Fahad Shuja

A novel tool for three-dimensional roadmapping reduces radiation exposure and contrast agent dose in complex endovascular interventions

OBJECTIVEnThe volume and complexity of endovascular procedures are increasing. Multidetector computed tomography (CT) made precise three-dimensional (3D) planning of these procedures possible, but intraoperative imaging, even with the use of modern flat-panel detectors, is limited to two dimensions. Flat detectors, however, allow C-arm cone-beam CT. This technology can be used to generate a 3D data set that can be fused with a preoperative high-resolution CT scan, thus generating a live 3D roadmap. We hypothesized that use of a novel image fusion software, VesselNavigator (Philips Healthcare, Best, The Netherlands), facilitates precise and expeditious procedures and therefore reduces radiation exposure and contrast agent dose.nnnMETHODSnA retrospective review of patients undergoing standard aortobi-iliac endovascular aneurysm repair at our institution between January 2011 and April 2014 was performed. Conventional imaging was compared with VesselNavigator-assisted imaging, and a matched analysis based on body mass index (BMI) was performed because of the dependence of radiation dose on body habitus. Outcome parameters were procedure time, fluoroscopy time, radiation, and contrast agent dose.nnnRESULTSnA total of 75 patients were identified. After matching based on BMI, control and VesselNavigator groups each had 16 patients with BMI of 27.0 ± 3.6 kg/m(2) and 27.0 ± 3.6 kg/m(2), respectively (mean ± standard deviation). R(2) was 6.37 × 10(-7). Radiation dose measured as air kerma was lower with VesselNavigator (1067 ± 470.4 mGy vs 1768 ± 696.2 mGy; P = .004). Fluoroscopy time was shorter (18.4 ± 6.8 minutes vs 26.8 ± 10.0 minutes; P = .01) and contrast agent dose was lower (37.4 ± 21.3 mL vs 77.3 ± 23.0 mL; P < .001) with VesselNavigator compared with control. Procedure time was also shorter with VesselNavigator (80.4 ± 21.2 minutes vs 110.0 ± 29.1 minutes; P = .005).nnnCONCLUSIONSnImage fusion using VesselNavigator enhances the functionality of conventional fluoroscopy in standard endovascular aneurysm repair. It reduces radiation exposure to patients and providers. It also limits the amount of contrast agent and shortens the overall procedure length. The benefit of this technology is demonstrated on this typically straightforward procedure but may be even more useful for complex procedures.

Comparison of Renal Complications between Endografts with Suprarenal and Infrarenal Fixation

OBJECTIVESnSurgeons have multiple grafts options available for the endovascular treatment of abdominal aortic aneurysm (EVAR), and some hypothesize that suprarenal fixation endografts may result in higher rates of renal complications than infrarenal endografts. This study aimed to compare the outcomes of contemporary suprarenal and infrarenal endografts.nnnMETHODSnThe Targeted Vascular Module of the National Surgical Quality Improvement Project was utilised to identify patients undergoing EVAR for infrarenal aneurysm from 2011 to 2013. Pre-operative and operative variables and 30 day outcomes were compared among suprarenal (Zenith and Endurant) and infrarenal fixation devices (Excluder). Renal complications included creatinine increase > 2xa0mg/dL or new dialysis, as defined by NSQIP. Multivariate regression was completed to account for patient demographics, comorbidities, and operative characteristics.nnnRESULTSnA total of 3587 patients were evaluated including 2273 (63%) with suprarenal grafts and 1314 (37%) with infrarenal grafts. Patients with suprarenal grafts were less commonly white (84% vs. 88%, pxa0<xa0.01) and more commonly male (83% vs. 80%, pxa0=xa0.03). There were no differences in age or comorbidities. Renal complications (1.1% vs. 0.1%, pxa0<xa0.01) and length of stay more than 2 days (34% vs. 25%, pxa0<xa0.01) occurred more commonly after suprarenal fixation. After adjustment, suprarenal grafts had significantly higher rates of renal complications (OR, 12.0; 95% CI, 1.6-91) and length of stay more than 2 days (OR, 1.4; 95% CI, 1.2-1.7).nnnCONCLUSIONnOverall rates of renal complications following EVAR are low. Patients selected for suprarenal stent grafts are at increased risk of renal complications and prolonged length of stay, which may be due to selection bias, deployment techniques, or the presence of a bare stent overlying the renal arteries. Further studies are necessary to evaluate the mechanism and duration of renal dysfunction and important long-term outcomes of interest.

