinal symptoms (hematemesis, melena, severe nausea, vomiting, or abdominal pain). No patients required upper endoscopy or extension of prophylactic proton pump inhibitor.



Figure 2. (a) Celiac arteriography in a 48-year-old woman with metastatic neuroendocrine tumor who required embolization of the GDA demonstrated an accessory left hepatic artery (black arrow) from the left gastric artery, a right hepatic artery (white arrow), and a middle hepatic artery supplying segment 4 (dashed white arrow). The GDA (dashed black arrow) originated from the right hepatic artery distal to the origin of the middle hepatic artery. The middle hepatic artery demonstrated a tight kink at its origin, precluding use of an antireflux microcatheter, but supplied approximately 400 mL of diffuse tumor in segment 4. Redistribution of the middle hepatic artery territory by coil embolization was rejected because of irregular intrahepatic vessels occluded by tumors that may have jeopardized successful redistribution. (b) Plug embolization of the GDA (black arrow) and coil embolization of the right gastric artery (white arrow) were performed before microsphere administration in 3 separate doses, administered via the replaced left hepatic artery, the middle hepatic artery, and the right hepatic artery.

Commentary

Routine embolization of the gastroduodenal artery has previously been recommended in the context of Y90 radioembolization with resin microspheres to prevent gastrointestinal ulceration. This action has potential risks; however, including coil migration, recanalization, increased procedure costs, and development of hepaticoenteric collateral vessels prior to treatment. In addition, the overall risk of gastrointestinal ulceration following radioembolization is relatively low, with only 3.7% of patients demonstrating symptoms in the randomized multi-center SIRFLOX trial. Ward et al demonstrate that routine embolization of the gastroduodenal artery may not be necessary given developments that increase the safety of resin microsphere administration (eg. cone-beam CT and ARMC). In addition, 5% dextrose was utilized instead of sterile water for suspension and flushing of resin microspheres during treatment in order to decrease vasospasm and vascular stasis. Microspheres were also administered a day before official calibration so the activity per sphere was 65 Gy/sphere instead of 50 Gy/sphere. This allowed for administration of approximately 23% fewer microspheres and decreased the risk of vascular stasis. With these precautions, there were no observed gastrointestinal complications at follow-up for any of the patients in the study. This study was limited as a retrospective single center study with all procedures performed by two operators with significant experience in resin microsphere radioembolization, potentially limiting the generalizability of the results. In addition, patients did not undergo routine upper endoscopy and biopsy, so the authors were unable to rule out subclinical gastrointestinal ulceration. The results; however, suggest that leaving the gastroduodenal artery intact prior to radioembolization with resin microspheres is safe and has the potential to save procedural time and costs.

Click here for abstract

Ward TJ, Louie JD, Sze DY. Yttrium-90 Radioembolization with Resin Microspheres without Routine Embolization of the Gastroduodenal Artery. J Vasc Interv Radiol. 2017 Feb;28(2):246-253.

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

Thomas J. An, BA
Vanderbilt University School of Medicine

Thursday, January 26, 2017

From the SIR Residents and Fellows Section (RFS)


Teaching Topic: Cryoneurolysis in Patients with Refractory Chronic Peripheral Neuropathic Pain


Yoon JH, Grechushkin V, Chaudhry A, Bhattacharji P, Durkin B, Moore W. J Vasc Interv Radiol. 2016 Feb;27(2):239-43. doi: 10.1016/j.jvir.2015.11.027.

Click Here for Abstract

Approximately, 15 million people in the United States and Europe experience chronic neuropathic pain. In the current climate, non-opiate based pain control is a topic of discussion among doctors and patients as well as at the national level among politicians. Therefore, studies showing efficacy of percutaneous interventions for the purpose of pain alleviation are paramount. In this study, the authors performed ultrasound guided cryoneurolysis on 22 patients with refractory peripheral neuropathic pain. Mean pain levels were 8.3 +/- 1.9 prior to intervention with a statistically significant decrease in mean pain scores at 1, 3, 6, and 12 months post procedure with repeat intervention required in 50%. This suggests this method may be efficacious for moderate term pain relief. Limitations of the study included small sample size and non-uniform concurrent pain regimens. However, the results are quite promising given the positive response to therapy and the superior safety profile of cryoneurolysis compared to alternative invasive therapies for the treatment of neuropathic pain.

