Athlete's Heart Blog

Dr Larry Creswell

Dr. Larry Creswell on athletes and heart health.
About Larry / Contact
  • Facebook
  • RSS
  • Twitter

Writing on…

Copyright © 2023 · Wintersong Pro Theme on Genesis Framework · WordPress · Log in

You are here: Home / Archives for anatomy

Mitral Valve Prolapse

March 18, 2013 By Larry Creswell, MD 43 Comments

 

Mitral valve prolapse (MVP) may well be the most common problem with the heart valves.  This condition may be present in as many as 5% of the general population.  Women are affected more often than men.

Recall that the mitral valve sits between the left atrium and the left ventricle, the main pumping chamber in the heart.  And remember that the mitral valve closes while the left ventricle contracts, allowing only one pathway for blood to exit the heart–through the aortic valve and into the aorta.

MVP is a problem with the valve closing properly.  The mitral valve consists of 2 leaflets–an anteior (front) and posterior (back) leaflet.  The diagram above shows the normal situation as well as the prolapse situation, where (in this case) one of the leaflets does not close properly.

There are several potential causes, including rheumatic fever, inherited conditions such as Marfan’s syndrome, infection (endocarditis) of the heart and valves, and as a consequence of coronary artery disease and heart attack.  But the most common cause is simply wear and tear, a problem that we call degenerative disease of the valve.

Symptoms may include chest pain, fatigue, and palpitations.  Importantly for athletes, the chest pain is most often unrelated to activity.

Patients with MVP often have a classic sound–a mid- to late systolic click–that can be heard with the stethoscope.  Nonetheless, this condition is most often identified by an echocardiogram that was obtained to sort out the cause of a patient’s symptoms.  The ultrasound pictures show the improper closure of the mitral valve and may show any associated problems such as leaking (regurgitation) of the valve.

We generally think of MVP as a benign condition–that is, one that has few harmful effects other than the symptoms.

Medical treatment with beta-blockers–medications that slow the heart rate and reduce the blood pressure–may alleviate the symptoms.  Current guidelines suggest that individuals with mitral valve prolapse do not need to take antibiotics to prevent infections (endocarditis) of the heart and heart valves.

If regurgitation becomes moderate to severe, because of continued degeneration of the valve over time, surgical repair or replacement of the valve may be necessary.

Recommendations for Athletes

Consensus recommendations for athletes come from the Proceedings of the 36th Bethesda Conference.

Athletes with MVP can participate fully if they don’t have:  a history of syncope (blacking out); repetitive arrhythmias; severe regurgitation of the valve; reduced heart function; a history of stroke or transient ischemic attack (TIA); or a family history of sudden death related to MVP.  Athletes with any of those additional problems should receive further evaluation and should participate only in low-intensity sports.

Filed Under: Heart problems Tagged With: anatomy, heart, mitral valve prolapse

More on Long-term Cardiac Risks of Endurance Sport

December 28, 2012 By Larry Creswell, MD 2 Comments

Last week I got an inquiry from Casey R. Ruff at the Simon Fraser University in Burnaby, British Columbia, Canada in response to my blog post, “Don’t Stop Running Yet!” from earlier this month.

Ruff wanted to share his report from earlier this year, entitled “Consequnces of decades of intense endurance training:  Is there a cardiovascular overtraining phenomenon?”  This is an excellent review of the data on this topic.  If you’re scientifically-minded, I would encourage you to give it a read.  If you’re interested in pursuing further reading, the reference list is extensive and useful.

The report makes the case for the hypothesis that intense endurance training over many years may produce unwanted heart disease.  The situation is summed up well in this figure which suggests a sweet spot, or “healthy zone,” for training volume.  Less or more exercise leads to greater heart disease risk over the long term.

I’ve noted before that many biological systems are known to have a “sweet spot” phenomenon.  This may be no different.

For the sake of balance, I shared some of my questions with Ruff:

1.  Is there any evidence for increased mortality rate or shorter life-expectancy because of participation in some sort of endurance sport?

2.  What explanation would you provide for the observation that most incidents of sports-related sudden cardiac death (SCD) occur in NON-veteran athletes?  And with autopsies that often show relatively unremarkable cardiac findings?

