Mending Brian Vickers’ Broken Heart

 Brian Vickers, Medicine, News  2 Responses »
Aug 222010
 

Having stepped out of his ride due to the discovery of blood clots – very unusual for an otherwise healthy 26-year old – Brian Vickers’ future in racing has been a big question mark.  Brian is one of the smartest (and kindest) drivers I’ve met.  He is one of the few drivers that could have his choice of a wide range of careers if racing were on the list of permanently prohibited activities.  Luckily, as we found out Saturday, it’s not.

The heart is a pump that circulates blood throughout the body.  The adult heart has four chambers:  two atria and two ventricles.   Ventricles send oxygenated blood through the arteries to muscles and organs.  The right ventricle discharges into the lungs, where the blood picks up oxygen molecules.  The left ventricle discharges its blood toward the rest of the body via the aorta.  Veins carry the de-oxygenated blood back to the atria (plural of atrium).  The picture is from wikipedia.

That’s the adult heart – you don’t start out with four chambers:  you start out with one ventricle and one atrium. The septum primum starts growing downward, which divides the single atrium into a left and right side, as I’ve tried to show schematically below .  (The word “septum” almost always denotes a flexible division, whether it is chambers of a heart or between a vial and air.  The cartilage that separates your nostrils is a nasal septum.)  The septum primum (literally “first septum”) that divides your atrium isn’t entirely continuous – there is a hole in this septum.

Somewhere around the third to fourth week of gestation, a second septum (the septum secundum) grows on the right side of the first septum.  This second septum, which is parallel to the first one, covers most of the original opening, but not all of it.  This opening, called the foramen ovale, is not a hole – a hole would allow blood to flow in either direction.  The foramen ovale is a one-way flap that allows blood to flow only from the right atrium to the left and not vice-versa.  In the womb, a baby gets oxygenated blood via the placenta through the umbilical cord.  Blood doesn’t need to make the trip to the lungs to gather up oxygen because the baby isn’t breathing air.  Bypassing the lungs isn’t a big deal for a baby in utero.

In 75% of the population, this one-way path closes within three months after birth.  The blood pressure in the left atrium becomes greater than that in the right, pressing the foramen ovale against the septum, which allows the tissue to grow together and seal the flap.  In about a quarter of people, the flap doesn’t seal over the hole completely, which is called a PFO – a patent foramen ovale.  The PFO is a shunt, which means a shortcut, in this case between the right and left atrium.  In most cases, the hole is a few millimeters in diameter – large enough to present a problem because it allows blood shortcut the circulatory system.

The symptoms of PFO are: well, none.  You’re unlikely to know if you have a PFO unless something dramatic happens, like extreme pain in your extremities, or (the worst case situation) a stroke.  The first medical report of undiagnosed PFO related to stroke was in 1877.  A young woman had an embolic stroke – blockage of an artery, usually by a blood clot, but blockages can also be caused by air bubbles, cancer cells, clumps of bacteria from an infection or even fat.  Brian noted that they found a blood clot in his left pinkie (I think it was his pinkie – I was driving and not taking notes.), which was an indication that there was someplace in his circulatory system that was allowing blood (and clots) to go where it shouldn’t.

As Brian mentioned during his press conference, diagnosing PFO (or any other kind of heart defect) requires invasive procedures, such as transesophageal echocardiography – an ultrasound device is threaded through the mouth, down the esophegous to allow better images of the heart that you could get from outside the body.  Other means of diagnosis include threading an ultrasound probe into the heart, or heart catheterization.  Although many people successfully undergo these diagnostic processes, there is an inherent risk anytime you start poking around the inside someone’s body.  Once a PFO is found in an otherwise healthy person, most doctors advise having the hole fixed.

It used to be that open-heart surgery was the only way to fix these types of heart problems – I think Brian telling us he was doing 30-60 miles of cycling in Denver within a month after the surgery is pretty strong evidence he didn’t go that way.  I have no inside knowledge as to the particular type of repair Brian had, but the most likely surgery would be catheter introduction of a device that seals the hole.

