The Current Status of the Use of Carbon Dioxide in Diagnostic and Interventional Angiographic Procedures

Successful endovascular management with a covered stent of an external iliac pseudoaneurysm following allograft nephrectomy using CO2 as contrast medium: a case report

Iodinated contrast agents for angiography in chronic kidney disease (CKD) patients could further deteriorate their renal function leading to adverse sequelae. The use of carbon dioxide (CO₂) is reported in the literature and has been safely used for a variety of angiographic procedures, particularly to guide aortic and renal interventions. We report the case of the successful endovascular treatment with a covered stent of a right external iliac artery pseudoaneurysm following graft nephrectomy in a CKD patient, using CO₂ as contrast medium.

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.

The outcomes of carbon dioxide digital subtraction angiography for percutaneous transluminal balloon angioplasty of access circuits and venous routes in hemodialysis patients

The outcomes of carbon dioxide digital subtraction angiography (CO2-DSA) for performing percutaneous transluminal balloon angioplasty (balloon PTA) in hemodialysis patients has not been fully clarified. The purpose was to compare the outcomes of balloon PTA of hemodialysis shunts in terms of vessel patency between patients treated using CO2-DSA and conventional digital subtraction angiography using iodine contrast medium (C-DSA).We retrospectively evaluated 76 patients (38 males and 38 females, mean age: 65.0 ± 14.0 years). They were under hemodialysis and treated with balloon PTA using CO2-DSA or C-DSA at our institution between 2009 and 2016. Mean duration of the follow-up period was 25.59 ± 21.45 months. We compared the patency rates obtained after CO2-DSA-based balloon PTA with those after C-DSA-based balloon PTA. Secondary patency, which was defined as the duration of patency after all further endovascular interventions until surgical repair, was considered as the endpoint in this study.Overall, 19 and 57 patients underwent CO2-DSA- and C-DSA-based balloon PTA, respectively. CO2-DSA- and C-DSA-based balloon PTA produced clinical success rates of 100% and 96.5%, respectively. Blood vessel injury occurred in one patient who underwent C-DSA-based balloon PTA. No major complications occurred in CO2 group. At 24 months, the post-PTA secondary patency rates of CO2-DSA- and C-DSA-based balloon PTA were 94.1% and 93.9%, respectively (P = .9594).CO2-DSA is safe for hemodialysis patients. Compared with C-DSA, CO2-DSA-based balloon PTA produces have a similar secondary patency rate.

Carbon dioxide angiography during peripheral angioplasty procedures significantly reduces the risk of contrast-induced nephropathy in patients with chronic kidney disease

BACKGROUND

Iodinated contrast media are amongst the most frequently prescribed medications, however, their use is not without complications. With contrast-induced nephropathy constituting a major concern, alternative non-iodine based approaches have been explored such as carbon dioxide angiography. The purpose of this study is to report the incidence of contrast-induced nephropathy following carbon dioxide angiography in patients with impaired renal function that underwent peripheral angioplasty compared with a historical cohort of patients that underwent angioplasty with use of solely iodine contrast medium. The historical cohort of patients treated with iodinated contrast was used as control. Baseline demographics and renal function tests were recorded. Primary outcome was incidence of contrast-induced nephropathy within 48-72 h post intervention. Receiver-Operating-Characteristic curve analysis was used to correlate the volume of iodinated contrast with the risk of contrast-induced nephropathy.

RESULTS

Carbon Dioxide was used as an alternative to iodinated contrast media in patients with impaired renal function (eGFR<60mls/min/1.73 m2) undergoing peripheral angioplasty procedures. Fifty, consecutive patients (baseline eGFR = 38.6 ± 13.2mls/min/1.73 m2) were included in a prospective clinical audit. These were matched (1:2) with a historical cohort of patients (baseline eGFR = 43.3 ± 12.2mls/min/1.73 m2) treated with Iodinated contrast media. The incidence of contrast-induced nephropathy was 14% (n = 7/50) in case of carbon dioxide vs. 29% (n = 29/100) in the matched cohort group (p = 0.045). Receiver-Operating-Characteristic analysis showed that use of >25mls of contrast was 94.4% (95% CI:81-99%) sensitive in predicting contrast-induced nephropathy.

CONCLUSION

Carbon dioxide imaging during peripheral angioplasty procedures protects against contrast-induced nephropathy. Use of >25mls of iodinated contrast media in high-risk patients is a predictor of contrast-induced nephropathy.

