Current status of carbon dioxide angiography

A Pilot Study of Endovascular Repair for Ruptured Aortic Aneurysms With the Use of Carbon Dioxide Angiography Alone

INTRODUCTION

Endovascular aortic repair (EVAR) of a ruptured abdominal aortic aneurysm (rAAA) has become a common approach. Hemorrhagic shock associated with the use of iodinated contrast medium (ICM) increases the risk of acute kidney injury (AKI). Theoretically, eliminating ICM from EVAR can decrease that risk. The aim of this pilot study was to analyze the feasibility and safety of emergent EVAR performed with the exclusive use of carbon dioxide (CO2) for a rAAA.

METHODS

Since 2021, all consecutive rAAAs with hemorrhagic shock and suitable anatomical criteria for a standard endograft have been treated by EVAR with the exclusive use of CO2 using an automated CO2 injector (Angiodroid SpA, San Lazzaro di Savena, Italy).

RESULTS

Eight percutaneous EVARs were performed under local anesthesia. Median age was 78 (interquartile range [IQR]=6) years, 5 patients were male. The technical success was 100%, the 30-day mortality was 25% (n=2), the median amount of administered CO2 was 400 (IQR=60) ml. The median change in serum creatinine level between admission, post-operative and 30-day values was an increase of 0.14 mg/dL and a decrease of 0.11 mg/dL, respectively. Post-operative AKI occurred in the two patients who died. All 6 surviving patients showed sac shrinkage >5 mm, and no reinterventions at a median follow-up of 10 months.

CONCLUSIONS

Endovascular repair of rAAA with the exclusive use of CO2 as contrast agent is technically feasible and safe. Further studies are needed to determine whether CO2 increases survival rate and limits the progression of renal dysfunction after endovascular repair of rAAA.Clinical ImpactThe recorded rate of post-operative AKI after endovascular repair of rAAA performed with the use of CO2 found in this pilot study was significantly lower than the one reported in the literature with the use of ICM. Our hyphotesis is that the use of CO2 during rEVAR might increase survival rate and limits the progression of renal dysfunction.

Carbon Dioxide Digital Subtraction Angiography for Central Venous Recanalization in a Kidney Transplant Patient: A Case Report

BACKGROUND

We present the case of a kidney transplant recipient with elevated serum creatinine who developed left upper limb swelling due to left subclavian vein thrombosis. Concerned about potential hemodialysis resumption, the patient prioritized preserving their arteriovenous fistula.

METHODS

To address the swelling and maintain fistula function, central venous recanalization was necessary. Given the risk of iodine contrast-induced acute kidney injury, particularly with elevated creatinine, the patient opted for carbon dioxide (CO2) angiography. Following forearm fistula puncture, a catheter was inserted, and 50 mL of CO2 was injected. Angiography revealed a left subclavian vein filling defect and stenosis, preventing guidewire passage. The stenosis was dilated using an 8 mm × 20 mm balloon, followed by implantation of a 6 mm × 10 mm vascular stent. Postintervention CO2 angiography confirmed successful vein opening. Oral rivaroxaban was prescribed for anticoagulation.

RESULTS

The patient's limb swelling gradually resolved, and serum creatinine remained stable.

CONCLUSION

CO2-DSA represents a potentially viable alternative imaging modality for patients requiring vascular interventions who are at elevated risk of iodinated contrast-induced nephropathy.

Utilizing CO2 Cone Beam Computed Tomography for Post-Procedure Completion Control Following Fenestrated Endovascular Repair of Complex Aortic Aneurysm With a Standardized CO2 Protocol

PURPOSE

To assess the feasibility and efficacy of a standardized CO2 protocol and CO2 cone beam computed tomography (CBCT) for procedural completion in fenestrated endovascular aneurysm repair (FEVAR) of complex aortic aneurysms in patients with chronic kidney disease (CKD).

MATERIALS AND METHODS

Ten patients with complex aortic aneurysms and CKD (estimated glomerular filtration rate <90 ml/min) underwent FEVAR with custom-made fenestrated devices, using CO2 as the primary contrast agent. Procedures were conducted in a hybrid operating room following a standardized CO2 protocol with optimized injection parameters and visualization techniques to maximize CO2 imaging efficacy. CO2 CBCT was performed intraoperatively to verify stent graft deployment, bridging stent positioning, target vessel patency, and the presence of potential endoleaks.

RESULTS

All 10 procedures were completed successfully without intraoperative complications or CO2-related adverse effects. Completion CO2 CBCT provided clear visualization of visceral and renal vessels, and no significant endoleaks were detected. One procedure was entirely iodine contrast-free, while minimal iodine contrast was used in others to address diagnostic uncertainties. Postoperative renal function remained stable across all patients.

CONCLUSION

CO2 CBCT is a feasible and effective alternative for completion imaging in complex FEVAR procedures for patients with CKD, potentially reducing the need for iodine contrast and the associated risk of nephropathy. A standardized CO2 protocol can enhance procedural safety. Further research with larger cohorts is needed to confirm these findings.Clinical ImpactCO2 serves as the preferred contrast medium for the endovascular treatment of patients with iodine contrast allergies or those afflicted with chronic kidney disease (CKD) to preserve further renal deterioration. Ensuring protection from potentially harmful substances is paramount during endovascular repair in such patients. Equally crucial is performing the procedure safely through a standardized protocol and confirming its accuracy upon completion. Nevertheless, the possibility of employing CO2 for cone beam computed tomography provides invaluable insights into procedural efficacy, thereby enhancing outcomes for CKD patients undergoing complex endovascular repair.

Editor's Choice - Feasibility and Safety of Using Carbon Dioxide Exclusively in Regular Endovascular Aortic Aneurysm Repair: Results of a Multicentre, Prospective, Zero Iodine Contrast Endovascular Aneurysm Repair Study

OBJECTIVE

Carbon dioxide (CO2) angiography has emerged as a viable alternative to regular iodinated contrast medium (ICM) for guiding endovascular aneurysm repair (EVAR) procedures. This study aimed to evaluate the feasibility and safety of a standardised EVAR procedure using only CO2 angiography.

METHODS

A prospective, multicentre, national study enrolled consecutive patients between January 2023 and January 2024 with asymptomatic abdominal aortic aneurysms measuring ≥ 55 mm and for whom a standard endovascular graft (instructions for use) was anatomically feasible. The study involved the use of an automatic CO2 injector to standardise intra-operative imaging. A strategy comprising five standardised steps was devised to visualise a target vessel (TV) that could not be seen during the first CO2 angiogram. The five steps were: (A) place the introducer closer to the TV; (B) tilt the table by 5 - 10° in the direction opposite to the TV; (C) selectively cannulate the TV; (D) cannulate the contralateral gate (only for repositionable devices); CO2 angiography was repeated in steps 1 - 2; and (E) use ICM.

RESULTS

Two hundred and ninety-three patients were enrolled (10 centres), with a median age of 78 (interquartile range [IQR] 72, 83) years; 256 (87.4%) were male. The overall procedure time, fluoroscopy time, and injected CO2 volume were 90 (IQR 65, 125) minutes, 15 (IQR 10, 22) minutes, and 600 (IQR 400, 800) mL, respectively. The 30 day mortality, complication, and re-intervention rates were 0.3% (n = 1), 6.8% (n = 20), and 2.4% (n = 7), respectively. CO2 related adverse events were rare (1%; n = 3) and minor. A zero iodine contrast EVAR procedure was feasible in 240 (patients 81.9%). The five standardised steps were used extensively: step A, 170 procedures (58.0%); step B, 109 procedures (37.2%); step C, 21 procedures (7.2%); step D, 14 procedures (4.8%); and step E, 53 procedures (18.1%), with a median volume of 20 (IQR 10, 35) mL. Significant predictors for ICM use were aneurysm diameter > 70 mm and a lowermost renal artery positioned between 3 and 9 o'clock.

