**6. Application to peripheral arterial surgery**

HEMS has been also applied to peripheral arterial surgery for assessing the blood flow in the saphenous vein graft anastomosed to the paramalleolar artery [19]. Blood flow in vascular prosthesis such as Dacron or Polytrafluoroethylene (PTFE) graft cannot be assessed due to poor penetration of fluorescence (Figure 7). Although there are varying time delay from ICG injection to opacification of graft, assessment of arterial graft via intravenous ICG injection is an advantage of HEMS. Since the target (graft) is immobile unlike coronary angiography, the image is clear despite a long distance from the injection site [18, 19].

**Figure 7.** HEMS assessment of graft in peripheral arterial surgery. Visual image and ICG angiogram in ePTFE graft (A,B) and saphenous vein graft (C, D). Opacification is poor in PTFE graft. PTFE: polytetrafluoroethylene. SV: saphenous vein. Arrow heads show native peripheral arteries.

**Figure 6.** HEMS assessment of coronary arterial grafts. Coronary arterial bypass grafts images created by HEMS (A-C) and fluoroscopic angiography (D-F). Arrows indicate coronary anastomoses, arrow heads indicate occluded point of graft. A: Smooth opacification of graft and distal coronary artery. B: Delayed graft flow. C: Absence of fluorescence in the left anterior descending artery (LAD) despite of opacification of left internal thoracic artery (LITA) graft. There was perfusion defect in the anterior myocardial wall (circled dot line), while myocardial perfusion in the diagonal region is

HEMS has been also applied to peripheral arterial surgery for assessing the blood flow in the saphenous vein graft anastomosed to the paramalleolar artery [19]. Blood flow in vascular prosthesis such as Dacron or Polytrafluoroethylene (PTFE) graft cannot be assessed due to poor penetration of fluorescence (Figure 7). Although there are varying time delay from ICG injection to opacification of graft, assessment of arterial graft via intravenous ICG injection is an advantage of HEMS. Since the target (graft) is immobile unlike coronary angiography, the

apparent. D-F: Fluoroscopic coronary angiography corresponding to A to C, respectively.

image is clear despite a long distance from the injection site [18, 19].

**6. Application to peripheral arterial surgery**

88 Artery Bypass

Figure 8 compares the intraoperative HEMS image and postoperative CT angiogram in a case of arterial revascularization. The blood flow through the anastomosis was smooth (Figure 8A) and there was no stenosis at the anastomosis by CTA (Figure 8B). Figure 9 demonstrates the data of a case who underwent bypass grafting to the posterior peroneal artery (PTA) with a saphenous vein graft [19]. HEMS revealed an inadequate blood flow in the PTA distal to the anastomosis (Figure 9A), although TTF showed fairly acceptable graft flow (7 mL/min of mean flow: Figure 9B). Based on the HEMS findings, an additional bypass to the PTA was placed with a saphenous vein graft. HEMS following additional grafting showed smooth flow in the graft as well as in the PTA distal to the anastomosis (Figure 9C). The TTF assessment showed doubled graft flow (15 mL/min, Figure 9D). Since the TTF data can be largely affected by hemodynamic condition as well as peripheral perfusion area, it is not easy to make reliable TTF criteria. HEMS may be helpful for making a decision in such instances.

**Figure 9.** HEMS assessment and transit time flowmetry (TTF) data in peripheral arterial surgery. A: HEMS image of sa‐ phenous vein (SV) graft which was anastomosed to the posterior tibial artery (PTA). Fluorescence is poorly detected in the PTA (b). B: TTF data showing graft flow in the initial bypass (a). C: An improved flow in HEMS assessment in addi‐ tional SV (c) as well as in the PTA (d). D: TTF data showing doubled graft flow after revised bypass (c).(Reprinted from

Intraoperative ICG Angiography in Cardiovascular Surgery

http://dx.doi.org/10.5772/55311

91

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

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

Eur J Vasc Endovasc Surg 2012; 43:426- 432)

**7. Application to AAA surgery**

arises at the most distal portion of the aorta.

longer duration for imaging.

**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.

**Figure 9.** HEMS assessment and transit time flowmetry (TTF) data in peripheral arterial surgery. A: HEMS image of sa‐ phenous vein (SV) graft which was anastomosed to the posterior tibial artery (PTA). Fluorescence is poorly detected in the PTA (b). B: TTF data showing graft flow in the initial bypass (a). C: An improved flow in HEMS assessment in addi‐ tional SV (c) as well as in the PTA (d). D: TTF data showing doubled graft flow after revised bypass (c).(Reprinted from Eur J Vasc Endovasc Surg 2012; 43:426- 432)
