09/13/2006
Lithium Batteries Power a Heart
This past Monday was a beautifully clear, crisp day just as it was five years earlier on that date. Ever since then, any such day brings back memories of the events of 9/11. I had posted my column for 9/11 the night before the Trade Center attacks. Ironically, on that day of death, my column was on the origin of life. Five years later, 9/11 is still taking its toll in death and suffering among those who labored in and breathed the toxic mix that was the atmosphere around Ground Zero. I went back in the archives to see what I had written following that terrible day and found that my columns of 9/18, 9/25 and 10/2/2001 (especially the first and last of these) captured my feelings and the prevailing mood pretty well. (If you’re interested, click on “Archives” at the end of this column.)
This seems like a good time to talk about saving lives. After retiring from Bell Labs in 1989, I joined a battery group in the Bioengineering Division of the Surgery Department at UMDNJ Robert Wood Johnson Medical School. There, I wrote a proposal to NIH (National Institutes of Health) to work on a lithium battery for use in a ventricular assist device (VAD), an implantable device that assists a weakened heart. The proposal was approved but not funded. Naturally, I was interested to read last week that the FDA had approved an artificial heart powered by lithium batteries. An article by Angela Stewart in our September 7 Star-Ledger headlined “A self-contained heart comes to Jersey” reported the FDA’s action and the selection of Robert Wood Johnson Hospital in New Brunswick as one of two hospitals in New Jersey to implant this mechanical heart, known as the AbioCor.
Those of you old enough will remember the excitement back in 1982 when Barney Clark, a 61-year-old dentist, received an implanted artificial heart known as the Jarvik-7. (Younger readers may only know Robert Jarvik, the inventor of Jarvik-7, for his current TV commercials for a cholesterol-lowering drug!) Clark lived 112 days with the Jarvik heart and suffered a number of strokes caused by blood clots. Because the heart was air- driven, it relied upon a large compressor about the size of a washing machine. Clark was tied to that machine and had very limited mobility. His experience and quality of life did not bode well for the future of artificial hearts.
However, research and development continued and the AbioCor appears to be the most promising device to date. In a clinical trial of 14 patients, the longest-lived patient with the implanted AbioCor lived for 17 months while another lived for 10 months, according to the Star-Ledger article. I couldn’t find detailed results of the clinical trial but did find additional information on the AbioCor on the Web site of Abiomed, its manufacturer.
The AbioCor artificial heart is the thoracic unit, the replacement for the heart containing valves and a motor-driven pump. This artificial heart weighs only about two pounds but is still on the large side, suitable only for men and too large to fit some smaller men. Abiomed is working to reduce the size so as to fit men and women. The thoracic unit does not stand alone. A rechargeable lithium battery and a controller unit are implanted in the abdomen with connections to the thoracic unit, to each other and to a third component implanted in the chest. This is the TET (transcutaneous energy transmission) device, essentially a coil for the transmission of energy from a source outside the body.
By placing an external TET (another coil connected to a power supply) on the chest over the internal TET, electrical energy is transmitted through the skin to the internal TET. This powers the controller, the artificial heart and/or charges the internal lithium battery. No wires pass through the skin, eliminating a potential source of infection. In addition to the external TET, the patient carries or wears a lithium battery pack and a control module. A console supplies the energy to charge the batteries.
Let’s look at the mobility issue, a key to an acceptable quality of life. If you want to take a shower or engage in another activity unencumbered by the external gear, you have about a half hour, running on the internal lithium battery. The internal battery normally is on a continuous charge and should be capable of delivering full capacity. Even so, being a battery person, I would not want to push the outer limits of that half hour! Wearing the external battery pack, you can manage about 4 hours before needing to hook up with your console. It’s clear that a patient must always be aware of the time and plan activities carefully in case of unanticipated problems - traffic jams, for example.
Not everyone is eligible for an AbioCor implant. Currently, you must have end stage heart failure with a life expectancy of less than 30 days; you also must be ineligible for a human heart transplant and have no other treatment options. If you qualify, you’re clearly at death’s door and the restricted life you’d lead with an artificial heart would still seem a desirable alternative! Certainly the AbioCor patient will have a much greater degree of freedom and mobility than poor Barney Clark. There’s another factor that could determine one’s eligibility for an AbioCor – cost. The Ledger article estimates the cost at about $250,000 and insurance coverage is currently uncertain.
I feel obligated to finish in a lighter vein. In a recent Week in Review column, Brian Trumbore kindly mentioned an amazing (for me) round of golf a couple of weeks ago in which I made par on all four par 3s and one par4. I’ve never had par on all the par 3s on any course and five pars in a round is a record for me. Last Friday I returned to normal on the same course, with only one par and a score 10 strokes higher. However, it was an interesting round, relating in a sense to a TV show premiering this week called Six Degrees, apparently based on that old bit about anyone being related in some fashion to anyone else by six degrees of separation.
I was teamed up with a psychiatrist and an attractive young blond woman. The poor psychiatrist missed three or four complete holes due to calls from patients on his cell phone even though it was his day off! The blond gal had an accent and I determined she was Swedish. She hit the longest drives of any woman I’ve ever played with. Regular readers will know that I shamelessly take any occasion to mention my hole-in-one and breaking my leg on the same hole. Naturally, I mentioned it to my playing companions. The gal said her husband had a hole-in-one on the very same hole, which I thought quite a coincidence.
Then, after witnessing her amazing drives for 17 holes, I jokingly asked her if her maiden name was Sorenstam. No, but her best friend and frequent golfing buddy was on a national junior team in Sweden with Anika! The friend came to the U.S. on a golf scholarship and dispenses many golfing tips when the two play together. I now feel there are only three (or is it two?) degrees of separation between me and Anika and, having observed the blond lady’s swing very carefully, expect my golf game to improve significantly.
Allen F. Bortrum
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