Resonance Raman Spectroscopy Detects Ischemia in Experimental Coarctation of the Aorta in a Rodent Model.

Abstract

Coarctation of the aorta (CoA) can cause aortic obstruction, ischemia, and death. Resonance Raman Spectroscopy (RRS) measures tissue oxyhemoglobin (ShbO) and mitochondrial redox state (3RMR) non-invasively. Metal wire was placed around the aorta of Sprague Dawley rats to generate a systolic blood pressure (SBP) gradient. RRS-ShbOand 3RMR were measured pre- (hand) and post-obstruction (foot). In model 1 (n&#x2009;=&#x2009;8), the gradient rapidly reached 120&#xa0;mmHg. In model 2 (n&#x2009;=&#x2009;30), gradients of 20&#xa0;mmHg (n&#x2009;=&#x2009;9) and 40&#xa0;mmHg (n&#x2009;=&#x2009;12) were maintained for 2&#xa0;h. In model 1, foot-ShbOand 3RMR changed significantly (P&#x2009;=&#x2009;0.004 and P&#x2009;=&#x2009;0.007) at SBP gradients&#xa0;of 80-mmHg or above. In model 2, the 40-mmHg gradient group showed significant declines in foot-ShbO2 (P&#x2009;=&#x2009;0.014) and increases in 3RMR (P&#x2009;=&#x2009;0.008)&#xa0;by 1 h. Foot-ShbOand 3RMR correlated strongly with serum mixed venous saturation (ShbO: r&#x2009;=&#x2009;0.73, P&#x2009;<&#x2009;0.0001; 3RMR: r&#x2009;=&#x2009;-0.55, P&#x2009;<&#x2009;0.0001). RRS effectively detects ischemia caused by aortic obstruction in a CoA model.