Carbon dioxide digital subtraction angiography-assisted endovascular aortic aneurysm repair in the azotemic patient

Safety, Effectiveness and Pitfalls of Carbon Dioxide Routine Use as a Contrast Agent for Endovascular Abdominal Aortic Repair

BACKGROUND

Despite the evidence of good performance, carbon dioxide (CO2) routine employment as a contrast agent for endovascular procedures is far from being adopted with its use currently limited to patients with renal impairment and known allergy to iodinated contrast medium (ICM). The purpose of our study is to evaluate the safety and effectiveness of CO2 guided endovascular abdominal aortic aneurysm repair (EVAR) in a standard population and to assess the rationale for a future widespread use.

METHODS

We retrospectively collected data of every patient who underwent CO2 guided standard EVAR from September 2020 to May 2021 and compared them with the data of every patient who underwent EVAR using ICM from December 2019 to August 2020 in our unit. The selection of the contrast medium was not based on any preoperative factor as the contrast medium was routinely used in every patient in both periods. The primary end point of the study was the technical success rate. Secondary end points were the early and late complication rates, radiation exposure and renal function impairment.

RESULTS

49 patients underwent ICM guided EVAR and 52 patients underwent CO2 guided EVAR in our unit in the time frames specified above. The technical success rate was 100% in both groups with no accidental coverage of any target vessel. Intraoperative endoleaks were observed in 14% of ICM patients and 25% of CO2 patients. The radiation exposure was higher in the CO2 group if compared to the ICM group (311.48 vs. 159.86 median mGy/cm2 - P < 0.001). The incidence of postoperative acute kidney injury was low and similar in the 2 groups. No significant worsening over time of the renal function has been reported in both groups.

CONCLUSIONS

EVAR can be safely performed under CO2 guidance without the integration of any quantity of ICM but with an increase in radiation exposure. The nephroprotective role of CO2 guided EVAR in a standard population is unclear and the same role in renal impaired patients should be validated with further studies on selected populations.

The efficacy of CO2 angiography in the endovascular treatment of an acute iliac pseudoaneurysm

CO2 angiography has been used extensively for the endovascular treatment of aorto-iliac and femoral-popliteal-tibial pathologies, specifically in patients with chronic kidney disease or allergy to iodinated contrast medium (ICM). However, its use in urgent treatment of an acute pseudoaneurysm has never been described before. We report a case of a 39-year-old woman, allergic to iodine, with a recent kidney transplant, who presented in the emergency room with severe pain in the left iliac fossa. Angio CT-scan showed an acute pseudoaneurysm of the left common iliac artery. She was emergently treated with a stent-graft and CO2 was used as main contrast medium. The intraoperative angiographies performed with carbon dioxide showed very well the rupture site and the pseudoaneurysm; the latter were more clearly visible with CO2 compared with ICM. The reported case shows the efficacy of CO2 as contrast medium also in urgent settings and arterial ruptures. The lower viscosity of CO2 probably leads to an easier diffusion through the arterial lesion into the pseudoaneurysmal sac. Therefore, in this case the use of carbon dioxide not only guaranteed prevention of massive allergic reaction to iodine and preservation of postoperative renal function, but also resulted in higher image quality in the operating room.

Carbon Dioxide Guided Endovascular Aortic Aneurysm Repair in Impaired Renal Function: Propensity Score Matched Study

OBJECTIVE

Carbon dioxide (CO2) is the preferred contrast agent in patients with impaired renal function and or contrast allergy and, particularly, in patients who require large volumes of contrast for complex endovascular procedures. In this study, the aim was to clarify the possible protective effects of CO2 guided endovascular aneurysm repair (EVAR) for patients with impaired renal function by propensity score matching.

METHODS

A retrospective analysis of the database was performed for 324 patients having EVAR between January 2019 and January 2022. A total of 34 patients treated with CO2 guided EVAR were evaluated. This cohort was matched for age, sex, pre-operative serum creatinine levels and glomerular filtration rate (GFR) levels and specific comorbidities to obtain homogeneous groups that included only patients with impaired renal function (eGFR < 60 mL/min/1.73m2). The primary endpoint was to compare the decrease in eGFR from baseline and development of contrast induced nephropathy (CIN) using propensity score matching. Secondary endpoints were the need for renal replacement therapy, other peri-procedural morbidity and mortality.

RESULTS

Thirty-one patients (9.6%) of the total population developed CIN. There was no difference in the rate of CIN development between the standard EVAR group and the CO2 guided EVAR group in the unmatched population (10% vs. 3%, p = .15). After matching, the decrease in eGFR values after the procedure was more pronounced for the standard EVAR group (from 44 to 40 mL/min/1.73m2, interaction p = .034). Meanwhile, CIN development was more frequent for the standard EVAR group (24% vs. 3%, p = .027). In matched patients, early death did not differ between the groups (5.9% vs. 0, p = .15) CONCLUSION: Patients with impaired renal function are at higher risk of CIN after an endovascular procedure. CO2 guided EVAR is a safe, effective, and feasible treatment option, especially for patients with impaired renal function. CO2 guided EVAR may be a protective measure for contrast induced nephropathy.

The Potential Biotherapeutic Targets of Contrast-Induced Acute Kidney Injury

Contrast-induced acute kidney injury (CI-AKI) is manifested by an abrupt decline in kidney function as a consequence of intravascular exposure to contrast media. With the increased applicability of medical imaging and interventional procedures that utilize contrast media for clinical diagnosis, CI-AKI is becoming the leading cause of renal dysfunction. The pathophysiological mechanism associated with CI-AKI involves renal medullary hypoxia, the direct toxicity of contrast agents, oxidative stress, apoptosis, inflammation, and epigenetic regulation. To date, there is no effective therapy for CI-AKI, except for the development of strategies that could reduce the toxicity profiles of contrast media. While most of these strategies have failed, evidence has shown that the proper use of personalized hydration, contrast medium, and high-dose statins may reduce the occurrence of CI-AKI. However, adequate risk predication and attempts to develop preventive strategies can be considered as the key determinants that can help eliminate CI-AKI. Additionally, a deeper understanding of the pathophysiological mechanism of CI-AKI is crucial to uncover molecular targets for the prevention of CI-AKI. This review has taken a step further to solidify the current known molecular mechanisms of CI-AKI and elaborate the biomarkers that are used to detect early-stage CI-AKI. On this foundation, this review will analyze the molecular targets relating to apoptosis, inflammation, oxidative stress, and epigenetics, and, thus, provide a strong rationale for therapeutic intervention in the prevention of CI-AKI.

