**8. Limitation of ICG angiography**

Despite the advantages of HEMS, quick and less invasive assessment without contrast agent as well as assessment of tissue perfusion superimposed on the color views [9, 19, 29], it also has several limitations to be noted.

First, penetration of fluorescence is less than 2 to 3 mm and visualization of blood flow is limited to the superficial portion of the vessel and tissue [25]. The coronary artery covered with adipose tissue or hemostatic stuff cannot be visualized clearly.

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 is not feasible.

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, the results cannot be simply compared among individuals.

**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

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

Despite the advantages of HEMS, quick and less invasive assessment without contrast agent as well as assessment of tissue perfusion superimposed on the color views [9, 19, 29], it also

First, penetration of fluorescence is less than 2 to 3 mm and visualization of blood flow is limited to the superficial portion of the vessel and tissue [25]. The coronary artery covered with

image of surgical field facilitates to precisely locate the ischemic region [19].

adipose tissue or hemostatic stuff cannot be visualized clearly.

**8. Limitation of ICG angiography**

has several limitations to be noted.

2012; 43:426- 432)

92 Artery Bypass

**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‐ vasc Surg 2012; 43:426- 432)
