An “Occult” Popliteal Vein Aneurysm Causing Pulmonary Embolism

Abstract

Popliteal vein aneurysm (PVAs), though uncommon, can be a cause of pulmonary emboli. They can also result in pulmonary vein embolism despite the use of anticoagulation therapy. We report the case of an otherwise fit, 64-year-old male who had a history of sudden onset of dyspnea on exercise with near syncope. A computed tomography pulmonary angiogram confirmed filling defects in the lung bases in keeping with pulmonary emboli. He was anticoagulated and a venous duplex scan revealed a fusiform suprageniculate PVA with no evidence of thrombus in the lumen. He underwent resection of the aneurysm with lateral vein patch graft repair and was placed on anticoagulation for 6 months with no recurrence after 2 years of follow-up. PVAs are rare and can either be symptomatic or asymptomatic. We advise early surgical treatment to prevent the significant morbidity and mortality associated with thromboembolization. Written consent was obtained from the patient for publication of case and use of images.

Popliteal vein aneurysm (PVA) first reported in 1968 by May and Nissl ¹ is a rare clinical condition. Since then, ∼150 cases have been reported in the world literature. ²

PVAs are usually asymptomatic ³ but can frequently present with sudden, unexplained dyspnea and chest pain due to pulmonary embolism (PE) ⁴ as the sole symptom. PVAs can also present as a popliteal mass ⁵ and calf pain.

The management of patients with asymptomatic PVAs remains uncertain, although there have been anecdotal reports purporting a conservative route with close surveillance using B mode and color flow duplex imaging, ^{3 6} while others insist that the risk of thromboembolism is so high that regardless aneurysm size and the presence or absence of intraluminal thrombus, definitive treatment is favored. ⁷ The mainstay of symptomatic PVA remains open surgical intervention with postoperative anticoagulation. ⁸

Our case is that of a patient who initially had an undiagnosed PVA with recurrent bouts of PE and underwent open repair and anticoagulation. He remains symptom free after 2 years.

Case Report

A 64-year-old male presented elsewhere with sudden onset of dyspnea while exercising despite no prior medical issues or history of trauma and a history of excellent exercise tolerance with a previous venous duplex reported as being normal.

A stress echocardiogram showed diminished exercise tolerance due to severe dyspnea with no wall motion abnormalities to suggest flow limiting coronary disease. However, his pulmonary pressure was significantly elevated to suggest a PE despite no clinical evidence of deep vein thrombosis.

D-dimer was positive and computed tomography-pulmonary angiogram (CT-PA) showed filling defects in the basal, lingual segmental branches of the left lower lobe, medial lobar and medial segmental branches of the right lower lobe, with the remaining branches and the main pulmonary artery enhancing normally.

He was placed on anticoagulant therapy resulting in rapid resolution of his dyspnea over the next 5 days. He was discharged. A week later, he presented to our service with worsening dyspnea on exertion and with repeat CT-PA showing recurrent PE.

A repeat venous duplex scan revealed a large dilated venous 3.87cm by 2.17cm mass in the popliteal region of the left lower limb consistent with PVA.

A CT venogram of the lower limb confirmed a 4 cm long by 2cm (TS) signal focal saccular dilatation of the popliteal vein ( Figs. 1 and 2 ).

Fig. 1.

Computed tomography venogram of the left lower limb showing popliteal vein aneurysm.

Fig. 2.

Popliteal vein aneurysm with sling on tibial nerve.

Surgical intervention was performed with the patient in a prone position and a lazy S incision was made and dissection the popliteal vein, resection of aneurysm, and a vein patch repair of the popliteal vein (aneurysmectomy plus lateral venorrhaphy) were performed with uneventful sequelae post operatively. He was placed on anticoagulation for PE leading to gradual resolution of his dyspnea.

Repeat color flow duplex imaging was done at 6 months and 1 year, both showing good compressibility of the popliteal vein with no evidence of thrombosis or recurrence of aneurysm.