CONCLUSION

This study demonstrated that the standardised zero iodine contrast EVAR protocol reported here is both safe and feasible and is applicable in 82% of consecutive non-selected patients. Limitations primarily arose from anatomical factors, and adjunctive standardised manoeuvres can effectively address these challenges in most cases.

Comparing the accuracy and safety of automated CO2 angiography to iodine angiography in peripheral arterial disease with chronic limb ischemia: a prospective cohort study

Introduction

Diagnostic angiography of peripheral arteries using carbon dioxide (CO2) is feasible in nearly all areas below the diaphragm. Using carbon dioxide as a contrast material in angiography provides the highest quality diagnostic results in the vascular segments above the knee. However, its diagnostic reliability decreases as it moves toward the distal side of the vessels below the knee. This study investigated the diagnostic accuracy and consistency between CO2 and iodine contrast angiography in patients with peripheral vascular disease (PVD) with chronic limb ischemia (CLI).

Methods

The study prospectively enrolled 35 patients with PVD and CLI and performed both CO2 and iodine contrast angiography, comparing the results for each patient. Image quality, stenosis severity, and anatomical location were analyzed.

Results

In this study, a total of 35 patients (19 male) with an average age of 56.91 ± 10.73 were examined. Among them, 13 patients (37.1%) had involvement in the femoral region, 8 patients (22.9%) in the popliteal region, 8 patients (22.9%) in the tibial region, and 6 patients (17.1%) in the foot region. CO2 angiography produced excellent image quality in 40% of cases, with good quality in another 25.7%. The quality decreased in the popliteal and foot regions. While stenosis assessment was comparable between the two methods in the femoral, popliteal, and tibial regions, there was a significant difference in the foot region. The sensitivity, specificity, positive predictive value, and negative predictive value of CO2 angiography were all 100% in the femoral and popliteal areas. However, these values were lower in the tibial and foot areas.

Discussion

The study concluded that the use of CO2 angiography, particularly for vascular lesions above the popliteal cavity, is a valuable and safe method for peripheral vascular examination of the lower limbs. It can serve as an alternative to iodine contrast angiography, especially in patients with kidney failure.

Effects of renal denervation on the kidney: albuminuria, proteinuria, and renal function

Renal denervation has attracted attention as a novel antihypertensive treatment for hypertensive patients who are poorly controlled by medicine. Clinical studies have shown the antihypertensive effects of renal denervation in patients with treatment-resistant hypertension. However, renal denervation potentially has other beneficial effects, such as improving glucose metabolism and cardioprotection beyond its antihypertensive effects. In this mini-review article, we summarize and discuss the effects of renal denervation on proteinuria, albuminuria, and renal function based on the recent findings of clinical studies, and review the renoprotective effects of renal denervation.

Carbon dioxide angiography during angioembolization for trauma patients increases the detection of active bleeding and leads to reliable hemostasis: a retrospective, observational study

BACKGROUND

Angiography with carbon dioxide (CO2) has long been used as an alternative when iodine contrast media (ICM) cannot be used due to allergy to iodine or renal dysfunction. Conversely, CO2 angiography is also known as a provocation method for active bleeding. In this study, we examined the efficacy of CO2 angiography in angioembolization (AE) for trauma patients.

METHODS

This was a single-center, retrospective, observational study of trauma patients who underwent AE at our facility between January 2012 and April 2023.

RESULTS

Within this period, 335 AEs were performed. CO2 angiography was performed in 102 patients (30.4%), and in 113 procedures. CO2angiography was used to provoke active bleeding which went undetected using ICM in 83 procedures, and to confirm hemostasis after embolization in 30 procedures. Of the 80 procedures wherein, active bleeding was not detected on ICM, 35 procedures (43.8%) were detected using CO2. The spleen had the highest detection rate of active bleeding by CO2 angiography among the organs. There were 4/102 (1.9%) patients with CO2 contrast who underwent some form of reintervention. Two patients were re-embolized with n-butyl-2-cyanoacrylate because of recanalization after embolization with gelatin sponge. The other two patients had pseudoaneurysm formation which required reintervention, and CO2 angiography was not used. Vomiting was the most common complication of CO2 angiography in 10 patients (9.8%), whereas all were transient and did not require treatment.

CONCLUSIONS

CO2 angiography of trauma patients may have a better detection rate of active bleeding compared with ICM, leading to reliable hemostasis.

Severe liver injury successfully treated with transarterial embolization using carbon dioxide angiography: A case report

Angiography using carbon dioxide (CO2) has gained attention as a method of inducing active bleeding in patients for whom bleeding cannot be detected with iodine contrast medium (ICM). We experienced a case in which CO2 angiography was performed during transarterial embolization (TAE) for severe liver injury with active bleeding. A woman in her 40s was struck by a minitruck while crossing the road and rushed to our hospital. Upon admission, she was in shock vital with blood pressure of 75/38 mmHg and pulse rate of 130 bpm. Blood transfusion was promptly started after arrival and her blood pressure increased. Abdominal ultrasonography showed echo free space in Morrison's pouch. Contrast-enhanced CT showed deep liver laceration in the right lobe and intra-abdominal hemorrhage with active bleeding. We selected TAE for hemostasis. ICM angiography showed extravasation of contrast medium from the anterior and posterior segmental branches, which was embolized with a gelatin sponge. After embolization, CO2 angiography revealed new extravasation that could not be detected by ICM, which was additionally embolized. There was no rebleeding or pseudoaneurysm after embolization. In TAE for deep liver injury, ICM alone may underestimate active bleeding. CO2 angiography may lead to better outcomes when injured vessels are reliably identified and TAE is performed.

CO2 Angiography in the Standard and Complex Endovascular Repair of the Abdominal Aorta-A Narrative Review of the Literature

Background/Objectives: Carbon dioxide digital-subtraction angiography (CO2-DSA) is an increasingly adopted technique in endovascular aortic repair (EVAR) and fenestrated/branched EVAR (F/B-EVAR); it is used to reduce the amount of iodinate contrast medium (ICM) and prevent postoperative renal function worsening (PO-RFW). Our aim is to report results from the literature on EVAR and F/B-EVAR procedures using CO2-DSA, together with wider applications in aortic endovascular treatment. Methods: We performed a literature review by searching electronic databases for published data on CO2-DSA during EVAR and F/B-EVAR procedures. The endpoints were postoperative renal function worsening (PO-RFW) and efficacy of intraoperative arterial visualization. Further, applications of CO2 for thoracic endovascular aortic repair (TEVAR) were described. Results: Seventeen studies reporting results on CO2-DSA in EVAR (644 patients) were retrieved. Overall, 372 (58%) procedures were performed with CO2 alone, and 272 (42%) were performed with CO2+ICM. Eight studies analyzed the effect of CO2-DSA angiography on PO-RFW; four studies showed a significantly lower rate of PO-RFW compared to ICM. Five studies (153 patients) analyzed intraoperative arterial visualization with CO2-DSA; renal and hypogastric arteries were effectively visualized in 69% and 99% of cases, respectively. The use of CO2-DSA in F/B-EVAR has not been widely investigated. The largest series reported that PO-RFW was lower in the CO2 vs. ICM group. Conclusions: Carbon dioxide is widely applied in modern aortic endovascular treatment. CO2-DSA for EVAR and F/B-EVAR is an efficient technique for reducing PO-RFW while allowing acceptable arterial intraoperative visualization.

In vitro comparison of the leakage of carbon dioxide and iodine contrast media in a bleeding model

BACKGROUND

We aimed to compare the hydrodynamic values of carbon dioxide (CO2) and iodine contrast media for bleeding detection using an in vitro model.

MATERIALS AND METHODS

We created a bleeding model with large and small wounds in simulated blood vessels. We connected a syringe to the bleeding model and the blood pressure transducer, filling the circuit with CO2 and iodine contrast media. The syringe's piston was pressed, and the flow rate and intravascular pressure of the CO2 and iodine contrast media leaking from the bleeding model were measured. We compared each leaked contrast medium's volume, sphere-equivalent diameter, and sphere-equivalent area. These values were analyzed to compare the visibility of the leakage objectively.