Development of a risk prediction model for transfusion in carotid endarterectomy and demonstration of cost-saving potential by avoidance of "type and screen".

OBJECTIVEnPreoperative testing for carotid endarterectomy (CEA) often includes blood typing and antibody screen (T&S). In our institutional experience, however, transfusion for CEA is rare. We assessed transfusion rate and risk factors in a national clinical database to identify a cohort of patients in whom T&S can safely be avoided with the potential for substantial cost savings.nnnMETHODSnWith use of the National Surgical Quality Improvement Program database, transfusion events and timing were established for all elective CEAs in 2012-2013. Comorbidities and other characteristics were compared for patients receiving intraoperative or postoperative transfusion and those who did not. After random assignment of the total data to either a training or validation set, a prediction model for transfusion risk was created and subsequently validated.nnnRESULTSnOf 16,043 patients undergoing CEA in 2012-2013, 276 received at least one transfusion before discharge (1.7%); 42% of transfusions occurred on the day of surgery. Preoperative hematocritxa0<30% (odds ratio [OR], 57.4; 95% confidence interval [CI], 29.6-111.1), history of congestive heart failure (OR, 2.8; 95% CI, 1.1-7.1), dependent functional status (OR, 2.7; 95% CI, 1.5-5.1), coagulopathy (OR, 2.5; 95% CI, 1.7-3.6), creatinine concentration ≥1.2xa0mg/dL (OR, 2.3; 95% CI, 1.6-3.3), preoperative dyspnea (OR, 2.0; 95% CI, 1.4-3.1), and female gender (OR, 1.6; 95% CI, 1.1-2.3) predicted transfusion. A risk prediction model based on these data produced a C statistic of 0.85; application of this model to the validation set demonstrated a C statistic of 0.81. In the validation set, 93% of patients received a score of 6 or less, corresponding to an individual predicted transfusion risk of 5% or less. Omitting a T&S in these patients would generate a substantial annual cost saving for National Surgical Quality Improvement Program hospitals.nnnCONCLUSIONSnWhereas T&S are commonly performed for patients undergoing CEA, transfusion after CEA is rare and well predicted by a transfusion risk score. Avoidance of T&S in this low-risk population provides a substantial cost-saving opportunity without compromise of patient care.

Superior mesenteric artery stenting using embolic protection device for treatment of acute or chronic mesenteric ischemia

Objective: The objective of the study was to report the feasibility and results of superior mesenteric artery (SMA) stenting using embolic protection devices (EPDs) to treat acute mesenteric ischemia (AMI) and chronic mesenteric ischemia (CMI). Methods: A retrospective review was conducted of consecutive patients who underwent SMA stenting with EPDs from 2007 to 2016. EPDs were used selectively in patients with occlusions, severe calcification, or acute thrombus. A two‐wire technique with SpiderFX 0.014‐inch filter wire (Medtronic, Minneapolis, Minn) combined with a 0.018‐inch wire was used to provide support and to facilitate stenting and EPD retrieval. Presence of macroscopic debris in the EPD was recorded and graded as minor (minimal debris) or major (large thrombus or plaque). End points were technical success, presence of EPD debris, embolization, early morbidity, and mortality. Results: SMA stenting was performed in 179 patients, of whom 65 (36%) had EPDs. The mean age was 73 ± 11 years, and 49 were female (75%). Clinical presentation was CMI in 48 patients (74%) and AMI or acute‐on‐CMI in 17 (26%). Indications for EPD were severe calcification in 22 patients (34%), acute thrombus in 18 (28%), and total occlusion in 16 (25%). Bare‐metal stents were used in 33 patients, covered stents in 26, and both types in 6. Adjunctive therapy included thrombolysis in seven patients, thrombectomy in four, and atherectomy in three. Technical success was 100%. There were no instances of filter retention or arterial trauma due to filter manipulation. Distal embolization was noted in four patients (6%), of whom two had AMI. All large emboli were retrieved using catheter aspiration devices, but one small distal embolus was left untreated with no clinical consequences. Two patients had vessel spasm treated by nitroglycerin. Macroscopic debris was noted in 43 patients (66%) and was major in 21 (49%) or minor in 22 (51%). Of the patients with AMI, five (29%) required exploratory laparotomy and four (23%) had bowel resection. Eight additional patients (12%) had early complications (five CMI, three AMI), including cardiac complications, brachial hematoma, acute cholecystitis, and acute respiratory distress syndrome in two patients each. There were no deaths among CMI patients and two early deaths (12%) among those who had AMI. Conclusions: Use of EPDs during SMA stenting is safe and feasible with a two‐wire technique. Large macroscopic debris was noted in one‐third of the patients when the filter was applied selectively in patients with acute symptoms, occlusions, or severely calcified lesions. Despite the use of EPD, distal embolization occurred in 6% of patients and was successfully treated using catheter aspiration devices. Graphical abstract: Figure. No caption available.

