Transient arterial insufficiency and neurologic deficit following external iliac vein stent reconstruction for malignant compression.

Acute iliofemoral deep vein thrombosis may present with pain and swelling or phlegmasia cerulea dolens. When thrombosis occurs in the setting of an underlying venous obstruction, stent reconstruction should be performed after thrombus clearance to prevent rethrombosis. Stent reconstruction after thrombus clearance is associated with high technical success rates and durable patency. This report describes transient lower extremity arterial insufficiency and neurologic deficit after external iliac vein stent expansion and reconstruction within a confined space resulting from a malignant obstruction. It serves as a cautionary tale that, in rare cases, aggressive venous stenting within a confined space can transfer clinically significant forces to adjacent arteries and nerves.

Acute iliofemoral deep venous thrombosis (DVT) presents with lower extremity pain and swelling or phlegmasia cerulea dolens. Thirty percent will develop post-thrombotic syndrome (PTS). In patients with symptomatic iliofemoral DVT, catheter-directed thrombolysis, mechanical thrombectomy, or pharmacomechanical catheter-directed thrombolysis, compared with standard anticoagulation, may restore in-line patency more quickly, preserve valve function, improve quality of life, and decrease the severity of PTS. Iliofemoral DVT is associated with preexisting obstructive lesions.

In one study, 84% of patients with iliofemoral DVT had iliac vein compression on computed tomographic venography. For these patients, the use of self-expanding metallic venous stents to treat the obstructive lesion is a prerequisite for durable results. Iliac venous stenting may be performed with minimal morbidity and is associated with acceptable long-term patency rates.,

This report describes a patient with acute iliofemoral and femoropopliteal DVT owing to malignant external iliac venous compression who developed arterial insufficiency from compression of the external iliac artery after venous stenting.

Case report

Institutional review board approval was not required. The patient's consent was obtained.

A 75-year-old woman with bladder cancer presented with 5 weeks of progressive right lower extremity pain and edema that had become debilitating. A computed tomography scan with contrast performed 3 weeks prior showed an enhancing mass along the right pelvic sidewall that resulted in extrinsic compression and occlusion of the right external iliac vein (Fig 1). Right lower extremity venous duplex ultrasound examination was obtained, showing occlusive acute thrombosis of the right external iliac, common femoral, and femoral veins. Apixaban 5 mg twice daily was initiated.

Fig 1

Computed tomography (CT) scan with administration of intravenous contrast 3 weeks before stent reconstruction. A, Coronal and (B) axial reformations showing a patent right external iliac artery (EIA) (arrows) traversing the site of metastatic recurrence along the right pelvic sidewall. C, Coronal and (D) axial reformations showing complete effacement of the right external iliac vein (EIV) at the site of metastasis (arrows). There is tumor encasement of the EIA and EIV and abutment of the iliac body creating a rigid confined space. At this time, there is normal opacification of the EIV immediately peripheral to the tumor (arrowhead) without evidence of thrombosis.

Two days later, after considering conservative therapy, the patient returned for venous recanalization, thrombectomy, and stent reconstruction (Fig 2). Ascending venography, performed from a right popliteal vein approach, demonstrated a transition from nonocclusive-to-occlusive thrombus in the common femoral vein and minimal venous collateralization. Mechanical thrombectomy of the common femoral and femoral veins was performed using the ClotTriever mechanical thrombectomy device (INARI Medical, Irvine, Calif). Post-thrombectomy venography demonstrated high-grade stenosis of the external iliac vein, corresponding with the site of malignant external compression on computed tomography scanning.

