More Stuff to Know Before You Have Your Operation: Venous Thromboembolism and the Grim Reaper

This article is about something called venous thromboembolism or VTE. To start with and to help you, the reader, better understand what I'm talking about and why it's important, let's start with a story that at first glance has nothing to do with surgery. All the major details of this story are true.

The daughter of a nice lady from Georgia and the daughter's boyfriend leave on a two-week trip to Australia. They have the most wonderful time and after exploring as many sights as they can possibly fit it, head home. Mom is planning to meet them at the airport with flowers. Two weeks is a nice, long time to go to Australia and anything less would be hurried because it's such a long flight.

Now as Mom is standing at the gate where passengers deplane, she sees a few EMTs with a stretcher rushing by. Ten minutes later, Mom sees the stretcher coming back out, but her daughter is now on it, with the boyfriend running close behind! As Mom's heart and mind race out of control, she has the foresight to ask what's going on.

All anyone knows is that the daughter started to get sick an hour or two before the plane landed; by the time it did, she had collapsed in her seat.

She is rushed to the hospital, where a massive blood clot blocking blood flow to her lungs is discovered and sadly, shockingly, she dies two days later.

PE or Pulmonary Embolus

The big blood clot is called a PE or a pulmonary embolus. It can be triggered when someone keeps their legs still for very long periods of time.

Blood in the big veins of the lower extremities is moved through these veins back to the heart in two ways. First, there is just the regular flow of blood through the veins from the pumping of the heart when your knees are locked. But the big veins are different from the arteries in the body: these veins have one-way valves that keep blood from flowing backward away from the heart.

When we activate our calf muscles, this "squeezes" the blood in the veins forward. Think of soldiers all lined up at attention for long periods with their knees locked (like in the "trouping of the colours" before the Queen in England). A few soldiers invariably faint since without the extra blood to the heart from squeezing, the brain doesn't quite get what it needs and the soldier faints.

At the same time, this squeezing from the contraction of the calf muscles pushes blood out of the corners of the valve or the valve "pockets." Getting blood out of these pockets is really crucial: if the blood stays in there for over a few hours, it starts to form tiny clots. And these tiny clots can then continue to grow and grow if there's no calf muscle contraction until they become plugs of solidified blood that may be a few centimeters to a few meters long. The medical term for one on these plugs is a venous thrombus. If part of the venous thrombus breaks off in the bloodstream, it is then referred to as a venous embolus. In general, doctors and scientists tend to call the whole process from tiny plug to thrombus to embolus VTE or venous thromboembolism.

Depending on your genetics, your age, the medicines you take and most importantly how long you stay inactive, the progression in your legs from tiny clot to thrombus to embolus may stop at any point and may resolve spontaneously and you might never even know you had it. But this becomes less and less likely as the VTE grows in size. A famous example in which long periods of inactivity caused many unexpected deaths from VTE was during the bombing of London in World War II with people stuck in cramped bomb shelters for long hours.

Quantas Airlines knows very well the real danger of inactivity and advises their passengers to exercise their legs every two hours. They even have a video about it (pay special attention to the parts on flexing your feet and legs):

Even video gamers who sit without ever moving their legs for hours and hours can sometimes suffer from VTE. In fact, VTE is such a big problem that the Surgeon General of the United States issued a "call to action" to make doctors more aware of the issue; you can actually buy the report on Amazon for $14.99. In the report, there's a story about the CBS news reporter David Bloom who died from a VTE while covering the war in Iraq at 39 years old and in great health. He'd been stuck in a cramped tank for long periods of time.

Laura Landro, the medical writer for the Wall Street Journal, wrote in a 2009 article:

Recovering from surgery on his bladder and prostate in a South Florida hospital, 65-year-old Jorge Blau was stable the day after the procedure as he sat in a chair chatting with family members. Suddenly he asked to get back in bed. There, he became short of breath, and he died moments later.

The title of Landro's article was "In the Hospital, Facing a Scourge of Killer Clots."

But many people also have a VTE and are fortunate enough not to die. But they are not out of the woods — not by a long shot. VTE can lead to chronic swelling of the leg, ulceration, pain, and disability. It does this by damaging the venous valves. By one measure the devastating effect of VTE is considered the second major cause of "disability adjusted life years." This basically means the reduction in the number of non-disabled years you live. Once you get a VTE, you may be unable to work or enjoy life as much. VTE complications cut straight to your long term quality of life!

If you don't die from VTE, you might end up with your leg looking like the photo below.

James Heilman, MD [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]

The Connection Between VTE and Surgery

Did you know that VTEs are the #1 cause of death in a hospital? 10% of all hospital deaths are from VTE — clearly the Grim Reaper's method of choice.

