Nathan K. Itoga

The contemporary management of renal artery aneurysms

BACKGROUND Renal artery aneurysms (RAAs) are rare, with little known about their natural history and growth rate or their optimal management. The specific objectives of this study were to (1) define the clinical features of RAAs, including the precise growth rate and risk of rupture, (2) examine the current management and outcomes of RAA treatment using existing guidelines, and (3) examine the appropriateness of current criteria for repair of asymptomatic RAAs. METHODS A standardized, multi-institutional approach was used to evaluate patients with RAAs at institutions from all regions of the United States. Patient demographics, aneurysm characteristics, aneurysm imaging, conservative and operative management, postoperative complications, and follow-up data were collected. RESULTS A total of 865 RAAs in 760 patients were identified at 16 institutions. Of these, 75% were asymptomatic; symptomatic patients had difficult-to-control hypertension (10%), flank pain (6%), hematuria (4%), and abdominal pain (2%). The RAAs had a mean maximum diameter of 1.5 ± 0.1 cm. Most were unilateral (96%), on the right side (61%), saccular (87%), and calcified (56%). Elective repair was performed in 213 patients with 241 RAAs, usually for symptoms or size >2 cm; the remaining 547 patients with 624 RAAs were observed. Major operative complications occurred in 10%, including multisystem organ failure, myocardial infarction, and renal failure requiring dialysis. RAA repair for difficult-to-control hypertension cured 32% of patients and improved it in 26%. Three patients had ruptured RAA; all were transferred from other hospitals and underwent emergency repair, with no deaths. Conservatively treated patients were monitored for a mean of 49 months, with no acute complications. Aneurysm growth rate was 0.086 cm/y, with no difference between calcified and noncalcified aneurysms. CONCLUSIONS This large, contemporary, multi-institutional study demonstrated that asymptomatic RAAs rarely rupture (even when >2 cm), growth rate is 0.086 ± 0.08 cm/y, and calcification does not protect against enlargement. RAA open repair is associated with significant minor morbidity, but rarely a major morbidity or mortality. Aneurysm repair cured or improved hypertension in >50% of patients whose RAA was identified during the workup for difficult-to-control hypertension.

Safety and efficacy of antiplatelet/anticoagulation regimens after Viabahn stent graft treatment for femoropopliteal occlusive disease.

OBJECTIVE We aimed to determine the safety and efficacy of antiplatelet/anticoagulation regimens after placement of Viabahn stent graft (W. L. Gore & Associates, Flagstaff, Ariz) for the treatment of femoropopliteal occlusive disease. METHODS Clinical, angiographic, and procedural data for patients undergoing endovascular treatment of femoropopliteal occlusive disease using Viabahn covered stent grafts at a single institution between 2006 and 2013 were retrospectively reviewed. Graft patency and freedom from thrombolysis, major adverse limb event, and reintervention were determined by Kaplan-Meier analysis. The influence of relevant variables on clinical outcome was determined through univariate and multivariate Cox proportional hazards analyses. RESULTS Viabahn stent grafts were placed in a total of 91 limbs in 61 patients (66% men; mean age, 69 ± 12 years) during the study period. Indication for intervention was either claudication (n = 59) or critical limb ischemia (n = 32), with the majority (70%) classified as TransAtlantic Inter-Society Consensus II C (n = 33) or D (n = 31) lesions. Mean follow-up was 38.3 months (range, 1-91 months). Postprocedural pharmacologic regimens included aspirin, clopidogrel, and warfarin (47%); indefinite aspirin and clopidogrel (46%); or aspirin and temporary clopidogrel (7%). Primary and secondary patency rates were 60%, 44%, and 36% and 95%, 82%, and 74% at 1 year, 3 years, and 5 years, respectively. Kaplan-Meier analysis demonstrated more aggressive antiplatelet/anticoagulation regimens to be associated with improved primary patency and freedom from reintervention. Cox proportional hazards analysis demonstrated TransAtlantic Inter-Society Consensus II D lesions, tobacco use, coronary artery disease, and smaller stent diameter to be independent risk factors for stent graft failure. Bleeding events were limited to those in the aspirin, clopidogrel, and warfarin group (11.6% [n = 5]; P = .052), although the majority of these events were not life-threatening, and only two cases required blood transfusion. CONCLUSIONS Increasingly aggressive antithrombotic regimens after Viabahn stent graft placement trended toward improved overall clinical outcomes, although the marginal patency benefit observed with the addition of warfarin to dual antiplatelet therapy was tempered by an observed increased risk of bleeding complications. Longer term follow-up and multicenter studies are needed to further define optimal type and duration of antithrombotic therapy after endovascular peripheral interventions.

