Dangerous Medical Devices: A Personal Story
Medicine
Dan Walter, 08/23/2011

Dangerous Medical Devices: A Personal Story

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Early one morning in March 2002, in preparation for a procedure to treat my wife’s irregular heartbeat, a cardiologist at Johns Hopkins Medicine opened a sterile package that revealed a Biosense Webster Lasso Mapping Catheter – and ultimately laid bare a fundamental flaw in the Food and Drug Administration’s process for approving many medical devices.

The FDA’s so-called 510(k) system has come under fire recently, with a report by the Institute of Medicine (IOM) calling for the FDA to scrap it altogether for failing to reliably screen many medical devices for safety and effectiveness. The executive editor of The New England Journal of Medicinereached the same conclusion. But device manufacturers are dismissing the report and the FDA announced that it will seek public comment.

Both lives and money are at stake, and the outcome of the debate will say much about the values of our society.

Currently, medical devices considered to be of moderate risk (including pacemakers, blood pressure monitors, and a wide range of other devices) can be approved if they are deemed to be “substantially equivalent” to similar devices that are already on the market. The problem is that each similar, or (in legal parlance) “predicate,” device had likely been approved because it was deemed to be substantially equivalent to its predecessor, and in this way a device can become transformed by many increments over the years and evolve into an unrecognizable descendent of the original.

The Biosense Webster Lasso Mapping Catheter is a case in point. At the time of my wife’s procedure, the Lasso was an innovation in the array of complex devices developed for a procedure called “catheter ablation for atrial fibrillation.”

The version of the procedure used on my wife consisted of locating, or mapping, areas of the heart wall where the errant electrical impulses originated. Then an ablation catheter was used to burn lines of scar tissue at these places. Creating scar tissue had been shown to block the path of errant electrical impulses and control atrial fibrillation.

In its 510(k) application summary for FDA approval, Johnson & Johnson, parent company for Biosense Webster, said: “The Lasso Mapping Catheter is substantially equivalent to the predicates with the addition of the Nitinol formed ‘Lasso’ assembly . . . The platinum ring electrodes are located on the lasso assembly rather than on the catheter tip . . . ” The FDA agreed with this assessment, and therefore, Biosense Webster did not need to conduct clinical trials to prove that the Lasso was a safe and effective device with which to explore the inner workings of the human heart.

In February 2001, the company began a study with its new mapping catheter to, among other things, train doctors to become specialists in the burgeoning field of electrophysiology – that is, medicine involving the electrical activity of the heart. The study was conducted by Hugh G. Calkins, head of the electrophysiology lab at Johns Hopkins Medicine and a longtime paid adviser to numerous device manufacturers, including Johnson & Johnson.

Over the next six years, at least 517 people underwent catheter ablations at Johns Hopkins as part of this study. Although the study was set up to gather data, it was not considered a clinical trial and therefore was not subject to ethical guidelines for clinical trials or oversight by an institutional review board.

My wife, Pam Walter, was among the earliest group of patients in the study. At 7:45 a.m. on March 25, 2002, she was sedated and wheeled into Lab Room 101 at the Johns Hopkins Electrophysiology Service. A cardiology Fellow whom we had never met was about to get a lesson in the performance of catheter ablation for atrial fibrillation.

Being new on the job and unfamiliar with the new catheter, the cardiology Fellow turned the catheter control knob to the left instead of the right, which transformed the lasso into a corkscrew that wound its way through the complex web of muscles of Pam’s mitral valve and became entangled there. The catheter was stuck. These and other details emerged in depositions and written statements as part of a lawsuit brought by my wife against the Hopkins doctors. After about 45 minutes, a colleague of Calkins’ was called in. With considerable difficulty, the catheter was finally removed, but in the process Pam’s mitral valve was damaged.

The doctors took Pam down the hall to surgeons, who said that she might die if she did not have emergency open heart surgery to replace her valve. Shortly after the surgery, she suffered a stroke and hovered near death in a coma for the next three weeks.

What caused all this in the first place? Calkins had a case study of Pam’s surgery and complications published in the Journal of Cardiovascular Electrophysiology, in which he laid the blame on the Lasso assembly of the new and improved version of the Biosense Webster Lasso Mapping Catheter: “the circular spine of our catheter became entangled in the chordae tendineae. The design, relative stiffness, and entrapment of the preformed circular spine in the mitral apparatus prevented complete straightening or relaxation of the circular tip. We suspect that the abrasive nature of the 20 electrodes caused resistance, which contributed to the inability of the catheter to slide off the mitral valve apparatus...”

The Lasso assembly has gotten tangled in other mitral valves, prompting doctors at Harvard to publish a paper about how to deal with this “complication.” The most recent model, the Lasso 2515, was recalled in 2008, although the model used on Pam is still on the market.

Perhaps if lobbying efforts of the medical device industry had not been so successful in perpetuating the 510(k) process, the Lasso catheter would have been properly vetted for safety and efficacy before it was launched into the marketplace. As it stands now, the marketplace is what the device industry uses to evaluate safety and effectiveness, and people like my wife are the proving grounds.

Dan Walter is a writer who lives in Deale, Maryland. He is the author of Collateral Damage: A Patient, a New Procedure and the Learning Curve.

Posted by Susan Gilbert at 08/23/2011 04:09:30 PM