Protection from injury of organs adjacent to a renal tumor during percutaneous cryoablation

Renal cryoablation has become accepted as treatment for small renal tumors as an alternative to surgery. However, parallel with the increase in the use of this therapy, there also has been increases in the number of reports of complications related to renal cryoablation. One potential complication is injury to important non-renal structures adjacent to the ablated renal tumor, such as the colon, duodenum, ureter, psoas muscle and so on. To prevent injury of adjacent organs, separating organs from the tumor is desirable. Over the past 15 years, several techniques have been developed to protect against injury of organs adjacent to renal tumors that are targets of cryoablation. The most commonly used technique for this purpose has been hydrodissection. Others include dissection with gas, balloon dissection and probe traction. To avoid injury of a ureter running near the renal tumor, pyeloperfusion is known to be useful. The rate of cases necessitating avoidance of organ injury by using these techniques is relatively high. In some cases, more than two techniques are combined. In the present review, we provided an overview of techniques currently available to protect against organ injuries, and discussed the advantages and disadvantages of each technique.

The Growing Field of Imaging of Atherosclerosis in Peripheral Arteries

In the past decades, peripheral arteries have represented a model for the comprehension of atherosclerosis as well as for the development of new diagnostic imaging modalities and therapeutic strategies. Peripheral arteries may represent a window to study atherosclerosis. Pathology has prominently contributed to move the clinical and research attention from the arterial lumen stenosis and angiography to morphological and functional imaging techniques. Evidence from large and prospective cohort or randomized controlled studies is still modest. Nevertheless, several emerging imaging investigations represent a potential tool for a comprehensive "in vivo" evaluation of the entire natural history of peripheral atherosclerosis. This constitutes a demanding assignment, as it would be desirable to obtain both single-lesion focused and extensive arterial system views to achieve the most accurate prognostic information. Our narrative review rests upon the fundamental pathological evidence, summarizing the rapidly growing field of imaging of atherosclerosis in peripheral arteries and presenting a selection of both currently available and emerging imaging techniques.

Imaging patients with renal impairment

Imaging with intravascular contrast media is generally considered safe, particularly in patients without renal failure. However, as renal function deteriorates, the potential risk of nonallergic-type adverse events increases. This presents a unique challenge, particularly when the use of intravenous contrast media is deemed essential for diagnostic purposes. Following a discussion regarding the definition and epidemiology of kidney injury, this review focuses on the evolving understanding of both contrast-induced nephropathy and nephrogenic systemic fibrosis and discusses preventative strategies aimed at minimizing the risk of developing these entities. Alternative non-contrast imaging techniques are also discussed.

CARBON DIOXIDE ANGIOGRAPHY: SIMULATION OF OPERATIVE CONDITIONS FOR DIAGNOSTIC IMAGE OPTIMIZATION

Carbon dioxide angiography is based on the visualization (i.e., the radiographic contrast) of gas bubbles injected in blood vessels. By using an experimental X-ray bench, the energy response of a flat panel detector has been measured (Varian CB4030) and, with a dedicated phantom and a software simulation, the image contrast of vessels is injected with Iodine and CO 2. Moreover, the dynamical behavior of a moving gas bubble has been studied with the software simulator. The results show that the contrast generated by carbon dioxide is about one fourth of that obtained with iodine, demonstrating that CO 2 angiography should use different radiological settings with respect to iodine angiography. In particular, a kVp increase has a lower reduction of contrast-to-noise-ratio (CNR) with carbon dioxide than with iodinated contrast medium (CM), suggesting possible technological improvements both on radiological emission and image enhancement methods.

Novel use of carbon dioxide arteriography in renal artery pseudoaneurysm in patients with poor renal function

Renal artery pseudoaneurysm (RAP) is a rare complication of partial nephrectomy, but is usually effectively managed with renal vessel embolisation. We report a particularly challenging case of a patient with chronic kidney disease (CKD) who developed a RAP following a laparoscopic heminephrectomy and was treated using superselective renal vessel coil embolisation with carbon dioxide (CO2) as the primary contrast agent for arteriographic localisation of the RAP and feeder artery. To the best our knowledge we report the first utilisation of CO2 arteriography in the definitive diagnosis and treatment of RAP following heminephrectomy in a patient with severe CKD.