Fig 2

Iliofemoral and femoropopliteal venous recanalization, mechanical thrombectomy, and stent reconstruction. A, Prone positioning and initial venography, from right popliteal access, showing multiple defects within the popliteal and femoral veins consistent with a nonocclusive thrombus with filling of venous collaterals. B, Ascending venography showing occlusive thrombus within the common femoral vein (CFV) and high-grade stenosis of the low external iliac vein at the site of malignant compression (arrow). C, The collection bag and coring (arrow) element of the Inari ClotTriever were deployed above the most central extent of the thrombus, and thrombectomy was performed. D, Completion femoropopliteal venography showing in-line flow. E, Residual waist (arrow), at the site of malignant extrinsic compression, after deployment of a 14-mm × 10-cm Venovo stent and angioplasty to 14-mm. F, Using a buttressing technique, a 15-mm × 5-cm Gianturco Z-stent was deployed within the Venovo stent (double arrows), centered at the waist, and angioplasty was performed to 16-mm resulting in near resolution of the waist. The stent construct was extended centrally into the common iliac vein (CIV) with a 14-mm × 8-cm Venovo stent and peripherally across the inguinal ligament with a 12-mm × 6-cm Wallstent. G, Completion iliofemoral venography showing in-line flow with no filling of venous collaterals.

A 14-mm × 10-cm Venovo stent (Bard Peripheral Vascular; Tempe, Ariz) was deployed across the malignant stenosis and post-dilated with a 14-mm balloon. Repeat venography showed persistent stenosis at the site of compression, which was, therefore, buttressed with a 15-mm × 5-cm Gianturco Z-stent (Cook Medical; Bloomington, Ind). Postdeployment angioplasty was performed with a 16-mm balloon. To completely cover all residual venous disease and ensure adequate inflow and outflow, the stent construct was extended peripherally across the inguinal ligament into the common femoral vein with a 12-mm × 6-cm Wallstent (Boston Scientific; Marlborough, Mass) and centrally into the common iliac vein with a 14-mm × 8-cm Venovo stent. Postdeployment angioplasty was performed with 14-mm and 12-mm balloons in the common iliac and common femoral veins, respectively. Completion venography showed in-line flow from the popliteal vein into the inferior vena cava. The patient was transitioned to enoxaparin 1 mg/kg twice daily and maintained on aspirin 81 mg daily.

The following morning, the patient described numbness and tingling involving the dorsal and lateral aspects of her right foot with foot drop. The right dorsalis pedis and posterior tibial pulses were newly nonpalpable. Right ankle dorsiflexion strength was 2/5 compared with 5/5 on the left. Right lower extremity arterial and venous duplex ultrasound studies were performed. The ankle-brachial index was 0.31 on the right compared with 1.16 on the left. The right iliofemoral venous stents were widely patent. There was no popliteal hematoma. Velocity within the midsegment of the right external iliac artery was markedly increased at 497 cm/s. There was poststenotic turbulence and monophasic flow within the right common femoral artery. The remainder of the right lower extremity arteries showed dampened monophasic waveforms. Computed tomography angiogram demonstrated a severe, focal, nearly occlusive, right external iliac artery stenosis at the site of the pelvic sidewall tumor, directly adjacent to the location of the buttressed venous stent placement (Fig 3).

Fig 3

High-grade arterial stenosis after iliofemoral venous stent reconstruction. A-C, Sequential axial images from a pelvic computed tomographic angiography (CTA) through the site of pelvic side wall metastasis and venous Gianturco Z-stent buttressing show focal obliteration of the external iliac artery (EIA) (arrows) owing to extrinsic compression from both the venous stent construct (arrowheads) and tumor. There is normal opacification of the EIA immediately distal to the obstruction. The level of obliteration corresponds with the adjacent Venovo and Gianturco Z-stent (B; arrowhead). D, Three-dimensional reconstruction from pelvic CTA showing high-grade EIA stenosis (arrow). E, Anteroposterior and (F) 30° left anterior oblique views, with stent subtracted, showing concentric, near-occlusive, EIA stenosis.

A multidisciplinary discussion occurred. External iliac artery stent placement was feasible, but thought to be associated with a risk of thrombosis and stent fracture owing to crossing of the inguinal ligament. A left-to-right femorofemoral bypass graft was considered; however, the patient had edema from prior DVT, and it was thought that this factor would increase the risk for graft infection. Based on these considerations and because the patient could be monitored closely in the hospital for worsening symptoms, conservative management with anticoagulation alone was continued.