A State-of-the-Art Review of Intra-Operative Imaging Modalities Used to Quality Assure Endovascular Aneurysm Repair

Endovascular aortic aneurysm repair (EVAR) is the preferred method for elective abdominal aortic aneurysm (AAA) repair. However, the success of this technique depends greatly on the technologies available. Intra-operative imaging is essential but can come with limitations. More complex interventions lead to longer operating times, fluoroscopy times, and greater contrast doses. A number of intra-operative imaging modalities to quality assure the success of EVAR have been developed. A systematic literature search was performed with separate searches conducted for each imaging modality in the study: computed tomography (CT), digital subtraction angiography (DSA), fusion, ultrasound, intra-operative positioning system (IOPS), and non-contrast imaging. CT was effective at detecting complications but commonly resulted in increased radiation and contrast dose. The effectiveness of DSA can be increased, and radiation exposure reduced, through the use of adjunctive technologies. We found that 2D-3D fusion was non-inferior to 3D-3D and led to reduced radiation and contrast dose. Non-contrast imaging occasionally led to higher doses of radiation. Ultrasound was particularly effective in the detection of type II endoleaks with reduced radiation and contrast use but was often operator dependent. Unfortunately, no papers made it past full text screening for IOPS. All of the imaging techniques discussed have advantages and disadvantages, and clinical context is relevant to guide imaging choice. Fusion and ultrasound in particular show promise for the future.

Intravascular Ultrasound Versus Computed Tomography Angiography in Sizing and Operative Management of Endovascular Aortic Aneurysm Repair

OBJECTIVES

An abdominal aortic aneurysm (AAA) is a potentially life-threatening condition, the management of which has dramatically evolved over the past 2 decades with an increasing tendency toward endovascular repair (EVAR) rather than open surgical repair. Classically, contrast-enhanced multislice computed tomography (CT) angiography (CTA) is performed preoperatively for procedure sizing and EVAR planning. This entails voluminous contrast injection with risk of allergic reaction, nephropathy, and radiation exposure. Intra-vascular ultrasound (IVUS) has been increasingly used to guide EVAR procedures intraoperatively. The aim of this study is to investigate the accuracy of IVUS in sizing AAAs, device selection, and EVAR planning compared to the gold standard CTA.

DESIGN

This is a prospective observational study enrolling 10 patients who underwent standard infrarenal EVAR procedures performed for unruptured infrarenal AAAs over the course of 1 year. All patients had a preoperative CTA done upon which aneurysm sizing and device planning were performed, and the measurements obtained were compared to those obtained from intraoperative IVUS.

METHODS

All participating patients had unruptured infrarenal AAA, had no renal impairment, and had anatomical suitability for EVAR according to the instructions for use (IFU) of the device manufacturer. Primary endpoint was comparing anatomical measurements recorded by IVUS with those obtained from the preoperative CTA.

RESULTS

Mean age was 65.6 (±6.19), all patients were males and hypertensives and 4 (40%) had a positive family history for AAA. On comparing mean measurements taken by CTA and IVUS, there was no statistically significant differences with exception of maximal aortic diameter and aortic diameter at site of bifurcation (both p-values <.001). There were no statistically significant differences in length measurements between the 2 imaging modalities. Computed tomography angiography was more associated with neck thrombus detection, and IVUS was more associated with calcification detection.

CONCLUSION

Although CT angiography is still the gold standard imaging modality for AAA, IVUS use is very beneficial in EVAR sizing and planning, in addition to intra-operative guidance of the procedure, saving the patient significant time, contrast administration, and radiation exposure, especially in patients with renal impairment and contrast allergy.

CLINICAL IMPACT

A preoperative CT angiogram is the gold standard required investigation for planning and sizing EVARs, with subsequent contrast injection entailing a risk of contrast induced nephropathy and allergic reactions. IVUS has been used as an adjuvant technique to guide EVAR stent graft deployment. However, our study concluded that it can also be reliably used in sizing and planning of the EVAR stent graft along with complementary non contrast imaging, especially in patients with high risk for contrast induced nephropathy and contrast allergy.

The optimal operative protocol to accomplish CO2-EVAR resulting from a prospective interventional multicenter study

OBJECTIVES

Carbon dioxide (CO₂) angiography for endovascular aortic repair (CO₂-EVAR) is used to treat abdominal aortic aneurysms (AAAs), especially in patients with chronic kidney disease or allergy to iodinated contrast medium (ICM). However, some technical issues regarding the visualization of the lowest renal artery (LoRA) and the best quality image through angiographies performed from pigtail or introducer sheath are still unsolved. The aim of this study was to analyze different steps of CO₂-EVAR to create an operative standardized protocol.

METHODS

Patients undergoing CO₂-EVAR were prospectively enrolled in five European centers from 2019 to 2021. CO₂-EVAR was performed using an automated injector (pressure, 600 mmHg; volume, 100 cc); a small amount of ICM was injected in case of difficulty in LoRA visualization. LoRA visualization and image quality (1 = low, 2 = sufficient, 3 = good, 4 = excellent) were analyzed at different procedure steps: preoperative CO₂ angiography from pigtail and femoral introducer sheath (first step), angiographies from pigtail at 0%, 50%, and 100% of proximal main body deployment (second step), contralateral hypogastric artery (CHA) visualization with CO₂ injection from femoral introducer sheath (third step), and completion angiogram from pigtail and femoral introducer sheath (fourth step). Intraoperative and postoperative CO₂-related adverse events were also evaluated. χ² and Wilcoxon tests were used for statistical analysis.

RESULTS

In the considered period, 65 patients undergoing CO₂-EVAR were enrolled (55/65 [84.5%] male; median age, 75 years [interquartile range (IQR), 11.5 years]). The median ICM injected was 17 cc (IQR, 51 cc); 19 (29.2%) of 65 procedures were performed with 0 cc ICM. Fifty-five (84.2%) of 65 patients underwent general anesthesia. In the first step, median image quality was significantly higher with CO₂ injected from femoral introducer (pigtail, 2 [IQR, 3] vs introducer, 3 [IQR, 3]; P = .008). In the second step, LoRA was more frequently detected at 50% (93% vs 73.2%; P = .002) and 100% (94.1% vs 78.4%; P = .01) of proximal main body deployment compared with first angiography from pigtail; similarly, image quality was significantly higher at 50% (3 [IQR, 3] vs 2 [IQR, 3]; P ≤ .001) and 100% (4 [IQR, 3] vs 2 [IQR, 3]; P = .001) of proximal main body deployment. CHA was detected in 93% cases (third step). The mean image quality was significantly higher when final angiogram (fourth step) was performed from introducer (pigtail, 2.6 ± 1.1 vs introducer, 3.1 ± 0.9; P ≤ .001). The intraoperative (7.7%) and postoperative (12.5%) adverse events (pain, vomiting, diarrhea) were all transient and clinically mild.

CONCLUSIONS

Preimplant CO₂ angiography should be performed from femoral introducer sheath. Gas flow impediment created by proximal main body deployment can improve image quality and LoRA visualization with CO₂. CHA can be satisfactorily visualized with CO₂ alone. Completion CO₂ angiogram should be performed from femoral introducer sheath. This operative protocol allows performance of CO₂-EVAR with 0 cc or minimal ICM, with a low rate of mild temporary complications.