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.

Carbon dioxide contrast enhancement for C-arm CT utility for treatment planning during hepatic embolization procedures

A pilot study was performed to evaluate the use of carbon dioxide (CO2) as a contrast medium for C-arm computed tomography (CT). C-arm CT using CO2 was performed during embolization procedures in12 patients with hepatic malignancies and severe iodine allergy or high risk for nephrotoxicity. C-arm CT using gadolinium or iodinated contrast medium was performed for comparison. Of segmental arteries identified by conventional contrast enhancement, 96% were also seen with CO2 enhancement, but subsegmental arteries were not reliably depicted. CO2 enhancement identified 60% of tumors. Small, hypovascular, and infiltrative tumors were difficult to detect. CO2 is a promising alternative intraarterial contrast agent for C-arm CT.

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.

Mechanical aspects of CO₂ angiography

The aim of this paper is to clarify some physical-mechanical aspects involved in the carbon dioxide angiography procedure (CO₂ angiography), with a particular attention to a possible damage of the vascular wall. CO₂ angiography is widely used on patients with iodine intolerance. The injection of a gaseous element, in most cases manually performed, requires a long training period. Automatic systems allow better control of the injection and the study of the mechanical behaviour of the gas. CO₂ injections have been studied by using manual and automatic systems. Pressures, flows and jet shapes have been monitored by using a cardiovascular mock. Photographic images of liquid and gaseous jet have been recorded in different conditions, and the vascular pressure rises during injection have been monitored. The shape of the liquid jet during the catheter washing phase is straight in the catheter direction and there is no jet during gas injection. Gas bubbles are suddenly formed at the catheter's hole and move upwards: buoyancy is the only governing phenomenon and no bubbles fragmentation is detected. The pressure rise in the vessel depends on the injection pressure and volume and in some cases of manual injection it may double the basal vascular pressure values. CO₂ angiography is a powerful and safe procedure which diffusion will certainly increase, although some aspects related to gas injection and chamber filling are not jet well known. The use of an automatic system permits better results, shorter training period and limitation of vascular wall damage risk.

[Visualization of stenosis in vascular access by bubble method under carbon dioxide (CO2) angiographic procedures]

A percutaneous transvascular angioplasty (PTA) is performed to relieve failed vascular access for hemodialysis. Angiography using non-ionic iodinated contrast media is the imaging modality of choice for performing PTA. However, the use of iodinated contrast media is contraindicated for patients with a history of iodine allergy. Since 1920, carbon dioxide (CO(2)) has been used as a safe contrast medium in various studies. In CO(2) shunt angiography for hemodialysis, visualization of the vascular structures was often suboptimal due to shunt-specific conditions, such as rapid flow and narrow diameter of the vessels. In the present report, we attempted an improvement of the visualization by injection of CO(2) bubbles in view of the properties of CO(2) (floating and low viscosity). The results indicated that the CO(2) bubbles angiography clearly demonstrated the narrow vessels and stenotic portions that were not visualized by conventional CO(2) angiography. In addition, the required volume of CO(2) could be reduced in comparison with previous studies in the literature. Therefore, the method seemed to be effective in reducing exposure and preventing complication by CO(2). Thus, CO(2) bubbles angiography may be useful for shunt angiography and sequential angioplasty when experiencing shunt problems.

An evaluation of the use of carbon dioxide angiography in endovascular aortic aneurysm repair

INTRODUCTION

Renal dysfunction after endovascular aortic aneurysm repair is an increasingly recognised problem. Carbon dioxide (CO(2)) angiography has been used to limit the risk of contrast nephrotoxicity during endovascular procedures. This prospective study evaluates the performance of CO(2) angiography during EVAR.

METHODS

Seventeen patients undergoing EVAR over a 12 month period were included. All were males with a median age of 74 (range 62-86) years. The median preoperative creatinine was 105 (range 77-165) micromol/L. CO(2) angiography was used routinely in all patients for graft positioning. Contrast was used for completion angiograms and whenever CO(2) did not satisfactorily demonstrate the anatomy.

RESULTS

All patients had successful deployment of stent graft. The median contrast usage was 59 (range 20-250)ml. CO( 2) angiography successfully demonstrated the aortic and iliac bifurcation in all 17 cases and the renal artery anatomy in 9. 7 out of 17 patients had both CO(2) and contrast completion angiography. CO(2) correlated with contrast angiography in 6 of the 7 patients. There was no significant difference in pre and post-operative creatinine values (P >0.9; Wilcoxon test).