Modern Fixed Imaging Systems Reduce Radiation Exposure to Patients and Providers

High-definition fluoroscopic imaging is required to perform endovascular procedures safely and precisely, especially in complex cases, resulting in longer procedures and increased radiation exposure. This is of importance for training institutions as trainees, even with sound instruction in as low as reasonably achievable (ALARA) principles, tend to have high radiation exposures. Recently, there was an upgrade in the imaging system allowing for comparison of radiation exposure to patients and providers. We performed an analysis of consecutive endovascular aneurysm repair (EVAR) and superficial femoral artery (SFA) interventions in the years 2013 to 2014. We recorded body mass index (BMI) and fluoroscopy time (FT) and subsequently matched 1:1 based on BMI, FT, or both. We determined radiation dose using air kerma (AK) and also recorded individual surgeons’ badge readings. Allura Xper FD20 was upgraded to AlluraClarity with ClarityIQ. We identified a total of 77 EVARs (52 pre and 25 post) and 134 SFA interventions (99 pre and 35 post). Unmatched results for EVAR were BMI pre 26.2 versus post 25.8 (kg/m2, P = .325), FT 28.1 versus 21.2 (minutes, P = .051), and AK 1178.5 versus 581 (mGy, P < .001), respectively. After matching, there was a 53.2% reduction in AK (846.1 vs 395.9 mGy; P = .004) for EVAR. Unmatched results for SFA interventions were BMI pre 28.1 versus post 26.6 (P = .327), FT 18.7 versus 16.2 (P = .282), and AK 285.6 versus 106.0 (P < .001), respectively. After matching, there was a 57.0% reduction in AK (305.0 vs 131.3, P < .001). The total deep dose equivalent from surgeons’ badge readings decreased from 39.5 to 17 mrem (P = .029). Aortic and peripheral endovascular interventions can be performed with reduced radiation exposure to patients and providers, employing modern fixed imaging systems with advanced dose reduction technology. This is of particular importance in the light of the increasing volume and complexity of endovascular and hybrid procedures as well as the prospect of decades of radiation exposure during training and practice.

IP235. Transfusion Timing and Postoperative Myocardial Infarction and Death in Patients Undergoing Common Vascular Procedures

Results: In this study, 33 patients (16 diabetic, 17 nondiabetic) who underwent femoral endarterectomy for high-grade occlusive disease were evaluated. No significant difference in key demographics was observed. Tissue plaque FAS content was 69.8% higher in diabetic compared with nondiabetic patients (P 1⁄4 .011); cFAS was also elevated by 41.7% in diabetic patients compared with nondiabetic patients (P 1⁄4 .048). Correlation analysis of 23 patients’ paired samples revealed a significant correlation between cFAS and plaque FAS content (Spearman r 1⁄4 0.4711; r 1⁄4 0.229; P 1⁄4 .023). Conclusions: Our study is the first to evaluate cFAS levels in patients with high-grade, symptomatic, lower extremity peripheral artery disease and demonstrates evidence that cFAS and tissue FAS levels correlate in patients withdiabetes. Future studieswill helpdeterminewhether cFAS is a relevant biomarker for disease severity and progression in diabetic patients.

Image Fusion and 3-Dimensional Roadmapping in Endovascular Surgery

Practitioners of endovascular surgery have historically used 2-dimensional (2D) intraoperative fluoroscopic imaging, with intravascular contrast opacification, to treat complex 3-dimensional (3D) pathology. Recently, major technical developments in intraoperative imaging have made image fusion techniques possible, the creation of a 3D patient-specific vascular roadmap based on preoperative imaging which aligns with intraoperative fluoroscopy, with many potential benefits. First, a 3D model is segmented from preoperative imaging, typically a computed tomography scan. The model is then used to plan for the procedure, with placement of specific markers and storing of C-arm angles that will be used for intraoperative guidance. At the time of the procedure, an intraoperative cone beam computed tomography is performed, and the 3D model is registered to the patients on-table anatomy. Finally, the system is used for live guidance in which the 3D model is codisplayed with overlying fluoroscopic images. There are many applications for image fusion in endovascular surgery. We have found it to be particularly useful for endovascular aneurysm repair (EVAR), complex EVAR, thoracic EVAR, carotid stenting, and for type 2 endoleaks. Image fusion has been shown in various settings to lead to decreased radiation dose, less iodinated contrast use, and shorter procedure times. In the future, fusion models may be able to account for vessel deformation caused by the introduction of stiff wires and devices, and the user-dependent steps may become more automated. In its current form, image fusion has already proven itself to be an essential component in the planning and success of complex endovascular procedures.