How do you fix a hole in the heart?  It’s actually a little like fixing a hole in drywall.  Most of the devices for fixing holes in adult hearts deploy through catheters (thin tubes that can be fished through your arteries and veins much like wire is fished through a wall when you’re wiring a stereo system).  Sorry for all the home repair analogies.  I spent a lot of time at Lowe’s this week.   The catheter is inserted into a vein in the groin and slowly threaded up to the heart.

Although there are a number of different types of devices, most work on the same principle – two discs designed to sit on either side of the hole.  The devices are usually made of Nitinol (an alloy of nickel and titanium) which forms a mesh frame onto which fabric is adhered.  Nitinol is popularly called ‘memory wire’.  You can form a material into a shape at high temperature, for example.  Let’s say we make a disk from a hot piece of nitinol.  Then we cool it down and deform it like an umbrella.  That allows us to stuff the device into the catheter (which is really just a tube).  (Here’s a YouTube video showing the effect with a spring shape.)

When the catheter reaches where it needs to be, it can be heated (by thermal conduction or current) and  recovers its original, disk-like shape.  An alternative method is simply to coil the device up inside the catheter and push it out once it reaches the target area.  One disk is inserted on either side of the hole and the two patches are pulled together.  The implant provides a scaffold for heart tissue to grow and cover the hole.  The tissue might not be able to span the hole by itself, but the implant gives it a path to do so.

Nitinol not only has a good memory, it is also biocompatible – the body doesn’t mind having it in there.  Some new eyeglass frames are made from nitinol – if you step on them (as long as you don’t actually break them) they can be heated and spring right back into shape.  We haven’t finished working on the self-healing materials problem.  Nitinol got its name from the elements from which it is made and the place it was discovered:   Nickel Titanium Naval Ordnance Laboratory.

A typical type of implant — and again, I do not know what Brian and his doctors chose -  is GORE HELEX – the nitinol is spiral shaped and uncoils when pushed from the tube, as shown in the picture at left.  The wispy white stuff is a polyer fabric.  The green tube in the picture is the catheter – you can see how small the device has to be to get in there and then how large it can expand.  There is a tether between the two disks that can be tightened to place the device so that it is entirely covering the hole on either side, and then locked in place.  I don’t know whether the shape-memory properties of Nitinol are being used here, or whether the superelasticity properties are the important thing.  I’m thinking it is the latter.  The primary competition is the Amplatzer septal occluder.  These are relatively new devices, earning FDA approval in 2001 and 2006.  Both have outstanding success rates in fixing holes in the heart.

Such a device shouldn’t set off metal detectors in the airport and, yes, you can have MRIs done after having such a device implanted.  The danger of the MRI is that metal heats up in the radio-frequency field of the MRI.  Also, MRI magnet strength is increasing – higher fields means better resolution – and there is always some concern that very high magnetic fields might cause a device to migrate.  The device could also blur MRI images in the region.  When you have such a device implanted, they give you a card with all these notices on it that you need to have and present anytime you get tests done.

The other issue Brian was facing is May-Thurner syndrome, which is when the left common iliac vein (which runs from the left leg to the large vein in the abdomen that leads to the heart) is compressed by the right common iliac artery.  The right common iliac artery runs to the right leg and normally travels over the left common iliac vein.  May-Thurner syndrome significantly increases the risk of deep vein thrombosis, which is forming blood clots in veins deep inside the body as opposed to surface veins.

Three primary components contribute to blot clot formation, a triad that is called “Virchow’s triad” after the German physician Rudolf Virchow, even though Virchow did not propose these elements, nor was he the one to suggest that there were three primary components for blood clot formation.  Those three components (in medical-ese and regular English) are:

  • Hypercoagulability (the blood likes to form clots more than it should);
  • Hemodynamic changes (the motion of the blood changes:  it slows down, lingers too long in one area, or becomes more turbulent); and
  • Endothelial injury/dysfunction (the blood vessels are damaged in some way)

The first factor is the reason why people with blood clots are put on Coumadin, Plavix or other blood thinners/anticoagulents.  These medications decrease the ability of the blot to clot.