Risk of Contrast-Associated Acute Kidney Injury in Patients Undergoing Peripheral Angiography with Carbon Dioxide Compared to Iodine-Containing Contrast Agents: A Systematic Review and Meta-Analysis

The aim of this systematic review was to summarise the comparative evidence on the risk of contrast-associated acute kidney injury (CA-AKI) with CO₂ or iodinated contrast medium (ICM) for peripheral vascular interventions. We searched Ovid MEDLINE, Cochrane Library, Embase, Epistemonikos, PubMed-similar-articles, clinical trial registries, journal websites, and reference lists up to February 2022. We included studies comparing the risk of CA-AKI in patients who received CO₂ or ICM for peripheral angiography with or without endovascular intervention. Two reviewers screened the references and assessed the risk of bias of the included studies. We extracted data on study population, interventions and outcomes. For the risk of CA-AKI as our primary outcome of interest, we calculated risk ratios (RRs) with a 95% confidence interval (CI) and performed random-effects meta-analyses. We identified three RCTs and five cohort studies that fully met our eligibility criteria. Based on a random-effects meta-analysis, the risk of CA-AKI was lower with CO₂ compared to ICM (8.6% vs. 15.2%; RR, 0.59; 95% CI 0.33-1.04). Only limited results from a few studies were available on procedure and fluoroscopy time, radiation dose and CO₂-related adverse events. The evidence suggests that the use of CO₂ for peripheral vascular interventions reduces the risk of CA-AKI compared to ICM. However, due to the relevant residual risk of CA-AKI with the use of CO₂, other AKI risk factors must be considered in patients undergoing peripheral vascular interventions.

Fully Ultrasound-Assisted Endovascular Aneurysm Repair (EVAR): preliminary report

BACKGROUND

Reducing fluoroscopy times and iodine contrast administration during endovascular exclusion (EVAR) of infrarenal aortic aneurysms (AAA) remains a challenge. The purpose of this study was to evaluate the preliminary results of a fully ultrasound-assisted EVAR without iodine contrast administration.

METHODS

Twentyseven consecutive patients, underwent an elective IVUS-assisted EVAR with final CEUS control of correct aneurysm exclusion. In no case intraprocedural injection of iodine contrast medium was performed. The primary study's endpoints were the overall duration of the procedure, duration of fluoroscopy, cumulative radiation dose, the length of intraoperative CEUS control and the comparison of findings between intraoperative CEUS and CT-scan at one month.

RESULTS

Mean duration of the procedure was 130 ± 35 minutes. Overall duration of fluoroscopy was 22 ± 18 minutes. Mean radiation dose was 66 mGy (range, 24 - 82). The mean length of CEUS final control was 8 ± 2 minutes. No type I or type III endoleak was detected either at CEUS or at angio-CT scan at one month from EVAR. CEUS revealed a type II endoleak in 6 patients (22%) , compared to 9 type II endoleaks (33%) detected at angio-CT scan one month after the procedure (p = 0.5).

CONCLUSIONS

Fully ultrasound (IVUS and CEUS) -assisted EVAR is safe, feasible and reliable, completely eliminating the need for iodine contrast medium and reducing the radiation exposure for both patients and surgeons.

CO2 Automated Angiography in Endovascular Aortic Repair Preserves Renal Function to a Greater Extent Compared with Iodinated Contrast Medium. Analysis of Technical and Anatomical Details

BACKGROUND

Contrast induced nephropathy occurs in up to 7.5% of cases in endovascular aortic repair (EVAR). Carbon dioxide (CO₂) has been proposed as an alternative agent to iodinated contrast medium (ICM); however, specific protocols are not universally adopted, and the visualization of the renal arteries may be suboptimal in some cases. The aim of this study was to analyze our CO₂-EVAR experience with automatic injections, in order to identify the anatomical characteristics associated with the best visualization of all the aortic vessels, with particular attention to the lowest renal artery (LoRA).

METHODS

From 2016 to 2019, all EVAR performed with either CO₂ or ICM were analyzed and compared. CO₂-EVAR was performed using an automated injector (600 mm Hg pressure; 100 cc volume); a small amount of ICM was injected in case of difficulty in LoRA visualization or doubts at the completion angiogram. Clinical and CT-Scan preoperative characteristics were considered. The study endpoints were technical success, amount of ICM and radiation dose, postoperative renal function and possible CO₂-related adverse events. Statistical analysis was by Fisher's exact, t-Student, Mann-Whitney tests and ROC curve.

RESULTS

In the considered period, 321 EVAR procedures, 72 (22.4%) with CO₂ and 249 (77.6%) with ICM, were performed. The 2 groups were similar for clinical characteristics and preoperative renal function. ICM was injected in a significantly lower amount in the CO₂-EVAR group (52.8 ± 6.1 vs. 88.1 ±9.2 cc, P < 0.001), which received a significantly higher mean radiation dose (Total DAP: 500,550.8 ± 377,394.6 mGy/cm² CO₂-EVAR vs. 332,301.8 ±230,139.3 mGy/cm² ICM-EVAR, P = 0.001). Postoperative eGFR decreased significantly less in the CO₂-EVAR (2.3 ± 1.1 mL/min) compared with the ICM-EVAR group (10.6 ±5.3 mL/min), P < 0.001. LoRA was correctly visualized in 50/72 (69.4%) cases of CO₂-EVAR, which had a significantly longer proximal neck (Median [IQR]: 30 [14] vs. 18 [15] mm, P = 0.001). At ROC curve, a proximal neck length >24.5 mm was predictive of LoRA visualization (72.1% sensitivity, 73.8% specificity). Three CO₂-EVAR cases had intraoperative transient hypotension with no consequences. Sixteen/72 (22.2%) CO₂-EVAR procedures were performed using 0 cc of ICM.

CONCLUSIONS

CO₂-EVAR by automated injections is safe and requires a lower amount of ICM if compared with ICM-EVAR, with a consequent significant benefit on postoperative renal function. If specific anatomical situations are present, ICM may be completely unnecessary. The radiation dose is however significantly higher, therefore procedural protocols need further refinements.

Feasibility of Intraoperative Fusion Imaging Using Non-Contrast CT Scan for EVAR in Ruptured Abdominal Aortic Aneurysm

Introduction

Acute renal failure is a frequent major complication (24%) of endovascular repair for ruptured abdominal aneurysm (rAAA). Iodinated contrast media is known to be nephrotoxic. This report describes a case of endovascular aneurysm repair (EVAR) under fusion imaging guidance in a patient diagnosed with a rAAA after non-contrast CT. Written consent was obtained from the patient.

Report

A 73 year old patient with stage IV chronic kidney failure and contrast-induced nephropathy was diagnosed with rAAA using non-contrast CT. Subsequently, the patient was treated with EVAR using fusion imaging.

Discussion

EVAR with fusion imaging after non-contrast CT was safe in a patient with rAAA. It could represent an option for patients with acute renal failure in emergency settings.