3.  Do you believe that veteran endurance athletes are at increased risk of SCD compared to non-veteran athletes?  And what is the magnitude of that risk?

4.  What are the consequences to the athlete who develops atrial arrhythmias?  How bad is that problem?

Ruff and his colleagues correctly suggest that further investigation with longitudinal studies are sorely needed.  I’m hopeful that with increased participation in endurance sports and increasing public dialog about this issue that these studies will be undertaken.

My Related Posts and Articles:

1.  Don’t Stop Running Yet!

2.  Short-term and Long-term Injury to the Heart with Exercise

3.  Ironman and Heart Health:  My Take on Things

Filed Under: Exercise & the heart Tagged With: anatomy, athlete, exercise, heart, physiology

Don’t Stop Running Yet!

December 3, 2012 By Larry Creswell, MD 8 Comments

 

There has been a lot of conversation this week about an article that appeared in the Wall Street Journal (WSJ) in its November 27th U.S. print edition, entitled “One Running Shoe in the Grave.”  The online version carries the additional subtitle, “New Studies on Older Endurance Athletes Suggest the Fittest Reap Few Health Benefits.”  The article by Kevin Helliker offers information and comment about an editorial by Mid America Heart Institute cardiologist, James O’Keefe, MD, entitled, “Run for your life … at a comfortable speed and not too far” that was published online last week by the British medical journal, Heart.

Obviously the headlines from the WSJ article and the Heart editorial are sensational.  The headlines were designed to attract readers.  And they did.  What editor or publisher wouldn’t want that, I suppose?  The British newspaper, Globe and Mail ran with the headline, “Running can shorten your life.”  Really?

There have been a bunch of opinion pieces this past week about the WSJ article, Dr. O’Keefe’s editorial, and the general topic of endurance sport and cardiac health.  Here are some links to thoughtful pieces that are good reading:

Chris Carmichael, CEO/Head Coach at Carmichael Training Systems, shares a blog piece about cycling, running, and the importance of fitness.

John Mandrola, MD, cardiologist/electrophysiologist and cyclist, reviews the issue in his Cycling Wednesday blog post, “I Told You So….”

Alex Hutchinson shares a review of the issue at the online version of Runners World, taking issue with many of the assertions by the WSJ and Dr. O’Keefe.

Michel Accad shares a blog piece, entitled, “O’Keefe on exercise:  prescient or premature?”.  There’s a video clip of an 18-min. TED talk by Dr. O’Keefe about the potential dangers of exercise.  It’s worth watching.  And Accad’s comments are worth considering.

You might finish reading my blog entry here and then return to read the others’ takes on this issue.  There’s an array of opinion.

A Review Article

The conversation actually began in June of this year when Dr. O’Keefe and his colleages in Kansas City authored a review article for the Mayo Clinic Proceedings, entitled “Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise.”  This is an excellent article because, in 8 short pages (excluding the references), it gathers almost everything important that scientists know about the issue of long-term adverse consequences of endurance sport.  There is also a long list of scientific references for those who want to do additional reading.  If you’re an endurance athlete, I would encourage you to read the article.

Here’s my condensed list of facts that are presented:

1.  The opening sentence reads, “regular exercise is one of the cornerstones of therapeutic lifestyle changes for producing optimal cardiovascular (CV) and overall health.”  True.  The health benefits of exercise are many and undeniable.

2.  A small number of endurance athletes will die while exercising from “suden cardiac death” (SCD)–a suden, fatal arrhythmia.  These are rare events but can occur at any age and with any form of sport.  The cause is most often an underlying, unrecognized heart problem.

3.  Over the long term, endurance athletes may develop a condition known broadly as “athlete’s heart,” a collection of structural adaptations to chronic exercise.  The authors speculate that these changes may not always be healthy.  At present, though, there is scant evidence in animals or humans to help us understand this issue completely.

4.  Immediately after endurance events, athletes have been found to have release of heart enzymes (troponin) into the bloodstream that might suggest injury to the heart.  Moreover, studies have shown some athletes to have a decrement in heart function immediately after such events.  The accumulated body of evidence suggests that these changes are short-lived and the long-term consequences of repeated episodes remain unknown.