Grim Reaper by scheusal242 from Pixabay

Suppose you're in the hospital for major surgery like a hysterectomy. You are 70 times more likely to get a VTE than a similar individual who isn't having the surgery! You might wonder why surgery makes you more likely to have a VTE?

As doctors, we know a lot about the clots that cause heart attacks and strokes. These are often called "white clots" from their appearance. But up until recently we knew much less about the clots in the lower extremities caused by surgery and lack of movement during long plane rides or long periods of sitting still in cramped quarters. These VTEs are often called "red clots" because they look red when they are examined.

Fortunately, in the past 20–30 years there has been an explosion of our knowledge on what causes "red clots" and new treatments are being developed to treat them. What we know for sure is that the stress of surgery makes the blood vessel walls in the valve pockets where VTEs begin "stickier." And at the same time your body is usually paralyzed with an anesthetic drug to give the surgeon better operating conditions. So if your legs are paralyzed during your surgery (don't worry, you'll be asleep and won't know), the blood isn't flowing very much and definitely not being squeezed out of the valve pockets. That's why "squeezers (also called ICDs or intermittent compression devices)" are usually put on your legs before surgery. But try as doctors might, surgery — especially any kind of big surgery — still greatly increases VTE risk.

Now let's go back to my first blog post on surgery where I mentioned precision medicine in which you can hopefully get your whole genome tested when you visit your anesthesia provider in the PSH or perioperative surgical home model for surgery. It turns out that around one-third of all VTEs occur in people with abnormal genes. If you do get tested, you might find you have a blood condition called "Factor V Leiden," named after the city in the Netherlands where it was first identified in 1994.

It turns out that around 5% of Caucasians have Factor V Leiden, which means 1 out of 20. It's much rarer in persons of Asian or African descent. But if you have it, it increases your risk of getting a VTE to 700%! That's still usually a very low risk, and most people with Factor V Leiden don't even know they have it.

But what if you don't know you have Factor V Leiden and get stuck in a tank like David Bloom for hours (obviously, not very likely) or have a big surgery? Then you might have an unwelcome VTE a day or two later or even up to five or six weeks later for hip and knee replacement surgeries. It usually takes some time for a VTE to grow to a size big enough to cause symptoms. Now I don't know about you, but if I'm having major or even minor surgery, I'd like someone to use that Illumina machine or some other one on the market and find out if I have one or more of those abnormal clotting genes.

Caitlin's Story

Let's take a look at another example: the story of Caitlin, a healthy 18 year old college student who had her tonsils out during college break and didn't know she was positive for Factor V Leiden. Her surgeon told her to just rest on the couch after the surgery and be careful if any bleeding starts (one of the complications after tonsils are removed). As pain in her calves became more intense and she became sicker, no one thought about a possible VTE. By the time someone did figure it out, she was near death. But this story has a happy ending and it is well worth listening to:

Important Points About VTE to Remember

VTE can be deadly and is the #1 cause of in-hospital deaths (around 10% of them). Surgery greatly increases the risk of VTE. Many are only diagnosed at autopsy.

One-third of VTEs are associated with genetic mutations, which are not uncommon.

Age is also one of the biggest risk factors. The older you are, the greater the risk. Part of this has to do with age-related changes in your valve cusps.

What You Can Do

OK, now that you know about the problem, and that it's a huge public health issue, what can you do?

Get your genes tested if you can, especially if you're going to have major surgery. There are many things your surgeon and/or anesthesia provider can do if they know ahead of time that you have an increased risk.

Move! The sooner you get out of bed and start walking the better. Most surgery centers encourage this emphasis on getting up and moving.

Make sure they put "squeezers" on your legs if possible and that these are turned on before the anesthesia starts. Portable squeezers are available that can be kept on during your entire hospital stay and (when you can get them) appear to be very effective.

Whenever possible (e.g., for a hip or knee replacement), tell your anesthesia provider and surgeon you want a spinal or epidural anesthetic. Don't worry, you'd still be very sedated. But spinals or epidurals cut your VTE risk after surgery in half.

Keep hydrated both before and after surgery. The more you drink, the better. This keeps you from being dehydrated and improves blood flow.

Last but not least, be sure everyone "thinks" about a VTE, especially if you are an older patient, have a genetic risk factor, or are on hormone replacement therapy or birth control pills. The whole point of the Surgeon General's "call to action" was to get people to be aware of VTE and its enormous societal cost.

If your surgery team thinks about VTE and if you are at risk, they might also put you on a blood thinner to lessen your risk. There is a lot your surgical team can do to prevent a VTE, but only if everyone thinks about it. Even surgeons sometimes forget when they themselves are having an operation, even a minor one. Watch this video by Don Beringer, the head of surgery at a hospital in central Georgia:

No one is immune! But having a little knowledge ahead of time can really affect your own experience. That old expression is true: "An ounce of prevention is worth a pound of cure."