The intracranial effects of flow reversal during transcarotid artery revascularization.

Background: This study aimed to assess intraoperative cerebral hemodynamic responses and embolic events during transcarotid artery revascularization via transcranial Doppler, near-infrared spectroscopy, and bispectral index monitoring. Methods: Twelve patients (7 males, 5 females; mean age: 72.8±9.0 years; range, 63 to 91 years) undergoing transcarotid artery revascularization with simultaneous transcranial Doppler, near-infrared spectroscopy, and bispectral index monitoring were analyzed in this retrospective study between September 2017 and December 2019. The mean flow velocity and pulsatility index of the middle cerebral artery, alongside near-infrared spectroscopy and bispectral index values, before flow reversal, during flow reversal, and after flow reversal phases were investigated. The presence and frequency of high-intensity transient signals were recorded to evaluate embolic incidents. Results: Significant reductions in middle cerebral artery mean flow velocity were noted during flow reversal (40.58±10.57 cm/sec to 20.58±14.34 cm/sec, p=0.0004), which subsequently returned to and exceeded baseline values after flow reversal cessation (53.33±17.69 cm/sec, p=0.0005). Near-infrared spectroscopy (71±4.4% to 66±6.2%) and bispectral index (45.71±8.5 to 40.14±8.1) values mirrored these hemodynamic changes, with notable decreases during flow reversal, and recoveries after flow reversal. The highest concentration of high-intensity transient signals was observed during stent deployment, signifying a critical embolic phase. No perioperative neurological complications or other significant adverse events were documented. Conclusion: Transcranial Doppler, near-infrared spectroscopy, and bispectral index effectively monitor cerebral hemodynamics and embolic potential during transcarotid artery revascularization, providing real-time data crucial for optimizing perioperative management. These findings underscore the clinical value of multimodal monitoring in improving patient outcomes in transcarotid artery revascularization procedures.

Dynamic Computed Tomography Angiography is More Accurate in Diagnosing Endoleaks than Standard Triphasic Computed Tomography Angiography and Enables Targeted Embolization.

BACKGROUND: The primary objective was to compare the accuracy of dynamic computed tomography (CT) angiography (d-CTA) with standardized triphasic contrast enhanced CT angiography (t-CTA) in diagnosing endoleak type after endovascular aortic repair (EVAR) using digital subtraction angiography (DSA) as reference standard. The secondary objective was to study the impact of d-CTA on image fusion-guided endoleak embolization. METHODS: A retrospective review of patients who underwent d-CTA imaging after EVAR between March 2019 and July 2021 was performed. Deidentified images were independently reviewed by two-two blinded readers to document endoleak type and target vessels. An impact of d-CTA-guided embolization was evaluated by a number of planning angiograms, radiation exposure, and accuracy of target vessel overlay. RESULTS: During the study period, 52 patients underwent d-CTA and 19 had all 3 modalities available for analysis. DSA imaging confirmed 4 (21.0%) type-I, 14 (73.7%) type-II, and 1 (5.3%) type-III endoleak. Findings from d-CTA matched with DSA in 19/19 cases (100%), whereas t-CTA matched in 14/19 cases (73.7%). In type-II endoleaks, the number of target vessels identified by d-CTA, t-CTA, and DSA were 23, 17, and 16, respectively. Mean dose-length product from d-CTA and t-CTA was 1,445 ± 551 and 1,612 ± 530 mGy × cm (P = 0.26). Nine patients underwent d-CTA-guided type-II endoleak embolization, using a median of 1 (range: 1-4) planning angiogram before embolization using 21.6 (± 8.7)% of total procedural radiation dose. Target vessel overlay was accurate in 9/9 (100%) cases. CONCLUSIONS: Dynamic, time-resolved CTA is more accurate compared to standardized triphasic contrast enhanced CTA in diagnosing endoleak type after EVAR. In type-II endoleak, d-CTA better identified target vessels and enabled safe, targeted embolization.

Dynamic, Time-Resolved CT Angiography After EVAR: A Quantitative Approach to Accurately Characterize Aortic Endoleak Type and Identify Inflow Vessels.