Discussion

PVA is an uncommon condition with less than 200 cases reported in the world literature. ² PVAs can be asymptomatic ³ but often present with sudden unexplained dyspnea and chest pain due to PE in 45 to 73% of cases. ^{4 5 6}

There is no consensus definition for venous aneurysms; however, it has been proposed that it is dilation twice the normal venous diameter by McDevitt et al, ⁹ while Maleti et al defined it as three times the size of the proximal part of the popliteal vein, or > 20 mm the normal diameter of the popliteal vein. ¹⁰

Aneurysm of the veins involves all three layers of the venous wall. ^{10 11 12} Pathogenesis is unknown, although it has been postulated that mechanical trauma, degenerative wall disease, inflammation, congenital wall weakness, and hemodynamic changes all play a role in its development. ¹³

It is also suggested that aneurysmal dilatation is a response to increased hemodynamic pressure at a site of mural weakness since most PVAs are seen in patients with either superficial or deep venous reflux. ^{14 15 16}

In 75% of cases, PVA was saccular, fusiform in 20% and unspecified in 5% of cases. ⁶ There is no clear evidence of risk of thromboembolic complications based on type of aneurysm, though large saccular ones are suggested to be more prone. The same applies when size of aneurysms is considered as “small” ones are also prone to thromboembolic complications as much as “large” sizes with no critical definition or distinction between large or small diameters. ^{7 14 15 16 17}

Generally, primary venous aneurysms are uncommon and in most cases of little clinical significance, ^{18 19 20} however, PVAs are a form of potentially life-threatening disease because they have been recognized to be a source of recurrent PE. ^14–16 PVAs have presented at various ages. The youngest is a 12-year-old girl with a history of Klippel–Trenaunay syndrome and angiodysplasia who presented with PE. ¹⁸ Cormier et al reported 44 more cases of angiodysplasia with PVA. ¹⁹

The most common presentation of PVA is with PE ^{4 8 14 15 18} ; it is seen incidentally in patients with chronic venous insufficiency either due to symptoms suspected to be deep vein thrombosis or symptoms of varicose veins sent for venous duplex. ^{3 17 19}

A few of the PVA in literature were detected on physical examination with patient having leg pain and swelling, though these symptoms were not said to be due to the aneurysm. ^{15 19}

The incidence of asymptomatic PVAs quoted by Labropoulos et al as 0.18%. ³

Most of the PVAs reported in literature are located in the proximal part of the popliteal vein and primarily unilateral with only approximately eight cases found to be bilateral. ^{6 9 10}

In literature, most of the cases of PVA were diagnosed on conventional venography, and though invasive, it has been shown to effectively define the details of venous anatomy prior to surgical repair. Moreover, it can be used to assess flow in the popliteal vein after a repair. ^{7 15 18}

The noninvasive diagnostic tool of choice is venous duplex scanning that can identify the size of the aneurysm as well as the presence of thrombus in the aneurysm. ³ PVAs can also be diagnosed and assessed using CT venography and magnetic resonance venography. ^{8 15 17}

Asymptomatic patients can be treated conservatively with routine follow-up venous duplex studies and anticoagulation. ³ However, the majority of surgeons proport early intervention due to the risk and mortality and morbidity associated with PE that can occur even on anticoagulation therapy. ^{14 15 18}

The surgical technique most frequently used is tangential aneurysmectomy and lateral venorrhaphy as described by Aldridge et al. ^{8 12} Other forms of repair in literature include aneurysmal resection with vein interposition vein grafting. This is done when tangential resection and repair cannot be done, particularly if configuration of the PVA is fusiform. ^{8 14} There has been no report of recurrence of PVA after surgical repair in literature.

Conclusion

PVA is uncommon cause of thromboembolic phenomenon that could potentially be fatal. Early diagnosis using duplex scan and surgical treatment is essential to prevent the consequences of the pathology.

Funding Statement

Funding None.