Clinical Pearls


What is the basic pathophysiology of pain generation?


Nociceptors in the tissue convert a noxious stimuli to an electric impulse signaling an efferent nerve. This signal travels to the dorsal root ganglion and ascend centrally via the spinothalamic tract. Glutamate is thought to be involved in signaling at this level. The electrical signaling continues to the thalamus where it then relays the stimulus to various centers in the brain including the primary sensory cortex, periaqueductal grey, amygdala, pons and reticular formation in the brainstem among others. Under normal circumstances, inhibitory pathways in the periaqueductal grey and Lissauer tract release endogenous opioids, norepinephrine (NE), and serotonin mediated by GABA inhibitory neurons to mediate the perceived pain.

What is the pathophysiology of Cryoneurolysis on the peripheral nerve?

Temperatures of at least -30°C causes axonotmesis (disruption of the axon) and results in Wallerian degeneration of the nerve distal and slightly proximal to the induced thermal injury. There is preservation of the perineurium and epineurium and, therefore, regeneration of the nerve may occur over time. According to the authors, some studies show that the time for nerve regeneration is proportional to length of cryoablation.

Questions to Consider


What are other common percutaneous interventions available for neuropathic pain and what are their drawbacks?

Percutaneous nerve blocks are among the most common types of anesthesia for neuropathic pain. This technique typically employs a steroid/analgesic concoction to chemically decrease inflammation and axonal conduction, respectively. Drawbacks include: relatively short term relief, adverse systemic effects of corticosteroids, and possible nerve damage with subsequent neuritis.

Thermal ablation including microwave ablation and radiofrequency ablation/pulsed radiofrequency ablation cause tissue/nerve necrosis at predictable temperatures. Arguably, there is increased risk of thermal injury to potentially sensitive adjacent structures with thermal ablation.

Currently, what are the recommended first, second, and third line options for patients with neuropathic pain?

First line therapies: Tricyclic antidepressants, dual NE and serotonin reuptake inhibitors, calcium channel α2-δ ligands (gabapentin and pregabalin), and topical lidocaine.

Second line therapies: Opioid analgesics and Tramadol

Third line: Bupropion, Citalopram, Paroxetine, Antiepileptic medications, other topical ointments (i.e. capsaicin).

Additional references:
Chen H, Lamer TJ, Rho RH, Marshall KA, Sitzman BT, Ghazi SM, Brewer RP. Contemporary management of neuropathic pain for the primary care physician. Mayo Clin Proc. 2004 Dec;79(12):1533-45.

O'Connor AB, Dworkin RH. Treatment of neuropathic pain: an overview of recent guidelines. Am J Med. 2009 Oct;122(10 Suppl):S22-32.

Post Author:
Lindsay Karr Thornton, MD
SIR RFS Clinical Education Chair
University of Florida

Monday, January 23, 2017

Image-Guided Cryoablation for the Treatment of Phantom Limb Pain in Amputees: A Pilot Study