Primer in Cerebrovascular Disease: Innominate and Subclavian Disease

Diseases of the subclavian and innominate arteries, including stenosis and aneurysm, are rare entities that are most commonly identified as incidental findings on routine imaging. When present, symptoms may result from distal embolization, low-flow state, mass effect, or rupture. All patients with occlusive disease should be treated with an aspirin and statin. While there is no formal consensus for the treatment of asymptomatic patients, all symptomatic lesions merit surgical intervention. Among patients with suitable anatomy an endovascular approach is considered first line. There are no formal guidelines to direct postoperative imaging; however, due to the risk of restenosis, routine surveillance with duplex or computerized tomography imaging is warranted following open or endovascular intervention for stenosis.Abstract Diseases of the subclavian and innominate arteries, including stenosis and aneurysm, are rare entities that are most commonly identified as incidental findings on routine imaging. When present, symptoms may result from distal embolization, low-flow state, mass effect, or rupture. All patients with occlusive disease should be treated with an aspirin and statin. While there is no formal consensus for the treatment of asymptomatic patients, all symptomatic lesions merit surgical intervention. Among patients with suitable anatomy an endovascular approach is considered first line. There are no formal guidelines to direct postoperative imaging; however, due to the risk of restenosis, routine surveillance with duplex or computerized tomography imaging is warranted following open or endovascular intervention for stenosis.

In Patients with Acute Mesenteric Ischemia Does an Endovascular or Hybrid Approach Improve Morbidity and Mortality Compared to Open Revascularization

Acute mesenteric ischemia (AMI) covers a broad range of vascular pathologies ranging from acute arterial embolism or thrombosis, to the eventual manifestation of untreated chronic mesenteric ischemia. In recent decades, with improved anticoagulation management, the incidence of SMA embolism has declined. Currently, the most common presentation is an acute exacerbation of chronic atherosclerotic mesenteric vessel occlusion. The clinical manifestations and time course of this are much more variable and difficult to stratify. Regardless of the cause, in the absence of timely restoration of blood flow, there will be progression to bowel ischemia, peritonitis and death. The entity was first described in 1895, however it was not until the 1950s that techniques for restoration of mesenteric blood flow were described. Initial operative strategies included SMA embolectomy, SMA thromboendarterectomy and aorto-mesenteric bypass. Angiography was used primarily for diagnostic purposes but early reports of intra-arterial thrombolysis using heparin and streptokinase were published in the 1970s. With further advancements in endovascular techniques, percutaneous revascularization has become the preferred modality for treating patients with chronic mesenteric ischemia. However, the standard of care for AMI remains unclear and mortality rates remain quite high. Traditionalists would argue that there is no substitute for an open abdominal exploration and assessment of bowel viability. They are skeptical of recent publications citing favorable outcomes with purely percutaneous treatments for AMI, maintaining that it does not allow for assessment of bowel viability, requires advanced technical skills and is more time consuming compared to open approach. Alternatively, a combined open and endovascular, or “hybrid” approach can be viewed as a compromise that still honors traditional surgical principles to evaluate bowel viability. Milner et al. were the first to publish a case report on a “hybrid” approach to AMI. They combined open and endovascular strategies to establish mesenteric blood flow. Briefly, the SMA is exposed at the base of the transverse mesocolon. A patch angioplasty is then performed at the site of intended arterial puncture site, through which, an SMA stent is deployed via retrograde cannulation. Proponents of this technique assert that it allows for assessment of bowel viability, and offers direct access to SMA revascularization rather than the long and sometimes challenging transbrachial or transfemoral approach. Since the first description of this technique in 2004, several groups have published their experience with this approach. In this chapter, we aim to summarize the literature on endovascular techniques (including hybrid approach) for treating acute mesenteric ischemia, and how they compare to the traditional open revascularization strategies.