Standardization of a Carbon Dioxide Automated System for Endovascular Aortic Aneurysm Repair

Endovascular aortic repair (EVAR) is presently the preferred treatment for abdominal aortic aneurysm; however, it requires the injection of a contrast medium, which can hamper the renal function. Other nontoxic agents such as carbon dioxide (CO₂) have been sporadically tested in this setting with uncertain results. The aim of the study is to investigate the efficacy of a new standardized CO₂ injection method in standard EVAR procedures.

Between August and October 2016, 31 consecutive patients (median age 76.1 [interquartile range {IQR}: 7.4] years) were submitted to standard EVAR. Proximal and distal endograft landing zones were identified by the injection of 100 mL of CO₂ at 300 mm Hg, through an 11 cm 10F femoral sheath by a specifically manufactured automated injection device (Angiodroid Srl, San Lazzaro, Bologna, Italy). Before EVAR deployment, a confirmative injection with a conventional contrast medium was accomplished. The possibility of precisely visualizing the proximal and distal landing zones by CO₂ digital subtraction angiography (DSA) was evaluated considering the contrast medium injection obtained in the same procedure as a gold standard. Similarly, the possible presence of endoleak was assessed at the end of the procedure by the 2 techniques.

CO₂ DSA allowed to identify the juxtarenal landing zone of the endograft in 19/31 cases (61%) and the distal one in 31/31 (100%). In 12 (39%) cases, CO₂ injection failed to visualize at least the lowest renal artery. This occurred in large aneurysms with scarce thrombotic apposition and a luminal volume greater than 95.9 (IQR: 25.2) mm³. Completion CO₂ DSA detected type II endoleaks (ELIIs) in 10 cases compared with 2 of conventional contrast media.

The injection of nontoxic CO₂ through an automated device allowed to perform EVAR procedures effectively, in the majority of cases. In some cases, a single injection of a minimum amount of conventional contrast medium can be used to overcome the lack of renal artery visualization by CO₂. ELIIs are more frequently visualized with CO₂ compared with standard contrast medium. Although the CO₂ injection technique needs further amelioration particularly in the renal arteries detection, this technique appears promising and possibly substitutive of the standard contrast medium, with significant benefit for the renal function.