Phantom limb pain (PLP) affects up to 50-80% of patients with limb loss amputations. This condition is defined by unpleasant, often painful, sensations that are perceived to originate from the amputated limb. Prologo et al present the results of a single-arm pilot study with 21 patients investigating the efficacy of percutaneous cryoneurolysis for treatment of PLP refractory to conventional treatments. The study patients underwent a two-step protocol consisting of initial computed tomography-guided perineural injection with 0.25% bupivacaine and betamethasone. If initial injection improved PLP symptoms, the patients underwent cryoneurolysis at a later date. Study endpoints included changes in pain intensity and functional impairment as measured by a visual analog scale and the Roland Morris Disability Questionnaire, respectively. At 7-days post-cryoablation, pain intensity scores decreased by 0.8 (5.4 versus 6.2) and functional impairment decreased by 1.9 (9.4 versus 11.3) compared to baseline; however, these changes were not statistically significant. At 45-days post-cryoablation, pain intensity scores decreased by 3.9 (2.3 versus 6.2) and functional impairment decreased by 8.0 (3.3 versus 11.3) compared to baseline, and these changes were statistically significant (p<0.0001). There were no statistically significant differences in pain intensity and functional impairment scores between the 45-day post-procedure visit and long-term follow-up visits (194 days +/- 99 days). Four patients volunteered to undergo repeat cryoablation and demonstrated consistent response to the second treatment with respect to both functional impairment and pain intensity score improvement. There was 100% technical success in the study with no reported adverse events related to treatment or participation in the study. Six patients (29%) required additional nonsteroidal anti-inflammatory drugs during the initial days following cryoneurolysis due to procedure related pain.




Commentary

This pilot study by Prologo et al provides preliminary data demonstrating safety and efficacy of cryoneurolysis for reducing refractory phantom limb pain. At 45-days post-treatment, patients demonstrated significant decreases in both pain intensity and functional impairment. The study had 100% technical success and no reported adverse events related to treatment or inclusion in the study. Interestingly, pain in the residual limb was a significant covariate for both baseline pain intensity and response to cryotherapy. Patients with residual limb pain had lower baseline pain and less overall change in pain intensity compared to patients without residual limb pain. This study was limited as a pilot study without a control arm or randomization. In addition, the authors did not collect or evaluate medication logs to determine how treatment affected use of pain control medication. The reported exploratory data; however, supports the design of a larger, parallel-arm randomized controlled trial in the future with more comprehensive outcome measurements. Overall, percutaneous cryoneurolysis has the potential be a safe and effective treatment option for refractory PLP.

Click here for abstract

Prologo JD, Gilliland CA, Miller M, Harkey P, Knight J, Kies D, Hawkins CM, Corn D, Monson DK, Edalat F, Dariushnia S, Brewster L. Percutaneous Image-Guided Cryoablation for the Treatment of Phantom Limb Pain in Amputees: A Pilot Study. J Vasc Interv Radiol. 2017 Jan;28(1):24-34.

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

Thomas J. An, BA
Vanderbilt University School of Medicine

Thursday, January 19, 2017

From the SIR residents and fellows section (RFS)


Teaching Topic: Whether or Not to Use Free Hepatic Vein Pressure to Calculate the Portal Pressure Gradient in Cirrhosis.


Martin Rössle, MD, Philipp Blanke, MD, Benjamin Fritz, MD, Michael Schultheiss, MD, and Dominik Bettinger, MD. Free Hepatic Vein Pressure Is Not Useful to Calculate the Portal Pressure Gradient in Cirrhosis: A Morphologic and Hemodynamic Study. J Vasc Interv Radiol 2016; 27: 1130-1137

Click here for abstract

In a recent study published in JVIR, researchers from the University Hospital Freiburg investigated the role of using free hepatic vein pressure in calculating the hepatic venous pressure gradient. Diameter and pressure measurement were obtained in multiple locations within the hepatic vein, IVC, and right atrium on 30 hepatic venograms in 29 consecutive patients with planned TIPS creation. The authors found a wide range of pressure measurements and diameters across the length of the hepatic vein creating a significant amount of variability in measured pressure gradients that were not reflective of the hemodynamic changes occurring within the portal system. This challenges the current guideline recommendations of measurement in the hepatic vein or the IVC, disregarding the right atrium as an internal reference. The manuscript concludes that using the free hepatic vein pressure (FHVP) to calculate the hepatic vein pressure gradient (HVPG) is not recommended given changes with catheter tip position and vein morphology. However, the high agreement between the wedged hepatic vein/IVC pressure gradient (HCPG) and hepatic atrial pressure gradient (HAPG) suggest that both may be used.

Clinical Pearls


What is the significance of the hepatic venous pressure gradient (HVPG)?