PURPOSE: Our purpose was to study the accuracy of dynamic computed tomography angiography (d-CTA) in characterizing endoleak type, inflow vessels as compared with digital subtraction angiography (DSA) using qualitative and quantitative analysis. METHODS: Between March 2019 and January 2021, all patients who underwent d-CTA imaging after EVAR were retrospectively reviewed. Two blinded independent reviewers qualitatively reviewed d-CTA and DSA images. Quantitative region of interest (ROI) analysis was performed by measuring time-resolved contrast enhancement within the aorta and endoleak lesion(s) in the aneurysm sac. Differences between time-to-peak enhancement (Δ TTP) across different ROIs were quantified. RESULTS: A total of 48 patients underwent d-CTA during the study period, of whom 24 patients had abdominal EVAR and DSA imaging for comparison. Qualitative review of DSA imaging showed type I (n=4), type II (n=16), and type III (n=2) and no endoleak (n=2). In 23 of 24 patients (95.8%), d-CTA findings correlated with DSA findings for endoleak type. One patient had a type III endoleak that was demonstrated only in d-CTA (arising from defect in polymer sealing ring of Ovation stent graft) imaging. In type II endoleak cases, d-CTA identified more inflow vessels than DSA imaging (33 vs 21 vessels, p=0.010). Quantitative analysis showed mean (±SD) Δ TTP values for type I endoleak as 1.8 (±1.8) seconds, type II as 9.6 (±3.5) seconds, and for type III endoleak as 5.6 (±1.3) seconds. CONCLUSION: Dynamic CTA can accurately characterize aortic endoleak type, inflow vessels as compared with DSA imaging. Quantitative parameters such as Δ TTP enhancement can help better differentiate endoleak types and provide an objective approach to endoleak diagnosis.

Added Value of Selective Intra-arterial Cone-Beam CT Angiography in the Management of Visceral Artery Aneurysms.

PURPOSE: The aim of this study is to evaluate the value of selective intra-arterial cone-beam computed tomography angiography (CBCTA) relative to conventional computed tomography angiography (CTA) in understanding visceral artery aneurysm (VAA) morphology, and its impact on treatment planning. MATERIALS AND METHODS: Between January 2017 and August 2021, all patients who had a diagnosis of VAA and underwent intraoperative CBCTA imaging were retrospectively reviewed. Impact on treatment decisions, optimal C-arm angulations derived from CBCTA, and additional radiation exposure were reported. Two blinded independent reviewers qualitatively reviewed CBCTA and conventional CTA images. A 5-point Likert scale (1=poor image quality, 5=excellent image quality) was used to assess the overall image quality of each modality. Number of vessels arising from the aneurysm sac was counted. RESULTS: A total of 16 patients had a diagnosis of VAA during the study period, of whom 10 patients had intraoperative CBCTA and conventional CTA available for review. Out of 10 patients, 7 underwent successful endovascular treatment, 2 were deemed not amenable for endovascular embolization based on intraoperative CBCTA findings, and 1 had resolved pseudoaneurysm. Total fluoroscopy time and radiation dose (dose area product [DAP] and skin dose) for all procedures were 27.7 ± 19.9 minutes, 28 362 (±18 651) µGy*m2, and 1879 (±1734) mGy, respectively. Radiation exposure from CBCTA (DAP and skin dose) was 5703 (±3967) µGy*m2 and 223.6 (±141.3) mGy, respectively. In patients who underwent endovascular treatment, the proportional DAP from CBCTA was 18.3% (±15.3%) of the total procedural radiation dose. Qualitative rating of overall image quality of CBCTA images was superior to CTA images (mean score: 4.55 vs 3, p<0.001). More branch vessels arising from the VAA were identified by all reviewers in CBCTA as compared with conventional CTA (median, min-max: 3, 0-4 vs 2,1-3 vessels). CONCLUSION: Intraoperative CBCTA after selective intra-arterial contrast injection, with better spatial resolution, provided better delineation of visceral aneurysm morphology as compared with conventional, intravenous CTA and enabled optimal treatment planning at a reasonable additional radiation exposure. CLINICAL IMPACT: Visceral artery aneurysms (VAA) are often diagnosed incidentally by conventional computed tomographic angiography (CTA). Endovascular treatment typically requires selective angiographies at multiple projections to better understand aneurysm morphology, location, and efferent branch vessels. Intra-arterial cone-beam CT angiography (CBCTA) for VAA has the advantage of selective contrast opacification, better spatial resolution, and three-dimensional/multi-planar visualization of aneurysm morphology. In addition, CBCTA enables identification of optimal C-arm working projection for subsequent endovascular treatment. The aim of this study is to evaluate the value of intraoperative CBCTA relative to conventional CTA in understanding visceral artery aneurysm morphology and its impact on treatment planning.

Dynamic, Time-Resolved Computed Tomography Angiography Technique to Characterize Aortic Endoleak Type, Inflow and Provide Guidance for Targeted Treatment.

