**7. Application to AAA surgery**

**Figure 8.** Intraoperative ICG angiogram compared with postoperative CT angiogram. The patient underwent femorotibial arterial bypass with saphenous vein graft. A: ICG angiogram of femoro- tibial arterial bypass with saphenous vein graft. Blood flow through the anastomosis is smooth. B: The CTA showed there was no anastomotic stenosis.

90 Artery Bypass

Intestinal ischemia is one of undesirable complications in AAA surgery. It can be well demarcated caused by embolism of mesenteric artery or poorly demarcated in diffuse malperfusion. HEMS is capable of visualizing the blood flow in the mesenteric artery as well as tissue perfusion in the intestinal wall (Figure 10) [9, 19]. The mesenteric artery is opacified first, then marginal artery, and illuminescence sequentially spreads to the entire intestines and colon, but slightly delayed in the sigmoid colon, probably because inferior mesenteric artery arises at the most distal portion of the aorta.

Bowel necrosis can develop under markedly reduced perfusion despite the presence of detectable blood flow in the mesenteric artery [19, 26]. Assessment of tissue perfusion such as intestinal wall appears to be a unique and advantageous feature of HEMS which allows a longer duration for imaging.

HEMS does not provide the projectional image as in fluoroscopic angiography but the en-face view of superficial layer. Therefore, densitometric analysis for assessing the severity of stenosis

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The intensity of brightness is not absolute but rather relative. Furthermore, HEMS assessment can be affected by hemodynamic status such as blood pressure or cardiac output. Therefore,

**Figure 11.** HEMS images showing intestinal ischemia. A,B: Segmental ischemia in the sigmoid colon in an 85 year-old female patient who underwent emergent surgery for ruptured abdominal aortic aneurysm (AAA). The sigmoid colon appears slightly ischemic in visual inspection (A) but is apparent in ICG angiograms (B). C,D: Diffuse and spotty ische‐ mia in an 80 year-old female patient after transient hypotention during AAA surgery. (Reprinted from Eur J Vasc Endo‐

the results cannot be simply compared among individuals.

is not feasible.

vasc Surg 2012; 43:426- 432)

**Figure 10.** HEMS images showing sequential mesenteric perfusion. A: Fluorescence appears first in the mesenteric ar‐ teries (arrow). B: The entire mesenterium and intestinal wall is opacified. (Reprinted from Eur J Vasc Endovasc Surg 2012; 43:426- 432)

Champagne et al. reported the incidence of ischemic colitis following surgery for ruptured AAA as 42% [27]. Shock status in the preoperative period is the most important predictor of ischemic colitis [28]. Although resection of necrotic intestine and colon is necessary to rescue the patients, it is not easy to determine the extent of resection by visual inspection. Figure 11 shows the corresponding images of inspection and HEMS images in two cases. Figure 11A shows the appearance of intestine in an 85 year-old woman who underwent emergent surgery for rup‐ tured AAA. HEMS revealed malperfusion in the sigmoid colon (Figure 11B). Figure 11C is the visual finding of an 80 year-old woman after transient hypotension during AAA surgery. The intestine appeared to be diffusely malperfused in spotty fashion (Figure 11C). HEMS showed spotty malperfusion of intestinal wall (Figure 11D). ICG opacification in addition to the color image of surgical field facilitates to precisely locate the ischemic region [19].
