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Letters to the Editor  |   September 2016
Transient Ischemic Attack After Foam Sclerotherapy
Author Notes
  • Biocompatibles Inc, Oxford, Connecticut 
  • Financial Disclosure: Biocompatibles Inc is the manufacturer of polidocanol endovenous microfoam 1%. 
Article Information
Letters to the Editor   |   September 2016
Transient Ischemic Attack After Foam Sclerotherapy
The Journal of the American Osteopathic Association, September 2016, Vol. 116, 571-572. doi:10.7556/jaoa.2016.114
The Journal of the American Osteopathic Association, September 2016, Vol. 116, 571-572. doi:10.7556/jaoa.2016.114
To the Editor: 
In the May 2016 issue of The Journal of the American Osteopathic Association, Kim et al1 reported the case of a 55-year-old woman who presented to the emergency department after experiencing symptoms indicative of a transient ischemic attack. Earlier in the day the woman had undergone endovenous chemical ablation of her varicose veins at an outpatient facility. Chemical ablation was performed by the attending physician using foam that was prepared extemporaneously at the bedside, otherwise known as physician-compounded foam (PCF). After cardiac and neurologic examination, the patient received a diagnosis of transient ischemic attack due to microembolism caused by PCF in the presence of a patent foramen ovale (PFO). 
This case report is a timely contribution to the literature. There has been in-creased awareness of neurologic sequelae and inconsistency in the efficacy of PCF prepared at the bedside. Although the authors use this case report as an opportunity to remind vascular specialists to screen for contraindications before administering endovenous foam, 2 statements in the discussion warrant clarification. 
First, from a safety perspective, it is critical that a distinction be made between nonproprietary PCF, which is made from room air and has a high nitrogen content (>70%), and US Food and Drug Administration (FDA)–approved polidocanol endovenous microfoam 1%, which has a low nitrogen content (<0.08%) and a median bubble size of less than 100 μm in diameter. Because the body does not have a mechanism for the disposal of nitrogen in the circulatory system, nitrogen bubbles continue to circulate in the blood and increase the risk of microembolism. This risk is amplified in patients with a PFO because in the presence of a right-to-left shunt, microemboli are more likely to migrate into the cerebral vasculature. 
Polidocanol endovenous microfoam 1% is produced according to Current Good Manufacturing Practice guidelines. Safety data from more than 1300 patients revealed that no clinically significant neurologic adverse events occurred when this formulation was used.2-4 Incidentally, Kim et al1 referenced a clinical trial of polidocanol endovenous microfoam 1%, in which 75% of the patients with a right-to-left shunt had cerebral emboli but no cerebral lesions or cardiac abnormalities developed.5 
Second, to echo the authors’ suggestion, physicians should assess for the presence of a PFO before administering PCF because of the inconsistent bubble size and formulation. However, the authors report on a publication from a 1984 autopsy analysis of healthy human hearts, which concluded that PFO is present in about 25% of the population.6 A 2010 study by Wright et al7 found that in patients with varicose veins, PFO prevalence is closer to 50%. These data indicate that there is an increased risk of introducing cerebral emboli in patients with a PFO when using inconsistent foam formulations or PCF. For this reason, patients should be properly screened for PFO before undergoing endovenous chemical ablation using PCF. However, the concern is obviated in low-nitrogen FDA-approved polidocanol endovenous microfoam 1%. 
References
Kim M, Niroumandpour M, Poustinchian B. Transient ischemic attack after foam sclerotherapy in a woman with a patent foramen ovale. J Am Osteopath Assoc. 2016;116(5): 320-323. doi:10.7556/jaoa.2016.063. [CrossRef] [PubMed]
Gibson K, Kabnick L; Varithena 013 Investigator Group. A multicenter, randomized, placebo-controlled study to evaluate the efficacy and safety of Varithena (polidocanol endovenous microfoam 1%) for symptomatic, visible varicose veins with saphenofemoral junction incompetence. Phlebology. March 24, 2016: pii:0268355516635386.
King JT, O’Byrne M, Vasquez M, Wright D; VANISH-1 Investigator Group. Treatment of truncal incompetence and varicose veins with a single administration of a new polidocanol endovenous microfoam preparation improves symptoms and appearance. Eur J Vasc Endovasc Surg . 2015;50:784-793. doi:10.1016/j.ejvs.2015.06.111. [CrossRef] [PubMed]
Todd KLIII, Wright DI; VANISH-2 Investigator Group. The VANISH-2 study: a randomized, blinded, multicenter study to evaluate the efficacy and safety of polidocanol endovenous microfoam 0.5% and 1.0% compared with placebo for the treatment of saphenofemoral junction incompetence. Phlebology. 2014;29:608-618. doi:10.1177/0268355513497709. [CrossRef] [PubMed]
Regan JD, Gibson KD, Rush JE, Shortell CK, Hirsch SA, Wright DD. Clinical significance of cerebrovascular gas emboli during polidocanol endovenous ultra-low nitrogen microfoam ablation and correlation with magnetic resonance imaging in patients with right-to-left shunt. J Vasc Surg. 2011;53(1):131-137. doi:10.1016/j.jvs.2010.06.179. [CrossRef] [PubMed]
Hagen PT, Scholz DG, Edwards WD. Incidence and size of patent foramen ovale during the first 10 decades of life: an autopsy study of 965 normal hearts. Mayo Clin Proc. 1984;59(1):17-20. [CrossRef] [PubMed]
Wright DD, Gibson KD, Barclay J, Razumovsky A, Rush J, McCollum CN. High prevalence of right-to-left shunt in patients with symptomatic great saphenous incompetence and varicose veins. J Vasc Surg. 2010;51(1):104-107. doi:10.1016/j.jvs.2009.08.008. [CrossRef] [PubMed]