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Noninvasive Radiation Therapy Halts Deadly Heart Rhythm (nytimes.com)
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.
"A spot-radiation treatment is a much more costly and risky procedure than a (remaining) lifetime of beta blockers? Probably."
It is more costly initially because there are so few Centers offering it. This is not your Daddy's Radiotherapy, done with Electron Linacs delivering X-Rays, or 60Co Sources delivering Gammas. Unfortunately the Delivery System is barely mentioned; they just say "Radiation" and mention a dose of 25Gy. But the pinpoint precision mentioned and the lack of damage to surrounding tissue implies Bragg Peak Radiotherapy using Ions. (Typically Protons, but Alphas and Heavy Ions have been used as well.)
BPR is quick, not surgically invasive, and utterly painless. First developed at the 184" Cyclotron decades back, BPR depends on an obscure property of Accelerated Ions; they give up most of their Energy at the end of their paths in Matter. So Ions can go through tissue, slow down a bit, and BANG! right where they are needed, at the Bragg Peak. Stereotactic Body Radiation Therapy uses Real-Time Imaging and multiple Ports to zap just the Lesions or Tumors on such things as a beating Heart, or an AVM in the Brain.
I am not up on the recent advances here; when I was involved in Beam Delivery years back, our Subjects were already Terminal. To put it bluntly, they were Guinea Pigs. (I frankly couldn't take the pressure, and went back into Spectroscopy instead.)
Scale this up, and may almost be an Assembly Line affair, somewhat like LASIK is now.
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.
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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 the vault, and people with metal implants were not allowed to volunteer. On top of all of that shielding, they still had to cancel testing any day there was a thunderstorm within a couple hundred miles because it produced too much noise. Makes me wonder how common that problem is, e.g. do SQUID based MRI setups that use the Earth's magnetic field instead of a large DC magnet (still has some light weight excitation coils) have the same problem?
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.
I did a six week rotation at Barnes-Jewish (where Wash U does their RadOnc treatments) for my Radiation Therapy degree last December / January and witnessed one of these being done on an Edge machine. It's the most refined version of Varian's linear accelerators that they commonly use for Radiosurgery. It's on-board CT is really high resolution and nice gating capabilities (ability to turn it on only when the target area is in the right position) to allow for pretty precise delivery. I believe an additional EKG component was added to the CT based gating to ensure the radiation delivery was timed with the heart beat. Alternately, they have a ViewRay in the RadOnc department which has real-time MRI capabilities which should be able to do similar guidance.
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...