Advances in the pathogenesis and prevention of contrast-induced nephropathy

With the increasing application of medical imaging contrast materials, contrast-induced nephropathy has become one of the leading causes of iatrogenic renal insufficiency. The underlying mechanism is associated with renal medullary hypoxia, direct toxicity of contrast agents, oxidative stress, apoptosis, immune/inflammation and epigenetic regulation in contrast-induced nephropathy. Up to date, there is no effective therapy for contrast-induced nephropathy, and thus risk predication and effective preventive strategies are keys to reduce the occurrence of contrast-induced nephropathy. It was found that the proper use of contrast medium, personalized hydration, and high-dose statins may reduce the occurrence of contrast-induced nephropathy, while antioxidants have not shown significant therapeutic benefits. Additionally, the role of remote ischemia preconditioning and vasodilators in the prevention of contrast-induced nephropathy needs further study. This review aims to discuss the incidence, pathogenesis, risk prediction, and preventive strategies for contrast-induced nephropathy.

Endovascular Aneurysm Repair Assisted by CO2 Digital Subtraction Angiography and Intraoperative Contrast-Enhanced Ultrasonography: Single-Center Experience

BACKGROUND

Allergy to iodinated contrast (IC) agent and advanced chronic kidney disease are major limitations to endovascular repair (EVAR) of abdominal aortic aneurysms (AAAs). We describe our experience combining CO₂-assisted EVAR with intraoperative contrast-enhanced ultrasound (CEUS) in an attempt to avoid contrast-induced allergy or nephropathy.

METHODS

Observational cohort study using prospectively acquired data on patients undergoing CO₂-assisted EVAR in single institution. EVAR planning was performed using computed tomographic angiography or magnetic resonance aortography in patients contraindicated for IC. Patients were considered if their estimated glomerular filtration rate was <40 mL/min and anatomically suitable for conventional infrarenal EVAR. Outcomes of interest included technical success rate and reintervention rates, total radiation dose, length of hospital stay, and graft kinking or migration.

RESULTS

Fifteen patients (10 male) were treated across a 5-year period. Technical success was achieved in all cases. Completely IC-free EVAR was performed in 9 cases, whereas the remaining 6 required IC administration for adjunct procedures. CO₂ completion angiography detected all type I endoleaks (2 Ia and 1 Ib) but was less sensitive to type II. Intraoperative CEUS confirmed all type I and 2 cases of type II endoleaks. Median hospital stay was 4 days. No significant deterioration in renal function was seen postoperatively.

CONCLUSIONS

In patients with abdominal aortic aneurysms and with contraindication for IC, a combined approach of using CO₂ digital subtraction angiography and CEUS can be used safely and efficiently to minimize or obviate the need for IC agents with satisfactory mid-term results.

Endovascular Infrarenal Aortic Aneurysm Repair Performed in a Hybrid Operating Room Versus Conventional Operating Room Using a C-Arm

BACKGROUND

To compare contrast usage and radiation exposure during endovascular aneurysm repair (EVAR) using mobile C-arm imaging in a conventional operating room (OR) or fixed angiographic equipment in a hybrid OR (HR).

METHODS

A retrospective unicenter study from May 2016 to August 2019. All consecutive patients undergoing standard EVAR were included. Patients were divided into 2 groups. Group OR included EVARs performed in a conventional OR with a mobile C-arm (May 2016 to April 2018) and group HR included EVARs performed with a fixed angiographic equipment in an HR (May 2018 to August 2019). Data collected included patient demographics, aneurysm diameter, neck length, radiation dose: median dose-area product (DAP), fluoroscopy time, total operative time, contrast use, and 30-day clinical outcomes.

RESULTS

A total of 77 patients were included in the study (42 patients in group OR and 35 patients in group HR). There was no difference in age, body mass index (BMI), mean aneurysm, and neck length between groups. Patients in the group HR received less contrast volume (108.6 mL [±41.5] vs. 162.5 mL [±52.6]; P < 0.001), but higher radiation dose (154 Gy cm² [±102.9] vs. 61.5 Gy cm² [±42.4]; P < 0.001). There were no differences in fluoroscopy time (20.4 min [±8.5] vs. 23.2 min [±12.4]; P = 0.274) and total operative time (106.4 [±22.3] vs. 109.4 [±25.8]; P = 0.798). No difference was found in terms of 30-day complication rates or operative mortality between groups. DAP was positively correlated with BMI in the group OR (Spearman's rank correlation coefficient r_s, 0.580; P < 0.001), but no correlation could be seen in the group HR (r_s, 0.408; P = 0.028).

CONCLUSIONS

Routine EVAR performed in a hybrid fixed-imaging suite may be associated with less contrast usage, but higher radiation exposure in our center. The significantly higher radiation exposure when the mobile C-arm is replaced by an HR should not be underestimated.

Percutaneous Endovascular Aortic Aneurysm Repair with INCRAFT Endograft Guided by CO2 Digital Subtraction Angiography in Patients with Renal Insufficiency

Iodinated contrast is the most common contrast agent used during endovascular abdominal aneurysm repair (EVAR). However, its use may worsen kidney function in patients with renal insufficiency. Previous studies have demonstrated the safety and effectiveness of carbon dioxide (CO₂)-EVAR. Here, we report cases of three male patients with mild renal insufficiency (mean age: 79 years) that successfully underwent CO₂-EVAR using INCRAFT ultra-low profile endografts. CO₂ angiography provided the necessary vascular roadmap for safe and effective percutaneous EVAR, eliminating the need for iodinated contrast media and preventing contrast-induced nephropathy.

Utilization of Carbon Dioxide Angiography and Percutaneous Balloon Angioplasty for Treatment of Transplant Renal Artery Stenosis

BACKGROUND

Transplant renal artery stenosis (TRAS) may lead to graft dysfunction and failure. Progressive deterioration of renal allograft function may be exacerbated by contrast-induced nephrotoxicity during iodine contrast administration for renovascular imaging of allografts. We present our institutional experience of endovascular management for TRAS using CO₂ digital subtraction angiography (CO₂-DSA) and balloon angioplasty to manage failing renal transplants.

METHODS

Four patients with renal allografts from March 2017-May 2018 were referred for graft dysfunction and pending renal transplant failure. Indications for referral included refractory hypertension, decreasing renal functioning, and elevated renovascular systolic velocities.

RESULTS

Median age of the four patients was 41.5 years (22-60 years). There were two male and female patients. Chronic hypertension and type 2 diabetes mellitus were the most common comorbidities. An average total of 75 mL of CO₂ was used, supplemented with 17.4 mL of iodinated contrast. All patients had improvements in renal function following intervention with a mean decrease in systolic and diastolic blood pressure of 25.8% and 21.4%, respectively. We also observed a mean decrease of BUN by 13.6% and creatinine by 37.4%. Additionally, eGFR increased by 37.7%. All allografts survived after surgery, and only one patient required repeat angioplasty for recurrence.