The second and third factors are affected by May-Thurner syndrome affects:  If the blood slows down, or has to move around an obstruction, clots are more likely.  The iliac artery crosses over the iliac vein:  In May-Thurner syndrome, the artery actually presses the vein against the spine, squishing the vein and preventing blood flow, as shown in the picture.

Your arteries and veins normally are pretty strong; however, your blood pulses with your heart contractions, so if the artery is too close, it doesn’t just rest on the vein, it actually rubs against the vein and causes the vein to rub against the spine.  All this rubbing can damage the vein, leading to compression and blood pooling.  Symptoms can include swelling and pain in the left-side extremities.

The solution to this problem is the same one you would use if you had an artery or vein that had collapsed due to other types of injury: a  stent.  A stent is a hollow tube, also often made of nitinol mesh, that is collapsed to fit in a catheter, then inserted into an artery or vein to help keep it open and allow blood flow.  A balloon is usually inserted through the target site (again using a catheter) to ensure that the area is clear before the stent is inserted.  (They use a balloon to measure how large the hole in the heart is, too.)   Stents can be impregnated with drugs to aid in healing the artery or vein, or even to discourage clots.

The prognosis for both these conditions is excellent, although frequent checks with the doctors are necessary to make sure that nothing unexpected happens.  Both conditions really needed to be addressed to minimize the likelihood of something happening in the future.  Although these types of surgery are inherently risky, the probability of success in a healthy young person is very high.

The main reason keeping Brian out of the car for the remainder of this season is the need to be on blood thinners:  blood thinners decrease the ability of the blood to clot, so what would normally be a minor injury could be major due to loss of blood.  A six-month course of blood thinners is recommended – the surgery was July 12th, so that puts mid-January as a perfectly reasonable time to return.

Here’s looking forward to seeing Brian back in the 83 at Daytona next year.

 Posted by diandra at 2:42 pm

A New Trackside Sign: Speech Limits

 NASCAR, News, Rules  6 Responses »
Jul 292010
 

The important stuff first:  Best wishes to Jack Roush (one of my personal heroes) for a speedy recovery from his accident, to Marcus Ambrose for finding a ride for next year, and condolences to the fans in St. Louis who won’t have the opportunity to see Nationwide or Truck racing in 2011.

Jenna Freyer of the AP reported that some NASCAR drivers have been fined recently for negative comments about the sport.  She wrote:

“The Associated Press has learned that NASCAR warned teams during the offseason that public criticism of the sport would no longer be tolerated, and at least two star drivers have been fined — one as much as $50,000 — for comments that were deemed destructive to the industry.”

When I first started in academia, I firmly denied the idea that we live in an ivory tower. Getting out of academia and working with companies and sanctioning bodies has been a real eye-opener for me. As a scientist, I have the right to make any assertion I want — as long as I can back it up with data. The whole point of scholarship is pursuit of the Truth (which we share with the field of capital-J Journalism). One of the most disappointing things I’ve learned as a result of my time with the ‘real world’ is that there are entirely to many people who believe they can dictate what people think by telling them what to say and do. In science, the determining factor is not who you are, but the veracity of what you say. I have the right – in fact, the responsibility – to correct something that is incorrect. It doesn’t matter if the speaker is a graduate student or a Nobel Prize winner.

Of course, when you start getting into the world of opinion (and yes, there is plenty of opinion in science because there are many things we still don’t know), the rules become fuzzier. We all know scientists who are so in love with their own theories that they are not as objective about their work as they should be. We have, unfortunately, had a number of recent cases of scientific misconduct, in which data were fabricated or even cherry-picked to make them look more convincing than they really were. When those cases are uncovered, the punishment is very clear – you lose the right to be a scientist at a reputable institution.  The funding agencies can go through due process and deny you the ability to compete for grants to support your research.  Papers in which incorrect data are  published must be retracted.  But unless I have evidence that someone has knowingly done something malicious, my accusing them of misconduct is libel, not opinion.