By the following day, the patient's right foot numbness and weakness improved, and she was able to ambulate. Over the next 2 days, she was able to walk independently for longer distances owing to decreased foot drop. On postprocedure day 4, the patient was discharged to home in stable condition.

The patient was seen at 1 month. Her right lower extremity edema and neurologic symptoms had resolved. Her right ankle-brachial index had improved to 0.74 from 0.31. The external iliac vein velocity was 443 mL/min, and computed tomographic venography confirmed patency of the right iliofemoral stent reconstruction. At 2 months, patency of the stented iliofemoral vein was noted on a nondedicated computed tomography, along with persistent severe stenosis of the external iliac artery at the site of aggressive venous stenting. The patient was placed on hospice care and deceased 4 months later.

Discussion

Residual venous obstruction and post-thrombotic reflux after iliofemoral DVT may be associated with chronic symptoms that decrease quality of life. If thrombus is not cleared adequately, patients may experience recurrence, valvular reflux, and PTS.7, 8, 9 Endovascular treatment in iliofemoral DVT is focused on facilitated thrombus removal, relief of outflow obstruction, and restoration of flow sufficient to maintain long-term patency. When an anatomic abnormality is identified, the culprit lesion typically requires stent placement to prevent rethrombosis.,

Iliocaval and iliofemoral stent reconstruction have proven successful in treating acute and chronic DVT resulting from extrinsic compression. Studies have shown favorable technical successes, long-term patency rates, and low complication rates.12, 13, 14, 15, 16 In one large study including both thrombotic and nonthrombotic iliac obstructions, the technical success rate was 83% and the 4-year primary and secondary patency rates were 35% and 72%, respectively. Stent patency rates for nonthrombotic lesions associated with iliac venous compression are more favorable, with primary patency rates ranging from 74% to 92% at 1 year and secondary patency rates over 90% reported at up to 5 years.,,,

In this patient, a Gianturco Z-stent modification technique was used to provide greater radial force at the site of malignant venous compression. The technique, as initially described, used a self-expanding Gianturco Z-stent to buttress the upper end of an iliac vein Wallstent stack, which increased radial force at the typical choke point near the iliocaval confluence to prevent compression, ostial coning, and migration. The authors showed primary and secondary patency rates at 2 years of 69% and 93%, respectively. Venovo stents may be less prone to migration associated with compression than Wallstents. This case, however, was felt to require buttressing with a Gianturco Z-stent as a means to increase radial force.

Recent improvements in stent technology have resulted in dedicated venous stents that achieve higher radial forces. The Venovo stent is a self-expanding nitinol stent with open cell design. It has the highest chronic outward force (4.83 N/cm) compared with similar self-expanding stents including Vici (1.39 N/cm) (Boston Scientific), Zilver Vena (2.02 N/cm) (Cook Medical), and Wallstent (0.85 N/cm). The Gianturco Z-stent radial forces depend on design. The six-point double body Z-stent produces radial forces up to 16 N with pinching force resistance owing to stainless steel construction.,

This report describes transient arterial insufficiency and neurologic compromise resulting from adjacent venous stent reconstruction. In retrospect, the arterial compression likely resulted from (1) the stent expansion into a confined space flanked laterally by the external iliac artery, tumor, and ilium, (2) the high radial force of the overlapping Venovo stent and Gianturco Z-stent construct, and (3) the length of the iliofemoral stent construct (common iliac to common femoral vein) that resulted in stiffening and straightening of the associated venous segment. The rapid resolution of symptoms was not surprising; acute occlusion of the proximal arteries in patients without significant peripheral arterial disease may be tolerated, depending on individual clinical circumstances. This finding may reflect robust autoregulation of existing collaterals.

In rare instances, standard venous stents do not provide sufficient radial force to overcome the compressive extrinsic force of the culprit lesion. This report serves as a cautionary tale that aggressive venous stenting within a confined space may transfer high radial forces to adjacent structures including arteries and nerves.