CONCLUSIONS

CO₂-DSA with balloon angioplasty can be successfully utilized to salvage deteriorating kidney allograft function in patients with TRAS.

Peroperative Intravascular Ultrasound for Endovascular Aneurysm Repair versus Peroperative Angiography: A Pilot Study in Fit Patients with Favorable Anatomy

BACKGROUND

The aim of this study was to compare intravascular ultrasound (IVUS) assistance for endovascular aortic aneurysm repair (EVAR) to standard assistance by angiography.

METHODS

From June 2015 to June 2017, 173 consecutive patients underwent EVAR. In this group, 69 procedures were IVUS-assisted with X-ray exposure limited to completion angiography for safety purposes because an IVUS probe does not yet incorporate a duplex probe (group A), and 104 were angiography-assisted procedures (group B). All IVUS-assisted procedures were performed by vascular surgeons with basic duplex ultrasound (DUS) training. The primary study endpoints were mean radiation dose, duration of fluoroscopy, amount of contrast media administered, procedure-related outcomes, and renal clearance expressed as the glomerular filtration rate (GFR) before and after the procedure. Secondary endpoints were operative mortality, morbidity, and arterial access complications.

RESULTS

Mean duration of fluoroscopy time was significantly lower for IVUS-assisted procedures (24 ± 15 min vs. 40 ± 30 min for angiography-assisted procedures, P < 0.01). Moreover, mean radiation dose (Air KERMA) was significantly lower in IVUS-assisted procedures (76m Gy [44-102] vs. 131 mGy [58-494]), P < 0.01. IVUS-assisted procedures required fewer contrast media than standard angiography-assisted procedures (60 ± 20 mL vs. 120 ± 40 mL, P < 0.01). The mean duration of the procedure was comparable in the two groups (120 ± 30 min vs. 140 ± 30 min, P = 0.07). No difference in renal clearance before and after the procedure was observed in either of the two groups (99.0 ± 4/97.8 ± 2 mL/min in group A and 98.0 ± 3/97.6 ± 5 mL/min in group B) (P = 0.28). The mean length of follow-up was nine months (6-30 months). No postoperative mortality, morbidity, or arterial access complications occurred. No type 1 endoleak was observed. Early type II endoleaks were observed in 21 patients (11%), 12 in the angiography-assisted group (11%) and nine in the IVUS-assisted group (12%). They were not associated with sac enlargement ≥5 mm diameter and therefore did not require any additional treatment.

CONCLUSIONS

Compared with standard angiography-assisted EVAR, IVUS significantly reduces renal load with contrast media, fluoroscopy time, and radiation dose while preserving endograft deployment efficiency. Confirmation from a large prospective study with improved IVUS probes will be required before IVUS-assisted EVAR alone can become standard practice.

Meta-analysis of computed tomography angiography versus magnetic resonance angiography for intracranial aneurysm

BACKGROUND

Whether the diagnosis value of computed tomography angiography (CTA) for intracranial aneurysm is in accordance with magnetic resonance angiography (MRA) remains inconclusive. This meta-analysis aims to synthesize relevant studies to compare the diagnostic efficacies of the 2 methods.

METHODS

Potentially relevant studies were selected through PubMed, Embase, Wanfang, Chongqing VIP, and China National Knowledge Infrastructure databases by using the core terms "computer tomography angiography" (CTA) and "magnetic resonance angiography" (MRA) and "intracranial aneurysm*" in the titles, abstracts, and keywords of the articles. Quality Assessment for Diagnostic Accuracy Studies (QUADAS-2) was utilized to evaluate the quality. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were count. Summary receiver operating characteristic curves (SROC) and area under the curve (AUC) were used to summarize the overall diagnostic performance. Statistical analyses were performed by Stata version 12.0 and MetaDisc 1.4 software.

RESULTS

Ten articles were identified in this current paper. For CTA, the pooled estimates of diagnostic parameters for intracranial aneurysm were as follows: sensitivity, 0.84 (95%CI = 0.81-0.86); specificity, 0.85 (95%CI = 0.79-0.89); PLR, 4.09 (95%CI = 2.45-6.81); NLR, 0.18 (95%CI = 0.11-0.28); DOR, 23.74 (95%CI = 10.49-53.74); AUC, 0.90, respectively. For MRA, the pooled estimates of diagnostic parameters for intracranial aneurysm were as follows: sensitivity, 0.80 (95%CI = 0.77-0.83); specificity, 0.87 (95%CI = 0.82-0.91); PLR, 3.61 (95%CI = 1.72-7.55); NLR; 0.27 (95%CI = 0.21-0.35); DOR, 16.77 (95%CI = 7.38-38.11); AUC, 0.87, respectively. No significant difference was found the AUC value between CTA and MRA for intracranial aneurysm (Z = 0.828, P > .05).

CONCLUSION

This comprehensive meta-analysis demonstrated that the diagnosis value of CTA was in accordance with MRA for intracranial aneurysm. However, considering the limitation of sample size, the results should be treated with caution.

The Assessment of Carbon Dioxide Automated Angiography in Type II Endoleaks Detection: Comparison with Contrast-Enhanced Ultrasound

Introduction

Iodinated contrast media completion angiography (ICM-A) may underestimate the presence of type II endoleak (ELII) after endovascular aortic repair (EVAR), particularly if they are at low flow. Contrast-enhanced ultrasound (CEUS) has been proposed as the gold standard in ELII detection during EVAR follow-up. Intraprocedural carbon dioxide (CO₂) angiography has been shown to be useful in this setting; however no comparative studies including these three techniques are currently available. Our aim was to investigate the accuracy of a new automated CO₂ angiographic (CO₂-A) system in the detection of ELII, by comparing it with ICM-A and CEUS.

Methods

A series of consecutive patients undergoing EVAR for abdominal aortic aneurysm (AAA) were enrolled and submitted to ICM-A and CO₂-A during the procedure. The iodinated contrast media were delivered through an automatic injector connected to a pigtail catheter in the suprarenal aorta. CO₂ was delivered through a recently available automatic injector connected to a 10 F sheath positioned in the external iliac artery. All patients were blindly evaluated by CEUS within postoperative day 1. The ICM-A and CO₂-A ability to detect ELII was compared with that of CEUS through Cohen's concordance Index (K).

Results

Twenty-one patients were enrolled in the study. One (5%), seven (33%), and four (19%) ELII were detected by ICM-A, CO₂-A, and CEUS, respectively. The only ELII detected by ICM-A was also detected by CO₂-A and CEUS. Three cases of ELII detected by CO₂-A were not detected by CEUS. All ELII detected by CEUS were visualized by CO₂-A. CEUS and ICM-A showed a poor agreement (Cohen's K: 0.35) while CEUS and CO₂-A showed a substantial agreement (Cohen's K: 0.65) for ELII detection.

Conclusion

CO₂-A is safe and effective method for ELII detection in EVAR, with a significantly higher agreement with CEUS if compared with ICM-A. This trial is registered with 155/2015/U/Oss.