RESULTS

At a constant flow rate, the intravascular pressure required for the model to leak was lower for the CO2 than that for the iodine contrast medium. The CO2 contrast medium leakage volume, equivalent circle diameter, and equivalent circle area were greater than those of the iodine one. These values indicate higher CO2 visibility during fluoroscopy.

CONCLUSIONS

In the bleeding model, a CO2 contrast medium may be more prone to leakage than the iodine one in large and small wounds. Regarding visibility, a CO2 contrast medium may be more likely to detect leakage than an iodine one.

Adverse reactions after intravascular iodinated contrast media administration and their management

Endovascular interventions and diagnostic examinations using iodinated contrast media (ICM) are standard of care in current vascular medicine. Although ICM use is generally considered safe, it may be associated with adverse reactions, vary from minor disturbances to rare, but severe life-threatening complications. This position paper of European Society of Vascular Medicine integrates current knowledge and summarizes the key information related to the use of intravascular ICM, serving as recommendation on prevention and management of acute, late, and very late adverse reactions. It should help the health professionals in all fields of vascular medicine to make decisions in daily practice for safe use of contrast media.

Fenestrated endovascular aortic repair of a superior mesenteric artery aneurysm using carbon dioxide angiography and intravascular ultrasound

Superior mesenteric artery aneurysms are rare; however, current guidelines suggest they all require repair due to the high rupture and mortality rates, and endovascular repair is an effective management strategy. Iodinated contrast traditionally used in endovascular repair can cause significant complications, including severe allergic reactions and contrast-induced nephropathy in patients with chronic renal disease. Therefore, other imaging methods should be used during endovascular procedures to reduce these risks. We describe a unique and innovative approach using carbon dioxide angiography and intravascular ultrasound during fenestrated endovascular repair of an uncommon superior mesenteric artery aneurysm in a patient with severe contrast allergies.

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.

Contrast-Free Endovascular Aneurysm Repair Combined With Fibrin Sealant Filling for Treating Abdominal Aortic Aneurysm: Technical Note

INTRODUCTION

Endovascular aneurysm repair using iodinated contrast agents risks contrast-induced nephropathy, especially in high-risk patients. This technical note describes a contrast-free endovascular aneurysm repair (EVAR) protocol using preoperative imaging measurement and fibrin sealant (FS) filling.

TECHNIQUE

Preoperative imaging measurement and intraoperative guidewire manipulation facilitated anatomical identification without contrast. After endograft deployment, the aneurysm sac was filled with FS if endoleak was indicated by pressure fluctuations.

RESULT

Between 2017 and 2020, 6 high-risk patients underwent contrast-free EVAR with FS filling. Complete exclusion was achieved in all cases. Over follow-up, no endoleaks, deterioration in renal function, or other complications were observed.

CONCLUSION

Contrast-free EVAR with FS filling shows early feasibility as an alternative technique for contrast-induced nephropathy (CIN) high-risk patients, while larger studies with long-term monitoring are imperative to validate outcomes.

CLINICAL IMPACT

This study showcases a contrast-free EVAR technique with fibrin sealant filling for high-risk CIN patients. It offers a safer approach for those with renal challenges, reducing CIN risk. The technique's feasibility in a small cohort suggests its utility in treating AAA without iodinated contrast, crucial for patients with specific health risks. For clinicians, it introduces a method that decreases nephrotoxic risks, potentially changing practice for vulnerable patients.

The feasibility, efficacy, and safety of RDN procedure using CO2 angiography through radial artery in severe chronic kidney disease patients

The recent evidence regarding the effectiveness of renal denervation (RDN) in blood pressure control is becoming increasingly substantial. However, many studies have excluded populations with severely impaired kidney function, even though these individuals have a higher prevalence of hypertension compared to the general population, and controlling their blood pressure is more challenging. The effectiveness and safety of RDN in patients with severe chronic kidney disease (CKD) lack strong evidence support. Concerns about worsening kidney function still exist, particularly in patients with CKD stage 5. We conducted an observational study involving 10 patients who were using at least 3 different antihypertensive medications and had an estimated glomerular filtration rate (eGFR) < 45 mL/min/1.73 m2 but had not undergone dialysis. For these patients, we performed RDN via the radial artery approach, with the assistance of carbon dioxide (CO2) angiography. Utilizing this approach, the systolic 24-hour ambulatory blood pressure monitoring did not exhibit a significant decrease at 3 months; however, a significant reduction was observed at 6 months after RDN. We also minimized contrast agent usage, observed no kidney function decline 3 months post-RDN, and experienced no vascular-related complications. Using the radial artery approach and CO2 angiography assistance for RDN may be an effective and safe blood pressure control method for patients with severe kidney impairment.

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.

Renal cryoablation combined with prior transcatheter arterial embolization in non-dialysis patients with stage 4 or 5 chronic kidney disease: a retrospective study

PURPOSE

To retrospectively evaluate cryoablation combined with prior transcatheter arterial embolization (TAE) for renal cell carcinoma (RCC) in non-dialysis patients with stage 4 or 5 chronic kidney disease (CKD).

MATERIALS AND METHODS

Patients with stage 4 or 5 CKD undergoing TAE and cryoablation for RCC between May 2012 and October 2021 were included. TAE was selectively performed using iodized oil with absolute ethanol or gelatin sponge 1-14 days before cryoablation. Local efficacy, safety, and changes in renal function were evaluated.

RESULTS

Nine patients (seven men and two women; median age, 64 years; range 52-88 years) with nine RCCs (mean diameter, 3.0 ± 1.0 cm; range 1.7-4.7 cm) were included. The mean pre-treatment estimated glomerular filtration rate (eGFR) was 24.2 ± 5.6 ml/min/1.73 m2 (range 10.4-29.2 ml/min/1.73 m2). The mean amount of contrast medium used in TAE was 58 ± 29 ml (range 40-128 ml). Except in one patient (grade 3 pyelonephritis), no grade ≥ 3 complications occurred. During the follow-up period (median, 18 months; range 7-54 months), no local tumor progression occurred. In two patients with pre-treatment eGFR of < 20 ml/min/1.73 m2, hemodialysis was initiated at 3 and 19 months after cryoablation. At their last follow-up, the remaining seven patients showed a decrease of 6.2 ± 5.3 ml/min/1.73 m2 (range 0.7-17.2 ml/min/1.73 m2) in their eGFR.

CONCLUSION

Cryoablation combined with TAE for RCC in non-dialysis patients with stage 4 or 5 CKD was effective and safe, with an acceptable impact on renal function.

Carbon dioxide angiography during peripheral vascular interventions is associated with decreased cardiac and renal complications in patients with chronic kidney disease

OBJECTIVE

Patients with chronic kidney disease (CKD) who undergo peripheral vascular interventions (PVI) with iodinated contrast are at higher risk of post-contrast acute kidney injury (PC-AKI). Carbon dioxide (CO2) angiography can reduce iodinated contrast volume usage in this patient population, but its impact on PC-AKI has not been studied. We hypothesize that CO2 angiography is associated with a decrease in PC-AKI in patients with advanced CKD.

METHODS

The Vascular Quality Initiative PVI dataset from 2010 to 2021 was reviewed. Only patients with advanced CKD (estimated glomular filtration rate <45 ml/min/1.73 m2) treated for peripheral arterial disease were included. Propensity matching and multivariate logistic regression based on demographics, comorbidities, CKD stage, and indications were used to compare the outcomes of patients treated with and without CO2.

