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Dr Larry Creswell

Dr. Larry Creswell on athletes and heart health.
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In the Medical News: Time for Updated Guidelines for Athletes with Long QT Syndrome?

February 13, 2013 By Larry Creswell, MD Leave a Comment

A new study by Drs. Johnson and Ackerman from the Mayo Clinic just published in the British Journal of Sports Medicine cast doubt on the current guidelines for athletes with congenital long QT syndrome (LQTS).

In a previous post, I wrote about the condition known as LQTS.  You may already know that this condition comes in an inherited, or congenital, form as well as an acquired form (as an unwanted side effect of various medications).  Today, we’ll focus on the congenital form.

Patients–particularly young athletes–with congenital LQTS have a well-documented increased risk of sports-related sudden cardiac death (SCD).  The magnitude of that risk depends upon the particular genetic defect responsible for the condition.

The latest consensus guidelines regarding athletes and heart disease were published in the United States in 2005 as Proceedings from the 36th Bethesda Conference and in that same year by European Society of Cardiology (ESC).  To summarize these guidelines in a nutshell….

Bethesda Guidelines

1.  Athletes should be limited to low-intensity sports (eg, billiards, bowling, cricket, curling, golf, riflery) if they have LQTS:  with any symptoms; if the QTc is >470 msec for males or >480 msec for females; or if they have an internal cardioverter-defibrillator (ICD).

2.  Athletes who are proven gene carriers for LQTS but who have no symptoms are allowed to participate fully in their sports.

ESC Guideline

1.  Athletes with LQTS, regardless of the presence or absence of symptoms, are disqualified from participating in any sports.

In the new study, the investigators reported on their experience with 353 patients age 6 to 40 with long LQTS who were evaluated initially between 2000 and 2010.  The majority of these patients–223–were not involved in sports or chose not to pursue their sports after their disease ws diagnosed.  The focus of the study was on the remaining 130 athlete-patients:  60 male and 70 female athletes; 20 had an ICD.

Among the 130 athlete-patients, 70 were asymptomatic (participating in sports contrary to the ESC guidelines but within the Bethesda guidelines).  The remaining 60 were symptomatic (and were participating in sports contrary to both sets of guidelines).

In follow-up that averaged 5.5 +/- 3.4 years, the authors reported that there was only 1 adverse event among the 130 athlete-patients–in one of the symptomatic patients (age 9) with an ICD who had an appropriate shock for a potentially fatal arrhythmia.  Among the asymptomatic patients, there were no adverse events.

Conclusions and Implications

1.  It’s important to remember that the vast majority of athlete-patients in this study were children and the findings may or may not extend to adult athletes with LQTS.  Further investigation is needed in the adult athlete population with LQTS.

2.  The current Bethesda and ESC guidelines for LQTS may be too restrictive, given the findings among the athlete-patients who continued their sports contrary to the 2005 guidelines.  In this study, these patients rarely had adverse events.

3.  It is still important for careful discussions regarding risk stratification (which may depend upon the precise genetic defect) and consideration of all treatment options before making decisions about continued participation in sports.

Related posts:

1.  Long QT syndrome

2.  Index to all of the posts at AthletesHeart through 2012

Filed Under: Heart problems Tagged With: cardiac screening, congenital heart disease, pre-participation screening, sudden cardiac death

Long QT Syndrome

February 12, 2013 By Larry Creswell, MD Leave a Comment

 

Congenital long QT syndrome (LQTS) is an inherited condition that affects heart muscle cells and predisposes individuals to potentially fatal ventricular arrhythmias.  This condition manifests (usually) with a prolonged time interval between the Q and T waves of the EKG and the occurence of either syncope (blacking out due to an arrhythmia) or sudden cardiac death (SCD) that is usually triggered by emotional stress or exercise.

Genetics

Much progress has been made with our understanding of the genetics of LQTS.  At least 13 different, but related, responsible genetic defects have been identified.  They all affect ion channels in the cell membranes of heart muscle cells and affect the way that electrical impulses travel through the heart.  The 3 most common genetic types are LQT1 (accounting for 40-55% of patients), LQT2 (30-45%), and LQT3 (5-10%).  Because these genetic defects affect the ion channels, LQTS is sometimes called a “channelopathy.”

The prevalence is usually said to be approximately 1 per 2000 individuals.

The triggers for lethal and non-lethal cardiac events are different for the genetic subtypes.  For carriers of LQT1, the most common trigger is exercise.  For carriers of LQT2, exercise is an very uncommon trigger; emotion may be a trigger, but most events occur during sleep or rest without arousal.  For carriers of LQT3, few events are triggered by exercise or emotion.

Diagnosis

Most patients come to attention because of a known family history or because of an episode of cardiac syncope or SCD with successful resuscitation.

