Medical-grade Liquid Silicone Research Articles

Patient-Tailored Silicone Plug for HeartMate 3™ Left Ventricular Assist Device Explantation

Purpose Cardiac recovery after mechanical circulatory support allows explantation of the left ventricular assist device (LVAD). So far, no FDA approved or CE certified plug is available for the explantation of newest generation HeartMate 3TM. Here, we present an individualized explantation strategy with an in-house developed patient-tailored silicone plug for the HeartMate 3™ LVAD avoiding (re-) sternotomy. Methods Hemodynamic evaluation of two HeartMate 3TM patients was performed in order to assess cardiac recovery and hereby planning a LVAD explantation strategy avoiding (re-) sternotomy. A preoperative CT scan was used to define the ideal dimensions of the silicone plug fitting with a HeartMate 3TM mock apical ring. The cylindrical plug was made out of medical grade liquid silicone elastomer MED-4820 (NuSil Silicone Technology LLC, Carpinteria, USA) using a patient specific high quality surface casting mold and subsequently sterilized in a clinical standard process. Its geometry was defined by the inner diameter of the apical cuff and the patient's CT data implementing one rounded end and a cylindrical head with cross-shaped suture guides on the other end. Results Following CT scans of two HeartMate 3TM patients, individualized explantation of the LVAD was planned with a patient-tailored silicone plug. Both patients could be successfully weaned from VAD support and explanted with a lateral thoracotomy. No apical bleeding occurred after VAD removal and silicone plug insertion. The plugs could be inserted easily and reliably secured with crossing sutures. The patients were monitored on ICU and could be discharged home in the following days. Conclusion The surgical removal of HeartMate 3TM is feasible using a patient-tailored silicone plug avoiding (re-) sternotomy. The medical grade liquid silicone elastomer allows perfect patient-specific fitting with pre-operative CT-measured dimensions.

New advances on tracheal stent manufacturing

Abstract Several complications, including tumors, can cause the obstruction of the trachea. To prevent from suffocation, tubular implants named stents are used. Commercially available stents are expensive and not anatomically adapted, and therefore big challenges need to be faced in order to improve them. This work presents several additive manufacturing methodologies to fabricate customized tracheal stents. Rapid tooling seems to be the best option. Two different molds were manufactured using open-source low-cost machines in order to reduce costs. In addition, a high speed machine was also used to fabricate another mold. The molds produced were poured either with a non-implantable medical grade platinum silicone or with an implantable medical grade liquid silicone rubber in order to obtain the final tailored tracheal stents. Finally, a mechanical behavioral test was performed with implantable medical grade liquid silicone rubber stents. The results showed an adequate Young Modulus suitable to favor the insertion and extraction of the stent from the human trachea. Future work is needed to fully study the tracheal stents manufacturing process and be able to introduce several important steps, such as the sterilization of the product and the certification of the entire process.

Flexible Carbon Nanotube Composite Sensors for Medical Device Application

Flexible carbon nanotube composite sensors for medical device applications have been developed using small loadings of multi-walled carbon nanotubes dispersed into medical grade liquid silicone rubber for the purpose of measuring stress, strain and load placed on or by a medical device. The sensors may be attached to a medical device or molded within a medical device, such as an expandable balloon.

Treatment of Acne Scars with Liquid Silicone Injections

This article addresses the use of liquid injectable silicone as both an immediate and long-lasting treatment for broad-based, depressed acne scars. The only filler substance that maintains precision and permanence in improving and/or correcting these types of acne scar defects is medical-grade liquid silicone. We describe five patients with a history of acne scarring who showed improvements from injections of liquid silicone at the initial treatment session and lasting over a 10-, 15-, and 30-year follow-up period. Monthly liquid silicone injections using a technique known as the microdroplet, multiple-injection approach. This article documents the safety, effectiveness, and precision of silicone in addition to highlighting the fact that its permanence is what distinguishes it from other filler materials. As a precise and permanent filling substance used for soft tissue augmentation, liquid injectable silicone can improve and/or eliminate depressed, broad-based acne scars through a technique known as the microdroplet, multiple-injection

Debilitating Silicone Granuloma of the Penis and Scrotum

The restoration and improvement of body contour have intrigued surgeons for over 100 years, generating much interest in the subcutaneous/intradermal injection of highly viscous fluids. The local complications of liquid silicone injection have been well documented over the past 30 years. Although Dow-Corning has not made medical-grade liquid silicone available for use in humans without an approved research application since 1966, practitioners, both licensed and unlicensed, have administered these injections worldwide for a variety of indications throughout the body. There is little or no information concerning the adulteration of these injectates. To date, there have been four case reports of penile injections--the indications being evenly split between the treatment of impotence/sexual inadequacy and augmentation. The most recent description was published in 1982. We present a case of debilitating silicone granuloma of the penis and scrotum secondary to large-volume injections into the corpora cavernosae and penile soft tissues administered in Belgium 14 years prior to presentation. The development of a silicone foreign body reaction, massive edema, and subsequent impotence lends itself to a clinical diagnosis and aggressive treatment with wide local excision and appropriate soft-tissue coverage. The metabolic fate of silicone in vivo remains inadequately characterized and a fertile area for research as new methods involving nuclear magnetic resonance spectroscopy have been devised to identify silicone and highly coordinated silicone complexes.

Rhinoplastic revisions with injectable silicone.

We report 20 years of experience with conservative and cautious injection of small amounts of medical-grade liquid silicone in 347 postrhinoplasty patients for a total of 1,937 treatments. Medical-grade silicone was found to be a safe, effective, and valuable adjunct to cosmetic rhinoplastic procedures. Microdroplet technique with very small doses is recommended for the correction of nasal defects that may not be amenable to revisional surgery. Controlled release of this material to the medical profession after appropriate evaluation is recommended, along with proper training prior to its use.

The Use of Free Revascularized Grafts in the Amelioration of Hemifacial Atrophy

Nine female and three male patients, 5 to 47 years old, were treated by free revascularized grafts for Romberg's disease. Greater omentum was transferred in nine, de-epithelialized skin flaps in three. Follow-up ranges from several months to 7 years. Microvascular failures or donor site complications did not occur. To further trim transferred tissue, overcome gravitational sag, or both, all but one patient required a secondary procedure. The only facial complication included partial loss of the transferred omentum and spotty necrosis of the overlying skin. The choice of omentum or de-epithelialized skin and subcutaneous fat is dictated by the extent of the facial defect. Generalized defects are corrected with omentum and localized segmental defects with de-epithelialized flaps. Because of observed late complications, including chronic inflammation, induration, and sinus tracts, we no longer recommend medical-grade liquid silicone as a therapeutic option in the palliation of Romberg's disease.

The current status of silicone fluid in plastic and reconstructive surgery.

Sufficient experimental data have been accumulated to demonstrate that medical-grade liquid silicone in recommended doses, using proper techniques, is both safe and effective. The problem becomes one of developing a rational and safe set of treatment guidelines.