Revisiting DVT: Assessing Athlete Risk

Fri, 4 Nov. 2011 - 8:36 p.m. MT
Credit: ARA Staff - American Running Association

In December Running & FitNews® explored the question of whether it’s safe to fly again after having experienced deep-vein thrombosis (DVT) in the past. The short answer was yes, with several precautions in place. Since then, we’ve heard from two athletic readers who have had DVT, one of whom was misdiagnosed. It has prompted a follow-up, looking at this vexing problem more closely on behalf of distance runners, whom it sometimes affects in a unique and troubling way.
Recall that DVT is the formation of a blood clot (or "thrombus") in a vein deep within the body, and it is considered a medical emergency, since it could lead to a pulmonary embolism, which occurs if the clot dislodges and travels to the lungs. More than 90% of pulmonary emboli arise from the legs.
Endurance athletes are exposed to many of the physical factors contributing to DVT, and Beth Parker, PhD, recently presented these at the AMAA Sports Medicine Symposium in Boston, along with a critical review of case studies. Her research, analysis, and recommendations, as developed with Paul Thompson, MD, Peter Kriz, MD, and Pierre d’Hemecourt, MD, account for the bulk of the information in this piece.
The post-race factors that can contribute to DVT include repetitive microtrauma and dehydration followed by periods of inactivity. Endothelial damage is also common (the endothelium is the thin layer of cells that line the surface of the blood vessels).

Finally, athletes often experience immobility (“stasis”) while recovering from an athletic event, and—perhaps most notably—while traveling home from it.
As author and regular AMAA Journal contributor Paul Keill, MD, has written, “I experienced the first of three major deep vein thromboses following the December 1987 Honolulu Marathon.” He cites the presence of classic risk factors including stasis, injury, and hypercoagulability. “It is amazing that thrombosis doesn't happen more often,” he writes. “Perhaps it does, with its symptoms ascribed to the usual muscle strains, shin splints, and hamstring pulls.”
One incident involved a female triathlete who completed a half-Ironman and traveled five hours the following morning by car. She subsequently experienced lower-left extremity swelling and pain, and later shortness of breath and lightheadedness upon exertion. She was not properly diagnosed until she reached the emergency room three weeks after the race.
Other cases included two separate male marathoners who were both initially misdiagnosed. They developed DVT and pulmonary embolism a week after their races, but doctors thought they were looking at either muscle strain or Baker’s cyst.
Symptoms of pulmonary embolism include shortness of breath, accelerated heart rate, chest pain or palipatations, anxiety and sweating, and a cough that results in production of blood. Always take these symptoms very seriously and get to the emergency room, where DVT is actually a relatively common diagnosis. But out of this context, and in one in which pain and soreness are expected, spotting DVT in these otherwise healthy, athletic, and often younger adults can be quite a challenge. Symptoms can mimic typical post-exercise musculoskeletal pain. Also, many distance runners may not exhibit an accelerated heart rate with pulmonary embolism due to a lower-than-average resting heart rate.
Dr. Parker and her colleagues call for rigorous data to support the premise that athletes may be prone to DVT traveling to and from endurance events, but they offer a scenario of why this might be so. After endurance exercise, both coagulatory and fibrinolytic activation occurs, meaning that there is an increase in both clot formation and in the breaking down of blood clots. In most athletes, the balance is sustained. But that balance can be disrupted when additional coagulatory stressors are introduced—prolonged stasis, air flight, genetic predisposition, and the use of estrogenic medications. Clot formation outperforms degradation, and DVT occurs.
Athletes should exercise vigilance in the crucial 24 hours after an endurance event, which may present an especially susceptible period of clot formation. This is also precisely when you are most likely to travel. Avoid prolonged periods of venous stasis by using active recovery. Counteract the effects of air travel by performing hourly leg exercises, avoid crossed legs, and remain hydrated throughout your flight home.
If you are prone to DVT, additional precautions include avoiding estrogenic medications, taking aspirin or low-molecular weight heparin prior to travel, and avoiding exercise during very cold conditions, when DVT risk is increased.
Dr. Keill says that he did find an answer only a few years ago. “One of the risk factors contributing mightily—at least in my case—was the presence of a clotting disorder, Factor V Leiden mutation, rendering me more vulnerable to venous clotting. It might be wise for runners to consult with their doctors to see if they, too, harbor this defect.”
Our other travel-induced pulmonary embolism survivor wrote in to say that after his event, which went dangerously misdiagnosed for almost three weeks, he and his doctor found that rosuvastatin worked better than long-term warafin therapy for an active patient. He sees none of the propensity toward bruising yet all the benefits of an improved lipid profile and significant reduction in DVT occurrence.
AMAA Journal, Winter 2010, Vol. 23, No. 1, p. 7-9,
Running & FitNews, Nov/Dec 2010, Vol 28, No. 6,

(RUNNING & FITNEWS® January / February 2011 • Volume 29, Number 1)

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