RESULTS

There were 20,706 PVIs performed in patients with advanced CKD, and only 22% utilized CO2 angiography. Compared with patients treated without CO2, patients who underwent CO2 angiography were younger and less likely to be women or White, and more likely to have poor renal function, diabetes, cardiac comorbidities, and present with tissue loss. Propensity matching yielded well-matched groups with 4472 patients in each group. The procedural details after matching demonstrated 50% reduction in the volume of contrast used (32±33 vs 65±48 mL; P < .01). PVI with CO2 angiography was associated with lower rates of PC-AKI (3.9% vs 4.8%; P = .03) and cardiac complications (2.1% vs 2.9%; P = .03) without a significant difference in technical failure or major/minor amputations. Low contrast volumes (≤50 mL for CKD3, ≤20 mL for CKD4, and ≤9 mL for CKD5) are associated with reduced risk of PC-AKI (hazard ratio, 0.59; P < .01).

CONCLUSIONS

CO2 angiography reduces iodinated contrast volume usage during PVI and is associated with decreased cardiac complications and PC-AKI. CO2 angiography is underutilized and should be considered for patients with advanced CKD who require endovascular therapy.

Carbon Dioxide Pyelography: A Convenient and Safe Alternative to Both Room Air and Iodinated Contrast Pyelography During Endourologic Procedures

Introduction/Background: There are increasing reports of serious complications related to the air pyelography technique, which raise concerns about the safety of room air (RA) injection into the renal collecting system. Carbon dioxide (CO2) is much more soluble in blood than nitrogen and oxygen and thus considerably less likely to cause gas emboli. Iodinated contrast medium (ICM) is expensive, and supplies may not be as reliable as previously assumed. CO2 pyelography (CO2-P) techniques using standard fluoroscopy and digital subtraction fluoroscopy (CO2 digital subtraction pyelography [CO2-DSP]) are described. Materials and Methods: During the endourologic stone cases, 15 to 20 mL of CO2 gas was typically injected into the renal pelvis through a catheter or sheath. Imaging was usually obtained with endovascular CO2 digital subtraction angiography settings using either a traditional fluoroscopy system (TFS) or robotic arm multiplanar fluoroscopy system (RMPFS) (Artis Zeego Care+Clear®; Siemens). Results: CO2-P was performed in 22 endoscopic stone treatment cases between March 2021 and August 2022, primarily using digital subtraction settings in 20 cases. CO2-DSP overall provided higher quality images of the renal pelvis and collecting system than CO2-P, but with a relatively higher radiation dose. Following a quality intervention, fluoroscopy doses for CO2-DSP cases were decreased by 81% overall. The use of CO2-P avoided fluoroscopic or intraoperative CT (ICT) artifacts seen with intraluminal ICM. Conclusions: CO2-P allows the urologist to obtain imaging of the renal collecting system without ICM and with much lower risk of air embolism compared with RA pyelography. CO2 is a nearly cost-free alternative to ICM. Because CO2 is widely available and the technique is easy to perform, we propose that CO2-P should be favored over traditional air pyelography to improve patient safety.

Total iodine contrast-free strategy for the endovascular management of abdominal aortic aneurysms in chronic kidney disease patients: a pilot study

OBJECTIVES

To retrospectively evaluate the feasibility and effectiveness of the endovascular treatment of patients with abdominal aortic aneurysm (AAA) and chronic kidney disease (CKD) without the need for using iodinated contrast media (ICM) throughout the diagnostic, therapeutic and follow-up pathway.

METHODS

A retrospective review of prospectively collected data concerning 251 consecutive patients presenting an abdominal aortic or aorto-iliac aneurysm who underwent endovascular aneurysm repair (EVAR) from January 2019 to November 2022 at our academic institution was performed in order to identify patients with feasible anatomy with respect to manufacturers' instructions for use (IFU) and with CKD. Patients whose preoperative workout included duplex ultrasound (DUS) and plain computed tomography (pCT) for pre-procedural planning were extracted from a dedicated EVAR database. EVAR was performed with the use of carbon dioxide (CO₂) as contrast media of choice, whereas follow-up examinations consisted of either DUS, pCT or contrast-enhanced ultrasound (CEUS). Primary endpoints were technical success, perioperative mortality and early renal function variations. Secondary endpoints were all-type endoleaks (EL) and reinterventions, mid-term aneurysm-related and kidney-related mortality.

RESULTS

Forty-five patients had CKD and were treated electively (45/251, 17.9%). Of them, seventeen patients were managed with a total ICM-free strategy and constituted the object of the present study (17/45, 37.8%; 17/251, 6.8%). In seven cases an adjunctive planned procedure was performed (7/17, 41.2%). No intraoperative bail-out procedures were needed. This extracted cohort of patients presented similar mean preoperative and postoperative (at discharge) GFRs values, 28.14 (SD 13.09; median 28.06, IQR 20.25) ml/min/1.73m² and 29.33 (SD 14.61; median 27.35, IQR 22) ml/min/1.73m² respectively (p= .210). Mean follow-up was 16.4 months (SD 11.89; median 18, IQR 23). During follow-up no graft-related complications occurred in terms of either thrombosis, type I or III EL, aneurysm rupture or conversion. The mean GFR at follow-up was 30.39 ml/min/1.73m² (SD 14.45; median 30.75, IQR 21.93), with no significant worsening in comparison with pre and postoperative values (p= .327 and p= .856 respectively). No aneurysm- or kidney-related deaths occurred during follow-up.

CONCLUSIONS

Our initial experience shows that total iodine contrast-free AAA endovascular management in patients with CKD may be feasible and safe. Such an approach seems to guarantee the preservation of residual kidney function without increasing the risks of aneurysm-related complication in the early and midterm postoperative period and it could be considered even in case of complex endovascular procedures.

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.

Carbon Dioxide Angiography for the Detection of Lower Gastrointestinal Arterial Bleeding Initially Occult to Angiography with Iodinated Contrast Media

This study evaluated the utility of carbon dioxide (CO₂) in angiography for the detection of lower gastrointestinal arterial bleeding initially occult to angiography with iodinated contrast media. Fourteen patients underwent CO₂-enhanced angiography. In all patients, extravasation was identified by contrast-enhanced computed tomography but not by initial iodinated contrast-enhanced angiography. After iodinated contrast-enhanced angiography, CO₂-enhanced angiography was performed from the same catheter position. The detection capability for extravasation on CO₂-enhanced angiography was evaluated. CO₂-enhanced angiography allowed for the visualization of extravasation and subsequent transcatheter arterial embolization in 11 of 14 (79%) cases, with extravasation seen during either CO₂-enhanced angiography (n = 8) or subsequent repeat iodinated contrast-enhanced angiography immediately after negative CO₂-enhanced angiography (n = 3). Conservative treatment was performed in the remaining 3 cases. In conclusion, CO₂-enhanced angiography appears useful for identifying occult lower gastrointestinal bleeding.

Quiescent-Interval Single-Shot Magnetic Resonance Angiography May Outperform Carbon-Dioxide Digital Subtraction Angiography in Chronic Lower Extremity Peripheral Arterial Disease

Nephroprotective imaging in peripheral arterial disease (PAD) is often crucial. We compared the diagnostic performance of non-contrast Quiescent-interval single-shot magnetic resonance angiography (QISS MRA) and carbon-dioxide digital subtraction angiography (CO2 DSA) in chronic lower extremity PAD patients. A 19-segment lower extremity arterial model was used to assess the degree of stenosis (none, <50%, 50−70%, >70%) and the image quality (5-point Likert scale: 1-non-diagnostic, 5-excellent image quality). Intra-class correlation coefficient (ICC) was calculated for inter-rater reliability. Diagnostic accuracy and interpretability were evaluated using CO2 DSA as a reference standard. 523 segments were evaluated in 28 patients (11 male, mean age: 71 ± 9 years). Median and interquartile range of subjective image quality parameters for QISS MRA were significantly better compared to CO2 DSA for all regions: (aortoiliac: 4 [4−5] vs. 3 [3−4]; femoropopliteal: 4 [4−5] vs. 4 [3−4]; tibioperoneal: 4 [3−5] vs. 3 [2−3]; all regions: 4 [4−5] vs. 3 [3−4], all p < 0.001). QISS MRA out-performed CO2 DSA regarding interpretability (98.3% vs. 86.0%, p < 0.001). Diagnostic accuracy parameters of QISS MRA for the detection of obstructive luminal stenosis (70%<) as compared to CO2 DSA were as follows: sensitivity 82.6%, specificity 96.9%, positive predictive value 89.1%, negative predictive value 94.8%. Regarding the degree of stenosis, interobserver variability for all regions was 0.97 for QISS MRA and 0.82 for CO2 DSA. QISS MRA proved to be superior to CO2 DSA regarding subjective image quality and interpretability for the imaging of chronic lower extremity PAD.

