Currently, many vascular surgeons perform afemoropopliteal bypass graft from the groin to the kneeto save the lower extremities of patients that have se-vere arterial disease. The most common cause of earlyfailure of a femoropopliteal bypass graft is usually tech-nical error. Sometimes, extrinsic compression by sur-rounding structures may result in impediment of bloodflow within the graft (1). The femoropopliteal bypassgraft can be entrapped by the medial head of the gas-trocnemius muscle in the popliteal fossa against thebone. The same situation is seen in “popliteal artery en-trapment syndrome”, in which the native popliteal

artery is compressed by the abnormally migrated medi-al head of the gastrocnemius (2).

In previous reports, physical examinations, Dopplerultrasonography, and conventional angiography of pa-tients undergoing a femoropopliteal bypass graft havebeen described (1-4). Multidetector row computed to-mography (MDCT) might also be a useful tool for diag-nosing this condition. MDCT offers high spatial resolu-tion and can provide excellent depiction of not only lu-minal patency but also adjacent anatomical structuresthat cause the extrinsic compression. We report a caseof iatrogenic entrapment of a femoropopliteal bypassgraft that was confirmed by the use of MDCT.

Case Report

A 56-year-old man visited our hospital with worseningleft lower leg pain. The patient had known histories ofhypertension, angina, and cerebrovascular attack. CTangiography was obtained with a 16-detector row spiralCT scanner (Sensation 16, Siemens, Forchheim,Germany) for evaluation of the lower extremity arteries.The patient was placed in the supine position on the CT

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Diagnosis of Iatrogenic Femoropopliteal bypass GraftEntrapment Syndrome by MDCT: A Case Report1

Hyunji Kim, M.D., Soon-Young Song, M.D., Jinoo Kim, M.D.2, Yongsoo Kim, M.D.3, Byung Hee Koh, M.D., On Koo Cho, M.D., Mi Jung Jang, M.D.4, Oh-Jung Kwon, M.D.5

1Department of Radiology, Hanyang University Hospital, HanyangUniversity College of Medicine, Korea

2Department of Radiology, Naval Pohang Hospital, Korea3Department of Radiology, Hanyang University Kuri Hospital, Korea4Departments of Radiology, Seoul National University Bundang Hospital,Seoul National University College of Medicine, Korea4

5Department of General Surgery, Hanyang University Hospital, HanyangUniversity College of Medicine, KoreaReceived June 20, 2007 ; Accepted September 4, 2007Address reprint requests to : Soon-Young Song, M.D., Department ofRadiology, Hanyang University Hospital, 17 Haengdang-dong,Seongdong-gu, Seoul 133-792, KoreaTel. 82-2-2290-9160 Fax. 82-2-2293-2111 E-mail: songsy@hanyang.ac.kr

Popliteal artery entrapment syndrome is a well-known congenital condition causinglimb ischemia. A similar entity caused by entrapment of a femoropopliteal bypassgraft by the muscle and tendons around the knee has also been described.Ultrasonography or MR imaging is considered as a choice of a noninvasive modalityfor this condition, but there are some limitations. We report a case of iatrogenic entrap-ment of femoropopliteal bypass graft that was confirmed by multidetector row com-puted tomography (MDCT).

Index words : Graft occulsion, vascularTomography, X-ray computedPopliteal artery

table. The acquisition volume included the abdomenand both lower extremities from the upper 12th thoracicspine to the lower end of both feet. An 18-gauge intra-venous cannula was inserted into a vein in the antecu-bital fossa. Scanning was performed after intravenousinjection of contrast medium (Ultravist 370; Schering,Berlin, Germany) with an automatic power injector at aflow rate of 3.5 mL/sec (total 150 mL). The scan time de-lay was determined by the automatic bolus trackingmethod. The R.O.I. was positioned at the descendingaorta at the level of the diaphragm. The CT scan started15 seconds after the attenuation reached 150 H.U. TheCT examination was performed by using 16 × 1.5 mmcollimation, a table feed of 24 mm per gantry rotation.The X-ray tube voltage was 120 kV, and the amperagewas 130 mAs. Volume data were reconstructed as 2-mmthickness at a 1-mm interval. We interpreted the recon-structed data set with the use of PC-based 3-dimensionalsoftware (Rapidia 2.8; Infinitt, Seoul, Korea) and appliedthe various post-processing algorithms (MPR, MIP,and/or volume rendering). CT angiography revealedcomplete occlusion of the left superficial femoral arteryat the proximal aspect with distal reconstruction at thepopliteal level via collaterals. Femoro-popliteal bypassgraft insertion using an autologous greater saphenousvein was performed. Postoperative MDCT angiographywas obtained after a week, and blood flow was absent in

