All of the planned means of tackling Stellan’s SVT today during his ablation failed initially. Heart block was induced each and every time from each and every angle they tried to ablate. Dr. A and his team were left with little choice but to ablate Stellan’s AV node in order to get rid of his accessory pathway. But before they did, one of Dr. A’s colleagues threw out a wild idea.

“Let’s try to go through his aorta.”

Not in the plan. Not even in the possible or hypothetical plans. Not considered safe or feasible or wise on a 10 kilo baby. But with few options left before destroying Stellan’s node, they decided to risk it.

To be honest, I’m glad I didn’t know about it at the time.

So from his groin, they threaded the catheter up into his aorta, down into his atrium and through his valve toward his ventricle. From that angle, even though Dr. A said they were in the exact same spot as they’d tried ablating earlier, there was a money shot. He tried cryoablation. It started to zap his SVT with no heart block. So he tried a little more cryo. Again, no heart block.

So Dr. A pulled out the big dog. The radio frequency ablation catheter. His ultimate goal was to get 2 to 3 seconds of ablating done, even if it destroyed his node.

1 second. 2 seconds. 3, 4, 5.

From that angle, through the aorta, Stellan’s AV node remained untouched.

Unbelievably, Dr. A was able to crank up the wattage and ablate Stellan’s extra pathway for one solid minute before declaring his pathway dead on arrival.

And his AV node is as happy as the day is long.

Dr.Wes aptly notes that this sort of thing does not meet with the idealized always-follow-the-guidelines-or-else strategy being espoused by Washington of late. On the one hand, I’m all for evidence-based medicine and adhering to known best practices. On the other, this is a clear example of the variability that occurs from patient to patient, and the importance of experience and skill on the part of physicians enabling them to know when to bend or break the guidelines. Bravo.

The article is entitled Models of cardiac cell [sic].

Kudos to Drs. Fenton and Cherry for the excellent article, it looks like it was quite a lot of work to put together!

This is from a post by Dr.Wes. A friend of one of the device nurses got the tattoo to go with her ICD. “No jumpstart needed” per the shirts that inspired the design.

It’s currently non-trivial to show movies in papers, so instead we do time-lapse type things called activation maps. These show the activation times as a series of lines (‘isochrones’ or ‘isochronal lines’, meaning that all of the points on the line are activated at the same time) or bands of color representing the same thing. We can extend this to also show repolarization times, or non-sequential data such as action potential duration maps and dominant frequency maps.

Here’s a sample activation map of a wave moving across a sheet from right to left:

Activation Map Right to Left

And here’s one of a spiral (this with 20ms isochrones):

Activation Map of a Spiral Wave

To give you an idea of the correspondence between an activation map and a movie of the simulation, here’s a movie of that spiral:
Spiral Wave

There’s a lot more to this — for instance, deciding when a cell has activated or repolarized, and back-end processing. We use a program I wrote that does the analysis in parallel, making it rather quick to analyze even huge datasets, provided you have the computing power.

If you have any questions about the process I’d be happy to answer them here or on the CardioSolv post.

Running cardiac electrophysiology (and mechanics) simulations has traditionally been really complicated. It involved learning a bunch of UNIX command-line tricks, dealing with queuing systems and their associated script files, and so on. Furthermore, there are many, many options in a sophisticated cardiac simulator, and the novice user (and even the expert) can easily get lost in all of the choices.

We’ve taken years of experience setting up, running, and analyzing simulations to build a really cool (excuse my excitement) web interface that handles all of the dirty work, and guides the user through the important choices when running simulations.

The video below is my first demo. In it, I demonstrate how to create a plane wave moving across a sheet of tissue, then create a spiral wave, all from the web interface.

Note: If you’d like to view the high-definition version, I suggest you either click through to YouTube or expand the video to full-screen mode.

The post about it on the company blog is here, with contact info and all of that.

The HPC service lets the small, five-employee company do the heavy lifting that would otherwise cost a fortune. “With what we could purchase out of pocket, we’d have to bootstrap very slowly, or look for VC [venture capital] funding,” said Dr. Brock Tice, the vice president of operations at Cardiosolv, a privately funded medical research firm. Instead, Tice uses a new HPC on-demand service from Penguin Computing called Penguin on Demand.

…

While Cardiosolv has its own small cluster on the premises for calculations, Tice estimates the resources he rents from Penguin would probably cost $500,000 to build, and other cloud options weren’t suitable.

“We can’t use [Amazon's Elastic Compute Cloud] EC2, since there’s a lot of latency between the nodes,” he said.

Brock Tice is one of those scientists. As vp of operations at the Baltimore, Maryland-based CardioSolv, he works to model, yes, the heart – simulating its mechanical and electrical activity. And though he can run some simulations on Amazon’s cloud – or on individual local machines – more complex models require HPC. “We’re [sic] tried on Amazon and it just doesn’t scale,” he tells The Reg. “We can run on single EC2 instances, but if we need to scale up to a dog or human heart, it’s just impossible.

“The connections between Amazon’s machines are Gigabit Ethernet and they’re shared. If you fire up 10 machines and you want to run them like a cluster, some might be in the same rack, and others might be halfway across the data center, five or six switches away.”

You can find the full story here.

One thing that is asked a lot of people graduating from anything is what they plan to do next. I have been waiting for some time to be able to answer that question, and now I can.

The lab of which I have been a member since late fall of 2002, the Trayanova lab is one of (if not the) the leading groups in the world when it comes to cardiac electrophysiology and mechanics research. I would guess that the lab as a whole has probably run an order of magnitude more simulations, at a minimum, than the next closest group. A lot of my time and effort as a graduate student went into improvement of the tools used for generating and running models, and I have nearly seven years of experience setting up, running, and analyzing simulations.

The lab does very interesting things, and cutting-edge research. Almost every new study is accompanied by tool and methodological development. However, there are a lot of practical applications that are never explored by the lab, because they don’t necessarily constitute scientific discovery of the kind valued in academia.

It takes a long time to train people to use simulation software developed in an academic research environment. It is extremely powerful, and has far more options available than any one user will ever use. This is acceptable for graduate students that will be spending years in the lab, and will often be digging in the guts of the code and adding their own features. It’s not acceptable for, say, industrial or academic wet-lab researchers that just want to run some simulations and figure something out.

That’s where CardioSolv comes in. CardioSolv, LLC, is a new cardiac simulation and services company. Its aim is to commercialize cardiac simulation, and make it easy for new users to rapidly produce scientifically valid and useful results. To that end, we are building a web interface that will by default handle most of the difficult choices for users, while still allowing them to specify detailed parameters if necessary.

My role in this company is Vice President of Operations. I’ll be managing the day-to-day operations of the company, interacting with customers, and guiding product development. My hope is that we can bring our technology and our discoveries out of academia, and into the drug and device development markets, with the ultimate goal of improving patients’ safety and quality of life.

Brock M. Tice

“Insights from accurate modeling of structural and functional
heterogeneities in cardiac tissue”

Wednesday August 5th, 2009
Talbot Library, Traylor 709
(JHU SoM Campus)
10:00-13:00

Thesis Committee Members:
Dr. Natalia Trayanova, Dr. Leslie Tung, Dr. Roselle Abraham, Dr. Joseph
Greenstein, Dr. Eric Young, Dr. Brian O’Rourke (alternate)

Almost there!

Very interesting stuff from Dr.Wes as usual!