Most, but not all affected individuals will have prolongation of the QT interval on the EKG.  Even without genetic testing, the diagnosis is usually established using a set of diagnostic criteria organized into 3 sections that produce a “Priori-Schwartz score”:

EKG findings
QTc >= 480 msec [3 points]
QTc 460-479 msec [2 points]
QTc 450-459 msec, for men [1 point]
QTc 4th minute of recovery from exercise stress test >=480 msec [1 point]
Torsades-de-Pointes [2 points]
T-wave alternans [1 point]
Notched T wave in 3 leads [1 point]
Low heart rate for age [0.5 point]

Clinical history
Syncope [2 points]
With stress [1 point]
Without stress [1 point]
Congenital deafness [0.5 points]

Family history
Family members with definite LQTS1 [1 point]
Unexplained sudden cardiac death younger than age 30 in family member [0.5 point]

A score of 3.5 points indicates a high probability of LQTS.  Some authorities recommend genetic screening for individuals with scores of greater than 3.0 points.

Treatment

Left untreated, symptomatic patients with LQTS have a mortality rate of ~20% in the first year.

Medical therapy includes beta-blockers (eg, propranolol, nadolol).  The effectiveness of these medications may depend upon the genetic subtype, but further investigation is ongoing.

One potential surgical option is left cardiac sympathetic denervation (LCSD), a procedure where the ordinarily stimulatory sympathetic nerves are disrupted.  This operation can be performed either in an “open” approach or by a thoracoscopic approach.  In either case, the first several thoracic ganglia (nerves) are removed.  Studies have shown this technique to be effective, particularly among patients with cardiac events despite beta-blocker usage and among patients with problems of various sorts with an implantable cardioverter-defibrillator (ICD).

The ICD is the remaining treatment option.  A device is implanted that includes a computer, battery, and leads that are attached to the heart.  In the event of a potentially fatal arrhythmia, the device provides a shock to terminate the arrhythmia and restore the normal heart rhythm.

Athletes and LQTS

Consensus guidelines for athletes with LQTS are provided in the Proceedings of the 36th Bethesda Conference.  These guidelines recognize that there is not sufficient information (yet) to stratify the risk of SCD for the various genetic subtypes, so a single set of recommendations was offered:

1.  Activity should be restricted to low-intensity sports (eg, billiards, golf, curling, riflery) for athletes with LQTS who have had cardiac arrest or an episode of syncope.

2.  Asymptomatic athletes with prolongation of the QT interval on the EKG should be restricted to low-intensity sports.

3.  Asymptomatic athletes, who are known gene carriers, may participate fully in their sports.

4.  Athletes with an ICD should participate only in low-intensity sports and should avoid all situations where bodily injury might occur.

Related Posts

1.  Index to all of the posts at AthletesHeart

Filed Under: Heart problems Tagged With: cardiac screening, congenital heart disease, sudden cardiac death

Athletes and Atrial Septal Defect (ASD)

September 4, 2012 By Larry Creswell, MD 130 Comments

 

Sometimes, congenital heart defects manifest for the first time in adulthood.  One such defect is the atrial septal defect (ASD), a “hole” between the upper chambers of the heart, the left atrium and right atrium.

There are 3 major types of ASD:  the secundum ASD, the primum ASD, and the sinus venosus ASD.  Each has distinguishing anatomical features, but today, for the most part, we’ll consider them as group.

We won’t consider another type of “hole” between the upper chambers of the heart, the patent foramen ovale (PFO).  In fetal life, the foramen ovale is a small hole which can persist after birth.  A PFO is usually small and ordinarily does not pose risk to the patient or athlete.

How is an ASD Discovered?

In adulthood, an ASD is often discovered incidentally during a diagnostic test such as an echocardiogram.  Adults can have no symptoms and be unaware of the defect.  If there are symptoms, an ASD can produce fatigue, arrhythmias, heart failure, or stroke.  An echocardiogram can delineate the exact type of ASD and also screen for any other types of structural heart disease which may be present.

A little bit of an aside for perspective….

In large-scale screening of school-aged athletes with echocardiograms, approximately 2% of individuals are found to have a structural heart problem.  Approximately one third of those defects are ASDs.

What are the Consequences of an ASD?

If the ASD is large enough (approxim. 1.0 cm or more), blood will flow through the defect in a left-to-right direction.  This results in extra blood in the right side of the heart and extra blood pumped to the lungs.  We can quantify the amount of extra blood flow to the lungs as a shunt fraction, or Qp:Qs ratio.  We say that the shunt is significant if the Qp:Qs ratio is greater than 1.5.  This indicates that the blood flow to the lungs is 50% greater than normal.