Natural history of gutter-related type Ia endoleaks after snorkel/chimney endovascular aneurysm repair

Objective: Alternative endovascular strategies using parallel or snorkel/chimney (chimney endovascular aneurysm repair [ch‐EVAR]) techniques have been developed to address the lack of widespread availability and manufacturing limitations with branched/fenestrated aortic devices for the treatment of complex abdominal aortic aneurysms. Despite high technical success and midterm patency of snorkel stent configurations, concerns remain regarding the perceived increased incidence of early gutter‐related type Ia endoleaks. We aimed to evaluate the incidence and natural history of gutter‐related type Ia endoleaks following ch‐EVAR. Methods: Review of medical records and available imaging studies, including completion angiography and serial computed tomographic angiography, was performed for all patients undergoing ch‐EVAR at our institution between September 2009 and January 2015. Only procedures involving ≥1 renal artery with or without visceral snorkel stents were included. Primary outcomes of the study were presence and persistence or resolution of early gutter‐related type Ia endoleak. Secondary outcomes included aneurysm sac shrinkage and need for secondary intervention related to the presence of type Ia gutter endoleak. Results: Sixty patients (mean age, 75.8 ± 7.6 years; male, 70.0%) underwent ch‐EVAR with a total of 111 snorkel stents (97 renal [33 bilateral renal], 12 superior mesenteric artery, 2 celiac). A mean of 1.9 ± 0.6 snorkel stents were placed per patient. Early gutter‐related type Ia endoleaks were noted on 30.0% (n = 18) of initial postoperative imaging studies. Follow‐up imaging revealed spontaneous resolution of these gutter endoleaks in 44.3%, 65.2%, and 88.4% of patients at 6, 12, and 18 months postprocedure, respectively. Long‐term anticoagulation, degree of oversizing, stent type and diameter, and other clinical/anatomic variables were not significantly associated with presence of gutter endoleaks. Two patients (3.3%) required secondary intervention related to persistent gutter endoleak. At a mean radiologic follow‐up of 20.9 months, no difference in mean aneurysm sac size change was observed between those with or without early type Ia gutter endoleak (−6.1 ± 10.0 mm vs −4.9 ± 11.5 mm; P = .23). Conclusions: Gutter‐related type Ia endoleaks represent a relatively frequent early occurrence after ch‐EVAR, but appears to resolve spontaneously in the majority of cases during early to midterm follow‐up. Given that few ch‐EVAR patients require reintervention related to gutter endoleaks and the presence of such endoleak did not correlate to increased risk for aneurysm sac growth, its natural history may be more benign than originally expected.

Transposition of the Left Renal Vein for the Treatment of Nutcracker Syndrome in Children: A Short-term Experience

BACKGROUND Nutcracker syndrome is caused by compression of the left renal vein between the superior mesenteric artery and the aorta. Invasive surgical intervention for this pathologic entity is controversial, particularly in the pediatric population. We aim to describe our early clinical and operative experience with such patients. METHODS We report 3 cases of pediatric patients undergoing successful left renal vein transposition for the treatment of nutcracker syndrome. RESULTS All 3 patients were female (age 9-17 years) and presented with a mean of 11.7 months of abdominal or left flank pain requiring chronic narcotic analgesia. Initial clinical presentations were associated with either hematuria or proteinuria. Diagnosis of nutcracker syndrome was supported in each case by an elevated renocaval pressure gradient and/or axial imaging demonstrating mesoaortic compression of the left renal vein. All patients underwent open surgical repair, which included left renal vein transposition, liberation of the ligament of Treitz and associated adhesions, as well as excision of periaortic nodal tissue (mean hospital length of stay 5.7 days). After mean follow-up of 13 months, all patients report complete resolution of symptoms and hematuria/proteinuria. CONCLUSIONS Transposition of the left renal vein is a safe and effective treatment for nutcracker syndrome in appropriately selected pediatric patients. Further experience and long-term follow-up are warranted to better evaluate the sustained efficacy of this procedure in this unique patient population.

Outcomes of Endovascular Repair of Aortoiliac Aneurysms and Analyses of Anatomic Suitability for Internal Iliac Artery Preserving Devices in Japanese Patients.

BACKGROUND Understanding that the common iliac arteries (CIA) are shorter in Asian patients, we investigated whether this anatomic difference affects the clinical outcomes of internal iliac artery (IIA) exclusion during endovascular aneurysm repair (EVAR) of aortoiliac aneurysm and thus limits the use of IIA-preserving devices in Japanese patients.Methods and Results:From 2008 to 2014, 69 Japanese patients underwent EVAR of aortoiliac aneurysms with 53 unilateral and 16 bilateral IIA exclusions. One patient had persistent buttock claudication during follow-up; however, colonic or spinal cord ischemia was not observed. Anatomic suitability was investigated for the iliac branch device (IBD) by Cook Medical and the iliac branch endoprosthesis (IBE) by WL Gore: 87 aortoiliac segments were analyzed, of which 17% met the criteria for the IBD, 25% met the criteria for the IBE and 40% met the criteria for either. Main exclusions for the IBD were IIA diameter >9 mm or <6 mm (47%) and CIA length <50 mm (39%). Main exclusions for the IBE were proximal CIA diameter <17 mm (44%) and aortoiliac length <165 mm (24%). CONCLUSIONS EVAR with IIA exclusions in Japanese patients showed low incidence of persistent buttock claudication and no major pelvic complications. Aorto-iliac morphology demonstrated smaller proximal CIA diameters and shorter CIA lengths, limiting the use of IIA-preserving devices.