the graft during extension of both knees. At that time,the patient did not have any ischemic symptoms. We re-peated the CT examination on the next day after dis-cussing the possible cause of apparent graft failure withthe physician. The dorsalis pedis artery of the patientwas normally palpable on flexion of the knee and it dis-appeared on extension. Therefore, we planed to repeatthe CT examination during two phases, both with flex-ion and extension of the knee. A further examination re-vealed that the flow was normalized and the lumen ofthe graft was patent without any stenosis seen on the CTscan during the first phase (the knee flexion at 30 de-grees). The degree of knee flexion was determined aftera physical examination at the point of disappearing dor-salis pedis pulse. On a CT scan during the second phase,with the knee extension the graft was seen to be nar-rowed and compressed extrinsically between the medialhead of the gastrocnemius muscle and the semimembra-nous tendon (Figs. 1, 2). We diagnosed the patient ashaving iatrogenic graft entrapment syndrome of thefemoro-politeal vein graft. As the patient did not haveany ischemic symptoms in his left lower leg, he refusedto undergo surgical revision of the graft.

Ten months later the patient revisited our hospital viathe emergency room complaining of pain and coldnessin his left lower leg for 3 days. There was diffuse throm-bosis within the graft lumen. Gangrenous change of the

Hyunji Kim, et al : Diagnosis of Iatrogenic Femoropopliteal bypass Graft Entrapment Syndrome by MDCT

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A B

Fig. 1. CT angiography of thefemoropopliteal bypass graft duringflexion of the affected limbSagittal MRP (A) and MIP (B) imagesshow the preserved normal patency ofthe graft without any extrinsic com-pression during flexion of the affectedlimb.

left foot was found.

Discussion

Popliteal artery entrapment syndrome is one of thewell-known causes of lower extremity ischemia (1). Asimilar occlusive condition can be created during a be-low-the-knee femoro-popliteal bypass graft. Femoro-popliteal bypass graft entrapment syndrome is definedas the compression of the graft occurring between themedial head of the gastrocnemius muscle and the ten-dons of the semitendinosus or femoral condyle (1-3, 5).There are many complications associated with graft en-trapment, such as degeneration or aneurysmal changesof the graft itself, or intraluminal thrombus formation

resulting in claudication and ischemic changes of the af-fected limb (1, 3).

Conventional angiography can be regarded as the goldstandard for evaluating this condition. However, it hasthe disadvantage of being invasive (6). In addition, con-ventional angiography does not show structures adja-cent to the graft that cause the extrinsic compression.Cross-sectional imaging modalities such as ultrasonogra-phy, CT, and MRI are useful non-invasive diagnostictools. They have the common capability of demonstrat-ing the cause of the extrinsic compression. However,Doppler ultrasonography is an operator-dependent pro-cedure and has its limitations when evaluating a deep-seated lesion (4, 7). Although MR angiography has excel-lent diagnostic capability for peripheral vascular disease

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Fig. 2. CT angiography of thefemoropopliteal bypass graft during ex-tension of the affected limbExtrinsic compression of the graft (ar-row) is noted on the axial image be-tween the medial head of the gastrocne-mius muscle and the semimembranoustendon on the axial image (A). Thesame findings are also noted on sagittalMPR (B), MIP (C), and volume render-ing images (D). This feature is sugges-tive of iatrogenic femoropopliteal by-pass graft entrapment syndrome. (*:Semimembranosus tendon, **:Gastrocnemius medial head)

B C D

A

(7), it is relatively expensive to use as a standard tool.Recently, many roles of conventional angiography havebeen substituted by the use of MDCT owing to the com-parable high diagnostic accuracy of the latter modality(8). MDCT angiography has superior spatial resolutioncompared with that of MR angiography, and it is sub-stantially less expensive to perform. Additionally, it al-lows three-dimensional visualization of the pathologicalsite from any angle and in any direction. Besides provid-ing the same information as conventional angiographyregarding the luminal patency of the femoropoplitealartery, it provides additional information regarding thecondition of the vessel wall and surrounding structures(9).