5.  There is an irrefutable relationship between long-term endurance exercise–in many sports studied–and atrial arrhythmias such as atrial fibrillation.  The exact mechanism is unknown, but it is reasonable to speculate that there are structural changes in the atria (the upper chambers of the heart) that lead to problems with electrical activity in those chambers.

6.  In a small number of long-term runners, abnormal fibrosis (scarring) has been identified in the heart’s walls using a magnetic resonance imaging (MRI) technique known as late gadolinium enhancement (LGE).  The origin of these findings and the significance of these findings is unknown, but such findings are typical after heart injury that occurs with myocardial infarction (MI), or “heart attack,” as it is commonly known.

Those are the important facts.  The authors share their concern about the possibility that too much exercise may be harmful and correctly note that all of these findings should stimulate our interest in better understanding the long-term consequences of endurance sport.  That’s certainly reasonable.

The New O’Keefe Editorial

In their new editorial in Heart, Dr. O’Keefe and his colleague, Carl J. Lavie, MD, extend their earlier conversation.  Unfortunately this article is only available online for subscribers of the journal.  They introduce the editorial with the ancient 490 BC story of Phidippides, the runner who made his way from Marathon, Greece to Athens to share news of the Greek victory in the Greco-Persian War, only to die suddenly on his arrival at the Acropolis.  But the editorial doesn’t focus on the issue of SCD in endurance athletes, it deals with the broader issue of potential cardiac harm.  This editorial appears to be a response to critics of their conclusions in the earlier review article and the authors single out Editor-at-Large for Runner’s World Magazine, Amby Burfoot, as one of those critics.

I take odds with virtually all of O’Keefe and Lavine’s assertions in the editorial.

The first major study mentioned in the editorial is a large prospective study of 416,000 individuals that was reported last year in the medical journal, Lancet.  In Figure 1 of the editorial, the authors display the reduction in all-cause mortality for individuals grouped according to the amount of their exercise:  one group with “vigorous” exercise and a second group with “light to moderate” exercise.  It is VERY important to note that the reduction in mortality occured for ALL amounts of exercise included in the observations.  With “vigorous” activity, individuals still were continuing to accrue additional benefit in reduction in mortality at the 45-min per day point at which observations were censored.  And moreover, those individuals enjoyed GREATER reduction in mortality than the group who did “light to moderate” exercise.

The authors then speculate about the cause of death last year of Micah True at age 58, the ultra-distance runner who once served as the basis for the popular running novel, Born to Run.  Here at the blog I’ve written previously about the details surrounding his death.  O’Keefe and Lavie note that at autopsy, True was found to have an enlarged heart with “focal areas of interstitial chronic inflammatory infiltrate.”  The medical examiner noted that True had “cardiomyopathy” of an unclassified origin that resulted in a fatal arrhythmia as he was running in the desert of New Mexico.  O’Keefe and Lavie speculate that True had some sort of “Phidippides cardiomyopathy.”  It sounds sensational to evoke Phidippides, but I’m not sure that most authorities would even recognize that term or that condition.  From my standpoint, even absent the most classic pathological findings, the most likely explanation for True’s death is Chagas disease (caused by parasitic infection common in the desert Mexican region that True inhabited) that produced the structural changes in his heart and lead to his fatal arrhythmia.

Lastly, the editorial shares information presented in abstract form at recent medical meetings.  It’s important to keep in mind that a great deal of scientific exchange happens at medical meetings, but there is very little scrutiny of what’s presented.  Essentially, if you’re invitied to speak at a meeting you can say what you want–whether it’s scientifically correct or not.  Attendees must use their own judgement about the scientific merit.  There’s a much higher standard when it comes to publishing results in a medical journal, where a manuscript is reviewed by one’s peers and a medical journal’s editors to be certain there’s scientific merit to the information that will be presented.  Neither of the cited presentations or abstracts have yet made their way to a medical journal yet.  And they might never, for all we know.  Again, the bar for scientific accuracy is generally LOW at medical meetings and we should keep that in mind.