Imagine you are one of the people in the NASCAR hierarchy who makes decisions about debris cautions or determines whether a car meets NASCAR’s somewhat fuzzy technical specifications.  How would you feel if one of the drivers got up and told the world that he lost the race because the officials called a fake debris caution to make the race more exciting?  That’s not “destructive to the industry”, that’s making a value judgment of the integrity of the official and the officiating body.  I agree with NASCAR that they should have every right to discipline people they license to participate in the sport if those people make unfounded statements that question the integrity of the sport.

Ramsey Poston refused to get into specifics, saying only:

“It is the sanctioning body’s obligation on behalf of the industry and our fans to protect the sport’s brand.  Any action taken by NASCAR has nothing to do with the drivers expressing an opinion — it’s focused on actions or comments that materially damage the sport.”

That’s come across in very different ways in different stories, which range from “NASCAR fines drivers for making disparaging comments about the sport” to tweets that “NASCAR muzzles drivers”.  Drivers (crew chiefs, owners, mechanics and anyone else) should have the right to state substantiated opinions.  Denny Hamlin ought to be mad about losing a race due to a late-race debris caution, and he ought to be able to state facts. If no one on his team saw any debris, that’s a perfectly fair thing to say.  He can do that without suggesting that there is a conspiracy.  NASCAR, for their part, ought to be able to point out the debris when they call a caution and everyone involved in racing ought to understand that sometimes you can’t tell whether the unidentified debris is metal or rubber, and that it is better to call a caution than to find out what the thing in the middle of the best driving line is made of by having someone run over it at 200 mph.  The NASCAR media got on the TV broadcasters last year about not showing caution-causing debris.  The broadcasters responded by trying to make sure they showed the debris and, in at least one case, wondering out loud where the debris was because they couldn’t find it.

Tony Stewart lit into Goodyear for a bad tire choice at the first Atlanta race in 2008.  He wasn’t the only driver upset about tire problems – Jeff Gordon and Ryan Newman (among others) said similar things, although in more reasonable and measured ways.  Goodyear invited Stewart to visit their tire operation and explained the process of specifying and making tires to him and he appeared chastened.  He still felt it was a bad tire, but he was a little more constructive with his criticism.  The simple act of Goodyear taking the time to explain how they work and how they are really doing the best they can raised my opinion of them.  Stewart’s admission that he overreacted raised my opinion of him, as well.  Sometimes, you’re just wrong and the best way to deal with it is to admit that you were wrong.

@jim_utter asked whether anyone could show him one instance in which fans didn’t go to the track because of something someone said. (Bonus points to @spencerlueders, who replied “The weatherman”  Spencer is, if I remember right, a science-loving motorsports lawyer who sent me a neat email when I did Charlotte Talks.)

I think most fans have the same reaction I do when I hear a whiny driver making no sense:  “What a schmuck.”  It has absolutely no impact on my attending or watching race.  Far more important are ticket prices, where and when races are located, whether I have a job, and how my favorite drivers are doing.   NASCAR’s taken the other road and refuses to talk about it, which has only stretched out the discussion because people wonder who was fined and what exactly they said.  If NASCAR is (as I suspect) in the right (in this case) and it’s analogous to fining a pitcher for making remarks about the integrity of the umpire, they would have done themselves so much more credit by being open about it.  If they want to “protect the brand” by trying to make sure no one says anything negative about it — even when true and justified — then that’s a strong reason for me to stop watching.

Is there any reason why NASCAR can’t collect the debris that causes cautions and put it on display, like they do the shock absorbers they select for dismantling?  Yes, this could result in embarrassment because sometimes a caution is called and it turns out to be a hamburger wrapper or a piece of foam – but honestly, if you can’t appreciate the importance of being very careful when you’re talking about people’s lives, you really shouldn’t call yourself a racing fan anyway.