If left untreated, the extra blood flow through an ASD can lead to enlargement of the right atrium and ventricle and irreversible changes to the pulmonary arteries that results in pulmonary hypertension.

Athletes should be aware that a large ASD may result in decreased exercise capacity.

Closure of ASD

We generally recommend closure of an ASD if:

1.  The shunt fraction is >1.5.
2.  There is evidence of enlargement or failure of the right heart chambers.

Many secundum ASDs can be closed with devices that are deployed by catheters threaded to the heart through the body’s blood vessels.  We call this procedure a percutaneous device closure.  This procedure is generally performed by a cardiologist and involves the procedure followed by a short hospital stay.

Ostium secundum and sinus venosus ASDs require conventional heart surgery for closure.  These procedures are performed by a cardiac surgeon.  Healthy patients usually require a short hospital stay after the operation.

The peri-procedural risk of these procedures is very low.

How quickly an athlete may return to their sports will depend upon the particular method of closure and also upon the demands of an athlete’s sport.  This issue should be part of a discussion with the doctor before the procedure.

Recommendations for Athletes

The Congenital Heart Disease Task Force for the 36th Bethesda Conference on Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities made several recommendations for athletes with ASD:

1.  Those with a small ASD, normal right heart volume, and no pulmonary hypertension can participate fully.

2.  Those with a large ASD and no pulmonary hypertension can participate fully.

3.  Those with an ASD and mild pulmonary hypertension can participate in low-intensity sports.  Any athlete with ASD and associated cyanosis and large right-to-left shunt cannot participate in competitive sports.

4.  After a satisfactory recovery, athletes can participate fully after ASD repair (device closure or surgical) after a period of 3-6 months.

5.  After ASD closure, if an athlete has pulmonary hypertension, arrhythmias, heart block, or impaired heart function, there must be an individualized approach to the issued of continued participation.

Filed Under: Heart problems Tagged With: ASD, congenital heart disease, hole in heart

Psychological Implications of Cardiomyopathy

June 26, 2012 By Larry Creswell, MD Leave a Comment

I was recently contacted by Ian Guyah-Low, BSc, MSc, from the University of Stirling….Scotlands University for Sporting Excellence.  Mr. Guyah-Low and his colleagues, including noted researcher, Professor David Lavallee, are investigating the psychological implications of cardiomyopathy diagnosis in former athletes.

These investigators are currently looking for former athletes with cardiomyopathy who they might interview for an ongoing research project.

If you are interested, please contact Professor Lavallee at headofsport@stir.ac.uk or visit at their website at www.stir.ac.uk/sport.

Filed Under: Heart problems Tagged With: cardiomyopathy, congenital heart disease

Swimming Induced Pulmonary Edema (SIPE)

April 13, 2012 By Larry Creswell, MD 36 Comments

 

I’ve been learning about swimming induced pulmonary edema (SIPE) and I thought I’d offer an introduction here based on my reading and conversations with experts in the field as well as affected athletes.

The problem of SIPE, or immersion pulmonary edema (IPE) as it was first known, was recognized at least as far back as the mid-1990s. Early reports in the scientific literature focused primarily on a small number of healthy scuba divers who experienced problems with unusual breathlessness (dyspnea), particularly when diving in cold water. Medical evaluation for the problem showed that the divers had low levels of oxygen in the blood (hypoxemia), often reported coughing up frothy, blood-tinged secretions, and had findings on chest x-ray that suggested pulmonary edema. In the setting of immersion in cold water, this collection of difficulties–dyspnea, hypoxemia, excess lung secretions, and pulmonary edema–became known as IPE.

Interestingly, the victims of IPE were often very experienced swimmers who had difficulties only with swimming and/or diving in cold water (~50-60 degrees Fahrenheit).

It’s worth taking a moment to review a few important facts about the anatomy and physiology of the lungs. We have two lungs, each about the size and shape of a 2-liter soda bottle. Healthy lungs are extraordinarily light and very spongy. For our discussion today, it will help to think of the lungs as sponges. The lungs are ordinarily almost colorless, but take on a pink hue because of blood that flows throughout the lung tissue.

The right ventricle of the heart pumps blood to the lungs through the pulmonary arteries which branch into smaller and smaller branches and eventually into miscrosopically small capillaries which come into contact with the air-filled spaces in the lungs. It’s here where the blood unloads carbon dioxide and picks up oxygen. The blood then flows into increasingly larger veins and eventually into the pulmonary veins that carry the blood back to the left side of the heart where it is pumped to the rest of the body.

Like I mentioned, the lungs are usually extraordinarily light. But when fluid escapes the bloodstream and collects in the spongy lung tissue outside the blood vessels, the lungs become water-logged, much the way that a sponge becomes heavy once it soaks up water. One of the consequences is that it is much more difficult for oxygen to get into the bloodstream and much more difficult for carbon dioxide to get out. We call this situation pulmonary edema.

