Microembolism during foam sclerotherapy of varicose veins.

To the Editor: Chronic venous insufficiency is a common disease in adulthood. One recently developed therapy for varicose veins is foam sclerotherapy.1 We used foam sclerotherapy in a 51-year-old man and a 33-year-old woman who had symptomatic varicose great saphenous veins and were otherwise healthy. Immediately after the initiation of treatment, transient scotomas developed in the man, and a migraine attack in the woman. On the basis of these observations, we decided to monitor by echocardiography the foam distribution during foam sclerotherapy in 33 consecutive patients with chronic venous insufficiency. The treatment in each patient was carried out according to European consensus guidelines.2 Briefly, patients received a single injection of 5 ml of 1% polidocanol foam (air-to-liquid ratio, 4:1). The foam was injected with the patient’s leg slightly elevated, while the saphenofemoral junction was manually compressed until full vasospasm occurred and blood-flow velocity in the great saphenous vein decreased to zero. In all patients studied, we detected foam microemboli in both the right atrium and ventricle between 45 seconds and 15 minutes after foam injection (Fig. 1A). In five patients, microembolism was also detectable in the left atrium and ventricle (Fig. 1B); however, neurologic signs did not develop in any of them. Careful echocardiographic examination of these five patients showed a right-to-left shunt through a patent foramen ovale. Because the neurologic symptoms observed in the two index patients could have reflected adverse effects of foam sclerotherapy due to a rightto-left shunt, we subsequently examined both patients by echocardiography and detected a patent foramen ovale in each. These findings suggest that foam-induced microembolism is a common phenomenon during foam sclerotherapy. The prevalence of patent foramen ovale, which can be a source of paradoxical embolism, is approximately 26% in the general population.3 Still, serious neurologic symptoms after foam sclerotherapy, which include scotomas, migraine, and stroke, occur in only 2% or less of patients.4,5 Thus, the findings in our cohort are in line with previous reports. Although the overall number of neurologic adverse effects during foam sclerotherapy might be underestimated, it appears that neurologic complications develop in relatively few patients with right-to-left shunts and foam microembolism. Nevertheless, we suggest that caution be exercised when foam sclerotherapy is performed in patients with a known patent foramen ovale and that patients with overt neurologic symptoms undergo an additional echocardiographic examination for the presence of a patent foramen ovale. Further prospective studies are needed to evaluate and confirm our observations.