Use of carbon dioxide as an intravascular contrast agent: A review of current literature

Use of X-ray contrast allows us to differentiate between two or more adjacent structures on radiographic studies. The X-ray contrast agent can be the one with increase X-ray absorption, like iodine and a barium X-ray contrast agent or the one with decrease X-ray absorption like air and carbon dioxide contrast agent. Each contrast agent possesses different risks and benefits in various ways. Carbon dioxide as an intravascular contrast agent can be used as an alternative intravascular contrast agent and has superior results in some cases. In patients with renal dysfunction or iodinated contrast allergy, the use of Iodinated Contrast Agent poses the risk of considerable morbidity. Similarly, use of Gadolinium is discouraged in subject with severe renal dysfunction. Use of carbon dioxide (CO₂) as an intravascular contrast, offers an alternative in such patients for certain procedures, as it is not nephrotoxic and it does not incite allergic reactions. It is inexpensive, readily available and due to its unique physical properties, it can be used to image a wide variety of vascular beds and chambers. The aim of this paper is to systemically review the current literature to describe the indications, contraindications, adverse effects, instruments, precautions, latest methodologies and data supporting for the use of CO₂ as a contrast agent.

Current status of carbon dioxide angiography

OBJECTIVE

Unfamiliarity of endovascular surgeons with carbon dioxide (CO₂) angiography is one of the main reasons for its limited use. This review is intended to familiarize the reader with the principles and applications of that modality.

METHODS

We conducted a comprehensive review of contemporary literature related to CO₂ angiography and its use in the field of vascular and endovascular surgery, including technical details and diagnostic and interventional applications.

RESULTS

Cardinal physicochemical characteristics of CO₂ include buoyancy, ultralow viscosity, and nonmixing with blood. Because of the risk of neurotoxicity, intra-arterial CO₂ angiography should only be performed below the diaphragm. Venous CO₂ angiography can be performed anywhere in the torso and extremities. Ultralow viscosity enables intraprocedural imaging during vascular interventions without the need to exchange for an angiographic catheter. Benefits, advantages, and emerging applications of CO₂ angiography are listed. Potential complications and their avoidance and troubleshooting are discussed.

CONCLUSIONS

CO₂ holds promise as an effective and versatile angiographic contrast agent. It is also a valuable modality for the guidance of endovascular interventions. Current availability of easy to use, safe, and portable CO₂ delivery systems will likely expand the use of that modality even beyond the traditional indications of renal insufficiency and iodinated contrast allergy.

Contrast induced-acute kidney injury following peripheral angiography with carbon dioxide versus iodinated contrast media: A meta-analysis and systematic review of current literature

OBJECTIVE

We conducted a meta-analysis to compare the incidence of acute kidney injury (AKI) with carbon dioxide (CO₂ ) versus iodinated contrast media (ICM).

BACKGROUND

Contrast induced-acute kidney injury (CI-AKI) is a known complication following endovascular procedures with ICM. CO₂ has been employed as an alternative imaging medium as it is nontoxic to the kidneys.

METHODS

Search of indexed databases was performed and 1,732 references were retrieved. Eight studies (7 observational, 1 Randomized Controlled Trial) formed the meta-analysis. Primary outcome was AKI. Fixed effect model was used when possible in addition to analysis of publication bias.

RESULTS

In this meta-analysis, 677 patients underwent 754 peripheral angiographic procedures. Compared with ICM, CO₂ was associated with a decreased incidence of AKI (4.3% vs. 11.1%; OR 0.465, 95% CI: 0.218-0.992; P = 0.048). Subgroup analysis of four studies that included granular data for patients with chronic kidney disease (CKD) did not demonstrate a decreased incidence of AKI with CO₂ (4.1% vs. 10.0%; OR 0.449, 95% CI: 0.165-1.221, P = 0.117). Patients undergoing CO₂ angiography experienced a higher number of nonrenal events including limb/abdominal pain (11 vs. 0; P = 0.001) and nausea/vomiting (9 vs. 1; P = 0.006).

CONCLUSIONS

In comparison to ICM, CO₂ use is associated with a modestly reduced rate of AKI with more frequent adverse nonrenal events. In studies that use CO₂ as the primary imaging agent, the average incidence of AKI remained high at 6.2%-supporting the concept that factors other than renal toxicity from ICM may contribute to renal impairment following peripheral angiography. © 2017 Wiley Periodicals, Inc.

Computerized tomography angiography by direct intra-aortic low volume contrast injection in patients being evaluated for EVAR

Background Computerized tomography angiography is an important tool for endovascular repair of abdominal aortic aneurysm planning. This study aimed to evaluate the utility of computerized tomography angiography using direct intra-aortic injection of low volume of iodinated contrast in patients being considered for endovascular repair of abdominal aortic aneurysm. Design A 5F high-flow angiographic catheter was positioned in the mid-thoracic aorta through femoral percutaneous access. Computerized tomography angiography was performed with image acquisition starting simultaneously with power injection of 10 mL of iopamidol 76% diluted with normal saline to 50 mL, at 6 mL/s through the angiographic catheter. Aortic enhancement was assessed with a circular region-of-interest within the aorta. Values ≥150 HU were considered adequate. Results Nine patients with abdominal aortic aneurysm and chronic renal dysfunction underwent computerized tomography angiography with intra-arterial contrast injection for endovascular repair of abdominal aortic aneurysm planning. Mean age 78.8 ± 5.0 years, mean baseline creatinine 1.8 ± 0.4 mg/dL and mean glomerular filtration rate 36.8 ± 4.2 mL/min. Adequate computerized tomography angiography aortic enhancement was obtained in all cases (mean intra-aortic density: 300.4 ± 72.8 HU). The total contrast volume used for the computerized tomography angiography and the endovascular repair of abdominal aortic aneurysm combined was 30.0 ± 21.4 mL. Seventy-five percent of the patients received ≤30 mL of contrast. No significant renal function deterioration occurred (creatinine clearance pre- and post-procedure 36.8 ± 4.2 mL/min versus 38.6 ± 6.1 mL/min, p = 0.32). Successful endovascular repair of abdominal aortic aneurysm was achieved in eight patients. One patient underwent open treatment based on computerized tomography angiography information. No endoleak or aneurysm growth occurred (median follow-up: 121 days (range 36-1242)). Conclusion Direct intra-aortic injection of low volume of iodinated contrast provides adequate and reproducible pattern of aortic enhancement on computerized tomography angiography. The computerized tomography angiography so acquired can be used for endovascular repair of abdominal aortic aneurysm limiting the total volume of iodinated contrast required.

