Abstract
The aim of this in vitro study was to evaluate the feasibility of movement compensation for CO2 coronary angiography. The use of CO2 as a contrast medium for coronary angiography in a routine clinical setting is still premature. Nonetheless, the gas can solve most of the problems related to iodine contrast-induced nephropathy and can be safely used for patients with renal insufficiency. In a previous work [I. Corazza et al., AIP Adv. 8(1), 015225 (2018)], we demonstrated that an adequate setting of the CO2 injection parameters (pressures and volumes) allows gas injection into the coronaries, avoiding reflux into the aorta and cerebral circulation. A mechanical mock simulating coronary circulation and movement was used to simulate different CO2 injection conditions. Simultaneous acquisition of ECG and optical images allowed synchronous frame extraction for post-processing analysis, like masking and stacking processes. A single test with a radiological apparatus was done to demonstrate the feasibility of the technique. By injecting CO2 at a pressure between the dicrotic notch and diastolic value, no reflux into the aorta was observed and the new software yielded final optical images of clinical quality after about 8 seconds of injection. The feasibility test under the X-ray apparatus gave promising results. CO2 coronary angiography is still far from becoming a clinical standard, but our bench evaluation demonstrates that if the injection parameters are well-controlled and physiological values known, CO2 can be used as a contrast agent not only for the lower part of the body, but also for the coronary arteries, respecting basic safety standards.
Highlights
We previously demonstrated that an injection pressure (InPs) between the dicrotic notch and the diastolic value with a high resistance catheter can generate a lower injection flow than that of blood, thereby allowing safe injection without reflux into the aorta
Since the images are acquired with a different system from that used for the optical images previously described, we developed and used a different algorithm based on a matrix correlation between selected ROIs to extract the synchronized frames
In our previous work,[8] we demonstrated that a fine control of the injection parameters, with respect to hemodynamic criteria reduces risk of reflux and allows angiography of the coronary arteries
Summary
CO2 arteriography is currently undertaken only for the lower part of the body to avoid the potential risk of cerebral ischemia.[1,2,3] As iodine contrast is nephrotoxic, the possibility to extend CO2 angiography to the coronary arteries could be of great benefit for patients with renal insufficiency.[1,4,5,6,7] To explore this scenario, we built a mechanical model of the coronary circulation to evaluate the relationship between CO2 injection and hemodynamic parameters to avoid arterial reflux and minimize the risk of ischemia.[8,9] We previously demonstrated that an injection pressure (InPs) between the dicrotic notch and the diastolic value with a high resistance catheter can generate a lower injection flow than that of blood, thereby allowing safe injection without reflux into the aorta. In the wake of our encouraging results, we improved our system by adding a simulator of coronary movements
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