PURPOSE: To illustrate dynamic, time-resolved CTA (d-CTA) imaging technique in characterizing aortic endoleak type/inflow using quantitative parameters and its value in providing image guidance for targeted treatment approach. TECHNIQUE: Dedicated endoleak protocol involved acquiring multiple time-resolved contrast enhanced scans using third-generation CT scanner (Somatom Force®, Siemens Healthineers). Parameters such as scan field of view (FOV), kV, number/timing of scans were customized based on patient's body-mass-index, timing bolus, and prior imaging findings. D-CTA image datasets were evaluated qualitatively and quantitatively using time-attenuation curves (TAC) analysis after motion correction using a dedicated software (syngo.via®, Siemens). D-CTA findings from 4 illustrative cases demonstrating type I, type II (inferior mesenteric and lumbar artery inflow), and type III endoleak were illustrated. TAC analysis with time to peak parameter enabled better characterization of endoleak type and inflow. During endoleak intervention, target vessels from d-CTA images were electronically annotated and overlaid on fluoroscopy using 2D-3D image fusion to provide image guidance for targeted treatment. CONCLUSION: D-CTA imaging with TAC analysis characterizes aortic endoleak type and inflow, in addition to providing image guidance for targeted endoleak treatment. Such dynamic, time-resolved imaging techniques may provide further insights into understanding aortic endoleak that remains an Achilles heel for endovascular aortic aneurysm repair.

CT-Guided Endovascular Exclusion of Pseudoaneurysmal Subclavian Bypass After Early-Age Surgical Correction of Complex Aortic Coarctation.

We describe a 64-year-old woman with subclavian pseudoaneurysm after aortic coarctation repair, treated using a hybrid approach involving true three-dimensional analysis and image fusion-guided placement of thoracic endovascular aortic repair stents. This case illustrates the potential complications of coarctation repair and need for lifelong surveillance in these patients. (Level of Difficulty: Advanced.).

Stent Grafts Can Convert Unusable Upper Arm Arteriovenous Fistulas into a Functioning Hemodialysis Access: A Retrospective Case Series.

INTRODUCTION: Not all newly created arteriovenous fistulas (AVFs) successfully mature and develop into a functioning access for hemodialysis. Percutaneous transluminal angioplasty (PTA) and balloon-assisted maturation (BAM) have been utilized to either treat flow-limiting stenoses or to promote and accelerate maturation. We hypothesized that unusable upper arm AVFs can be rescued by conversion to a functional access using the percutaneous placement of a stent graft (SG). METHODS: Clinical data on 12 patients with an early non-usable upper arm AVF underwent percutaneous revision using SGs. There were six brachial-cephalic, three brachial-basilic, and three brachial-brachial vein transposition AVFs. RESULTS: All patients had either at least two or more stenoses (>2 cm) within the fistula conduit, or a long segment stenosis (>4 cm) in combination with shorter segment stenoses. Nine patients had failed PTA. Three patients had failed BAM at outside access centers. All patients were referred for failure to achieve access cannulation and concomitant hemodialysis through the AVF. SGs were placed retrograde toward the arterial anastomoses and ranged in diameter (6, 7, and 8 mm in four, seven, and one patients, respectively). The average length of the SG was 10 cm (range 5-15 cm). All SGs were post-balloon dilated at the time of placement. All AVFs were salvaged, and patients were able to maintain functional use of their access with cannulation occurring through the SG. The primary patency rate at 6 and 12 months was 91% [95% confidence interval (CI), 56-98%] and 65% (95% CI, 32-87%), respectively (n = 11 and 5 at risk, respectively). The secondary patency rate at 6 and 12 months was 100 and 72% (95% CI, 46-93%), respectively (n = 11 and 7 at risk, respectively). CONCLUSION: This report outlines a successful initial experience using SGs to rescue, preserve, and convert an unusable upper arm AVF into a functioning hemodialysis access.

Current efficacy of open and endovascular interventions for advanced superficial femoral artery occlusive disease.

