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Medicine Science

Noninvasive Radiation Therapy Halts Deadly Heart Rhythm (nytimes.com) 28

schwit1 shares a report from The New York Times (Warning: source may be paywalled; alternative source): The patients were gravely ill, their hearts scarred by infections or heart attacks. In each, the electrical system that maintains a regular heartbeat had been short-circuited. They suffered frequent bursts of rapid heartbeats, which can end in sudden death. The condition kills an estimated 325,000 Americans each year, the most common cause of death in this country. And these people had exhausted all conventional treatments. So researchers at Washington University in St. Louis offered the patients something experimental: short bursts of radiation aimed at their hearts in an effort to obliterate the cells that were causing the electrical malfunctions. Results in the first five patients were published on Thursday in the New England Journal of Medicine, and the experiment seems to have worked -- offering hope to similar patients everywhere who have had no alternatives except a heart transplant. The treatment requires weeks to take full effect, so it cannot be used for cardiac patients who need immediate help. And the method must be studied in larger groups of patients over longer times, an effort that has already begun.
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Noninvasive Radiation Therapy Halts Deadly Heart Rhythm

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  • by Anonymous Coward

    I work for a medical device company and make 3D electro-anatomical maps for electrophysiologists. I'm really curious how you can map a heart without actually touching the endocardium.

    • by Anonymous Coward

      You may use magnetocardiography, measuring the magnetic field distribution of the heart with an array of SQUID magnetometers. The magnetic field distribution can be used to identify abnormal current pathways in the heart muscle if the measurement is done during an arrhythmia event. The technique is noninvasive.

      • Re: (Score:2, Informative)

        by Anonymous Coward

        A lab down the hall from where I used to work used SQUIDs for some mapping of nerves in organs. It was pretty cool work and reasonably detailed (I don't remember quantitatively what the resolution was). But the SQUIDs are super sensitive. They had a Faraday cage much sturdier than what I've seen used near high power pulsed experiments, and on top of that was a bunch of mu metal shielding to block lower frequency noises. Test subjects had to remove any metal jewelry, no metal instruments were used inside

    • by Ungrounded Lightning ( 62228 ) on Thursday December 14, 2017 @11:53PM (#55743605) Journal

      I'm really curious how you can map a heart without actually touching the endocardium.

      Just off the top of my head:

      There are a number of non-invasive imaging technologies that can be "strobed" in synchronization with the heart's motion to produce a series of 3-D images which, together, amount to a moving picture of the cyclic activity, complete with various annotation (such as blood velocity maps, electro-chemical activity, etc.).

      One stock device for cardiologists is synthetic-aperture doppler ultrasound sonar imaging. A wide hand-held probe, with the junction to the skin joined by a slimy jelly with about the same speed-of-sound as soft tissue, connected to a high-end laptop running appropriate software, can construct such mappings in real-time, in sessions lasting minutes, annotated with blood flow information.

      Other possibilities include magnetic resonance imaging (the functional version if you want to visualize the cyclic electrochemical activity) and computer aided tomography scanning.

      And that's just for starters.

      • One stock device for cardiologists is synthetic-aperture doppler ultrasound sonar imaging

        Alias "echocardiogram". I get a couple of these per year just for screening:
        - One resting.
        - A couple more as a "stress echo" - one just before and one just after a session on a treadmill (or an injection of a drug if my leg joints are acting up) to pump up the heart rate and dilate the vessels.

        I also get (using the same or a similar system) occasional measurements of blood flow in various vessels, such

    • MRI these days is fast enough to take full images of a beating heart and resolves 3D as well (unlike echocardiogram)

    • Great question. The noninvasive mapping technology is called Electrocardiographic Imaging (ECGI). Patients wear a vest of electrodes (http://www.medtronic.com/us-en/healthcare-professionals/products/cardiac-rhythm/cardiac-mapping/cardioinsight-mapping-vest.html) and undergo a standard CT scan. With the vest on, we induced the life-threatening heart rhythm problem, quickly mapped it (in seconds), then rescued the patient. This mapping allowed us to see EXACTLY where the problem originated. For a living, I
  • by dgatwood ( 11270 ) on Friday December 15, 2017 @03:10AM (#55744055) Homepage Journal

    Unfortunately, the last sentence hints that this was a short-term study. I'm a little skeptical that a long-term study will be nearly as positive.

    Cardiac ablation techniques have been used for treating atrial fibrillation for many years now. The problem is that after a few years, the heart finds new ways to route those bad signals through itself, and the fibrillation comes right back. I kind of expect the same thing to happen with ablation for v-tach.

    • Re: (Score:2, Informative)

      by Anonymous Coward

      I believe your estimation of the futility of cardiac ablation is a decade out of date. Particularly those with paroxysmal afib the outcomes are much better than that.

      • by dgatwood ( 11270 )

        That's quite possible; the people I know who have had the procedure with only short-term success did have it a decade or so back. Then again, at any given point in time, you can look at it and say that it is working for the recent patients... until it no longer is... hence my cynical skepticism. :-)

    • by SBRT_CR ( 5193927 ) on Friday December 15, 2017 @04:58PM (#55748087)
      Excited to see the dialogue about this! Ventricular tachycardia is a very different beast than atrial fibrillation. Medication and catheter ablation for afib is quite effective in most patients. Afib is not life threatening for most. In contrast, VT is very life threatening, and most patients would die from their VT if they didn't have an implanted defibrillator. Likewise, medications and catheter ablation for VT is less effective. Furthermore, once someone becomes refractory to standard VT therapies, their chances of dying from the VT become substantial. Likewise, options for these sick patients are quite limited - heroic attempts at repeat ablation, heart transplant, or even hospice. We employed a unique combination of non-invasive mapping of the VT using a "vest" of electrodes which can 3-dimensional map the VT (ECGI) and combined it with a known non-invasive ablative therapy (SBRT) which I typically use to treat tumors. SBRT is precise, focused, and has been used in thousands of patients. SBRT to the diseased part of the heart causing the VT is what makes this special. You are appropriately skeptical about the long term benefit of such a treatment. Standard therapies fail more than 50% of the time. We aren't proposing that this would necessarily be superior to standard therapies, but certainly provides an alternative to those with no alternatives. With time, it might even become a viable option for more patients. We are carefully studying this now in a prospective trial after we saw these initially encouraging results. We must be diligent about monitoring for unexpected toxicities and results. Thank you for your comments, and for keeping us honest. https://clinicaltrials.gov/ct2... [clinicaltrials.gov]

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