Hypersensitivity Reactions to Iodinated Contrast Media

At present, iodinated contrast media (ICM) are mostly non-ionic, have low osmolality, and are safe. Even if adverse drug reactions (ADRs) occur, most are chemo-toxic symptoms and require only observation or H1 antihistamines. However, rare, unpredictable, and even life-threatening hypersensitivity can still occur. The aim of this review is to summarize the issues that all relevant staff need to know about and be able to respond to. The most significant risk factor for ICM hypersensitivity is a history of ICM hypersensitivity. For high-risk populations, we must cautiously weigh the advantages and disadvantages of premedication and be aware that breakthrough reactions may still occur. The best policy for patients with a history of severe ICM hypersensitivity is to avoid the same ICM. If ICM are inevitable, skin tests, in vitro tests, and drug provocation tests may help to find a feasible alternative that is safer. The severity of the hypersensitivity is correlated with the positivity rate of these tests, so there is no need for further investigations for patients with only mild reactions. We should also keep in mind that even excipients in ICM may induce hypersensitivity. Detailed, standardized documentation is essential for correct diagnosis and the prevention of future occurrence.

Assessment and management of transplant renal artery stenosis. A literature review

BACKGROUND

transplant renal artery stenosis (TRAS) following kidney transplantation is a possible cause of graft failure. This review aimed to summarize the evidence about physiopathology, diagnosis and early and late effectiveness of the endovascular treatment (EVT), including angioplasty and stenting procedures.

METHODS

a literature research was performed using Pubmed, Scopus and the Cochrane Library databases (January 2000 to September 2020) according to PRISMA guidelines. Studies were included if they describe EVT, percutaneous transluminal angioplasty or stent placement of TRAS, published in English and with a minimum of ten patients.

RESULTS

56 studies were included. TRAS incidence ranges from 1% up to 12% in transplanted kidneys. The TRAS risk factors were: elderly donor and recipient, cytomegalovirus match status, Class II Donor Specific Antibodies (DSA), expanded donor criteria, delayed graft functioning and other anatomical and technical factors. The highest frequency of TRAS presentation is after 3-6 months after kidney transplantation. The most frequent localization of stenosis was para-anastomotic (ranging from 25% to 78%). In 9 studies, all patients were treated by percutaneous transluminal angioplasty (PTA), in 16 studies all patients received percutaneous transluminal stenting (PTS) and in 21 series patients received either PTA or PTS. The Twelve months patency rates after EVT ranged from 72% to 94%. The overall complication rate was 9%, with pseudoaneurysms and hematomas as most frequent complications.

CONCLUSION

TRAS can be successfully and safely treated through an endovascular approach. Stent delivery seems to guarantee a higher patency rate compared to simple angioplasty, however further studies are needed to confirm these results.

Adrenal vein sampling with gadolinium contrast medium in a patient with florid primary aldosteronism and iodine allergy

We describe a 35-year-old woman who was allergic to iodine contrast medium and was diagnosed with primary aldosteronism (PA) based on functional confirmatory tests. She was suspected to have unilateral PA because of marked hypertension, spontaneous hypokalemia, high plasma aldosterone, reduced plasma renin activity, and a right hypodense adrenal tumor. She wanted to become pregnant and requested adrenalectomy instead of medical treatment with mineralocorticoid receptor antagonists. Localization of PA by adrenal vein sampling (AVS) was necessary, but angiography with iodine contrast medium was not possible because of her allergy. AVS was performed using gadolinium contrast agent (gadoterate meglumine) instead of iodine, in combination with computed tomography angiography (CTA). In AVS, before and after adrenocorticotropin (ACTH) loading, 12 blood samples were drawn from the right adrenal vein, left adrenal central vein, left adrenal common duct, left and right renal veins, and the lower inferior vena cava with only 5 mL of gadolinium medium. There were no complications during AVS. Examination revealed an elevated aldosterone/cortisol ratio on the right side, lateralized ratio of 7.4, and contralateral ratio of 0.76; the patient was diagnosed with right unilateral PA. She underwent right adrenalectomy and showed improvements in aldosterone level from 312.4 pg/mL to 83.0 pg/mL, potassium from 3.0 mEq/L to 3.9 mEq/L, and systolic blood pressure from 138 mm Hg to 117 mm Hg. In PA patients with iodine allergy, AVS can be performed safely and precisely using gadolinium contrast combined with CTA.

CO2-based C-arm computed tomography (CACT) of the pelvic arteries: feasibility and diagnostic performance in comparison to CO2-angiography in patients with peripheral arterial disease

BACKGROUND

Patients with substantially impaired kidney function and peripheral arterial disease (PAD) underwent comparative CO₂-based depiction of the pelvic arteries (PAs).

PURPOSE

To evaluate the feasibility and diagnostic performance of CO₂-based C-arm computed tomography (CACT) and compare its depiction of PAs with CO₂-digital subtraction angiography (DSA).

MATERIAL AND METHODS

Fifteen patients (10 men, mean age 70 ± 11 years) with PAD received CO₂-DSA and CO₂-CACT of the PAs, depicted from the aorta to femoral arteries. These were divided into nine segments (135 in total) and graded by two independent readers for image quality (IQ; 1 = sufficient, 2 = minimal impairments, 3 = insufficient, 4 = outside field of view) and subsequent stenosis grading (SG; grade 1: normal to grade 4: occlusion), under exclusion of all segments with insufficient IQ. Inter-observer and inter-modality agreement calculation and subsequent consensus reading were performed and correlated to a standard of reference (StOR), representing a modality consensus.

RESULTS

Of 135 segments, 117 showed sufficient IQ, excluding 18 segments (10 CACT, 8 DSA). Inter-observer agreement for IQ and consecutive SG demonstrated good to excellent agreement: IQ_DSA: κ = 0.83, IQ_CACT: κ = 0.76; Stenosis_DSA: κ = 0.71, Stenosis_CACT: κ = 0.84. Inter-modality agreement for SG lay at κ = 0.76 and κ = 0.65, respectively. More stenoses could be detected by CACT, and analysis of pooled consensus values of SG in CACT_cons versus StOR showed an excellent agreement (κ = 0.96) that proved considerably higher than the moderate agreement between consensus values in DSA_cons versus StOR (κ = 0.43).

CONCLUSION

CO₂-CACT proved feasible, and has the potential to optimize angiographic work-up of PAD in patients with contraindications for other contrast media.

