Magnetic Mini-Mover Procedure for pectus excavatum: I. Development, design, and simulations for feasibility and safety.

BACKGROUND/PURPOSE Correction of pectus excavatum (PE) results in measurable improvement in lung capacity and cardiac performance as well as improved appearance and self-image. The Nuss and modified Ravitch approaches attempt to correct the chest wall deformity by forcing the sternum forward in 1 step and holding it in place using a metal strut. The initial operation requires extensive manipulation under general anesthesia and results in postoperative pain, requiring hospitalization and regional anesthesia. Pain and disability may last for weeks. Both procedures are expensive. A better principle would be a gradual bit-by-bit repair via small increments of pressure applied over many months. We developed the Magnetic Mini-Mover Procedure and applied this strategy to correct PE. METHODS The Magnetic Mini-Mover Procedure uses magnetic force to pull the sternum forward. An internal magnet implanted on the sternum and an external magnet in a nonobtrusive custom-fitted anterior chest wall orthosis produce an adjustable outward force on the sternum. Outward force is maintained until the abnormal costal cartilages are remodeled and the pectus deformity is corrected. RESULTS We implanted a magnet in human skeletons and measured the force applied to the sternum when the distance between the internal and external magnets was varied in increments. With the 2 magnets 1 cm apart, the outward force was adequate to move the sternum at least 1 cm. We also mapped the magnetic field in the two-magnet configuration and found that maximum field strengths at the surface of the heart and at the outer surface of the orthosis were at safe levels. CONCLUSIONS The Magnetic Mini-Mover Procedure allows correction of PE by applying magnetic force over a period of months. Crucial questions raised during our design, redesign, and simulation testing have been satisfactorily answered, and we have received a Food and Drug Administration Investigation Device Exemption (G050196/A002) to proceed with a phase I to II clinical trial.

[1]  Thomas S Tenforde,et al.  Magnetically induced electric fields and currents in the circulatory system. , 2005, Progress in biophysics and molecular biology.

[2]  M M Ravitch,et al.  THE OPERATIVE TREATMENT OF PECTUS EXCAVATUM , 1949, Annals of surgery.

[3]  E. Fonkalsrud,et al.  Force required to elevate the sternum of pectus excavatum patients. , 2002, Journal of the American College of Surgeons.

[4]  Determination of the mechanical requirements for a progressive correction system of pectus excavatum in children. , 2005, Journal of laparoendoscopic & advanced surgical techniques. Part A.

[5]  Hiromichi Kamamoto,et al.  Anesthetic management for the minimally invasive Nuss procedure in 21 patients with pectus excavatum , 2005, Journal of Anesthesia.

[6]  Scott Line,et al.  The Merck veterinary manual , 2005 .

[7]  Eric W. Fonkalsrud,et al.  Current Management of Pectus Excavatum , 2003, World Journal of Surgery.

[8]  D. Nuss.  Recent experiences with minimally invasive pectus excavatum repair "Nuss procedure". , 2005, The Japanese journal of thoracic and cardiovascular surgery : official publication of the Japanese Association for Thoracic Surgery = Nihon Kyobu Geka Gakkai zasshi.

[9]  A. Sastre,et al.  Occupational magnetic field exposure and cardiovascular mortality in a cohort of electric utility workers. , 2002, American journal of epidemiology.

[10]  M. E. Katz,et al.  A 10-year review of a minimally invasive technique for the correction of pectus excavatum. , 1998, Journal of pediatric surgery.

[11]  T. Sorahan,et al.  Mortality from cardiovascular disease in relation to magnetic field exposure: findings from a study of UK electricity generation and transmission workers, 1973-1997. , 2004, American journal of industrial medicine.

[12]  F. Schier,et al.  The vacuum chest wall lifter: an innovative, nonsurgical addition to the management of pectus excavatum. , 2005, Journal of pediatric surgery.

[13]  Alayar Kangarlu,et al.  Effect of static magnetic field exposure of up to 8 Tesla on sequential human vital sign measurements , 2003, Journal of magnetic resonance imaging : JMRI.