Feasibility of three-dimensional magnetic resonance angiography-fluoroscopy image fusion technique in guiding complex endovascular aortic procedures in patients with renal insufficiency

OBJECTIVE

Three-dimensional image fusion of preoperative computed tomography (CT) angiography with fluoroscopy using intraoperative noncontrast cone-beam CT (CBCT) has been shown to improve endovascular procedures by reducing procedure length, radiation dose, and contrast media volume. However, patients with a contraindication to CT angiography (renal insufficiency, iodinated contrast allergy) may not benefit from this image fusion technique. The primary objective of this study was to evaluate the feasibility of magnetic resonance angiography (MRA) and fluoroscopy image fusion using noncontrast CBCT as a guidance tool during complex endovascular aortic procedures, especially in patients with renal insufficiency.

METHODS

All endovascular aortic procedures done under MRA image fusion guidance at a single-center were retrospectively reviewed. The patients had moderate to severe renal insufficiency and underwent diagnostic contrast-enhanced magnetic resonance imaging after gadolinium or ferumoxytol injection. Relevant vascular landmarks electronically marked in MRA images were overlaid on real-time two-dimensional fluoroscopy for image guidance, after image fusion with noncontrast intraoperative CBCT. Technical success, time for image registration, procedure time, fluoroscopy time, number of digital subtraction angiography (DSA) acquisitions before stent deployment or vessel catheterization, and renal function before and after the procedure were recorded. The image fusion accuracy was qualitatively evaluated on a binary scale by three physicians after review of image data showing virtual landmarks from MRA on fluoroscopy.

RESULTS

Between November 2012 and March 2016, 10 patients underwent endovascular procedures for aortoiliac aneurysmal disease or aortic dissection using MRA image fusion guidance. All procedures were technically successful. A paired t-test analysis showed no difference between preimaging and postoperative renal function (P = .6). The mean time required for MRA-CBCT image fusion was 4:09 ± 01:31 min:sec. Total fluoroscopy time was 20.1 ± 6.9 minutes. Five of 10 patients (50%) underwent stent graft deployment without any predeployment DSA acquisition. Three of six vessels (50%) were cannulated under image fusion guidance without any precannulation DSA runs, and the remaining vessels were cannulated after one planning DSA acquisition. Qualitative evaluation showed 14 of 22 virtual landmarks (63.6%) from MRA overlaid on fluoroscopy were completely accurate, without the need for adjustment. Five of eight incorrect virtual landmarks (iliac and visceral arteries) resulted from vessel deformation caused by endovascular devices.

CONCLUSIONS

Ferumoxytol or gadolinium-enhanced MRA imaging and image fusion with fluoroscopy using noncontrast CBCT is feasible and allows patients with renal insufficiency to benefit from optimal guidance during complex endovascular aortic procedures, while preserving their residual renal function.

Carbon Dioxide as Contrast Medium to Guide Endovascular Aortic Aneurysm Repair

BACKGROUND

Iodine contrast medium (ICM) is considered to be gold standard in endovascular procedures, but its nephrotoxicity and hypersensitivity limit the widespread use. Carbon dioxide (CO₂) is considered as an alternative for endovascular procedures in patients with contraindication to ICM. However, no studies have compared the outcomes of endovascular aneurysm repair (EVAR) performed with ICM or CO₂ among patients with no contraindication to ICM.

METHODS

From May 2012 to April 2014, 36 patients with abdominal aortic aneurysms underwent EVAR in a prospective, randomized, and controlled study. Patients were randomized into 2 groups, CO₂ or ICM group.

RESULTS

We were able to perform the proposed procedures in all patients in this study. There were no conversions to open surgery and no CO₂-related complications. Endovascular material costs, duration of surgery, and time of fluoroscopy were similar between groups, and the cost of the contrast media was smaller in the CO₂ group than in the ICM group. Among CO₂ group procedures, 62.5% of the patients needed ICM complementary use.

CONCLUSIONS

The use of CO₂ as a contrast medium for EVAR is an alternative in patients with no restriction for ICM, with similar outcomes when compared to ICM, regarding duration of surgery, duration of fluoroscopy, and endovascular material costs. Using CO₂, there were no changes in creatinine clearance and no risk of hypersensitivity reactions; moreover, there was a reduction in contrast-related costs for EVAR procedures. However, in our study, additional use of ICM to visualize the internal iliac artery was needed in most procedures.

A Novel Bubble-Mixture Method to Improve Dynamic Images in Carbon Dioxide Angiography

Purpose: To present a novel method of preparing carbon dioxide (CO2) for contrast enhancement.Technique: CO2 angiography can often produce poor image enhancement, especially in dependent vessels due to buoyancy of the gas. A new technique for premixing the CO2 gas with the patient’s blood and dispersing it into the bubble mixture before injection was developed. Comparative dynamic images showed bubble-mixed CO2 angiography had less fragmentation, more even distribution, and more sustainability than the same volume of pure CO2. Conclusion: The alteration of CO2 gas toward a semiliquid form demonstrates an easy and reproducible concept to improve the dynamic image quality of traditional CO2 angiography.

Urgent endovascular repair for ruptured aortic aneurysm using computed tomography image fusion

Abdominal aortic aneurysm rupture remains a cardiovascular catastrophe with strikingly high morbidity and mortality rates. Endovascular aneurysm repair management has recently emerged as a valuable treatment modality for ruptured abdominal aortic aneurysm, but better outcomes have to be reached. Image fusion may potentially improve perioperative outcomes in selected patients, guiding navigation and device implantation and limiting contrast dosage during interventions. We report an 83-year-old man presenting with an 80-mm infrarenal aortic aneurysm rupture suitable for endovascular aneurysm repair. Endovascular navigation and stent graft deployment were achieved using computed tomography image fusion for the first reported case in English.

Endovascular therapy by CO2 angiography to prevent contrast-induced nephropathy in patients with chronic kidney disease: a prospective multicenter trial of CO2 angiography registry

OBJECTIVES

To assess the safety and efficacy of carbon dioxide (CO2) angiography-guided endovascular therapy (EVT) for renal, iliofemoral artery disease.

BACKGROUND

Patients with peripheral vascular disease (PVD) often have chronic kidney disease (CKD) and the use of iodinated contrast media may enhance the risk of contrast-induced nephropathy (CIN). Contrast volume reduction is an effective CIN preventive strategy.

METHODS

A prospective multicenter registry was developed and six clinical centers participated in the study. Patients with an estimated glomerular filtration rate (eGFR) of <60 ml/min/1.73 m2 and stage-3 CKD were recruited between February 2012 and March 2013. CO2 angiography-guided EVT was performed; incomplete CO2 angiograms were supplemented by intravascular ultrasound, pressure wire, and/or minimal iodinated contrast media. The primary endpoint was a composite of freedom from renal events and freedom from major CO2 angiography related complications.

RESULTS

This study included 98 patients with 109 lesions. The mean eGFR baseline was 35.2±12.7 ml min(-1). CO2 angiography-guided angioplasty were performed in 16 renal arteries, 31 aortoiliac arteries, and 62 superficial femoral arteries. The technical success rate was 97.9%. Average CO2 consumption was 281.4±155.8 ml, average dose of iodinated contrast media was 15.0±18.1 ml. Primary endpoint was 92.8% (91/98). Incidence of CIN was 5.1% (5/98) and CO2 angiography-related complications occurred in 17.3% (17/98). Two cases (2%) developed severe, fatal, nonocclusive mesenteric ischemia (NOMI).