CONCLUSION

CO(2) angiography is a useful adjunct to contrast during the performance of EVAR and helps reduce contrast load and the risk of contrast nephrotoxicity.

Preoperative imaging of left portal vein at the Rex recess for Rex shunt formation using wedged hepatic vein carbon dioxide portography

BACKGROUND

In children with extrahepatic portal vein obstruction (EHPVO), formation of a mesentericoportal bypass (Rex shunt) restores hepatopetal flow, relieves portal hypertension, and reduces variceal bleeding and hypersplenism. The Rex shunt is created by inserting a vein graft between the superior mesenteric vein and the umbilical segment (Rex) of the left portal vein within the Rex recess of the liver. The preoperative evaluation of a patient with EHPVO includes an accurate assessment of the venous inflow and outflow. The inflow portal vein is readily assessed by ultrasound and magnetic resonance imaging. The outflow intrahepatic portal vein is harder to assess. We report our experience of patients evaluated with wedged hepatic vein carbon dioxide portography (WHVCP).

METHOD

All children referred for venography from October 2001 to October 2007 were prospectively identified, and clinical and radiologic data were reviewed retrospectively. The imaging findings were correlated to findings at surgery.

RESULTS

Eleven children (range, 3-14 years, median, 6 years) were referred for preoperative wedged hepatic venography. The left portal vein at the Rex recess was clearly identified in 9 patients (82%). In the other 2 patients (18%), the Rex segment was not identified despite opacification of left and right intrahepatic portal veins; this was taken to indicate an occluded segment. Wedged venography was performed with carbon dioxide in 10 patients (91%). Carbon dioxide was contraindicated in the final patient because of the presence of a ventricular septal defect.

CONCLUSION

Our series demonstrates the use of WHVCP as a diagnostic tool in preoperative assessment of the Rex segment of left portal vein in children with extrahepatic portal vein obstruction.

Thermal protection during percutaneous thermal ablation procedures: interest of carbon dioxide dissection and temperature monitoring

Percutaneous image-guided thermal ablation of tumor is widely used, and thermal injury to collateral structures is a known complication of this technique. To avoid thermal damage to surrounding structures, several protection techniques have been reported. We report the use of a simple and effective protective technique combining carbon dioxide dissection and thermocouple: CO(2) displaces the nontarget structures, and its low thermal conductivity provides excellent insulation; insertion of a thermocouple in contact with vulnerable structures achieves continuous thermal monitoring. We performed percutaneous thermal ablation of 37 tumors in 35 patients (4 laser, 10 radiofrequency, and 23 cryoablations) with protection of adjacent vulnerable structures by using CO(2) dissection combined with continuous thermal monitoring with thermocouple. Tumor locations were various (19 intra-abdominal tumors including 4 livers and 9 kidneys, 18 musculoskeletal tumors including 11 spinal tumors). CO(2) volume ranged from 10 ml (epidural space) to 1500 ml (abdominal). Repeated insufflations were performed if necessary, depending on the information given by the thermocouple and imaging control. Dissection with optimal thermal protection was achieved in all cases except two patients where adherences (one postoperative, one arachnoiditis) blocked proper gaseous distribution. No complication referred to this technique was noted. This safe, cost-effective, and simple method increases the safety and the success rate of percutaneous thermal ablation procedures. It also offers the potential to increase the number of tumors that can be treated via a percutaneous approach.

Contrast-Induced Nephropathy

Contrast-induced nephropathy (CIN) is a well-recognized complication of radiographic contrast administration and is the third leading cause of hospital-acquired renal insufficiency. The use of contrast media is increasing, particularly in the area of endovascular therapy. Vascular interventionists need to be aware of strategies to reduce the risk of CIN. Numerous trials, meta-analyses, and expert guidelines for the prevention of CIN have been published between 1966 and 2006, but the majority of studies have been conducted on patients undergoing coronary interventions; few have involved vascular surgical population. The literature suggests that adequate hydration is essential in all patients due to receive contrast. No pharmacological agents have been shown to conclusively reduce the risk. Forced diuresis is harmful, and there is insufficient evidence to support routine use of hemodialysis or hemofiltration. Well conducted studies of other potential prophylactic techniques are needed in vascular populations.