Contrast-Associated Acute Kidney Injury in Patients with and without Diabetes Mellitus Undergoing Computed Tomography Angiography and Local Thrombolysis for Acute Lower Limb Ischemia

PurposeRepetitive iodinated contrast media exposure may be harmful for the kidneys. The aim of the present study was to evaluate if patients with diabetes mellitus (DM) undergoing CT angiography (CTA) and local continuous thrombolysis for acute lower limb ischemia (ALI) had an increased risk of developing contrast-associated acute kidney injury (CA-AKI) compared to patients without DM. Methods: This is a retrospective study of patients undergoing CTA and local continuous thrombolysis due to ALI between 2001 and 2018. CA-AKI was defined as a 25% increase in serum creatinine within 72 hours after latest contrast administration. Results: There was no difference (P = .30) in the frequency of CA-AKI between patients with (27.9%; n = 43) and without DM (20.6%; n = 170). Among patients with CA-AKI, patients with DM had a lower (P < .001) estimated glomerular filtration rate (eGFR) at discharge (55 ml/min/1.73 m²) than at admission (70 ml/min/1.73 m²), while no such difference was found in the group without DM (P = .20). The gram-iodine dose/eGFR ratio was higher (P < .001) in patients with CA-AKI (median 1.49, [IQR 1.34-1.81]) than in those who did not develop CA-AKI (median 1.05 [IQR 1.00-1.13]). There was a trend that gram-iodine dose/eGFR ratio (OR 1.42/standard deviation increment, 95% CI 1.00-2.02; P = .050) was associated with an increased risk of CA-AKI, after adjusting for DM, age, and gender. Conclusions: The frequency of CA-AKI was high after CTA and local continuous thrombolysis for ALI without shown increased frequency for the DM group. Among patients with CA-AKI, however, patients with DM had worse renal function at discharge than those without DM. The gram-iodine dose/eGFR ratio in these patients needs to be lower to improve renal outcomes, particularly in patients with DM.

Benefits and Role of Carbon Dioxide Angiography in Case of Misalignment Between Fenestration and Target Vessel During Fenestrated Endovascular Aneurysm Repair

PURPOSE

To report the benefits and the role of carbon dioxide (CO₂) angiography in case of misalignment between fenestration and target vessel during fenestrated endovascular aneurysm repair (F-EVAR).

TECHNIQUE

During F-EVAR, misalignment between fenestration and target vessel is a potentially catastrophic complication. In 2 patients, we experienced that one of the target vessels were not visible during standard angiography in different projections after positioning a fenestrated graft and even after cannulation of the corresponding fenestration. In both cases, the graft was sealed to the aortic wall but not in the predictable position. Consequently, acute occlusion of the target vessel was hypothesized. However, CO₂ angiography was useful to evaluate patency of the target vessel clarifying the relative position of the fenestration versus the target vessel. Rescue maneuvers were feasible under the guidance of CO₂ angiography in order to obtain the cannulation of both renal arteries. In both cases, the procedure was successfully accomplished.

CONCLUSION

In case of misalignment of a fenestration during F-EVAR and non-visualization of the target vessel with standard angiography, CO₂ angiography could have the unique and complementary role of clarifying the patency and position of the target vessel. In addition, CO₂ could guide the rescue maneuvers.

Outcomes in patients with known contrast allergy undergoing contrast-enhanced endourological procedures: a retrospective cohort study

BACKGROUND

Intravenous administration of iodinated contrast agents carries the risk of allergic reaction, yet this risk is unclear with administration into the urinary tract. We sought to evaluate patients with known contrast, iodine, or shellfish allergies for allergic response when undergoing urologic imaging requiring intraluminal, urinary tract contrast administration.

MATERIALS AND METHODS

We retrospectively reviewed consecutive patients undergoing endourologic procedures from 2010 to 2015 at our institution. Clinical records were reviewed for demographics, medical history, allergies, procedure details, fluids administered, anesthetic and pharmacologic agents administered, and continuous monitoring parameters. Patients with known allergies to iodine, shellfish, and/or contrast were identified and evaluated for clinical or hemodynamic signs of allergy. A convenience sample of 50 patients without allergy history was used as a comparison group.

RESULTS

We identified 1,405 procedures involving 1,000 consecutive patients. Procedures included retrograde pyelograms and antegrade nephrostograms. Eighty-six cases involving 58 patients with contrast, iodine, or shellfish allergies were identified. Of those with contrast allergy history, 18 (20.1%) cases involved patients with a history of anaphylactic reaction. Of these, 11 (61%) received steroid prophylaxis. No patients in either group (Allergy, No Allergy) were identified as having an allergic reaction during the procedure. There were no statistically significant differences in intraoperative intravenous fluids (p=0.931), procedure duration (p=0.747), or vasopressor use (p=0.973) between groups. Due to the zero event rate of contrast allergy, we used the Hanley and Lippman-Hand method, which places true population risk (95% confidence interval) of a significant event at less than 3.5%.

CONCLUSIONS

In 86 cases involving patients with a history of contrast allergy, we found no evidence of clinically significant allergic reaction to intraluminal endourologic contrast administration under continuous anesthesia monitoring. The risk of significant reactions to contrast administered within the urinary tract appears to be low in these patients, regardless of prophylaxis.

Acute kidney injury following endovascular intervention for peripheral artery disease

BACKGROUND

The incidence of, and risk factors for, acute kidney injury (AKI) after endovascular intervention for peripheral artery disease (PAD) remain unknown. The aim of this study was to assess the proportion of patients who develop AKI and explore the risk factors.

METHODS

Prospectively collected data on patients undergoing femoropopliteal endovascular intervention for symptomatic PAD across three vascular centres were analysed. The proportion of patients developing AKI (according to the Kidney Disease Improving Global Outcomes definition) within 48 h, and the proportion developing the composite Major Adverse Kidney Events (MAKE) endpoints (death, dialysis, drop in estimated glomerular filtration rate at least 25 per cent) at 30 days (MAKE30) and remains 90 days (MAKE90) were calculated. Multivariable regression analysis was used to assess predictors of AKI, and the association between AKI and death.

RESULTS

Some 2041 patients were included in the analysis. AKI developed in 239 patients (11.7 per cent), with 47 (2.3 per cent) requiring dialysis within 30 days, and 18 (0.9 per cent) requiring ongoing dialysis. The MAKE30 and MAKE90 composite endpoints were reached in 358 (17.5 per cent) and 449 (22.0 per cent) patients respectively. Risk factors for AKI were age, sex, congestive heart failure, chronic limb-threatening ischaemia, emergency procedure, and pre-existing chronic kidney disease. AKI, dementia, congestive heart failure, and major amputation were risk factors for medium-term mortality.

CONCLUSION

AKI is a common complication after intervention for PAD and is associated with medium-term mortality.

Duplex Ultrasound as a reliable alternative to CT angiography for treatment planning of Peripheral Artery Disease

BACKGROUND

The aim of this work is to compare the diagnostic accuracy of Duplex ultrasound (DUS) and CT angiography (CTA) in the study of arterial vessels, in patients with chronic peripheral arterial disease (PAD) of the lower limbs to undergo endovascular revascularization with the use of intraprocedural digital angiography (DSA).

METHODS

94 patients with obstructive pathology of the arterial axes of the lower limbs were enrolled in the study. In all patients, endovascular revascularization treatment was considered the most suitable therapeutic choice. For this reason, ultrasound and CTA was performed preoperatively in all and based on the data obtained it was decided to classify the arterial tree into five segments: iliac, common femoral, superficial femoral, popliteal and infra-geniculate. According to the degree of stenosis or occlusion, the arteries were scored in no stenotic, stenotic and occluded. The comparison of the data provided by the DUS and the CTA was carried out with reference to the parameters obtained by the DSA.

RESULTS

The results of our experience have shown that in the iliac arterial district DUS proved to be less accurate than CT angiography when compared to DSA (Cohen's Kappa agreement of 0.91 and 1.0, respectively). Good diagnostic concordance were found in the femoro-popliteal district (Cohen's Kappa agreement 33 between 0.96 and 0.93). On the contrary, when the data of the infra-geniculate area were compared, CT angiography showed a net deficiency compared to DSA and DUS (Cohen's k: 0.75).

CONCLUSIONS

Due to its accuracy, high-quality DUS performed by well-trained operators may therefore represent a good alternative to CTA in patients undergoing endovascular revascularization, in order to reduce the use of contrast-enhanced radiological imaging especially when a condition of intolerance to the contrast medium and/or renal insufficiency coexists.

Safety and outcomes of combined carbon dioxide angiography and OCT-guided femoro-popliteal chronic total occlusion crossing and directional atherectomy in patients with chronic kidney disease

BACKGROUND

Carbon dioxide angiography with addition of optical coherence tomography imaging may improve procedural success and clinical outcomes in patients with peripheral artery disease and chronic kidney disease.