There are many causes of pulmonary edema. The most commonly encountered cases are due to heart problems of one sort or another (eg, heart valve problems, weakness of the left ventricle), but other causes include: reactions to blood transfusion, direct injury to the lungs, infection, and perhaps various inflammatory conditions.

The exact cause of pulmonary edema with SIPE is not completely understood, but experts suspect that a combination of increased bloodflow into the lungs due to immersion combines with increased pressure in the pulmonary arteries and veins (because of exercise) to cause a leak of fluid out of the bloodstream and into the lung tissue.

It is not clear if exercise-induced pulmonary edema occurs on land.

 

SIPE and Triathlon

As many readers here will know, there have been a number of episodes of sudden cardiac death (SCD) in triathlons in recent years, and these episodes have occurred with a preponderance during the swim portion of triathlon events. The cause of most of these deaths appears to be typical sports-related SCD due to a sudden arrhythmia, but some have wondered if SIPE could have played a role. There have been a handful of thoughtful opinion pieces about this possibility and I’d refer you to one such article by Rudy Dressendorfer in a recent edition of Sports Medicine Bulletin, entitled “Triathlon Swim Deaths: Initial Steps Toward Prevention.” This article lays out one view on the issue. In my opinion, though, it is not at all clear that SIPE has had a role in triathlon-related swim deaths.

Charles Miller and colleagues at Texas Tech University Health Sciences Center published an interesting report in 2009 that dealt with the possibility of SIPE in triathletes. During late 2008, they distributed a questionnaire to the membership of USA Triathlon asking about athletes’ experiences with “swim-related breathing problems.” The response rate to the survey was tiny–at only 1.3%–and it’s important to remember that the low response rate might have tremendous bias with the results. Nonetheless, about 1.4% of respondents reported having a swim-related episode of “pink frothy or blood-tinged secretions” that was suggestive of pulmonary edema. Moreover, the authors identified several risk factors for this occurrence, including high blood pressure, female gender, increasing length of the swim, and use of fish oil supplements. Only a minority of reported episodes suggestive of SIPE occurred in the absence of one or more of these 4 risk factors.

I’ve heard from several triathletes about their personal experiences with SIPE and I thought I’d share their stories here.

Nathan Farrugia, an avid runner and triathlete from Malta, shares his story at his blog. He describes his experience of discovering the problem in 2009 and then learning about SIPE and eventually traveling to Duke University for detailed physiologic testing. He’s very thoughtful about the physiology of the condition and the factors that might promote SIPE while racing.

Katherine Calder-Becker, a triathlete from Montreal, wrote to me to share stories about her struggle with SIPE. You can read about her discovery of the problem, how it’s affected her triathlon racing, her visit to Duke University for testing, and her recipe for heading off the problem now at her website. In addition to her personal story, she shares useful links to additional scientific articles and press reports for those who might want to do some additional reading. Those of you with a physiology background, in particular, will enjoy reading about her visit to Duke Dive Medicine to participate in a study of athletes with SIPE.

I gather that Nathan’s and Katherine’s stories are typical. I know of other athletes who have experienced similar symptoms during open water swimming, particularly during races, who received medical attention, at the scene or the hospital, who were suspected of having pulmonary edema. Supportive care with rest and oxygen, if needed, resulted in a resolution of the symptoms. I’m not aware of any triathlon-related death where clinical or autopsy findings specifically suggested SIPE as a cause.

Athletes who have been bothered by SIPE have offered a variety of suggestions for how to avoid trouble. These are also summarized in the article by Dressendorfer:

1. Avoid overhydration on race morning (to limit the immersion-related increase in bloodflow to the lungs).

2. Become acclimated to the water conditions, and particularly the water temperature, immediately before a race with a gentle warm-up swim.

3. Avoid using a wetsuit that has a restrictive fit at the neck.

4. Think to signal and request assistance during the swim if symptoms of unusual breathlessness develop.

SIPE is an area of ongoing basic investigation. One prominent group of investigators is headed by Dr. Richard E. Moon at the Duke University Center for Hyperbaric Medicine and Environmental Physiology. This group continues to study (in human subjects) the various physiologic changes that accompany SIPE, trying to identify the causative mechanisms that are responsible. I’ve had a chance to speak with Dr. Moon recently and I’m encouraged that his team’s work will be productive in defining this condition more precisely, identifying the causes and risk factors, and suggesting ways to avoid or alleviate the problem among triathletes.

That’s what I can offer in the way of an introduction to this topic. It would be great to hear from readers who can share their experiences with SIPE so that we might all learn more about this condition.

Filed Under: Heart problems Tagged With: breathing, IPE, pulmonary edema, SIPE, swimming

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