My friend The Rocket Scientist likes to engage me in the occasional debate of whether NASCAR is a sport.  (It’s a boring debate that doesn’t really interest me, but I sometimes play along just because it gets fun.  Like the time someone suggested that a sport was anything people paid to watch.  TRS noted that this would technically make stripping a sport.)  It’s become a running game with a group of friends:  what makes a sport a “real” sport?  During the World Cup, another friend, Owl, suggested that a true sport doesn’t allot points for style.

I’ve got a new one to run by them: A true sport doesn’t have secret rules.

 Posted by diandra at 10:46 am

Eight Issues NASCAR Needs to Address in 2010

 Aerodynamics, Greenness, journalism, News, Non-Dairy Coffee Creamer, The Chase, Tires  No Responses »
Jan 042010
 

Because NASCAR likes nothing better than unsolicited suggestions, right?

If I could change just one thing about NASCAR during the off season, it would be banning people from calling into Sirius radio talk shows and suggesting versions of The Chase that rival the BCS and string theory for complexity. If you want to know what NASCAR might ever consider changing, check out the patent NASCAR holds on The Chase (patent number 7,207,568 entitled “Method of Conducting a Racing Series”).

I’m especially tired of whining about The Chase format when there are much more significant things to be addressed. Let’s talk about the state of motorsports journalism, for example. A number of excellent newspaper sports writers have been laid off in the last two years. Newspapers can’t afford to have dedicated motorsports coverage, you say? Apparently neither can NASCAR Scene, which laid off a significant fraction of their writing and editorial staff just today. My sympathies are with the folks who lost their jobs today. Some have been with the magazine literally their entire careers and some very recently moved from good situations to take what they thought was the ‘job of a lifetime’. I guess NASCAR fans are going to have to start getting the majority of their news from the NASCAR Citizen Journalists Media Corps.

All aspects of racing are facing the prospect of change, including the concept of racing itself. At the World Motorsport Symposium in England last November, people from all varieties of racing talked with great concern about the economic situation and how racing fits into the 21st Century. People repeatedly mentioned one phrase: ‘the need for racing to be relevant‘.

Old-time fans can scoff that racing ought to be loud and smelly and it’s just a bunch of Prius-driving tree huggers that are causing all the problems, but the fact of the matter is that the world is changing. Race tracks in Europe are facing closure due to noise issues and emissions issues. Either racing changes or natural selection does the same number on racing it did on the dodo bird.

Between highly customizable entertainment coming at us from all directions, the glaccially slow economic recovery, people’s microsecond-long attention spans, animated gophers, and the fact that we must deal with increasing global tempertures, racing is a very obvious (although not justifiable) target. Racing series need to think about long-term planning. Not just what they’ll do next year, but what they’ll do in the next five years. Racing has an unfortunate history of being reactive. It’s time to get proactive. Now.

I normally struggle with my own New Year’s resolutions, so I thought maybe this year I’d just make resolutions for other people and see if they do any better. My suggestions, of course, focus on science. I do have a suggestion for changing The Chase, but it requires non-linear differential equations, non-dairy coffee creamer and quantum field theory, so I’m keeping it to myself. I’ve tried to order my suggestions, but take each of the heading numbers with about a plus or minus 2. Starting from least to most important (insert drumroll here):

8. Take Pit Road speeding penalties out of the race.

7. Get serious about diversity or stop talking about it.

6. Get serious about being ‘green’.

5. Rethink ‘parity’.

4. Beef up the ‘research and development’ part of the NASCAR Research & Development Center and establish formal mechanisms for involving the teams.

3. Stop being fuelish.

2. Give the New Car the tires it deserves

1. Fix the aero problems with the New Car.

I’ll be blogging about each one of these issues in the coming weeks.

Incidentally, I’m going to be double posting for a few weeks while I consolidate the buildingspeed.org and stockcarscience.com websites. Believe it or not, some of my sports car racing friends took umbrage at being talked aboout on a ‘stock car’ site! Plus, keeping up with the two different sites was stretching me just a little too thin, since I’m now also blogging about everything from Christmas tree lights to climate change at Cocktail Party Physics.

 Posted by diandra at 10:53 pm  Tagged with:
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