The HVPG is the calculated difference of the wedged hepatic vein pressure (WHVP) from the free hepatic vein pressure (FHVP). A value of more than 10 mm Hg is considered clinically significant portal hypertension. A reduction to less than 12 mm Hg or a reduction of more than 10% from the baseline value is associated with decreased risk of variceal hemorrhage and improved survival. Traditionally, FHVP should be measured close to the hepatic vein orifice within a distance of 4-5 cm of the IVC. When pressure measurement differences of more than 1-2 mm Hg exist between the hepatic vein and the IVC, the pressure measured at the IVC at the level of the entrance of the hepatic veins should be used in place of the FHVP.

This study sought to reevaluate the use of HVPG for several reasons. First, in patients with advanced cirrhosis, hepatic veins may be narrowed, irregular, or compressed. This may result in erroneous measurements with an apparently high FHVP and a low HVPG. Second, postprocedural measurement of the FHVP is difficult or impossible. Therefore, measurements are commonly performed in the IVC or right atrium, which is considered the “sea level” of the vascular system and therefore the natural reference for hemodynamic measurements.

What are the recommendations of the Baveno Consensus Workshop?


The most recent expanded Baveno VI Consensus recommends TIPS within 72 hours (ideally < 24 hours) in patients bleeding from esophageal or gastric varices at high risk of treatment failure (Child class C < 14 points or Child class B with active bleeding) after initial pharmacologic and endoscopic therapy (Class 1b; Level A). Persistent bleeding despite combined pharmacologic and endoscopic therapy is best managed by PTFE-covered TIPS (Class 2b; Level B). Rebleeding during the first five days may be managed by a second attempt at endoscopic therapy. If rebleeding is severe, PTFE-covered TIPS is likely the best option (Class 2b; Level B). New guidelines in this workshop now recommend TIPS for patients with refractory ascites who are intolerant to non-selective beta blockers (NSBB) (Class 5, Level D). TIPS can be considered in patients with transfusion-dependent portal hypertensive gastropathy in whom NSBB and/or endoscopic therapies fail (Class 4; Level C). The stepwise approach to management of Budd-Chiari syndrome/hepatic venous outflow tract obstruction is: anticoagulation, angioplasty/thrombolysis, TIPS, and orthotopic liver transplantation (Class 3b; Level B).

Morning Report Questions


What factors may contribute to the inaccuracy of FHVP measurement?

Aside from narrowed, irregular, or compressed veins in patients with cirrhosis, relative obstruction of a hepatic vein by a catheter may erroneously increase the measured FHVP. In this study, the percentage of vessel obstruction by the 8-F catheter (diameter, 2.4 mm) was 40% in the peripheral position and decreased to 10% in the central (proximal) position. Small hepatic veins with a diameter of < 6 mm have a considerable obstruction of 20% or more irrespective of the location of the tip of the catheter. This study found excellent correlation between the wedged hepatic vein/IVC pressure gradient (HCPG) and the hepatic atrial pressure gradient (HAPG), which justifies using either the IVC or right atrium as internal references to calculate the portosystemic pressure gradient, not the free hepatic venous pressure. If using the HAPG, the systemic difference of 2 mm Hg should be regarded by resetting the threshold for symptomatic portal hypertension at an HAPG of 14 mm Hg.



What concerns exist about the use of the right atrium as an internal reference when calculating the portosystemic pressure gradient?

The authors mention previous studies in which pressure measurement in the right atrium is neglected because changes in intraabdominal pressure may affect the portoatrial pressure gradient but not the portohepatic pressure gradient. Therefore, it can be argued that the portosystemic pressure gradient will be significantly higher when using right atrial pressure as an internal reference as compared to using the hepatic veins or IVC. These studies placed sandbags over the abdomen to mimic high intraabdominal pressure, which led to uniform increase in pressure downstream of the obstruction in the hepatic and portal veins but left the right atrium unaffected or even reduced. The authors argue that increased intraabdominal pressure in patients with true ascites reflects an “open” system and that such increased pressures result in a change in their respective blood pools but may have only a short and limited effect on the intravascular pressure.

