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Star Lotulelei will no longer participate in NFL Scouting Combine workouts due to the detection of an abnormal heart condition during medical exams—news that shocked the football world when ESPN's Chris Mortensen first broke the story on Sunday.

According to Mortensen, Lotulelei's heart is functioning at a lower-than-normal level:

Lotulelei was discovered to have an abnormally low Ejection Fraction, detecting that the left ventricle of his heart was pumping at only 44 percent efficiency, sources said. The normal range is between 55-70 percent efficiency.

In other words, the standout lineman may be suffering from a type of "dilated cardiomyopathy"—or chronic heart muscle disease—though it is impossible to know with certainty how long Lotulelei's heart has been under-performing. Precise medical details are also unavailable to the public, as always.

Many scouts and draft experts projected Lotulelei to be taken within the first handful of picks. Matt Miller, Bleacher Report's NFL Draft Lead Writer, was one of them. He told me, "Star entered the combine as my No. 2 overall player. He was a powerful tackle used to stop the run but shows potential as a pass-rusher."

For now, however, those projections might need to be put on hold, and the NFL community's thoughts turn to the well-being of the former Utah Utes defensive tackle.

Mortensen reports that Lotulelei will undergo further testing in Salt Lake City. To understand what exactly doctors will be looking for, let's first more closely examine the findings of the medical exam.

Mechanistically, the heart is a pretty simple organ. Essentially, it fills up with oxygen-depleted blood, pumps it to the lungs to pick up oxygen, receives the oxygenated blood back from the lungs and finally sends it to the rest of the body.

That's basically it. It contains complex electrical circuitry, four different chambers and four valves, but at its core, the heart is merely a distribution center.

Nevertheless, the incredible reality of the heart is that with each and every beat, it squeezes hard enough to send blood from head to toe.

Even more amazing? It does so roughly once per second for decades.

Sometimes, though, the heart tires out for one of any number of countless reasons. Other times, damage to the heart muscle prevents it from squeezing hard enough—such as after a heart attack. That is where the ejection fraction comes in.

The left ventricular ejection fraction—LVEF for short—is a value used by the medical community to monitor heart fatigue or failure. It represents the percentage of blood within the heart that is sent forward with each beat. Doctors use echocardiography, an ultrasound of the heart, to directly visualize the beating heart and determine the LVEF by comparing its full and squeezed volumes.

As Mortensen mentions, a normal LVEF is between 55 and 70 percent. That means a healthy heart will squeeze out 55 to 70 percent of the blood filling its left ventricle—the strongest and most muscular heart chamber that is responsible for sending blood outward to the rest of the body—with each beat.

However, the heart and blood stream are a closed circuit. That means that every drop of blood sent forward necessitates a drop of blood returned. In other words, the heart must not only eject blood forward, but also drive it to return.

When a heart begins to fail, as detected by a decreasing LVEF, blood not only doesn't get to where it needs to go, it also backs up in the heart, lungs and elsewhere.

Is that what is happening to Lotulelei? Right now, it's too early to tell.

Lotulelei's LVEF of 44 percent is certainly low, but it isn't anything to write home about. Symptoms of poor blood flow, such as shortness of breath and lightheadedness, generally don't begin until 40 percent.

When an LVEF dips to 35 percent, fatigue and difficulty breathing often limit most activities. Around 25 percent, most physical tasks become impossible, and the threat of damage to internal organs due to low blood flow becomes very large.

So what's the problem with 44 then? Simply, doctors do not yet know if Lotulelei's LVEF is on its way up or down. Whether the low LVEF represents a permanent change or is reversible remains up in the air as well.

The tests Lotulelei will undergo in Utah should help answer those questions, but the cause of a dilated cardiomyopathy is still a mystery in up to 50 percent of cases.

Given the fact that Lotulelei's heart condition was unknown until Sunday, and assuming that he had no symptoms, his low LVEF implies one of two things. Either his heart's power has been slowly and steadily declining for some time now, or a recent insult caused a sudden drop. Hopefully, and more likely, it is the latter; acute changes are more likely to be reversible.

Causes of cardiomyopathies are too numerous to count. Anything from viral illnesses to alcohol consumption to hormone abnormalities can affect a heart's pumping ability. Even extreme emotion or a "broken heart" following the end of a romantic relationship or death of a loved one—I'm not kidding; it's called Takotsubo cardiomyopathy—can cause symptoms.

Genetic mutations can also be to blame, sometimes representing irreversible, lifelong disease.

Yet as mentioned, many causes are indeed reversible. For example, viral-induced heart failure often resolves once the body clears the infection, and correcting any existing hormone imbalances can kick the heart back into normal gear. Certain vitamin deficiencies can produce Lotulelei's condition as well, and blood tests to determine vitamin levels in his blood could tease them out.

While an asymptomatic LVEF of 44 percent does not really constitute frank heart failure, Lotulelei will require intense monitoring for some time. If his low ejection fraction is due to a chronically progressing underlying disease, he will need to immediately start treatment to halt or delay its course.

Until a cause is identified, Lotulelei must avoid extreme physical exertion, as along with the rest of the body, the heart must also send blood to itself. If the heart cannot meet its own blood demand, heart attacks or life-threatening irregular heartbeats can ensue, and intense exercise only increases that demand.

Moreover, Lotulelei's finding is just the next chapter in the hotly contested debate over pre-participation screening for cardiac disease. Hypertrophic cardiomyopathy (HCM)—a disease that can cause sudden death in young, otherwise healthy athletes—has gained fame as a preventable cause of death if the condition is identified before it manifests itself.

In part due to questions over cost-effectiveness, no standardized cardiac screening protocol yet exists in the United States. However, a number of international organizations and European countries officially recommend cardiac screening, and Italian law requires it before participation in competitive athletics.

Fortunately, this particular condition was caught early.

The threat posed by Lotulelei's slightly lower heart function remains to be seen, and details will keep surfacing in the coming weeks as medical evaluations continue. Scouts and fans alike are certainly crossing their fingers that this will resolve on its own, and Lotulelei's agent already confirmed the defensive standout's plans to participate in Utah's March 20 Pro Day.

Make no mistake, though—some of the causes of decreased heart function could threaten his playing career altogether. That said, others will not drop his draft stock in the slightest, and according to a Monday report by USA Today's Mike Garafolo, the hope is that recent weight loss and possible dehydration caused abnormalities in the salt levels in Lotulelei's blood—and thus the condition.

If so, that would be incredible news for Lotulelei, and his professional prospects would not be hurt at all.

Nevertheless, since many reversible causes of cardiomyopathy take quite some time to resolve, and since some are chronic, progressive conditions, nothing is a given. His situation should be more clear by April's NFL draft.

By then, Lotulelei's scare may just as well be a distant memory.

Let's hope so, for his sake.

Dave Siebert is a medical Featured Columnist for Bleacher Report. He will graduate from medical school in June and plans to specialize in both Family Medicine and Primary Care (non-operative) Sports Medicine. Information discussed above is based on his own knowledge. Quotes were obtained firsthand unless otherwise noted.

Follow @DaveMSiebert