Cost-effectiveness analysis of asymptomatic peripheral artery disease screening with the ABI test:

Screening for asymptomatic peripheral artery disease (aPAD) with the ankle–brachial index (ABI) test is hypothesized to reduce disease progression and cardiovascular (CV) events by identifying individuals who may benefit from early initiation of medical therapy. Using a Markov model, we evaluated the cost effectiveness of initiating medical therapy (e.g. statin and ACE-inhibitor) after a positive ankle–brachial index (ABI) screen in 65-year-old patients. We modeled progression to symptomatic PAD (sPAD) and CV events with and without ABI screening, evaluating differences in costs and quality-adjusted life years (QALYs). The cost of the ABI test, physician visit, new medication, CV events, and interventions for sPAD were incorporated in the model. We performed sensitivity analysis on model variables with uncertainty. Our model found an incremental cost of US

Association of Blood Pressure Measurements with Peripheral Arterial Disease Events: A Reanalysis of the ALLHAT Data

338 and an incremental QALY of 0.00380 with one-time ABI screening, resulting in an incremental cost-effectiveness ratio (ICER) of

Ruptured Pseudoaneurysm of the Dorsalis Pedis Artery Following Ankle Arthroscopy

88,758/QALY over a 35-year period. The variables with the largest effects in the ICER were aPAD disease prevalence, cost of monthly medication after a positive screen and 2-year medication adherence rates. Screening high-risk populations, such as tobacco users, where the prevalence of PAD may be 2.5 times higher, decreases the ICER to

Giant Abdominal Aortic Aneurysms: A Case Series and Review of the Literature.

24,092/QALY. Our analysis indicates the cost effectiveness of one-time screening for aPAD depends on prevalence, medication costs, and adherence to therapies for CV disease risk reduction. Screening in higher-risk populations under favorable assumptions about medication adherence results in the most favorable cost effectiveness, but limitations in the primary data preclude definitive assessment of cost effectiveness.

Comparison of Bovine Carotid Xenograft Versus Expanded Polytetrafluoroethylene Grafts for Forearm Loop Hemodialysis Access

Background: Current guidelines recommend treating hypertension in patients with peripheral artery disease (PAD) to reduce the risk of cardiac events and stroke, but the effect of reducing blood pressure on lower extremity PAD events is largely unknown. We investigated the association of blood pressure with lower extremity PAD events using data from the ALLHAT trial (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial). Methods: ALLHAT investigated the effect of different antihypertensive medication classes (chlorthalidone, amlodipine, lisinopril, or doxazosin) on cardiovascular events. With the use of these data, the primary outcome in our analysis was time to first lower extremity PAD event, defined as PAD-related hospitalization, procedures, medical treatment, or PAD-related death. Given the availability of longitudinal standardized blood pressure measurements, we analyzed systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure as time-varying categorical variables (reference categories 120–129 mm Hg for SBP, 70–79 mm Hg for DBP, and 45–54 mm Hg for pulse pressure) in separate models. We used extended Cox regression with death as a competing risk to calculate the association of each blood pressure component with PAD events, and report the results as subdistribution hazard ratios and 95% CIs. Results: The present analysis included 33 357 patients with an average age of 67.4 years, 53.1% men, 59.7% white race, and 36.2% with diabetes mellitus. The median baseline blood pressure was 146/84 mm Hg. Participants were followed for a median of 4.3 (interquartile range, 3.6–5.3) years, during which time 1489 (4.5%) had a lower extremity PAD event, and 4148 (12.4%) died. In models adjusted for demographic and clinical characteristics, SBP <120 mm Hg was associated with a 26% (CI, 5%–52%; P=0.015) higher hazard and SBP≥160 mm Hg was associated with a 21% (CI, 0%–48%; P=0.050) higher hazard for a PAD event, in comparison with SBP 120 to 129 mm Hg. In contrast, lower, but not higher, DBP was associated with a higher hazard of PAD events: for DBP <60 mm Hg (hazard ratio, 1.72; CI, 1.38–2.16). Pulse pressure had a U-shaped association with PAD events. Conclusions: In this reanalysis of data from ALLHAT, we found a higher rate of lower extremity PAD events with higher and lower SBP and pulse pressure and with lower DBP. Given the recent revised blood pressure guidelines advocating lower SBP targets for overall cardiovascular risk reduction, further refinement of optimal blood pressure targets specific to PAD is needed. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00000542.