Monitoring of the state of intramural intestinal vessels in acute mesenteric ischemia with optical coherence angiography

Background. Objective data on the state of intramural microvessels are needed to select an effective therapy for the intestine reversibly damaged by mesenteric occlusion.

Aim. To monitor the condition of the small intestine blood vessels in acute mesenteric ischemia using the method of optical coherence angiography.

Material and methods. The study was carried out on male rats weighing 215–315 g (n=17) on a model of acute mesenteric ischemia. Monitoring of the microvascular bed was performed using the optical coherence angiography before ischemia modeling and 60, 120, and 180 minutes after the onset of ischemia. The data were evaluated by calculating the total length (L, mm) and area (S, mm2) of vessels on angiograms, as well as the S/L ratio, an index of vessel diameter that provides information about the diameter of vessels regardless of their length, what means it is sensitive to their dilation/spasm. The significance of differences in quantitative characteristics was assessed using the Mann–Whitney and Kruskal–Wallis criteria.

Results. In the devascularized sector, the state of the vascular wall changed in different directions for 180 minutes, as evidenced by statistically significant changes in the parameters L, S and their ratio. During the first hour of ischemia, the median S/L ratio decreased by 9.2%. By the 120th minute of ischemia development, the S/L ratio recovered and did not differ statistically from the initial values (p=0.339). After 180 minutes, there was a trend towards an increase in the diameter of the remaining perfused vessels — the median S/L on angiograms in the devascularized sector exceeded the initial level by 12.9% (p=0.045).

Conclusion. Areas of the small intestine, localized at the border of spread of ischemia, according to the optical coherence angiography, are characterized by multidirectional changes in the total length and area of the intramural vessels; during the first hour of ischemia, functional changes predominate, probably due to an increase in the tonus of the vascular wall; after 180 minutes of observation, signs of irreversible dilatation of microvessels are recorded.