The Discovery of a New Failure Mechanism Environmental Stress Cracking

On May 15, 1981, we received a Model 6991U arterial lead that had been removed from a human after only 5 months of implantation. The lead had about a 1in. gap in the insulation at the base of the J, similar to that shown in Fig. 4. Thorough analysis produced no evidence of chemical degradation of the device.970 For example, we found no changes in the surface or bulk infrared spectra. There was no change in the molecular weight of the sample. However, optical microscopic analysis revealed an...

Braunwald Cutter Cloth Covered Heart Valve

Introduced in the early 1970s, the Braunwald-Cutter cloth-covered caged-ball mechanical prosthetic heart valve had a ball fabricated from silicone and an open cage apex that was covered by polypropylene mesh struts.40 The major innovation was the cloth-covered cage struts, intended to encourage tissue ingrowth and thereby decrease thromboembolism. Complications of Cardiac Valve Substitutes Complications of Cardiac Valve Substitutes In preclinical studies of the Braunwald-Cutter valve concept...

Contributors

Becker, phd, President and CEO, Becker & Associates Consulting Inc., Washington, DC Michael D. Bednarek, jd, Senior Partner, Intellectual Property Group, Pilsbury Winthrop Shaw Pittman LLP, McLean, VA Robin Bostic, bs, Vice President, Reimbursement Affairs, Thoratec Corporation, Pleasanton, CA Sharon D. Brooks, jd, mph, Associate, Alston & Bird LLP, Washington, DC Mitchell I. Burken, md, mpp, Medical Director, TrailBlazer Health Enterprises, LLC, Timonium, MD Guy Chamberland,...

Accelerated Test Methods for Metal Ion Oxidation

As we analyzed the degraded polymer, we began to suspect that metal ions released from the conductor coils may somehow be involved as catalysts.77 In addition, the medical literature contained new reports revealing the discovery that oxygen free radicals actually could be produced in vivo. We discovered from studying the autoimmune disease and pathology literature that the mechanism by which implanted devices become encapsulated in fibrous tissue (known as the foreign body response) involved...

The Development of Accelerated Test Methods for Environmental Stress Cracking

A more global question was how to determine that design or process changes applied to new products would not cause ESC. How could we prove that the mechanism really was ESC In our investigation of the stress-cracking mechanism, we recognized several things ESC cannot occur without strain and the mechanism could not be duplicated in vitro. Obviously, if ESC requires a residual strain, then it should depend on processes that increased or reduced residual strain. It was also known that ESC...

Development Issues for a Combination Product With a Nonapproved Device

The issues encountered when developing a DES with a nonapproved device component are different from those encountered with approved devices. The nonclinical safety evaluation of the device is determined by performing biocompatibility studies in conformance with the International Standards Organization's (ISO's) standard ISO 10993.4 Part 1 of ISO 10993 describes the principles for evaluating medical devices and the tests required as a function of the type of product (e.g., long-term implant). In...

Phase II The Randomized Controlled TrialREMATCH

Organization and Funding of the Trial The study was conducted in 20 experienced cardiac transplantation centers with the expertise to provide sophisticated treatment of advanced heart failure. The trial was supported through a cooperative agreement with Columbia University, NIH's National Heart Lung and Blood Institute, and Thoratec Inc., who provided supplemental financial support for data collection and donated the LVADs for the trial. Patients' care costs, except for the initial LVAD...

The Development of a Chronic Postmarket Surveillance Study

We contracted three large implanting centers and sent a clinical specialist to visit them. The specialist went through patient records to determine the actual Fig. 6. A unipolar polyurethane-tined lead after 12 weeks implant in a canine is shown on the left. Note the relative freedom from encapsulation except at the distal tip. A typical silicone-rubber-insulated lead after 12 weeks implant in a canine is shown on the right. Note the thick encapsulation. Fig. 6. A unipolar polyurethane-tined...

Case Study The Exogen Sonic Accelerated Fracture Healing System

The Exogen Sonic Accelerated Fracture Healing System (SAFHS) shown in Fig. 1 was introduced into the market in 1994. At that time, the FDA indication was limited to the acceleration of the time to heal fresh fractures of the distal radius and tibia. These fractures had to be orthopedically managed by closed reduction and cast immobilization. The SAFHS accelerated bone healing in fresh fractures (fractures less than 3 months from date of fracture) of the tibia and radius. The usual and customary...

Adverse Event Reporting

Manufacturers have the most extensive reporting requirements. They are responsible for submitting individual reports regarding reportable malfunctions, as well as actual deaths and serious injuries. These reports must be submitted to the FDA through the MedWatch system on FDA Form 3500A within 30 days of becoming aware of the MDR-reportable event. Manufacturers are also obligated to provide incomplete or missing information submitted by user facilities, importers, or other initial reporters and...

Developing a Combination Product With a New Chemical Entity in Europe

Medical device companies tend to bring new devices into the clinic in Europe before the United States. Likewise, products are typically approved first in Europe and then in the United States, although it is not necessarily easier to bring a CP containing an NCE to clinics in Europe than in the United States.The European Community's (EC's) regulatory system differs greatly from that in the United States. The European system evolved because of the harmonization of many countries into one economic...