Expansion rates of asymptomatic popliteal artery aneurysms

Objectives. In the absence of symptoms the decision to operate on popliteal artery aneurysms (PA) is often made on RA diameter. Little information exists on growth rate and therefore optimum scanning intervals. The aim of this paper is to define growth rate of PA managed conservatively. Methods. A prospective study of patients with asymptomatic RA was carried out. Patients were invited for ultrasound scanning at 6-12 months intervals. Diameter changes between consecutive pairs of scans were measured. A decision to operate was made in fit patients if PA became symptomatic and/or had a diameter above 3 cm. Results. Twenty-one men (24 aneurysms) with a median age of 69 years (46-86) underwent 78 scans. Sixteen PA were on the right and eight on the left. Eighteen patients had bilateral aneurysms, 15 of which were complicated on one side at presentation and were dealt with surgically on that side. The median size at first scan was 19 mm (14-36). The median time interval to the first follow-up scan was 9 months and subsequent scans were 12 months. The mean rate of expansion at aneurysm sizes below 20 mm diameter was 1.5 mm/year. RA grew by 3.0 mm/year at sizes 20-30 mm and by 3.7 mm/year at sizes >30 mm. Among the risk factors analysed, hypertension appeared to increase the risk of aneurysm growth. Conclusion. The expansion rate of PA increases with increasing size of the PA. This rate of growth in relation to size at previous scan and threshold diameter for intervention should be borne in mind when planning surveillance intervals.