In the first study cited by the editorialists, Duck-chul Lee and colleages at the University of South Carolina and at Ochsner Health System in New Orleans reported in June at a meeting of the American College of Sports Medicine on a group of 52,656 adults aged 20-100 years who had a medical examination during 1971-2002 as part of the Aerobics Center Longitudinal Study.  They found that with average follow-up of 15 years, runners enjoyed a 19% lower risk of all-cause mortality than non-runners.  That’s important, but certainly not a new observation.  That observation has been made in countless previous studies.  O’Keefe and Lavie make note of the relationship between the AMOUNT of running and the reduction in mortality and show a Figure 4 bar graph that summarizes a hazard ratio of all-cause mortality for groups according to the amount of running.  Just glancing at the graph, the bars show lower hazard ratios for individuals with moderate (10-20 miles) amounts of running per week and higher hazard ratios for those who ran more.  But although they make much of the “U” shape of that bar graph suggesting a “sweet spot” for the amount of beneficial running, they don’t mention at all that the 95% confidence intervals for ALL of the bars are overlapping.  That is, from a statistical standpoint, the original scientists FAILED to find a relationship between the amount of running and the hazard ratio for mortality.  A reputable medical journal would preclude any conclusion other than:  “there is no association between the amount of running and the hazard ratio for mortality.”

In the second study cited by the editorialists, Dr. Peter Schnor, the chief cardiologist of the Copenhagen Heart Study made a presentation at the May 2012 EuroPRevent meeting in Dublin, entitled, “Assessing prognosis:  a glimpse of the future.  Jogging healthy or hazard?”  The Copenhagen Heart Study is a long-standing longitudinal study of 20,000 Danes since 1976.  Not surprisingly, Dr. Schnor reported that with follow-up for as long as 35 years, the risk of death among male joggers was 44% lower than for non-jogging males; the risk of death among female joggers was also 44% lower than for non-jogging females; male joggers lived 6.2 years longer than non-jogging males; and female joggers lived 5.6 years longer than non-jogging females.  Those are BIG, IMPORTANT numbers!  Take note.  Although the details have not (yet) been published, Schnor has shared with reporters that the greatest benefits were derived by those who did from 1 to 2.5 hours of jogging per week, over 2 to 3 sessions.  That may be true, but we must also keep in mind that Dr. Schnor has previously reported in the February 2012 issue of the European Journal of Preventive Cardiology that cyclists from that same Copenhagen Heart Study enjoyed the greatest health benefits if they cycled HARD and FAST!  Indeed, they reported that “Men with fast intensity cycling survived 5.3 years longer, and men with average intensity 2.9 years longer than men with slow cycling intensity.”  I refuse to believe that the human heart “knows” what form of endurance sport an athlete is doing, so we’re left to try to reconcile the discrepant findings for runners and for cyclists.  And absent more detailed, published information, I’m not sure how we can do that.

Some Final Thoughts

We need to keep an open mind as we continue to learn about the long-term cardiac consequences of endurance sport.  The issue of whether there can be “too much” exercise is an important one.  I think we’d all have to agree that if you’re exercising for more than 7-10 hours per week, you’re doing so because of some motivation other than simply your health.  Given the indisputable health benefits of exercise, though, I’d hate to see anybody choose a sedentary path because of concerns about possible adverse health consequences.  Runners should not return to the couch.

Lastly, I’d caution against sensationalism.  And that’s what this entire week’s discussions have screamed.  Physicians and scientists should use a voice of reason and editors should be sensitive to the issue of over-reaching when it comes to publication in the popular press.  We don’t need headlines.  We need science.

Filed Under: Exercise & the heart Tagged With: anatomy, exercise, heart, physiology

Nine Interesting Facts About the Athlete’s Heart

August 16, 2012 By Larry Creswell, MD Leave a Comment

In a recent column at EnduranceCorner, I wrote about “Nine Interesting Facts About the Athlete’s Heart.”  The heart is truly amazing!

Filed Under: Endurance Corner articles, Heart 101: The basics Tagged With: anatomy, athlete, heart, physiology

Coronary Artery Disease: The Essentials

November 22, 2009 By Larry Creswell, MD Leave a Comment

 

For those of you who have been following along, we’ve talked briefly before about the problem of coronary artery disease (CAD) and illustrated the problem last week with the story of Jim Fixx. And I’ve mentioned previously that CAD is the most common cause of sudden death in athletes over the age of 40. Today, we’ll talk about CAD in a little more detail. This should provide the foundation for future discussions that we’ll have about the many aspects of maintaining heart health as we age.