Regardless of the imaging modality performed, a diag-nosis can be made only in the appropriate clinical set-ting. In our patient, preserved intraluminal blood flowaccounted for the clearly depicted vein graft on MDCTduring flexion of the patient’s knee, while the bloodflow was seen to disappear during extension. This fea-ture is pathognomonic for iatrogenic vein graft entrap-ment syndrome.

Iatrogenic vein graft entrapment syndrome is a rarecause of graft failure. Our case demonstrates the effec-tiveness of the use of MDCT as a diagnostic tool for thisrare condition, providing many advantages over the useof other modalities. An severe ischemic change of the af-fected limb may be irreversible, often leading to ampu-tation, and thus it is important to understand the diag-

nostic features of iatrogenic femoropopliteal bypassgraft entrapment syndrome.

References

1. Gutierrez IZ, Barone DL, Currier C, Makula PA. Iatrogenic entrap-ment of the femoropopliteal bypass. J Vasc Surg 1985;2:468-471

2. Abbas M, Mwipatayi BP, Angel D, Haluszkiewicz E, Sieunarine K.Iatrogenic entrapment: Femoro-popliteal vein bypass graft. CurrSurg 2006;63:202-206

3. VanDamme H, Ballaux JM, Dereume JP. Femoro-popliteal venousgraft entrapment. J Cardivasc Surg 1988;29:50-55

4. Naredo E, Moller I, Moragues C, Agustin JJ, Scheel AK, Grassi W,et al. Interobserver reliability in musculoskeletal ultrasonography:result from a “Teach the Teachers” rheumatologist course. AnnRheum Dis 2006;65:14-19

5. Baker WH, Stoney RJ. Acquired popliteal entrapment syndrome.Arch Surg 1972;105:780-781

6. Rubin GD, Shiau MC, Leung AN, Kee ST, Logan LJ, Sofilos MC.Aorta and iliac arteries: single versus multiple detector-row helicalCT angiography. Radiology 2000;215:670-676

7. Sanni A, Mahawar K, Jones NA. Iatrogenic Femoropopliteal GraftEntrapment Leading to Thrombus Formation. Eur J Vasc EndocascSurg 2005;30:402-403

8. Sueyoshi E, Sakamoto I, Matsuoka Y, Ogawa Y, Hayashi H,Hashmi R, et al. Aortoiliac and lower extremity arteries: compari-son of three-dimensional dynamic contrast-enhanced subtractionMR angiography and conventional angiography. Radiology1999;210:683-688

9. Meissner OA, Verrel F, Tato、F, Siebert U, Ramirez H, Ruppert V,et al. Magnetic Resonance Angiography in the Follow-up of DistalLower-Extremity Bypass Surgery: comparison with DuplexUltrasound and Digital Subtraction Angiography. J Vasc IntervRadiol 2004;15:1269-1277

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대한영상의학회지 2007;57:429-432

다중채널 전산화 단층촬영으로 진단된 대퇴-슬와동맥우회 이식혈관 포획 증후군: 1예 보고1

1한양대학교 의과대학 영상의학과학교실2포항해군병원 영상의학과

3한양대학교 의과대학 한양구리병원 영상의학과4서울대학교 의과대학 분당서울병원 영상의학과

5한양대학교 의과대학 외과학교실

김현지·송순영·김진우2·김용수3·고병희·조온구·장미정4·권오정5

슬와동맥 포획 증후군은 하지의 허혈을 가져오는 잘 알려진 선천성 이상소견이다. 유사한 양상의 포획 증후군이

대퇴-슬와동맥 우회 이식혈관에서도 무릎주변의 근육과 힘줄에 의해 유발될 수 있다. 초음파나 자기공명영상 등이

이 질환을 진단하는 주된 비침습적인 검사법으로 알려졌으나, 제한점이 있다. 저자는 다중채널 전산화단층촬영으로

진단된 대퇴-슬와동맥 우회 이식혈관의 포획 증후군 1예를 보고하고자 한다.