CONCLUSIONS

This trial showed that CO2 angiography-guided angioplasty was effective for preventing CIN, however, CO2 angiography related complication was somewhat high.

Endoleak visualized with carbon dioxide angiography during endovascular aneurysm repair using the Endurant stent-graft

PURPOSE

To make interventionists aware of the potential for type IV endoleak on completion carbon dioxide (CO2) angiography during endovascular aneurysm repair (EVAR) using the Endurant stent-graft.

CASE REPORT

A 74-year-old man with chronic kidney disease underwent EVAR with an Endurant stent-graft using CO2 angiography to guide graft placement. Completion CO2 angiography demonstrated immediate accumulation of CO2 in the aneurysm sac suggestive of an endoleak, but confirmatory angiography with conventional iodinated contrast showed no evidence of an endoleak. We speculate that this is a type IV endoleak, and graft porosity may be responsible.

CONCLUSION

Interventionists should be alerted to the possibility of visualizing these endoleaks through Endurant stent-grafts under CO2 angiography. Further work should be done to elucidate the exact mechanism of the endoleak.

Carbon dioxide digital subtraction angiography as an option for detection of endoleaks in endovascular abdominal aortic aneurysm repair procedure

OBJECTIVE

The purpose of this study was to evaluate carbon dioxide digital subtraction angiography (CO2-DSA) as an option for the detection of endoleaks (ELs) in the endovascular abdominal aortic aneurysm repair (EVAR) procedure.

METHODS

Forty patients with abdominal aortic aneurysm who were scheduled to undergo EVAR were enrolled in the study. There were 35 men and five women (mean age, 77.9 years). All patients had both iodinated contrast conventional DSA (C-DSA) and CO2-DSA immediately after EVAR. The sensitivity and specificity were calculated for the ability of CO2-DSA to detect ELs. We also correlated with computed tomography findings 6 months after EVAR.

RESULTS

C-DSA showed that 27 of the 40 patients (68%) had 28 ELs (type I, four; type II, 20; type III, three; type IV, one). CO2-DSA showed that 16 of the 40 patients (40%) had 17 ELs (type I, four; type II, 10; type III, three; type IV, none). For the prediction of direct ELs (type I and type III) with use of C-DSA as the criterion standard, CO2-DSA has a sensitivity of 1.0 and a specificity of 1.0. For the detection of persistent type II ELs (n = 11) with use of computed tomography findings 6 months from EVAR as the criterion standard, CO2-DSA has a sensitivity of 0.87 and a specificity of 0.97. C-DSA has a sensitivity of 0.82 and a specificity of 0.64.

CONCLUSIONS

CO2-DSA is reliable for the detection of direct ELs and persistent type II ELs in EVAR. CO2-DSA can be an option to detect ELs in the EVAR procedure.

Considerations for patients undergoing endovascular abdominal aortic aneurysm repair

Endovascular aneurysm repair has taken over open surgery as the primary strategy for treatment of patients with abdominal and thoracic aneurysms. The minimally invasive nature of these techniques requires alterations in preoperative workup, intraoperative management, and familiarity with unique complications that can occur. Familiarity from the anesthetic standpoint of endovascular techniques, including treatment of patients with fenestrated, chimney, snorkel, and periscope grafts, is necessary for the contemporary cardiac anesthesiologist.

A prospective study of carbon dioxide digital subtraction versus standard contrast arteriography in the detection of endoleaks in endovascular abdominal aortic aneurysm repairs

BACKGROUND

The objective of this study is to compare intraoperative endoleak detection by carbon dioxide digital subtraction angiography (CO(2)-DSA) during endovascular aortic aneurysm repair (EVAR) with standard iodinated contrast angiography (ICA).

METHODS

Between 2006 and 2010, 76 patients with abdominal aortic aneurysms undergoing EVAR were enrolled in a prospective study. After EVAR, both an ICA and CO(2)-DSA completion study were performed. Two blinded vascular surgeons who were not involved with the EVAR separately interpreted the ICA and CO(2)-DSA results for the presence or absence of an endoleak. Identified endoleaks were classified by types. A third, "tie-breaker" blinded observer was used to resolve differences in interpretations. The sensitivity, specificity, negative predictive value, and positive predictive value were calculated for the ability of CO(2)-DSA to detect endoleaks. Cohen's κ statistic was used to assess interobserver agreement between the 2 initial interpreting surgeons.

RESULTS

Of the 76 patients undergoing EVAR, 66 were men with average age of 76 years, a mean aneurysm size of 5.8 cm (range, 4-10 cm), and creatinine of 1 (standard deviation, 0.33). ICA identified 35 type I and 15 type II endoleaks, respectively, while CO(2)-DSA identified 40 type I and 10 type II endoleaks. Overall, CO(2)-DSA had a sensitivity of 0.84, specificity of 0.72, positive predictive value of 0.86, and negative predictive value of 0.69 of intraoperative endoleak detection, with respect to ICA as the criterion standard. The interobserver κ between surgeons for ICA was 0.56, for detection of any endoleak or type I endoleak with CO(2)-DSA was 0.58, and for detection of type II endoleak with CO(2)-DSA was 0.29.

CONCLUSIONS

Interobserver agreement for the detection of endoleaks is superior with ICA compared to CO(2)-DSA. However, the sensitivity for detecting any endoleak and both the sensitivity and specificity for detecting type I endoleaks using CO(2)-DSA are acceptable. For detecting type II endoleaks using CO(2)-DSA, the sensitivity and positive predictive value are poor. Compared to ICA, CO(2)-DSA provides adequate images for endoleak detection during EVAR and is an acceptable alternative to ICA in patients at risk for contrast-related nephrotoxicity.

A New Technique of Branched Stent Graft Treatment for Ruptured Thoracoabdominal Aortic Aneurysms

Endovascular repair of thoracoabdominal aortic aneurysms (TAAAs) using a branched stent graft is a technically challenging procedure. A 64-year-old man with multiple medical problems, including severe renal impairment, is presented with a ruptured type IV TAAA. He underwent emergency repair using an off-the-shelf branched stent graft and carbon dioxide as the exclusive contrast agent.

Endovascular surgery for inflammatory abdominal aortic aneurysm with contrast allergy-usefulness of carbon dioxide angiography and intravascular ultrasound: a case report

We report a patient with inflammatory abdominal aortic aneurysm who underwent endovascular aneurysm repair, despite his having an allergy to iodinated contrast medium and anatomy unsuitable for the procedure. Intravascular ultrasound-guided and CO2-assisted aortic stent graft placement was performed, and the procedures resulted in the successful exclusion of the aneurysm with regression of the mantle sign and resolution of hydronephrosis.