METHODS

Single-center, retrospective analysis of patients with chronic kidney disease who underwent carbon dioxide angiography and optical coherence tomography-guided chronic total occlusion crossing and/or optical coherence tomography-guided directional atherectomy was performed. Patient and procedure-related characteristics, along with peri- and one-year post-procedural major adverse events, were analyzed.

RESULTS

A total of 18 vessels in 11 patients, with mean age 70 years were treated. All had co-morbidities such as hypertension, hyperlipidemia, had history or were current smokers with baseline peripheral artery disease. Majority were diabetic with coronary disease (82%); 55% baseline chronic kidney disease IV, 55% Rutherford class III and 45% class IV. Contrast was used in only two patients. Mean total fluoroscopy time and radiation dose was 24.1 min and 249.2 mGY, respectively. Half of the lesions were femoro-popliteal chronic total occlusions, and Ocelot catheter was used to cross seven of nine chronic total occlusions and was successful in six. Adjunctive optical coherence tomography-guided directional atherectomy was performed in 8 of 11 patients. Only two adverse events occurred: one clinically significant event of slow-flow intra-procedurally and one target limb revascularization within one year of index procedure in a vessel different than prior treated. Optical coherence tomography imaging in both chronic total occlusion-crossing and atherectomy resulted in 10-min mean fluoroscopy reduction time and 32 mGY reduction in radiation dose.

CONCLUSION

Carbon dioxide angiography with the addition of optical coherence tomography imaging for chronic total occlusion crossing and/or optical coherence tomography-guided directional atherectomy reduced the need for contrast agents, total fluoroscopy time, and radiation exposure in patients with peripheral artery disease and baseline chronic kidney disease.

Impact of a contrast-to-noise ratio driven and material specific exposure control on image quality and radiation exposure in angiography

Conventional detector-dose driven exposure controls (DEC) do not consider the contrasting material of interest in angiography. Considering the latter when choosing the acquisition parameters should allow for optimization of x-ray quality and consecutively lead to a substantial reduction of radiation exposure. Therefore, the impact of a material-specific, contrast-to-noise ratio (CNR) driven exposure control (CEC) compared to DEC on radiation exposure was investigated. A 3D-printed phantom containing iron, tantalum, and platinum foils and cavities, filled with iodine, barium, and gas (carbon dioxide), was developed to measure the CNR. This phantom was placed within a stack of polymethylmethacrylate and aluminum plates simulating a patient equivalent thickness (PET) of 2.5-40 cm. Fluoroscopy and digital radiography (DR) were conducted applying either CEC or three, regular DEC protocols with parameter settings used in abdominal interventions. CEC protocols where chosen to achieve material-specific CNR values similar to those of DEC. Incident air kerma at the reference point(K_a,r), using either CEC or DEC, was assessed and possible K_a,r reduction for similar CNR was estimated. We show that CEC provided similar CNR as DEC at the same or lower K_a,r. When imaging barium, iron, and iodine K_a,r was substantially reduced below a PET of 20 cm and between 25 cm and 30 cm for fluoroscopy and Dr When imaging platinum and tantalum using fluoroscopy and DR and gas using DR, the K_a,r reduction was substantially higher. We estimate the K_a,r reduction for these materials between 15% and 84% for fluoroscopy and DR between 15% and 93% depending on the PET. The results of this study demonstrate a high potential for skin dose reduction in abdominal radiology when using a material-specific CEC compared to DEC. This effect is substantial in imaging materials with higher energy K-edges, which is beneficial, for example, in long-lasting embolization procedures with tantalum-based embolization material in young patients with arterio-venous malformations.

Strategies to Minimize Iodinated Contrast Volume in Patients with Chronic Kidney Disease Undergoing Peripheral Vascular Interventions

Peripheral vascular interventions (PVI) utilize iodinated contrast medium (ICM) to visualize intravascular lesions and guide therapy. The use of ICM carries a risk of postcontrast acute kidney injury (PC-AKI), which is increased in the elderly and in patients with chronic kidney disease (CKD). Furthermore, the risk of PC-AKI increases with the volume of ICM used. This paper reports a 94-year-old patient with CKD stage 4 who presented with chronic limb threatening ischemia. He underwent successful endovascular revascularization using a combination of CO₂ and dilute ICM (total volume = 6.5 mL). The case demonstrates strategies to minimize ICM during PVIs.

Feasibility and safety of automated CO2 angiography in peripheral arterial interventions

Carbon dioxide (CO2) gas is an established alternative to iodine contrast during angiography in patients with risk of postcontrast acute kidney injury and in those with history of iodine contrast allergy. Different CO2 delivery systems during angiography are reported in literature, with automated delivery system being the latest. The aim of this study is to evaluate the safety, efficacy, and learning curve of an automated CO2 injection system with controlled pressures in peripheral arterial interventions and also to study the patients' tolerance to the system.From January 2018 to October 2019 peripheral arterial interventions were performed in 40 patients (median age-78 years, interquartile range: 69-84 years) using an automated CO2 injection system with customized protocols, with conventional iodine contrast agent used only as a bailout option. The pain and tolerance during the CO2 angiography were evaluated with a visual analog scale at the end of each procedure. The amount of CO2, iodine contrast used, and radiation dose area product for the interventions were also systematically recorded for all procedures. These values were statistically compared in 2 groups, viz first 20 patients where a learning curve was expected vs the rest 20 patients.All procedures were successfully completed without complications. All patients tolerated the CO2 angiography with a median total pain score of 3 (interquartile range: 3-4), with no statistical difference between the groups (P = .529). The 2 groups were statistically comparable in terms of comorbidities and the type of procedures performed (P = .807). The amount of iodine contrast agent used (24.60 ± 6.44 ml vs 32.70 ± 8.70 ml, P = .006) and the radiation dose area product associated were significantly lower in the second group (2160.74 ± 1181.52 μGym2 vs 1531.62 ± 536.47 μGym2, P = .043).Automated CO2 angiography is technically feasible and safe for peripheral arterial interventions and is well tolerated by the patients. With the interventionalist becoming familiar with the technique, better diagnostic accuracy could be obtained using lower volumes of conventional iodine contrast agents and reduction of the radiation dose involved.

Iliac vein stenting guided by intravascular ultrasound without iodinated contrast medium

Summary: Iliac vein compression syndrome, also known as May-Thurner Syndrome, is a type of vein reflux disorders which is often ignored due to lack of efficient diagnostic methods. The traditional gold standard of diagnosis is venography, but this has been challenged and largely replaced by intravascular ultrasound (IVUS). Here we report a case that a patient suffered with iodine anaphylaxis was successfully performed iliac vein stenting guided by using IVUS alone. This case provides the evidence that IVUS can offer necessary information for physicians in the diagnosis and treatment of iliac vein compression. We also find that balloon dilatation notch cannot precisely reflect the whole lesion, indicating it may be unreliable for diagnosis. Differ from the commonly accepted opinion, we find that comparing to IVUS, the notch of balloon dilatation cannot completely reflect the extent of lesion narrowness. Thus, we think the notch should not be used as a reference for seriousness of the lesion, and the diagnosis of stenosis cannot be ruled out even if there is no presence of notch.

Image quality and safety of automated carbon dioxide digital subtraction angiography in femoropopliteal lesions: Results from a randomized single-center study

PURPOSE

To evaluate the image quality and the safety of automated carbon dioxide (CO₂) digital subtraction angiography (DSA).

MATERIALS AND METHODS

Fifty patients receiving DSA for femoropopliteal peripheral arterial disease (PAD) were enrolled in this single-center prospective study. All patients received iodinated contrast media (ICM) and CO₂ as a contrast agent in the same target lesion. As a primary endpoint, four raters independently evaluated the angiography images based on overall image quality, visibility of collaterals, and assessment of stenoses/occlusions. Inter-rater agreement was assessed using the intraclass correlation coefficient (ICC) and differences between the raters were evaluated using Friedmann's test. Secondary endpoints were procedure safety and patient pain assessment.

