Tuesday, July 25, 2006

Defibrillators in Athletes

WSJ 7/25/06: Should competitive athletes with heart ailments be permitted to play sports with defibrillators? This is a hot topic with varying views by authorities in the field. And there is significant controversy:
The debate over whether athletes with heart conditions should be allowed to play raises issues of free will, medical ethics and legal liability. Is the love of sports -- and the dream of a professional career -- worth risking death? Should doctors be in the position of prohibiting adults from playing? What's the difference between competing with a heart defect and pursuing risky adventures like climbing Mount Everest? Should fans be forced to watch a player risk his life?

And there are probably not two more opposing views than those shared by Dr. David Cannom from Los Angeles and Dr. Barry Maron from the Hyopertrophic Cardiomyopathy Center at the Minneapolis Heart Institute Foundation. On one side, Dr. Cannom is careful to evaluate certain players and work in tandem with the players to structure a possible mechanism for them to continue playing competitive sports. On the other more conventional side, Dr. Maron argues that sudden death strikes 200 to 300 young athletes annually, and these might be prevented by restricting play. Dr. Maron is keenly aware of the changes in hemodynamic loads to the left ventricle during athletics in patients with hypertrophic cardiomyopathy. In fact, one recent study demonstrated the poor efficacy of external defibrillators (AED's) in saving athletes' lives. One wonders if internal defibrillators (like those recommended by Dr. Cannom) would be equally ineffective. But as acknowledged in the WSJ:
There's little solid medical evidence to guide doctors in assessing this risk. Studies show that barely one out of 100,000 athletes suffers sudden cardiac death. Yet as many as one in 500 people suffer from HCM. That suggests that dozens of athletes would need to be sidelined to save a single life. The risk of playing sports with a heart defect and a defibrillator has barely been studied. The number of people with defibrillators who want to play competitively is small. Dr. Cannom is now pursuing a study with a Yale University cardiologist.

The difficult choice between passion and protection makes some cardiologists yearn for a middle ground. Michael Ackerman, a Mayo Clinic cardiologist who has worked with Drs. Maron and Cannom, says, "I wish we could have a detailed discussion with the families instead of the default -- you have a defibrillator, you're kicked off the team."
There does seem to be consensus that contact sports, like football, are ill-advised, since the defibrillator could be easily damaged. But I feel the same is true for basketball. It can get pretty physical, and jumping up and down certainly puts significant stressors on the lead inside the heart. If leads can be fractured from weight lifting and jogging - why not basketball?

Further, defibrillators are complicated devices that work on a simple principle - heart rates that are too fast are abnormal. It seems that Dr. Cannom programs his athletes' defibrillators to a detect rate of 250 b/min in some cases. That means that only rates over 250 beats per minute will be shocked. This rate might make sense in athletes, but could also sacrifice sensitivity of detection for specificity - that is, abnormal rhythms of, say, 240 beats per minute would go undetected. So when we read about the following about Mr. Will Kimble of Peperdine University's evaluation after practice:
As he has done dozens of times, Mr. Kimble slid a round wand over his T-shirt and the defibrillator implanted in his left shoulder. A minute later, a Medtronic representative printed out a beat-by-beat report on Mr. Kimble's device and his post-game heart. There were no irregularities.
This might not be true - it just means the programmed settings of his defibrillator device didn't see any heart rates that exceeded 250 beats per minute.

Further, why would the University of Texas, El Paso decide that a Medtronic rep and trainer be adequate coverage for a game, rather than a physician?
Mr. Kimble played two seasons at the University of Texas El Paso without needing a shock from the defibrillator. "I love being out there," he says. "I wouldn't have done it if I had a doubt in my mind." But basketball team trainer Michael Gutierrez says he was nervous during each practice, and each time Mr. Kimble fell.
After playing 18 minutes in his second-to-last collegiate game in March, Mr. Kimble sat with the team trainer and a sales representative for Medtronic Inc., the maker of his defibrillator. The school required a company representative to be at every game, to test the device.

Hmmm. Great service, Medtronic. But how much liability is Medtronic willing to assume? (I've always noted that it's never good to have your company in Column 1 of the front page of the Wall Street Journal.)

Well, enough for now. Best of luck to you Mr. Kimble, but please realize the limitations of what the Medtronic reps are reporting to you after your practices.


1 comment:

CardioNP said...

The school required a company representative to be at every game, to test the device.

Wonder just exactly what they were testing? Pacing thresholds? Impedence? It is not as if he could induce VF and ensure device charging and termination of VF. Sounds like false reassurance.