Additional Citations:
De Franchis, Roberto. “Report of the Baveno VI Consensus Workshop: Stratifying Risk and Individualizing Care for Portal Hypertension.” Journal of Hepatology. 2015 September; 63(3): 743-752.

Post Author:
Rajat Chand, MD
Diagnostic Radiology Resident, PGY-2
John H. Stroger Hospital of Cook County

Thursday, January 12, 2017

Management of May–Thurner Syndrome in Adolescents 


Although there is a mature body of evidence supporting the safety and efficacy of endovascular intervention for May-Thurner syndrome (MTS) in adults, few studies have described results of intervention in the pediatric population. Goldman et al present a retrospective, single institution study of 10 adolescent patients, ages 12-18 years, who underwent endovascular therapy for MTS between 1998 and 2015. Six patients had pro-thrombotic risk factors including heritable conditions like factor V Leiden and/or oral contraceptive use. Acute deep venous thrombosis (DVT) was the presentation of 6/10 patients, who were treated with catheter-directed thrombolysis (CDT) alone or in combination with pharmacomechanical thrombolysis. The remaining 4/10 presented with symptoms of chronic venous outflow obstruction. All patients (thrombotic and non-thrombotic) were treated with venoplasty and stenting. Stent models included S.M.A.R.T, Wallstent, and Protégé stents, varying between 12-mm-16-mm diameters. Thrombolysis was technically successful in 4/5 patients and stenting was technically successful in 9/10 patients (the last patient did not have available imaging for review). No periprocedural complications were observed. All patients were treated with systemic anticoagulation for at least 3-months following intervention and were followed for median 32-months (range: 6-109 months). The rates of post-thrombotic syndrome (PTS) following intervention was 0% by Villalta score and 60% by modified Villalta score (designed for use in the pediatric population), and all cases with positive PTS were mild in symptom severity. Iliofemoral patency rates at 12-months were 79% (primary) and 100% (secondary), and at 36-months were 79% (primary) and 89% (secondary). One patient with antiphospholipid syndrome and homozygous MTHFR gene mutation, as well as non-adherence to medical anticoagulation presented with occlusive thrombus 14-months after initial intervention, but no invasive therapy was pursued given relatively mild symptoms.



Commentary


Venothromboembolism (VTE) is rare in the pediatric population, and pediatric MTS therefore remains a nascent area of study, for which optimal therapeutic approach is not fully elucidated. The risks for recurrent DVTs, and long-term debility from PTS in the adult MTS population has been well described, and pediatric patients may suffer similar outcomes without treatment. The experience described by Goldman et al suggests that CDT and stenting techniques may be applied with similar efficacy and safety in the adolescent population as the adult population, suggesting that these techniques should be considered in these patients. In particular, the high primary and secondary patency rates at 12 and 36-months compare favorably to those reported in adults. The authors highlighted the challenges to stenting MTS patients with underlying thrombophilic syndromes, which overall had poorer patency outcomes than those without thrombophilic syndromes and included a case of re-occlusion associated with prothromobotic syndrome and non-compliance with anticoagulation regimen. The study was subject to biases of a small patient population, retrospective imaging and clinical assessment, and non-standardized anticoagulation regimens as well as follow-up times. Furthermore, the majority of patients were of adult body habitus so the endovascular techniques and venous patency outcomes cannot be generalized to younger pediatric patients, who still have significant growth potential. Nonetheless, this study bolsters the limited evidence base for endovascular management of MTS in the pediatric population by demonstrating excellent long-term patency rates and safety profile, concordant with results seen in adults and further follow-up studies would be beneficial.

Click here for abstract

Goldman RE, Arendt VA, Kothary N, Kuo WT, Sze DY, Hofmann LV, Lungren MP. Endovascular Management of May-Thurner Syndrome in Adolescents: A Single-Center Experience. J Vasc Interv Radiol. 2017 Jan;28(1):71-77.

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

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