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An ongoing, multicenter investigational-new-drug (IND) trial involving patients with great-saphenous-vein incompetence and right-to-left cardiac shunts is investigating the clinical significance of gas emboli with the proprietary very-low-nitrogen microfoam. On pretreatment screening, the prevalence of right-to-left shunt was unexpectedly high (40%). During treatment, 36 patients had cerebral emboli, detected by transcranial Doppler studies, and underwent extensive monitoring, including diffusion-weighted magnetic resonance imagine (MRI) at 24 hours and 28 days. No cerebral lesions were detected, and no abnormalities were noted on perimetry or assessment of cardiac markers.2 The study will continue until 50 patients with cerebral emboli have been studied.
In contrast, the risk associated with physician-compounded room-air foams is difficult to quantify in the absence of specific data on the potential for cerebral infarction.
Janet E. Rush, M.D.
David D.I. Wright, M.B.
BTG International
West Conshohocken, PA 19428
Drs. Rush and Wright report being employees of BTG International, the company developing the proprietary microfoam Varisolve under an IND application. No other potential conflict of interest relevant to this letter was reported.
References
Foam can be produced with a variety of agitation techniques that result in differences in bubble size and rate of reabsorption.1 We applied the double syringe technique, which led to larger bubbles than Rush and Wright's specifically engineered Varisolve technique to dispense foam having a highly controlled bubble-size distribution. Moreover, for polidocanol-foam preparation, Rush and Wright used a very-low-nitrogen gas mixture, whereas we used room air, which is associated with increases in bubble number and size.2 Therefore, we believe that the results of the two studies are difficult to compare.
Although we still believe that foam sclerotherapy is a safe procedure and routine screening for patent foramen ovale before foam sclerotherapy is not recommended, we also believe that further research regarding foam characteristics and consequences of foam emboli is necessary.
Roeland P.M. Ceulen, M.D.
GROW School for Oncology and Developmental Biology
6202 AZ Maastricht, the Netherlands
rpmceulen{at}gmail.com
Kevin Vernooy, M.D., Ph.D.
Cardiovascular Research Institute Maastricht
6200 MD Maastricht, the Netherlands
References
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Related Letters:
Microembolism during Foam Sclerotherapy of Varicose Veins
Ceulen R. P.M., Sommer A., Vernooy K.
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Full Text |
PDF
N Engl J Med 2008;
358:1525-1526, Apr 3, 2008.
Correspondence
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