To put the problem of CAD into some perspective, you should realize that this is the most important chronic medical condition that Americans face. In fact, CAD affects more than 13 million Americans today. It’s the leading cause of death in the United States, with nearly 1 person dying every minute from this condition.

The Anatomy

The heart, as you know, is simply a muscle….but one that is in constant motion, usually beating 60-100 beats each minute, or upwards of ~140,000 times each day. And like other muscles of the body, it requires a generous blood supply to furnish the needed oxygen to keep things going. As the aorta leaves the heart, to take blood flow to the rest of the body, the first 2 branches are the left and right coronary arteries….the arteries that supply blood flow to the heart muscle itself. The left coronary artery branches into the left anterior descending and the circumflex coronary arteries. We often say, then, that there are 3–not 2–important coronary arteries.

We use the term CAD to refer to the progressive (over many years time) narrowing of the coronary arteries, the arteries that supply the heart muscle with its blood supply. This process, called atherosclerosis, usually starts with fatty streaks on the inside surface of the coronary arteries, but over years’ time progresses to larger, more space-occupying deposits of various lipids. The situation is not much unlike a typical plumbing problem, where a pipe might become clogged with unwanted material, thereby limiting blood flow.

What problems does CAD cause?

Individuals with CAD often experience no problems until the narrowing in the coronary arteries becomes severe. When the arteries become narrowed to less than 25-50% of their original diameter, the reduction in blood flow to the heart muscle can produce symptoms. At first, the symptom might be chest pain or discomfort (that we call “angina”) or perhaps unusually severe shortness of breath with exertion. Any of these symptoms should be a warning sign….and prompt you to be evaluated by your physician.

The plaques on the inside of the coronary arteries can sometimes rupture, leaving a raw surface exposed to the bloodstream, and lead to the formation of a blood clot at that site. This can produce chest pain at rest (unstable angina) or even acute myocardial infarction (MI), the situation where there is irreversible damage to the heart muscle.

Who gets CAD? What are the risk factors?

Much time and effort has been devoted to understanding who gets CAD. As you can imagine, this is the starting point for figuring out how to prevent CAD. We’ve learned that there are a handful of so-called risk factors, indicators of how likely it is that an individual will develop CAD. Some of these risk factors can’t be changed, but others can be modified to help reduce somebody’s risk.

There are some risk factors that you simply can’t change. One such risk factor is age. Men over the age of 45 and women over the age of 55 are more likely than their younger counterparts to have CAD. Unfortunately for men, men are just more likely than women to have CAD. And lastly, a family history of CAD in close relatives is a risk factor. As you can see, each of these risk factors is beyond your control.

On the bright side, though, several risk factors are under your control….and should be paid very special attention as we age:

1. Obesity (or even just being overweight)

2. High blood pressure

3. Smoking

4. High levels of blood cholesterol

5. Diabetes

6. Physical inactivity (although I’ll bet that most readers here are active!).

We’ll cover these risk factors in greater detail in upcoming posts.

Diagnosis and Treatment

Most patients with CAD come to medical attention because of symptoms such as angina or shortness of breath. Many others come to attention because of acute MI. And, sadly, some come to attention because of sudden death….and an autopsy shows CAD.

A stress test (which can be done in a variety of ways) or a cardiac CT scan can indicate the likelihood of CAD. The diagnosis is established, though, with coronary arteriography….a test in which dye is injected into the coronary arteries and motion picture x-rays are made. This creates a roadmap of the coronary arteries and shows any blockages.

If blockages in the coronary arteries are not severe, patients can be treated with medicines. Patients with severe blockages can be treated with angioplasty and stenting (to push the blockages aside) or with coronary artery bypass surgery.

That’s CAD in a nutshell. Like I said, I hope that this information provides the necessary foundation for us to have more detailed discussions about various topics down the road.

Filed Under: Heart 101: The basics, Heart problems Tagged With: anatomy, atherosclerosis, CAD, coronary artery disease, heart

  • 1
  • 2
  • Next Page »