Vein compression by arterial aneurysms☆

Popliteal aneurysms 

Nine patients had popliteal aneurysms involving compression of the popliteal vein. Clinical findings and treatment are summarized in Table I. Two of the three patients with DVT and five of the six patients with venous compression were correctly diagnosed with either noninvasive studies or phlebography to have venous obstruction from an adjacent aneurysm. The patients with DVT were given anticoagulant medication. Elective treatment for the seven patients whose aneurysms were correctly identified involved proximal and distal ligation, and femoral to below-knee popliteal bypass with in situ saphenous vein. All patients had an excellent result with successful distal revascularization and relief of venous compression.

Table I. Summary of patients with vein compression by arterial aneurysms

	Patient	Age (yr)/sex	Aneurysm location/size	Presenting symptoms	Strain-gauge plethysmography	Duplex imaging/sonogram	Phlebography	Treatment	Result
	1	73/M	L popliteal/4 cm	Calf pain, swelling	Abnormal	DVT + aneurysm	DVT	Anticoagulation, bypass*	Good
	2	86/M	R popliteal/4 cm	Calf pain	Abnormal	No DVT + aneurysm	Extrinsic compression	Bypass*	Good
	3	70/F	L popliteal/5 cm	Calf pain	Borderline	No DVT + aneurysm	Extrinsic compression	Bypass*	Good
	4	70/M	L popliteal/10 cm	Calf & ankle swelling	N/A	N/A	Extrinsic compression	No treatment	Aneurysm occlusion at 6 mo, BKA
	5	68/M	R popliteal/4 cm	Ankle swelling	Borderline	No DVT + aneurysm	Extrinsic compression	Bypass*	Good
	6	66/M	L popliteal/5 cm	Calf pain	Abnormal	No DVT + aneurysm	Extrinsic compression	Bypass*	Good
	7	78/M	R popliteal/4 cm	Calf pain	Borderline	N/A	Extrinsic compression	Bypass*	Good
	8	75/M	L popliteal/4 cm	Calf pain, swelling	N/A	N/A	DVT	Anticoagulation	Aneurysm occlusion at 3 mo, BKA
	9	66/M	R popliteal/5 cm	Calf pain, swelling	N/A	N/A	DVT	Anticoagulation, bypass*	Good
	10	69/F	L iliac/4 cm	Swollen leg	Borderline	Aneurysm	DVT	Anticoagulation	Embolization, Ischemia at 4 mo, bypass,† BKA
	11	59/M	L iliac/4 cm	Swollen leg	Borderline	ANeurysm	Extrunsic compression	Bypass†	Good
	12	65/M	L iliac/6 cm	Swollen leg	N/A	N/A	Extrunsic compression	Anticoagulation	Ruptured AAA at 2 mo, death
	13	68/M	L iliac/6 cm	Swollen leg	Abnormal	Aneurysm	Extrunsic compression	Bypass†	Good
	14	72/M	L iliac/3 cm	Swollen leg	Borderline	Aneurysm	Extrunsic compression	Bypass†	Good
	*Femoral-popliteal in situ saphenous vein bypass with ligation of the popliteal aneurysm. †Aortobifemoral bypass.

DVT, Deep vein thrombosis; N/A, study not performed; BKA, below-knee amputation.

One patient (No. 8) in whom phlebography identified DVT was treated with anticoagulation only (Fig. 1).

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Fig. 1. Ascending left leg phlebogram illustrates tibial vein thrombosis (arrows), which occurred in the distal infrapopliteal venous system despite the much more proximal popliteal vein compression by a 4 cm popliteal artery aneurysm.

A second patient with venous compression (No. 4) whose phlebogram was incorrectly interpreted as normal and who did not have any noninvasive studies performed was discharged without further treatment. The patient came for treatment 6 months later with thrombosis of the popliteal aneurysm (Fig. 2) with severe distal ischemia, eventually requiring a below-knee amputation.

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Fig. 2. Ascending left leg phlebogram (A) with compression of the above-knee popliteal vein. Accompanying arteriogram (B) shows contrast material filling upper part of the aneurysm.

Iliac aneurysms 

Five patients presented with left iliac vein compression caused by iliac aneurysms (Table I). All three patients in whom aneurysms were correctly diagnosed were treated with an elective aortobifemoral bypass with aneurysm exclusion, producing excellent results.

One patient (No. 12) was incorrectly diagnosed to have iliac vein thrombosis after phlebography and was given anticoagulation medication. The patient was observed for 2 months at which time he presented with rupture of the previously undiagnosed abdominal aortic and iliac aneurysms. The patient died within 2 hours of presentation despite an emergency operation. Review of his previous phlebographic studies confirmed extrinsic venous compression by the iliac artery aneurysm (Fig. 3).

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Fig. 3. Phlebogram of the left iliac vein with extrinsic compression by 6 cm left iliac artery aneurysm (arrow).

