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Abstract Purpose To determine the ability of CO2-enhanced angiography to detect active diverticular bleeding that is not detected by iodinated contrast medium (ICM)-enhanced angiography and its impact on clinical outcomes when used to confirm embolization, particularly the risks of rebleeding and ischemic complications. Materials and methods We retrospectively identified a cohort of patients with colonic diverticular bleeding who underwent catheter angiography between August 2008 and May 2023 at our institution. We divided them according to whether they underwent CO2 angiography following a negative ICM angiography study or to confirm hemostasis post-embolization (the CO2 angiography group) or ICM angiography alone in the absence of active bleeding or for confirmation of hemostasis post-embolization (the ICM angiography group). The ability to detect active colonic diverticular bleeding and clinical outcomes were compared between the two groups. Results There were 31 patients in the ICM angiography group and 29 in the CO2 angiography group. The rate of detection of active bleeding by CO2 angiography that was not identified by ICM angiography was 48%. The rebleeding rate was 23% in the ICM angiography group and 6.9% in the CO2 angiography group. Among the patients who underwent TAE, the ischemic complications rate was 7.1% in the ICM angiography group and 4.5% in the CO2 angiography group. Conclusions CO2 angiography may detect active diverticular bleeding that is not detectable by ICM angiography and appears to be associated with a lower rebleeding rate. Level of evidence IV. Graphical Abstract

Abstract Background Current guidelines recommend the use of mechanical circulatory support (MCS) for patients with cardiogenic shock that is refractory to medical therapy. Bleeding is the most common complication of MCS. Transarterial embolization (TAE) is often performed to treat this complication, because it is a less invasive hemostatic procedure. However, the TAE option needs to be carefully considered during MCS, as the access route may be limited during MCS. Case presentation A man in his 70 s was diagnosed with acute myocardial infarction and underwent percutaneous coronary intervention via venoarterial extracorporeal membrane oxygenation (VA-ECMO) and Impella. During treatment in the intensive care unit, he suffered damage to a branch of the internal thoracic artery during a cardiac drainage procedure, which was subsequently treated via emergency TAE. An ECMO return cannula and an Impella sheath were inserted into the patient’s right and left femoral arteries, respectively. An approach from the left brachial artery was selected, and the left internal thoracic artery was embolized. Subsequently, the patient required re-intervention to treat re-bleeding from another artery. Because it was difficult to target the target artery from the brachial one, owing to interference from the Impella catheter, the ECMO circuit near the return cannula was punctured and a guiding sheath was inserted. The ECMO flow and the patient’s blood pressure decreased following placement of this guiding sheath. We were thus able to maintain the patient’s blood pressure by increasing the infusion fluids and Impella flow, and embolize the target artery using a gelatin sponge to achieve hemostasis. Conclusion When TAE is difficult to perform during MCS using an approach from the upper extremities, a lower extremity approach with a sheath inserted into the ECMO circuit may represent a viable alternative.

Abstract 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.