by Frederic Jarrett, MD

Venous aneurysms are an uncommon problem in the practice of most vascular surgeons. For practical purposes, these aneurysms are seen in the neck in both pediatric and adult patients, and are almost entirely localized in the internal jugular vein. When looking specifically at the adult population, aneurysms can also be found in the lower extremity, primarily in the popliteal vein.

Etiology and Evaluation of Aneurysms

Aneurysms in these two locations have different natural histories and different implications for management. Curiously, venous aneurysms, along with splenic artery aneurysms, are the only aneurysms more common in females.

In the pediatric population, venous aneurysms usually present as a soft, non-tender anterior triangle neck mass that increases in size with the Valsalva maneuver. Other than that, only a laryngocele or an upper mediastinal cyst has the same presentation, and if any doubt exists as to the correct diagnosis, an ultrasound study can resolve the issue. Sometimes the aneurysms are described as phlebectasia, or in association with neurofibromatosis. In children, some surgeons advocate operative intervention to prevent possible future complications, which are rare but more often for cosmetic reasons and to prevent increase in size during growth, or to prevent rupture due to trauma. Neither of these two indications is well-grounded in the surgical literature. In adults, there is no reliable risk of pulmonary embolism, so the only indication for resection is cosmetic.

Lower extremity venous aneurysms can occur in the femoral, but most commonly develop in the popliteal vein. About 75% are saccular, and the remainder are fusiform. The diagnosis is rarely made by history or physical examination, but the universal availability of duplex scanning has resulted in the incidental identification of many popliteal aneurysms, usually asymptomatic.

Franco’s review of 3,500 lower extremity duplex scans found popliteal aneurysms in six patients—an incidence of 0.2%. The most common symptom prompting investigation with duplex scanning is pulmonary embolus, followed by venous insufficiency and deep venous thrombosis. L

ower extremity duplex studies—likewise done for a variety of symptoms—may uncover popliteal aneurysms that may or may not relate to the symptoms in question. Nevertheless, the finding of a popliteal aneurysm allows operative intervention and is one of the few instances which allow for definitive treatment of the cause of a pulmonary embolus.

Common complaints among patients who ultimately had aneurysms identified by investigations were:

• extremity pain (79%)
• a mass (64%)
• occasional swelling (43%)
• the incidence of pulmonary emboli varies from 24 to 71% in reported series, obviously contingent on the indication for investigation
• Popliteal venous aneurysms may also be found in association with chronic venous insufficiency or with ileofemoral venous thrombosis

Aneurysms of the deep venous system can be found in patients with Klippel-Trenaunay syndrome, in whom superficial varicosities and port-wine stains lead to investigation of the deep venous system. This syndrome is associated with a high incidence of thromboembolism and pulmonary emboli. Likewise, patients with popliteal aneurysms treated with anticoagulation alone had a high incidence of pulmonary embolism.

Operative Repair

Upper extremity venous aneurysms can be exposed with incisions usually used for arterial exposure or dialysis access. Femoral vein aneurysms can be exposed by customary groin incisions if they appear in the proximal femoral vein, and with a longitudinal incision and splitting of the adductor tendon if they appear in the mid-thigh and adductor canal.

For popliteal venous aneurysms, I have preferred to position the patient prone and use a longitudinal posterior incision. If the incision needs to cross the knee joint, a “z” incision across the popliteal crease can be used. The hamstring tendons and posterior tibial nerve can be retracted by dissecting directly on the aneurysm, which is exposed more easily and directly than with the medial infragenicular incision used for femoro-popliteal bypass. Most popliteal venous aneurysms are saccular, and after mobilization can be resected and the vein closed as a lateral venorrhaphy, with or without an autogenous or prosthetic patch.

Uncommonly, it may be necessary to reconstruct the vein with an end-to-end anastomosis, or with an autogenous vein graft. In the latter case, an appropriate length of the short saphenous vein can be harvested. I do not routinely use post-operative anticoagulation. Ligation of the popliteal vein as part of aneurysm resection is not recommended because of the significant incidence of chronic venous hypertension and edema afterwards.

The long-term patency of venous reconstructions depends on the type of repair performed. Aneurysm excision and lateral venorrhaphy has the best long-term patency, while complex venous reconstructions such as end-to-end anastomoses or interposition grafts have lower patency rates. Since most of the reports of popliteal venous aneurysms are case reports or small series, there is little long-term follow-up available and judgment is based on the experience with venous trauma.

Microscopic examination of venous aneurysms usually shows a diminution in the quantity of smooth muscle cells and elastic fibers—fragmentation of the internal elastic lamella, thickening by fibrous connective tissue-and diminished tissue-fibrinolytic activity are seen. Investigations have shown increased expression of MMP-2, MMP-9 and MMP-13 in a small series of patients with venous aneurysms.

We recently managed a case of false aneurysm of the popliteal vein, only once reported previously. Recurrent popliteal aneurysms have been reported.

Conclusion

Venous aneurysms are seen predominantly in the internal jugular vein, where operation should rarely be recommended, and in the popliteal vein, where operation is indicated because of the high incidence of pulmonary emboli. Dr. Jarrett reports no financial disclosures