A second patient (No. 10) with iliac vein thrombosis was given anticoagulation medication. The adjacent iliac artery aneurysm was not identified initially (Fig. 4).

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Fig. 4. Left iliac phlebogram with crescent-shaped extrinsic indentations from left iliac artery aneurysm (arrows).

Clinical diagnosis 

Major reviews of popliteal aneurysms emphasize that most patients characteristically present with lower extremity ischemia or an asymptomatic mass. Vermilion et al.1 reported that only 11 of 147 popliteal aneurysms (7%) had associated venous obstruction. Reilly et al.2 noted only 11 of 244 popliteal aneurysms (4%) with local complications, including venous compression. In the series of 88 popliteal aneurysms reported by Whitehouse et al.,3 no patients had DVT or symptomatic compression of nearby veins.

As a rule, iliac artery aneurysms come to the surgeon's attention at the time of diagnosis of an associated abdominal aortic aneurysm.4 Reviews of abdominal aortic aneurysms rarely mention the incidence of associated venous compression.5 In 71 isolated iliac aneurysms, McCready et al.6 failed to note any patient with venous compression. Schuler and Flanigan,7 in a collective review of isolated iliac aneurysms, found that iliofemoral venous compression was described in only 4 of 69 patients (6%).

Objective methods of diagnosis 

Although isolated case reports have presented radiologic evidence of venous compression by arterial aneurysms,8, 9 venous compression is mentioned only as a clinical finding in most series on popliteal aneurysms. Phlebography and in certain cases duplex imaging were used to document venous obstruction in our patients. Sullivan et al.10 reported the reliability of duplex imaging with a 92% specificity and 100% sensitivity compared with phlebography in detecting infrainguinal thrombosis. Duplex imaging also provides the additional benefit of detecting adjacent masses that can cause extrinsic compression. The depth of the iliac vein in the pelvic cavity and overlying bowel gas cause duplex imaging to be unreliable for detection of iliac vein compression or thrombosis.11

Strain-gauge plethysmography, which can physiologically assess venous obstruction, can be useful; however, some patients in this series had equivocal results. Because of these difficulties in assessing the origin of iliac vein compression, pelvic ultrasonography and CT scanning11, 12 were used when necessary to diagnose or confirm the iliac artery aneurysms.

Therapeutic approach 

The morbidity and mortality seen in the patients in this series whose aneurysms were not diagnosed are not unlike that reported in other large series in which known aneurysms were treated without operative repair.13, 14 If asymptomatic popliteal aneurysms are left untreated, severe limb-threatening complications can develop in approximately one third of the patients. Linton13 described 22 aneurysms in 15 patients; of these patients gangrene developed in six (27%) during observation in the hospital. All these patients required low thigh amputation. Gifford et al.14 noted that 13 of 35 asymptomatic popliteal aneurysms (37%) developed limb-threatening complications while under observation. A total of 23 of 68 popliteal aneurysms (34%) treated conservatively in the study by Gifford et al. ultimately had complications.

Vermilion et al.1 reported that 8 of 26 popliteal aneurysms (31%) had severe limb ischemia and complications while under observation. They emphasized that nonoperative treatment of patients even with severe medical conditions provided clearly suboptimal results. The development of limb ischemia from aneurysm thrombosis and/or distal embolization of atherosclerotic debris or thrombus critically limits the opportunity for successful distal revascularization. Early operative treatment of popliteal aneurysms in these series with aneurysm ligation and in situ saphenous vein bypass prevented limb loss.

In a similar fashion, iliac artery aneurysms are usually considered for repair once the diagnosis is made. Rupture of iliac artery aneurysms is frequently fatal and Schuler and Flanigan7 have documented that nonoperative treatment of isolated iliac artery aneurysms resulted in aneurysm rupture in 9 of 13 patients within an average of 5 months from the time of diagnosis. McCready et al.6 reported significant increases in aneurysm size in 9 of 13 patients with isolated iliac artery aneurysms observed for 6 years. In the present series, although iliac venous compression was caused by iliac components of combined abdominal aortic and iliac artery aneurysms, it was this iliac component that led to the appropriate diagnosis. Timely aortobifemoral bypass graft with aneurysm exclusion produced successful outcomes in the patients described in this series.

In the absence of a high index of suspicion even careful physical examination for pelvic and peripheral aneurysms may not lead to the correct diagnosis of venous compression caused by arterial aneurysm in some patients. We have documented in this study that judicious application of additional diagnostic techniques can be helpful. Physiologic assessment of the venous capacitance and outflow combined with phlebography, duplex imaging, and selective pelvic or abdominal ultrasound, or CT scanning can enhance diagnostic accuracy. Early diagnosis and appropriate arterial revascularization avoid delay, reduce morbidity and mortality, and simultaneously relieve venous symptoms in patients with venous compression or thrombosis caused by arterial aneurysms.