RESULTS

Inter-rater agreement between CO₂-DSA and ICM-DSA images was fair to excellent for overall image quality (ICC: 0.399-0.748), fair to excellent for the visibility of collaterals (ICC: 0.513-0.691), and poor to excellent for the assessment of stenoses/occlusions (ICC: -0.065-0.762). There were no significant differences between the raters. Two patients had a hematoma, one reported pain related to puncture, one became nauseous, and one vomited. No other adverse events were observed. Reported pain scores were significantly higher for CO₂-DSA vs. ICM-DSA (1.25 vs. 0625; p < 0.028).

CONCLUSION

CO2-DSA using automated injection system in combination with proprietary post-processing software is safe and comparable diagnostic test compared to ICM-DSA.

Impact of Superselective Renal Artery Embolization on Renal Function and Blood Pressure

Objectives:

To evaluate the effect of superselective renal artery embolization in terms of renal function and blood pressure, to compare the results between groups with different embolization extents, and to analyze risk factors of entire study population for postprocedural acute kidney injury (AKI).

Materials and Methods:

The inclusion criteria were patients who underwent renal artery embolization from January 2009 to December 2019, with available serum creatinine and blood pressure data. The exclusion criteria were non-selective embolization of main renal artery, AKI before embolotherapy, and follow-up of less than one month. According to the extent of embolization, the patients were divided into two groups: Group A (1 segment) and Group B (2–4 segments).

Results:

A total of 48 patients were enrolled. There was a significant difference between pre- and postprocedural estimated glomerular filtration rate (p = 0.030). There were no significant difference between pre- and postprocedural blood pressure. The incidence of postprocedural AKI in group B was significantly higher than that in group A (p = 0.044). There was no significant difference in the incidence of the worsening of hypertension between the two groups. Chronic kidney disease and high embolization grade were predictive for postprocedural AKI (p = 0.012, 0.021).

Conclusion:

Superselective embolization appears to be a safe procedure, but meticulous attention for AKI is required for patients who underwent embolization of more than one segmental artery. An attempt to minimize the extent of devascularization should be pursued to avoid postprocedural complications.

Digital Variance Angiography in Lower-Limb Angiography with Metal Implants

Purpose

The presence of metal implants may reduce angiographic image quality due to automated beam adjustments. Digital variance angiography (DVA) is reported to be superior to digital subtraction angiography (DSA) with increased contrast-to-noise ratio (CNR) and better image quality. The aim of the study was to evaluate whether DVA could counterbalance the image quality impairment of lower-limb angiographies with metal implants.

Materials and Methods

From November 2019 to January 2020, 85 raw lower-limb iodine contrast angiograms of 12 patients with metal implants were processed retrospectively with DVA analyses. For objective comparison, CNR of DSA and DVA images was calculated and the ratio CNR_DVA/CNR_DSA was determined. Visual image quality was evaluated in a paired comparison and by a five-grade Likert scale by three experienced radiologists.

Results

The CNR was calculated and compared in 1252 regions of interest in 37 image pairs containing metal implants. The median ratio of CNR_DVA/CNR_DSA was 1.84 with an interquartile range of 1.35–2.32. Paired comparison resulted in 84.5% in favour of DVA with an interrater agreement of 83.2% (Fleiss κ 0.454, p < 0.001). The overall image quality scores for DSA and DVA were 3.64 ± 0.08 and 4.43 ± 0.06, respectively (p < 0.001, Wilcoxon signed-rank test) with consistently higher individual ratings for DVA.

Conclusion

Our small-sample pilot study shows that DVA provides significantly improved image quality in lower-limb angiography with metal implants, compared to DSA imaging. The improved CNR suggest that this approach could reduce radiation exposure for lower-limb angiography with metal implants.

Level of Evidence

Level 4, case studies

Fatal Brain Injury Following Carbon Dioxide Angiography

INTRODUCTION

Carbon dioxide (CO₂) as a contrast agent has been in use as early as the 1920s for visualization of retroperitoneal structures. Digital subtraction angiography (DSA) using CO₂ as a contrast agent for vascular imaging was developed in the 1980s. Currently, CO₂  angiography is an alternative agent in patients with chronic kidney disease (CKD) and those who are at risk of developing contrast-induced nephropathy. However, CO₂ causes neurotoxicity if the gas inadvertently enters the cerebrovascular circulation leading to fatal brain injury.

CASE PRESENTATION

A 71-year-old female with h/o sickle cell trait, hypertension, obesity, metastatic renal cell cancer status post nephrectomy, bone metastasis, chronic kidney disease was admitted for elective embolization of the humerus bone metastasis. Given the high probability of contrast-induced nephropathy, CO₂ angiography was chosen for embolization of the metastasis. During the procedure, the patient became unresponsive. Emergent medical management with hyperventilation, 100% fraction oxygen inhalation was performed. Her neuroimaging showed global cerebral edema. An intracranial pressure monitor was placed which confirmed intracranial hypertension. Hyperosmolar therapy was administered with no improvement in clinical examination. She progressed to brain stem herniation. Given poor prognosis, the family opted for comfort measures and the patient expired.

DISCUSSION AND CONCLUSIONS

Inadvertent carbon dioxide entry into cerebrovascular circulation during angiography can cause fatal brain injury. Caution must be exercised while performing CO₂  angiography in blood vessels above the diaphragm.

A Late Post-EVAR Rupture in a 102-Year-Old Patient Related to a Type II Endoleak

PURPOSE

Endovascular abdominal aortic aneurysm repair (EVAR) is progressively being applied in the elderly population. Type II endoleaks are common and mostly benign, but they are related to more aneurysm sac expansion after EVAR. They may lead to rupture in <1% of cases. We present a case of a centenarian with a post-EVAR rupture, related to type II endoleak, and discuss the use of EVAR on the management of this type of endoleak in an extremely old patient.

CASE PRESENTATION

A 102-year-old man with a history of EVAR 12 years earlier, presented to the emergency department with a drop of consciousness. A computed tomography revealed a ruptured abdominal aortic aneurysm. Angiography showed a type II endoleak related to patent lumbar arteries deriving from collateral branches of the right internal iliac artery. Embolization was not successful and subsequently the ostium of the iliolumbar artery was overstented, obliterating the feeding branch. The postoperative course was complicated by a deterioration of chronic obstructive pulmonary disease and patient was discharged home on the seventh postprocedural day; nonetheless, he died on postoperative day sixteenth due to respiratory complications.

CONCLUSION

Complications following EVAR are a real threat and emphasize the need for follow-up. The current case report shows that age per se should not be a contraindication for EVAR nor for follow-up. Also, late ruptures due to type II endoleaks could be treated in the very elderly population although larger series are required for robust conclusions.

Carbon Dioxide As a Standard of Care for Zero Contrast Interventions: When, Why and How?

BACKGROUND

Traditional contrast media containing iodine remain the gold standard for vessel visualization during endovascular procedures. On the other hand, their use has several side effects and implications and may cause contrast medium-induced nephropathy. Carbon dioxide (CO2) angiography is an old alternative technique used only for critical patients in order to prevent kidney damages or allergic reactions. Zero contrast procedure: The availability of automated CO2 injectors has led to an increase in the use of CO2 angiography, providing an option for zero contrast interventions, preserving patient renal function and saving costs for the hospital facility. Taking advantage of the properties of CO2 gas, it is possible to improve the performance of some complex procedures such as atherectomy and the detection of type II endoleaks after EVARs. However, a learning curve is needed to get good imaging, and learn about the qualities and limitations of the technique.

CONCLUSIONS

The use of automatic delivery systems for CO2 angiography appears to be a good choice for the use of CO2 as the first imaging option. The standardization of injection protocols and the extensive use of this technique could lead to significant benefits both for the patient's prospects and health facilities.