Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Does endurance exercise promote life-threatening changes in athletes’ hearts?

22.01.2007
New study finds endurance athletes with ventricular arrhythmias have dysfunctional right ventricles

Some high-level athletes who take part in endurance sports can develop a rare but life-threatening condition called ventricular arrhythmia (VA) in which the heart beats at an abnormal rate and rhythm. Now, a new study has shown that most of the athletes with VA have dysfunctional right ventricles.

The finding adds weight to the hypothesis that endurance sports might contribute to changes in the heart that lead to dysfunction and heart rhythm disturbances, according to the authors of the report published in the European Heart Journal [1] today (Monday 22 January).

VA is a heart rhythm disturbance that occurs in the ventricles (lower chambers) of the heart. It can be the cause of sudden death in athletes. There are many underlying causes of VA and often it is due to inherited diseases. Previous studies have found that VA in endurance athletes, such as cyclists, runners and kayakers, often originates from the right ventricle (RV), even when there are no previous symptoms that would enable a diagnosis of a condition called arrhythmogenic right ventricular cardiomyopathy (ARVC) to be made, and no family history of ARVC. A family history is usually present in 30-50% of reported cases of ARVC.

Researchers at the University Hospital Gasthuisberg at the University of Leuven in Belgium, set out to study whether abnormalities in the functioning of the RV might be present in endurance athletes with VA.

They studied 22 endurance athletes [2] who had been referred to them with VA between July 1997 and April 2005. None had abnormal wall thickening of the left ventricle (hypertrophic cardiomyopathy) or coronary abnormalities. They compared them with 15 endurance athletes without VA and a control group of non-athletes without VA. The athletes were Belgian and Dutch men aged between 18 and 55.

Using four methods for quantitative angiography (X-ray of the heart chambers) to study the RV, they measured the volume of blood in the relaxed RV (end-diastolic volume, EDV), the volume of blood left in the RV after the heart had contracted (end-systolic volume, ESV) and the fraction of blood pumped out of the RV in each heart beat (ejection fraction, EF). In addition, they measured the change in the diameter of the part of the RV where the blood flows out to the arteries (RV outflow tract shortening fraction, SF), and the thickness of the ventricular walls.

Hein Heidbüchel, professor of cardiology/electrophysiology and director of the clinical EP laboratory who led the team, explained: “Although arrhythmogenic right ventricular cardiomyopathy is a known cause of arrhythmias in athletes, we found that we could diagnose it unequivocally in only six of the 22 athletes (27%). However, we could assign arrhythmias as definitely or probably originating from the right ventricle in 82% of the patients – an RV origin of the arrhythmia was manifest in 12 (55%) of the 22 and probable in six (27%) of them.

“All athletes had a higher end-diastolic RV volume compared to controls, as expected in an athlete’s heart. Importantly, we found that athletes with VA had an RV end-systolic volume that was significantly higher than athletes without VA, and, accordingly, athletes with VA had a significantly lower RV ejection fraction. This significance remained after we had excluded two athletes with presumed ARVC because of a family history of arrhythmias or sudden death.”

The decrease in EF was not profound (down by approximately a fifth) but consistent among all athletes with VA and consistent across all measurement methods. The difference between the two groups of athletes indicated that the RV was not fulfilling its function of pumping blood out from the heart effectively in those with VA.

Prof Heidbüchel said: “Our study clearly demonstrates RV functional abnormalities in high-level endurance athletes with VA. The observed RV dysfunction is more subtle than in familial or overt ARVC. ARVC was only present in a minority of the athletes, based on conventional, internationally accepted criteria. One explanation could be that these athletes presented with arrhythmias in the early stage of underlying ARVC, triggered by intense exercising. However, we know that athletes with ARVC are at increased risk of dying suddenly, in which case, diagnostic criteria for ARVC should be adapted to better detect this early manifestation of the disease.

“An alternative explanation for our findings is that exercise also acted as a promoter of the RV changes, maybe in synergy with other environmental or genetic factors, and hence led to arrhythmias. Our study does not provide definitive proof for either of these explanations, but our data contribute to the accumulating, indirect evidence that endurance exercise may have detrimental effects on the RV in some athletes.

“Determination of the underlying genetic profile of these athletes may provide further data and that work is under way. We also do not know whether substance abuse may have contributed to the observed changes, although all study subjects denied such use and there was no other evidence for it in any of them.”

Although they are still awaiting results of the genetic tests, Prof Heidbüchel and his colleagues questioned whether the findings were due to the expression of early ARVC, especially as there was other evidence to support the second explanation. “The hypothesis that high-level endurance exercise is an underlying cause of the VA is supported by other studies that suggest that endurance exercise and volume overload subject the thin-walled RV to a greater increase in workload than the thick-walled left ventricle, with subsequent changes to the structure of the RV.”

Prof Heidbüchel said that athletes who undertake endurance sports should not worry too much. Ventricular arrhythmias are very uncommon. “But they need to be vigilant and honest with themselves: if they have a family history of ARVC, arrhythmias, sudden death or other heart complaints, or if they have experienced exercise-induced light-headedness, palpitations or fainting, then they should see their doctor for an evaluation.”

[1]Reduced right ventricular ejection fraction in endurance athletes presenting with ventricular arrhythmias: a quantitative angiographic assessment. European Heart Journal. doi:10.1093/eurheartj/ehl468.

[2]“Endurance athletes” were men who had participated regularly in sessions of intense endurance sports lasting for at least two hours, three times a week for at least five years.

Emma Mason | alfa
Further information:
http://www.oup.com

More articles from Studies and Analyses:

nachricht Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung

nachricht Scientists reveal source of human heartbeat in 3-D
07.08.2017 | University of Manchester

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>