BACKGROUND: There has been a marked paradigm shift in the treatment of symptomatic femoro-popliteal disease with a shift from open to endoluminal therapy. The consequence of this shift in therapy is poorly described. The aim of this study is to examine the clinical efficacy of this shift in treatment strategies. METHODS: A database of patients undergoing open (OPEN) and endoluminal (ENDO) intervention for TASC II C and D femoro-popliteal lesions between 1990 and 2010 was retrospectively queried. Kaplan-Meier survival analyses were performed to assess time-dependent outcomes. Factor analyses were performed using a multivariant Cox proportional hazard model for time-dependent variables. RESULTS: A total of 2593 limbs underwent either OPEN or ENDO treatment for symptomatic and anatomically advanced femoro-popliteal disease over a 20-year period. There was a two-fold rise in endovascular interventions between the first and second decade. In the first decade, 80% of the interventions were OPEN, while in the second decade, 61% of the interventions were ENDO. There were equivalent comorbidities in both groups, and survival was also equivalent. Endoluminal therapy was more commonly performed on claudicants. Thirty-day mortality was equivalent, but major morbidity was higher in OPEN compared with ENDO. Cumulative patency was equivalent in both groups with a similar reintervention rate. In contrast, clinical efficacy (freedom from recurrent symptoms, maintenance of ambulation, and avoidance of major amputation) was significantly higher in the OPEN group (P = .002). The presence of critical limb ischemia, diabetes, end-stage renal disease, and poor tibial runoff were predictors of poor anatomic and functional outcomes in both groups. CONCLUSIONS: There has been a marked shift in treatment modality for advanced femoro-popliteal disease with a lowering of the symptomatic threshold for intervention over 2 decades, likely spurred by the ease of endoluminal interventions. Although peri-procedural and anatomic outcomes for both procedures are equivalent, it appears that open surgery carries a superior long-term clinical efficacy. This superiority is negatively influenced by poor preoperative ambulation status, high modified Cardiac Risk Score, worse presenting symptoms, the occurrence of major adverse cardiovascular events, poor tibial runoff, the absence of hemodynamic success, and occlusion of the original bypass.

Volume Flow Measurements in Arteriovenous Dialysis Access in Patients with and without Steal Syndrome.

Introduction. Dialysis associated steal syndrome (DASS) constitutes a serious risk for patients undergoing vascular access operations. We aim to assess the measured volume flow using ultrasound in patients with clinically suspected steal syndrome and determine differences in flow among types of arteriovenous (AV) access. Methods. Patients with permanent hemodialysis access with and without ischemic steal underwent duplex ultrasound (US) exams for the assessment of volume flow and quantitative evidence of hemodynamic steal. Volume flow was measured in the proximal feeding artery. Results. 118 patients underwent US of which 82 (69.5%) had clinical evidence of steal. Women were more likely to develop steal compared to men (chi-squared test P < 0.04). Mean volume flow in patients with steal was 1542 mL/min compared to 1087 mL/min (P < 0.002) in patients without evidence of steal. A significant difference in flow volumes in patients with and without steal was only seen in patients with a brachial-cephalic upper arm AV fistula (AVF) (P < 0.002). When comparing different types of access with steal, brachial-cephalic upper arm AVFs had higher volume flows than the upper extremity AV graft (AVG) group (P = 0.04). Conclusion. In patients with DASS, women were more likely to develop steal syndrome. Significantly higher volume flows were seen with brachial-cephalic upper arm AVF in patients with steal compared to those without. A physiologic basis of this US finding may be present, which warrants further study into the dynamics of flow and its relationship to the underlying peripheral arterial pathology in the development of ischemic steal.

A longitudinal view of improved management strategies and outcomes after iatrogenic iliac artery rupture during endovascular aneurysm repair.

BACKGROUND: Intraoperative rupture of the iliac artery is a serious complication of endovascular aneurysm repair (EVAR), the outcomes of which have changed with increasing experience and improved endovascular tools over the past 2 decades. Over the past 15 years, the incidence and management of iliac rupture has changed as devices have improved and experience has grown. This study reviews our longitudinal experience with this complication. METHODS: All cases of iliac artery rupture during EVAR from 1997 through 2011 were reviewed for presentation, treatment strategies, and outcomes. RESULTS: Iliac artery rupture complicated 20 (3%) of 707 EVARs performed. Sixteen (80%) common and four (20%) external iliac arteries were ruptured. Hypotension (systolic blood pressure: <90 mm Hg) was present in 11 (55%) cases. Five open bypasses were performed (25%), whereas 15 were repaired using an endovascular approach (75%). All open repairs (100%) were associated with postoperative morbidity (one wound infection, four multiorgan system failure), whereas three of the 15 patients (23%) repaired endovascularly experienced postoperative morbidity (cerebrovascular accident, myocardial infarction, line infection). There were no intraoperative deaths. There were four (20%) early deaths in the intensive care unit (<3 days postoperatively), all of which were associated with resection of bilateral hypogastric arteries and were due to complications of pelvic ischemia and/or multiorgan system failure. CONCLUSIONS: Iliac artery rupture remains relatively uncommon but can carry a high morbidity and mortality. As device technology, imaging quality for preoperative planning, and experience level have improved, iliac rupture has become less common, and outcomes in the setting of iliac rupture have significantly improved. Endoluminal management has evolved as the primary treatment strategy. Resection of both hypogastric arteries is associated with mortality from pelvic ischemia, a likely indicator of systemic disease.